M4: close out Save Points, with browser verification

Closes M4. The review's three findings are fixed, the durability rule the
specification always implied is now enforced, and M3's and M4's browser
behaviour has been verified in a real browser for the first time.

B-1 -- the Save Point list was an N+1 that loaded whole Action rows,
narration included, to answer "does a row exist here". It is now one bulk
two-column coordinate query plus one lineage: 53 SELECTs for 25 Save Points
became 5, and the count no longer grows with the list. The clause is an OR
of exact (branch, depth) pairs rather than two IN lists, because the cross
product would report a Save Point resolved on the strength of another one's
depth existing on this one's branch. A test builds exactly that trap.

B-2 -- reclassified during closeout from "missing warning" to a behaviour
defect, and fixed as one. STORY-BRANCH-SEMANTICS §19 says a named checkpoint
remains until explicitly deleted, and §28 already required future cleanup to
retain checkpoint-referenced paths; a cascade that silently removed Save
Points with a branch violated both, and a warning would only have documented
the violation. A branch a Save Point names can no longer be deleted. The
request is refused with the offending Save Points named, the user deletes
them explicitly -- which deletes no story -- and the branch then goes. The
scope is the subtree, because deleting a branch takes its descendants. Both
delete controls disable and explain. Recorded as a new §19.1; models.py,
TECHNICAL-DESIGN §8.8 and DATA-MODEL §8 had all recorded the cascade as the
rule and now record the refusal.

An earlier pass in this same closeout had kept the cascade and added a
warning. That was the wrong fix and its tests were replaced rather than left
standing, since they pinned the defect.

B-3 -- the D11/L03 automation never left one process, so it could not
distinguish durable state from a live Python object. It now spawns real
server processes, kills the first, and reads the campaign back with the
second.

C-5 -- creating a Save Point takes the campaign's turn lock. "Save where I
am" has to name one committed position, and the head is what a turn in
flight is about to move. Rename and Delete deliberately do not take it.

The architecture is untouched: a Save Point is still name + note +
(branch, depth), and restore is still coordinate -> head.move_to_node ->
head.move_to -> attempts.restore_state. No second restore path, no state
copied into a checkpoint, no fork on restore.

Browser verification -- the first in this project, and it covers both
milestones. Firefox 154.0.1 through geckodriver over the W3C WebDriver
protocol, driving the rendered DOM: 47/47 checks, twice, on independent
databases, no console errors. M3's Undo/Redo enable states, transcript
movement, Retry and the take pager, divergence retiring Redo; M4's whole
Save Point lifecycle, both confirmations, and the new branch-delete refusal
including its recovery. No dependency was added: the WebDriver client is
stdlib HTTP.

No application defect was found by the browser. Four failures occurred, all
in the harness -- a wrong SPA route, a wait comparing transcript length when
the empty-story placeholder is longer than the first turn, a fixture
deleting the branch it was reading, and a reload assertion that sampled
once instead of waiting. The last was checked against the app before being
called a harness bug.

Tests: 698 backend pass (was 680), 60 M4, 94 M3 history, 66 export/
migrations, 93 security/local-only. Frontend lint and build clean, Docker
build clean, loopback binding unchanged. No assertion weakened, no skip
added.

Planning: STORY-BRANCH-SEMANTICS §19.1 is the only behavioural change and it
strengthens §19. V1-ACCEPTANCE-TESTS records D11-D14, I04, L03 and the
E-series, keeping automated, live-runtime and browser evidence distinct, and
weakens no pass condition. DATA-MODEL records the coordinate with the retry
measurement that settles it. BROWSER-UX-SPEC rules for Moment over Turn.
BUILD-MILESTONES marks M4 COMPLETE, closes M3's browser condition, and lists
what M5 inherits. VERSION adds v2.6.

No new ADR: ADR 005 already decides that history is preserved rather than
overwritten, and §19.1 is that decision applied to checkpoint-referenced
history.

M4 is closed. M5 may now be briefed; it has not been started.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PWU4gTfLYY6Qq9U7aa9Qw2

DEVELOPMENT.md

@@ -46,6 +46,9 @@ ollama pull qwen2.5:3b-instruct
 ollama pull nomic-embed-text      # only if you want the memory bank
 ```
 
+There is no account to create and nothing to log in to. The application is
+single-user: whoever can reach it on loopback is its owner.
+
 ## Running
 
 **Development** — backend on `:8000`, Vite dev server on `:5173`:
@@ -88,21 +91,52 @@ decision that this project's threat model does not cover
 
 ## Pointing the storyteller at Ollama
 
-The endpoint, model and (unused) API key are **runtime settings stored in the
-database**, not environment variables. Set them on the app's Settings page, or
-with one request:
+The endpoint, the model and the generation parameters are **runtime settings
+stored in the database**, not environment variables. There is no API key field:
+M2 removed it along with the cloud providers, and Ollama does not use one. Set
+them on the app's Settings page, or with one request:
 
 ```bash
 curl -X PUT http://127.0.0.1:8000/api/settings \
   -H 'Content-Type: application/json' \
   -d '{"endpoint_url":"http://127.0.0.1:11434/v1","model":"qwen2.5:3b-instruct",
-       "api_mode":"chat","api_key":"","max_output_tokens":200,
+       "api_mode":"chat","max_output_tokens":200,
        "context_token_budget":4096}'
 ```
 
 `POST /api/settings/test` (the **Test connection** button) returns
 `{"ok": true, "models": [...]}` and is the fastest way to tell a wrong endpoint
-from a missing model.
+from a missing model. When it fails it says which kind of failure it was, and
+they need different things done about them:
+
+| `kind` | What it means |
+| --- | --- |
+| `rejected` | The endpoint is outside the policy below. Not a network problem. |
+| `unreachable` | Nothing answered. Ollama is not running there, or the port is wrong. |
+| `tls` | The certificate did not verify — install the CA (see below). |
+| `timeout` | It accepted the connection and then said nothing. |
+| `http` | It answered with an error status; the body is included. |
+
+A successful test also warns when the endpoint is reachable but has no model by
+the configured name, which is the commonest way for a correct endpoint to still
+fail every turn.
+
+### Which endpoints are allowed
+
+`backend/app/endpoints.py` decides, and it is deliberately narrow: **loopback,
+your own LAN, or nothing.** The allowed networks are `127.0.0.0/8`, the three
+RFC1918 ranges, link-local, IPv6 loopback and unique-local, and `100.64.0.0/10`
+(carrier-grade NAT, which is what a mesh VPN such as Tailscale hands out).
+
+Every address the endpoint's hostname resolves to must be in one of them. A
+public address is refused, a name resolving to both a private and a public
+address is refused, and known cloud inference hosts are refused by name so the
+error says why rather than looking like a DNS fault.
+
+The rule is applied when you save the endpoint *and* again before every
+outbound request, so a database edited by hand or a hostname that starts
+resolving somewhere new cannot turn a local install into an exfiltration path.
+There is no setting to relax it.
 
 ### Same host (the default)
 
@@ -137,9 +171,8 @@ Use an IP address or a name your own network resolves. Then:
 - the inference machine needs the models installed, not the storyteller;
 - no Internet is involved in either direction.
 
-`app/netguard.py` refuses private addresses only in hosted multi-user mode
-(`AIDND_MULTI_USER=1`), which local installs never turn on, so a LAN endpoint
-is accepted as configured.
+A LAN endpoint is accepted because it is on one of the allowed networks above.
+Nothing else about it is special.
 
 #### If that endpoint is HTTPS with your own CA
 
@@ -176,7 +209,7 @@ visible from within.
 ## Tests
 
 ```bash
-cd backend && .venv/bin/python -m pytest tests/ -q     # 648 tests
+cd backend && .venv/bin/python -m pytest tests/ -q     # 698 tests
 cd frontend && npm run lint && npm run build
 ```
 
@@ -192,6 +225,25 @@ suite as complete evidence.
 is lost from the union, or if a new HTTP client is added without the shared
 verification context.
 
+M4 added `test_save_points.py`, which fails if restoring a Save Point starts
+deleting history, stops going through the active head, forks on its own, lets a
+Save Point on one campaign be restored through another, or lets deleting a branch
+take a Save Point with it. It also fails if listing Save Points goes back to one
+query per Save Point, or starts fetching narration to render the list.
+
+`test_process_restart.py` is the durability guard: it starts the application as a
+real subprocess, kills it, and starts a second one against the same database. A
+Save Point that survived only because a Python object was still alive would pass
+an in-process test and fail a user's restart.
+
+M2 added two more. `test_endpoint_policy.py` fails if the set of reachable
+addresses widens, or if either place the rule is applied stops applying it —
+it resolves hostnames through a stub, so it tests the policy rather than
+whatever DNS the machine has. `test_local_only_surface.py` fails if a removed
+subsystem comes back as a route, if an API key becomes settable again, if the
+model timeout stops being configurable or becomes unbounded, or if a supported
+start path stops binding loopback.
+
 ## What was made offline-safe, and how to check
 
 Two runtime downloads were removed in Milestone M1. Both were invisible on a
@@ -226,21 +278,24 @@ docker exec app python -c "import socket; socket.create_connection(('1.1.1.1',44
 # -> OSError: Network is unreachable, and story turns still work
 ```
 
-`planning/reports/M1-BASELINE-REPORT.md` records the run this procedure is
+`planning/archive/milestone-reports/M1-BASELINE-REPORT.md` records the run this procedure is
 taken from, including the packet captures.
 
-## Things inherited from upstream that M1 deliberately did not touch
+## Things still inherited from upstream
 
-These are M2's scope (`planning/BUILD-MILESTONES.md`), listed here so nobody
-reports them as new:
+M2 removed the hosted, cloud, account, analytics, Postgres/Render and QuickJS
+scripting surfaces outright — `PROVENANCE.md` lists exactly what went. What is
+left of upstream that a newcomer might report as a defect:
 
-- hosted/multi-user/account/demo-key code, analytics tables, Postgres and
-  Render deployment paths, and the OpenRouter default endpoint constant all
-  still exist in the tree. None of them is reachable from a default local run,
-  and none requires a cloud service.
-- `docs/*.html` is upstream's GitHub Pages project site and still links Google
-  Fonts. It is not served by the application and is not part of any build.
-- `.github/workflows/ci.yml` is upstream's GitHub Actions pipeline. This
+- **Inert legacy tables and columns.** Five tables and four columns M2 emptied
+  of meaning are still in the schema, unmapped, so an M1-era campaign database
+  opens unchanged. Nothing reads or writes them. A cleanup migration waits for
+  the schema to settle after M5 (`planning/BUILD-MILESTONES.md`).
+- **Dual-dialect migration code.** `backend/app/migrations.py` still carries
+  SQLite/Postgres branches from upstream, although Postgres support itself is
+  gone and SQLite is the only store. Same cleanup, same milestone.
+- **`.github/workflows/ci.yml`** is upstream's GitHub Actions pipeline. This
   repository lives on a self-hosted Gitea; the workflow is kept for provenance
   and is not what runs the tests here.
-- QuickJS campaign scripting is still present and still tested.
+- **No frontend tests.** `npm run lint && npm run build` is the whole frontend
+  check. A test runner is M8's job.

Dockerfile

@@ -7,20 +7,15 @@ RUN npm ci
 COPY frontend/ ./
 RUN npm run build
 
-# Stage 2 — build Python wheels (quickjs compiles from source if no wheel
-# matches, so keep the toolchain out of the final image)
-FROM python:3.12-slim AS python-build
-RUN apt-get update && apt-get install -y --no-install-recommends gcc make \
-    && rm -rf /var/lib/apt/lists/*
-COPY backend/requirements.txt /tmp/requirements.txt
-RUN pip wheel --no-cache-dir -r /tmp/requirements.txt -w /wheels
-
-# Stage 3 — runtime
+# Stage 2 — runtime. Every remaining dependency ships a wheel, so there is no
+# compile step and no toolchain to keep out of the image. The wheel-building
+# stage that used to sit here existed for quickjs, which compiled from source
+# and which M2 removed with campaign scripting.
 FROM python:3.12-slim
 WORKDIR /app
 
-COPY --from=python-build /wheels /wheels
-RUN pip install --no-cache-dir /wheels/* && rm -rf /wheels
+COPY backend/requirements.txt /tmp/requirements.txt
+RUN pip install --no-cache-dir -r /tmp/requirements.txt && rm /tmp/requirements.txt
 
 # Layout mirrors the repo: main.py finds the SPA at ../../frontend/dist
 # relative to backend/app/main.py.
@@ -38,14 +33,11 @@ EXPOSE 8000
 # invitation to put the storyteller on the LAN, which is single-user and
 # unauthenticated in local mode.
 WORKDIR /app/backend
-# --proxy-headers lets uvicorn fix up the request scheme (https) behind the
-# platform's edge. We deliberately do NOT pass --forwarded-allow-ips "*": that
-# made uvicorn trust the LEFTMOST X-Forwarded-For value, which the client fully
-# controls, so anyone could rotate the header to dodge the per-IP rate limits.
-# The client IP used for rate limiting is derived in limits._client_ip from the
-# hop the edge appends (rightmost), which a client cannot spoof past; tune with
-# AIDND_TRUSTED_PROXY_HOPS if the platform adds more proxy hops.
-# Single worker on purpose: the turn lock, rate limiter, and debug log are
-# in-process state.
-CMD ["uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "8000", \
-     "--proxy-headers"]
+# Single worker on purpose: the turn lock and the debug log are in-process
+# state.
+#
+# No --proxy-headers. That existed for a hosted deployment behind a platform
+# edge, along with the per-IP rate limiting that read X-Forwarded-For. Neither
+# survives M2, and trusting a forwarded header on a loopback-published port
+# would be a way to lie to the app rather than a feature.
+CMD ["uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "8000"]

PROVENANCE.md

@@ -26,9 +26,11 @@ import is a merge of the pinned commit with `--allow-unrelated-histories`, so:
 
 - `git log d72f7c1bda0f34fccd84afb7a25c34eb01c901de` shows the real upstream
   history, not a squashed snapshot;
-- upstream paths are unchanged (`backend/`, `frontend/`, `docs/`, …), so a
-  later upstream commit can still be fetched and cherry-picked against
-  matching files;
+- upstream code paths are unchanged (`backend/`, `frontend/`, …), so a later
+  upstream commit can still be fetched and cherry-picked against matching
+  files. Upstream's own documentation trees, `plan/` and `docs/`, were removed
+  on 2026-09-03: they described the hosted, scripted, multi-user product this
+  fork is not. They remain in this repository's history and in upstream;
 - the planning package that predates the fork keeps its own history on the
   other parent of the merge.
 
@@ -78,10 +80,33 @@ text ships beside them as `OFL-cinzel.txt`, `OFL-crimsonpro.txt` and
 Regenerate with `python3 frontend/tools/vendor_fonts.py`, which also rewrites
 `frontend/src/styles/fonts.css`.
 
+## What this fork changed in Milestone M2
+
+M2 is subtractive. It reduced the inherited application to the intended
+single-user, local-first trust boundary. **Nothing was added that upstream did
+not have, except the endpoint policy and the tests that hold these removals in
+place.**
+
+Removed in full: campaign scripting and the QuickJS sandbox; multi-user
+accounts, guest sessions, login, registration and the shared demo key; the
+visitor analytics tables, dashboard and beacon; the access log; per-IP and
+per-user rate limiting and quotas; Render deployment config; Postgres/Neon
+support; cloud inference providers and the API-key field; session-cookie
+signing and API-key encryption at rest.
+
+Added: `backend/app/endpoints.py`, which decides what an inference endpoint may
+be, and a configurable model timeout.
+
+Three database tables (`scripts`, `adventure_scripts`, `analytics_daily`,
+`analytics_visitor_days`, `access_log`) and four columns (`adventures.script_state`,
+`settings.api_key`, `users.demo_turns_used`, `users.demo_turns_date`) are left
+in place, unmapped or inert, so that an existing M1 campaign database opens
+unchanged. They are not product functionality and nothing reads or writes them.
+
 ## What this fork changed in Milestone M1
 
 Nothing was removed from upstream. The changes are the offline/locality
-hardening M1 called for; see `planning/reports/M1-BASELINE-REPORT.md` for the
+hardening M1 called for; see `planning/archive/milestone-reports/M1-BASELINE-REPORT.md` for the
 evidence.
 
 - `backend/app/context/encoding.py` (new) and `backend/app/context/builder.py` —

README.md

@@ -1,39 +1,38 @@
-# AI D&D
+# Adventure Storyteller
 
-[![CI](https://github.com/parththakkar106/AI-DnD/actions/workflows/ci.yml/badge.svg)](https://github.com/parththakkar106/AI-DnD/actions/workflows/ci.yml)
 [![License: MIT](https://img.shields.io/badge/license-MIT-blue.svg)](LICENSE)
 
-An AI Dungeon-style interactive storytelling app that runs entirely on your own machine, with
-your own AI model. Create scenarios, play open-ended adventures where an LLM narrates the
-world, and extend the engine with **JavaScript scripts compatible with real AI Dungeon
-scripting**.
+An interactive storytelling app that runs entirely on your own machine, with your own model.
+Create scenarios and play open-ended adventures where a local LLM narrates the world, keeps
+track of what is true, and remembers what happened.
 
-> ### ▶️ Try it live: **[parththakkar106.github.io/AI-DnD](https://parththakkar106.github.io/AI-DnD/)**
-> The project page loads instantly and launches the hosted demo in one tap. Play a scenario as
-> a guest: no sign-up and no API key needed. The demo runs on a free tier that sleeps, so the
-> first load after it's been idle takes about 30 to 60 seconds to wake up.
+This is the **Adventure Storyteller** fork of [AI-DnD](https://github.com/parththakkar106/AI-DnD).
+It is deliberately narrower than its upstream: single-user, local-only, and pointed at a model
+you run yourself. The hosted deployment, the accounts and sessions, the cloud provider support,
+the Postgres path, and the JavaScript scripting engine have all been removed rather than
+disabled. What is left is a storyteller you can run offline.
+
+> **Local-only, by design.** The app talks to one place — an Ollama-compatible endpoint on this
+> machine or on a machine you control on your own network — and it refuses to be pointed at a
+> public address. There is no telemetry, no account, no cloud inference, and nothing is fetched
+> at runtime from the Internet.
 >
-> For the internals, read the **[design notes](https://parththakkar106.github.io/AI-DnD/guide.html)**.
-> They walk through the context budgeting, the world-state referee, and the memory bank, and
-> state the reasoning behind each one ([Markdown version](docs/GUIDE.md)).
+> For the internals, read [`planning/TECHNICAL-DESIGN.md`](planning/TECHNICAL-DESIGN.md) and
+> [`planning/CONTEXT-AND-MEMORY.md`](planning/CONTEXT-AND-MEMORY.md), which cover the context
+> budgeting, the state model and the memory bank as this fork builds them.
 
-Built with FastAPI and SQLAlchemy on the backend and React (Vite) on the frontend, running on
-SQLite locally and Postgres in the cloud. It works with **any OpenAI-compatible endpoint**:
-Ollama and LM Studio locally, or OpenRouter, OpenAI, Groq, or vLLM in the cloud. Endpoint, key,
-and model are all runtime settings, and OpenRouter's free-tier models make the whole experience
-cost nothing.
+Built with FastAPI and SQLAlchemy on the backend and React (Vite) on the frontend, storing
+everything in one SQLite file.
 
-![The play screen, with the world-state rail open](docs/images/play-world-state.jpg)
-
-*The play screen. The left rail shows live world state. The AI proposes changes each turn, and
-a Python engine decides what actually sticks. The chip under the narration reports what
-changed. The `‹ 2/2 ›` under a turn steps between the takes it has. Writing below a take that
-isn't the live one starts a new branch.*
+On the play screen, the left rail carries live world state. The AI proposes changes each turn
+and a Python engine decides what actually sticks; the chip under the narration reports what
+changed. The `‹ 2/2 ›` under a turn steps between the takes it has, and writing below a take
+that isn't the live one starts a new branch.
 
 ## Features
 
 - **The full play loop.** Do / Say / Story / Continue actions, streamed AI responses (SSE),
-  retry, undo, and edit. Reasoning models are supported: "thinking" streams into a collapsible
+  retry, undo, redo, and edit. Reasoning models are supported: "thinking" streams into a collapsible
   💭 panel with its own token budget.
 - **A branching story tree.** The story is a tree, not a list. Any turn can hold more than one
   **take**, and `‹ 2/4 ›` steps between them. Stepping is free: the story below simply empties,
@@ -47,7 +46,8 @@ isn't the live one starts a new branch.*
   cast; the adventure carries their live values. The AI proposes deltas, and a Python engine
   referees them: it clamps values to range, enforces per-turn caps and cooldowns, keeps counters
   monotonic and milestones sticky, then strips the machine-readable block out of the prose
-  (`backend/app/worldstate/engine.py`). Word-labeled bands (`40–60: minor damage`) make the
+  (`backend/app/worldstate/`: `apply.py` clamps, `parse.py` reads the block back).
+  Word-labeled bands (`40–60: minor damage`) make the
   model reliable at it. No dice and no scripting are required.
 - **AI Dungeon-compatible context engine.** Memory, author's note, and story cards (world
   info) are triggered by keywords in recent story text, then assembled under a token budget
@@ -55,41 +55,54 @@ isn't the live one starts a new branch.*
 - **Insights: total prompt transparency.** Every turn stores the exact prompt sent to the
   model. Open 🔍 on any AI action to see each context component, its token cost, and why it was
   included.
-- **JavaScript scripting, AI Dungeon-compatible.** `onInput` / `onModelContext` / `onOutput`
-  modifiers share `state` and a `worldEntries` API, and run in an embedded quickjs sandbox
-  (`backend/app/scripting/`). Real AI Dungeon scripts import and run as is. An in-app CodeMirror
-  editor is included.
 - **Auto-summarization and Memory Bank.** The modern AI Dungeon memory system: AI-generated
   memories every few actions, a running story summary, and embedding-based retrieval that
   pulls old-but-relevant facts back into context, with similarity scores visible in Insights
   (`backend/app/memorybank.py`).
-- **Undo and retry that actually roll back state.** Undo and retry roll back the world state
-  and script state to a per-node snapshot, not just the text, and prune the memories that
-  covered the removed turns. Nothing a retry replaces is discarded: the old attempt stays as
-  another take of that turn, one keystroke and one click from becoming a branch of its own.
-- **Import and export.** AI Dungeon-compatible formats for scripts and scenarios; JSON for
-  everything else. An adventure exports as `ai-dnd-adventure-v2`, which carries the whole tree:
-  every branch, every take, and the fork points, since those were chosen rather than computed.
-  Files saved in the old single-line format still import.
-- **Optional accounts for hosted deployments.** By default the app is single-user with zero
-  auth friction. Set `AIDND_MULTI_USER=1` and visitors play instantly as guests (signed
-  session cookie), can register (email and password) at any point to keep their data, and each
-  user gets isolated data plus their own encrypted-at-rest API key. A server-funded **shared
-  demo key** with a daily turn cap lets people try it without bringing a key
-  (`backend/app/auth.py`). Each new guest is also given a copy of a short pre-played
-  adventure, so the first screen shows real turns and their world-state changes without
-  spending a demo turn (`backend/app/starter.py`).
+- **Undo, Redo, and retry that roll back state and delete nothing.** Undo moves where the story
+  is being read; it removes no accepted turn, so Redo can walk forward into the turns it stepped
+  over. Both restore the world state from a per-node snapshot rather than just the text, and a
+  memory derived from a turn now behind the head stops being retrieved without being deleted or
+  re-embedded. Writing a new turn below a moved-back head is the moment the story forks: the
+  displaced future stays on the line it was written for, and ordinary Redo stops offering it.
+  Nothing a retry replaces is discarded either — the old attempt stays as another take of that
+  turn, one keystroke and one click from becoming a branch of its own.
+- **Save Points.** Name a moment — "Before entering the abbey" — keep playing,
+  restart the app, and come back to it. Restoring one moves the story back to
+  that moment and deletes nothing: the turns you wrote after it stay, Redo still
+  walks forward into them, and writing something different from the Save Point
+  is what starts a new line while the old one is kept. A Save Point is a name for
+  a position and holds no copy of the story, so restoring it is the same
+  movement Undo makes (`backend/app/routers/adventures/checkpoints.py`,
+  `backend/app/head.py`). They last until *you* delete them: deleting one deletes
+  no story, and deleting a branch a Save Point is kept on is refused until you
+  remove the Save Point yourself, so nothing takes a named moment away behind
+  your back.
+- **Import and export.** AI Dungeon-compatible scenario format; JSON for everything else. An adventure exports as `ai-dnd-adventure-v2`, which carries the whole tree:
+  every branch, every take, the fork points, which branches the story has left behind, the Save
+  Points and the position it is being read at — all of them chosen rather than computed, which is
+  the rule for what a bundle carries. A campaign opens where its head says, never at a Save Point
+  merely because it has one. A campaign exported after two Undos imports still undone, with its
+  retained future intact, instead of silently reopening at its newest turn. Files that predate
+  the head position, and files saved in the old single-line format, still import.
+- **Single user, no accounts.** There is no sign-up, no login, no session and no API key
+  anywhere in the product. The storyteller API binds to loopback and is unauthenticated by
+  design, because the only person who can reach it is the person running it. A new install
+  starts with a short pre-played adventure, so the first screen shows real turns and their
+  world-state changes rather than an empty page (`backend/app/starter.py`).
+- **A refusal you can rely on.** The inference endpoint is checked against an address
+  allowlist when you save it and again before every request, so a public endpoint is refused
+  even if the setting is edited in the database directly. TLS verification is never traded
+  against reachability: a privately issued certificate is verified against your machine's own
+  trust store, and there is no bypass switch.
 
 ## Screenshots
 
-| | |
-|---|---|
-| ![Insights panel](docs/images/insights.jpg) | ![Scenario editor](docs/images/scenario-editor-npcs.jpg) |
-| **Insights**: the exact prompt for the next turn, broken into components with token counts and the trigger word that pulled each story card in. | **Authoring**: stats with ranges, per-turn caps, cooldowns, and word-labeled bands; NPCs the AI addresses by id. |
-| ![Script editor](docs/images/script-editor.jpg) | ![Home](docs/images/home.jpg) |
-| **Scripting**: the three AI Dungeon hooks with shared persistent `state`, run in a quickjs sandbox. | **Home**: continue a story in progress or start from a scenario. |
-| ![The branch map](docs/images/branch-map.jpg) | ![The branches panel](docs/images/branches-panel.jpg) |
-| **The tree**: one lane per line, from the moment it left its parent to the moment it ends. The horizontal axis is the story's own clock, so a short branch reads as short. | **Branches**: every line the story has taken, and the three things you can do to one. A line the one you're reading was forked from can't be deleted, and says so. |
+None yet. The inherited screenshots showed upstream's UI — a Scripts tab, Log in and Sign up,
+a guest banner, scripting demo scenarios — none of which this fork has since M2, so they were
+removed rather than left standing as a picture of a product that no longer exists. The M4
+closeout drove the real application in a real browser, so the screens exist and work; taking
+presentable screenshots of them is a job for the UI pass in M8.
 
 ## Quick start
 
@@ -121,58 +134,67 @@ Open http://localhost:5173.
 
 ## Connect a model
 
-Open **Settings** in the app and point it at any OpenAI-compatible endpoint:
+Ollama is the inference backend v1 supports. Open **Settings** in the app and point it at one:
 
-| Provider | Endpoint URL | Notes |
+| Where Ollama runs | Endpoint URL | Notes |
 |---|---|---|
-| Ollama (local) | `http://localhost:11434/v1` | free, private; also serves embedding models for the Memory Bank (e.g. `nomic-embed-text`) |
-| LM Studio (local) | `http://localhost:1234/v1` | free, private |
-| OpenRouter | `https://openrouter.ai/api/v1` | `:free` models cost nothing (no embeddings on the free tier) |
-| OpenAI / Groq / vLLM / … | provider's `/v1` URL | anything speaking `/v1/chat/completions` |
-| Claude Code CLI (local) | `http://127.0.0.1:8787/v1` | your Claude subscription instead of an API key; see [Playing against Claude locally](#playing-against-claude-locally) |
+| The same machine | `http://localhost:11434/v1` | the default, and the simplest thing that works |
+| A machine on your own network | `http://<host>:11434/v1` or `https://<host>/v1` | explicitly configured; see below |
 
-Model name, API key, generation parameters, and (optionally) summary and embedding models for
-the Memory Bank are all configured there too. No config files and no rebuild are needed.
+Model name, generation parameters, and (optionally) summary and embedding models for the
+Memory Bank are configured there too. No config files and no rebuild are needed. There is no
+API key field, because there is nothing to authenticate to.
 
-### Playing against Claude locally
+The adapter underneath speaks the OpenAI-compatible protocol, because that is what Ollama
+serves. That is an implementation detail, not a promise of support for arbitrary local
+servers that happen to speak the same protocol. Public and cloud inference endpoints are
+prohibited outright — see `planning/DECISIONS/002-ollama-only-v1.md` and
+`planning/DECISIONS/011-local-inference-endpoint-policy.md`.
 
-`backend/tools/claude_shim.py` serves an OpenAI-compatible endpoint backed by the
-`claude` command line tool, so you can play the demos against a real model without an
-API key. Each request spawns one `claude --print` process, which suits the turn engine:
-the app assembles the whole prompt every turn and expects a stateless endpoint.
+### What the endpoint policy allows
+
+The address is checked when you save it and again before every request. Only loopback and
+private-network addresses are accepted; every public address is refused, by address rather than
+by hostname, so a name that resolves outward is refused too. A well-known cloud inference host
+is named in the error message only so the refusal says *why*.
+
+Running the model on a second machine you control is supported and expected — that machine
+does the inference while the storyteller itself stays bound to loopback on yours. If that
+machine serves HTTPS with a certificate from a CA you installed, it works: certificates are
+verified against your operating system's trust store as well as the bundled one. Verification
+itself is never relaxed, and there is no option to turn it off.
+
+### Playing against a local shim (development only)
+
+`backend/tools/claude_shim.py` serves an OpenAI-compatible endpoint on `127.0.0.1:8787`
+backed by a command-line tool, which is useful for testing the turn engine against a stronger
+model. Each request spawns one process, which suits the engine: the app assembles the whole
+prompt every turn and expects a stateless endpoint.
 
 ```sh
 cd backend
-.venv/Scripts/python.exe tools/claude_shim.py      # listens on 127.0.0.1:8787
+.venv/bin/python tools/claude_shim.py      # listens on 127.0.0.1:8787
 ```
 
-In Settings, choose the OpenAI-compatible provider, set the base URL to
-`http://127.0.0.1:8787/v1`, put any non-empty string in the API key field, and pick
-`sonnet`. The shim ignores the key and authenticates as you, through the CLI. Set the
-reasoning budget to `0` or `-1`: a positive budget sends a `reasoning.max_tokens` field
-that Claude 5 models reject.
+Set the base URL to `http://127.0.0.1:8787/v1` and pick a model the tool offers. Set the
+reasoning budget to `0` or `-1`: a positive budget sends a `reasoning.max_tokens` field that
+some models reject. Embeddings are not served — leave the embedding model blank, or point the
+Memory Bank at an endpoint that serves one.
 
-Embeddings are not served. Leave the embedding model blank, or point the Memory Bank at
-a real endpoint.
-
-Run it against a local backend only. The endpoint has no authentication, and anything
-reaching it spends your Claude quota. `app/netguard.py` blocks localhost endpoints when
-`AIDND_MULTI_USER` is set, so a deployed instance cannot be pointed at it.
+The shim has no authentication and spends whatever quota backs it, so run it on loopback and
+leave it there.
 
 ## How a turn works
 
 ```
 player input
-  → onInput script modifier
   → assemble context:  [narrator prompt] + [world state + stat guide] + [AI instructions]
                        + [plot essentials] + [story summary] + [retrieved memories]
                        + [triggered story cards] + [history along this branch, token-budgeted]
                        + [author's note] + [player action]
-  → onModelContext script modifier
   → snapshot context (Insights)
   → provider adapter → AI (streamed)
   → extract + referee the world-state delta block, strip it from the prose
-  → onOutput script modifier
   → store & render
 ```
 
@@ -180,18 +202,18 @@ player input
 
 ```
 frontend/   React + Vite SPA  ──HTTP/SSE──►  backend/  FastAPI
-                                              ├─ routers/      auth, scenarios, adventures, story cards, scripts, chat, settings, analytics, debug
-                                              ├─ models.py     SQLAlchemy: User, Scenario, Adventure, Branch, Action, StoryCard, Script, Settings, Memory
-                                              ├─ migrations.py hand-rolled, versioned via PRAGMA user_version (64 and counting)
-                                              ├─ auth.py       guest/registered users, sessions, shared demo key
-                                              ├─ security.py   password hashing, cookie signing, API-key encryption
+                                              ├─ routers/      scenarios, adventures, story cards, chat, settings, debug
+                                              ├─ models.py     SQLAlchemy: Scenario, Adventure, Branch, Action, StoryCard, Settings, Memory
+                                              ├─ migrations.py hand-rolled, versioned via PRAGMA user_version (79 and counting)
+                                              ├─ endpoints.py  the inference-endpoint address policy
+                                              ├─ tlstrust.py   one TLS context: the OS trust store unioned with certifi's
                                               ├─ tree.py       forking, promotion, and where a node is placed
+                                              ├─ head.py       the active head: where the story is read, and what moving it costs
+                                              ├─ checkpoints   Save Points: durable names for positions, in routers/adventures/
                                               ├─ attempts.py   the takes of one turn, grouped by parent
                                               ├─ context/      prompt assembly under a token budget + lineage/history windowing
                                               ├─ worldstate/   the stat engine: clamps, cooldowns, bands, milestones
-                                              ├─ scripting/    quickjs sandbox + AI Dungeon API surface
                                               ├─ memorybank.py auto-summarization + embedding retrieval
-                                              ├─ analytics.py  buffered visit counters + the owner's dashboard query
                                               ├─ bundle.py     the export/import formats, v2 (tree) and a v1 reader
                                               ├─ providers/    OpenAI-compatible adapter, streaming
                                               └─ data.db       SQLite (path overridable via AIDND_DB_PATH)
@@ -202,9 +224,10 @@ development, Vite proxies `/api` to FastAPI.
 
 ## Tests
 
-549 backend tests: unit tests plus full HTTP integration through the real quickjs scripting
-engine, with the LLM provider mocked. CI runs them on every push, alongside the frontend
-lint/build and a Docker image build.
+698 backend tests: unit tests plus full HTTP integration through the real turn engine, with
+the model provider mocked. They run with no route to the Internet, which is a requirement
+rather than a convenience — an offline claim proved on a machine that has been online once
+proves nothing.
 
 ```sh
 cd backend && pip install -r requirements.txt -r requirements-dev.txt
@@ -233,59 +256,20 @@ most interesting engineering in the repo.
   the number of SQL clauses is bounded by the context window rather than by the number of
   forks.
 
-## Visit analytics
-
-The hosted demo keeps its own analytics: an owner-only dashboard at `/analytics` shows
-traffic, which shared scenarios get played, turns and demo-key spend, errors, and a funnel
-from *visited* to *played a turn* to *signed up*. It is visible only to the emails listed in
-`AIDND_ANALYTICS_EMAILS`, and the route returns 404 for everyone else.
-
-This is built into the app rather than added with a third-party script, for reasons specific
-to this project: the CSP allows only `script-src 'self'`, ad blockers block the popular
-trackers, and none of those trackers can see the measurement that matters here, a turn. Counts
-are aggregated in memory and flushed as UPSERTs, so a visit is a write and never a read, and
-every dashboard query is a `GROUP BY` that returns tens of rows regardless of traffic volume.
-That matters: see the egress note above for what reading rows per request costs on this stack.
-
-## Deploy (Render)
-
-The repo ships a [`render.yaml`](render.yaml) blueprint: one Docker web service that serves
-the SPA and API same-origin, backed by external [Neon](https://neon.tech) Postgres. The free
-Render tier has no persistent disk, so the database lives off-box.
-
-1. Create a **Neon** project and copy its pooled connection string.
-2. In Render, choose **New → Blueprint** and point it at this repo. Render reads
-   `render.yaml`.
-3. Fill in the secrets it prompts for (`sync: false` vars): `AIDND_DATABASE_URL` (the Neon
-   string); `AIDND_DEMO_API_KEY` and `AIDND_DEMO_MODELS` to offer a no-signup demo; and
-   `AIDND_ANALYTICS_EMAILS` (your own account's email) to see the Visitors dashboard.
-   `AIDND_SECRET_KEY` is generated automatically and stays stable across deploys.
-4. Deploy. Pushes to `main` auto-deploy after this. The health check is `/api/health`.
-
-On the free tier the service sleeps after about 15 minutes idle, and the first request after
-that takes about 30 to 60 seconds to wake it. Point any keep-warm pinger at `/api/health`,
-which deliberately doesn't touch the database: waking the database around the clock costs far
-more than the cold start saves.
-
-If you put another proxy or CDN in front of Render, set `AIDND_TRUSTED_PROXY_HOPS` to the
-number of proxies in the chain. It defaults to 1. The rate limiter reads the client IP that
-many entries from the right of `X-Forwarded-For`, because the trusted edge appends the real
-one last. Leave it at 1 behind two proxies and the limiter reads an entry the caller
-supplied, so anyone can rotate the header for a fresh rate-limit bucket per request.
-
 ## Repo notes
 
-- `plan/` holds the phased implementation plan this project was built from, kept as a build
-  log. All fourteen phases are complete. The later files (11, 12, 14) also serve as design
-  notes for the state-revert, world-state, and story-tree work.
-  [`plan/STATUS.md`](plan/STATUS.md) is the running thread: what shipped, what was measured,
-  and what is owed next.
-- [`docs/GUIDE.md`](docs/GUIDE.md) holds design notes: how each subsystem works and why it was
-  built that way, with the measurements behind the decisions. It is also rendered as a
-  [reading page](https://parththakkar106.github.io/AI-DnD/guide.html).
-- `backend/.env.example` lists the few environment variables the backend reads.
-- [`docs/self-review.md`](docs/self-review.md) records a full-codebase self-review pass and
-  what came out of it. All correctness findings are resolved.
+- `planning/` is this fork's own package: the product specification, the architecture
+  decisions, the milestone plan, the acceptance contract, and a review report for every
+  milestone shipped. Start at [`planning/README.md`](planning/README.md).
+- [`planning/archive/`](planning/archive/README.md) holds the Phase 0 research that chose this
+  base and the completed milestone reports. It is history, not instruction.
+- [`DEVELOPMENT.md`](DEVELOPMENT.md) is how to set the project up, point it at a model, and run
+  the tests. [`PROVENANCE.md`](PROVENANCE.md) records what came from upstream and what changed.
+- `backend/.env.example` lists the two environment variables the backend reads. Everything
+  about the model is a runtime setting on the Settings page instead.
+- Upstream's own `plan/` build log and `docs/` project site were removed in the 2026-09-03
+  documentation pass: they described AI-DnD's hosted, scripted, multi-user product. Both are
+  still in Git history, and in upstream.
 
 ## License
 

backend/.env.example

@@ -1,110 +1,24 @@
 # Environment variables read by the backend.
 #
 # NOTE: the app reads real environment variables — it does NOT auto-load this
-# file. Set them in your shell, in docker-compose.yml, or in your host's
-# dashboard. This file is documentation (and a template for deploy configs).
+# file. Set them in your shell or in docker-compose.yml. This file is
+# documentation.
+#
+# There are two, and neither is required. Everything about the model — the
+# endpoint, the model names, the timeout, the context budget — is a runtime
+# setting stored in the database and edited on the Settings page, because it is
+# a preference rather than a deployment detail.
 
-# Absolute path for the SQLite database file. Parent directory is created if
-# missing. Default when unset: backend/data.db
-# Docker compose sets this to /data/data.db (a named volume).
+# Absolute path for the SQLite database file. The parent directory is created
+# if missing. Default when unset: backend/data.db
+# docker-compose.yml sets this to /data/data.db (a named volume).
 AIDND_DB_PATH=
 
-# ---------------------------------------------------------------------------
-# Phase 9 — production hardening
-# ---------------------------------------------------------------------------
-
-# Switch from SQLite to a server database (hosted deploys use Neon Postgres).
-# Any SQLAlchemy URL; postgres:// and postgresql:// schemes are rewritten to
-# the psycopg3 driver automatically. The platform-conventional DATABASE_URL
-# is honored too (AIDND_DATABASE_URL wins if both are set). Unset = SQLite.
-AIDND_DATABASE_URL=
-
 # Comma-separated list of allowed CORS origins. Only needed when the frontend
 # is served from a different origin than the API; the production build is
-# served same-origin by FastAPI, so hosted deploys can leave this unset.
+# served same-origin by FastAPI, so a normal run can leave this unset.
 # Default: http://localhost:5173,http://127.0.0.1:5173 (the Vite dev server).
+#
+# A wildcard is rejected. The storyteller API is unauthenticated by design and
+# bound to loopback; letting any origin call it would undo that.
 AIDND_CORS_ORIGINS=
-
-# How many proxy hops the rate limiter trusts in `X-Forwarded-For`. It reads
-# the entry that many places from the right, because the trusted edge appends
-# the real client IP last. Set this to the number of proxies in front of the
-# app. Default: 1, which is correct for a single edge such as Render.
-#
-# Get it wrong in either direction and the rate limits weaken. Too low reads an
-# entry the caller supplied, so anyone can rotate the header for a fresh
-# rate-limit bucket per request and walk past the auth and guest limits. Too
-# high reads past the real client. Only multi-user mode rate-limits at all, so
-# local installs can ignore this.
-AIDND_TRUSTED_PROXY_HOPS=
-
-# ---------------------------------------------------------------------------
-# Phase 8 — optional accounts & multi-user (all optional; defaults keep the
-# app in frictionless single-user "local mode")
-# ---------------------------------------------------------------------------
-
-# "1"/"true" turns on multi-user mode: guest sessions via signed cookies,
-# register/login UI, per-user data. Leave unset for local installs.
-AIDND_MULTI_USER=
-
-# Secret for signing session cookies and encrypting stored API keys at rest.
-# If unset in local mode, one is auto-generated into `secret.key` next to the
-# database (fine for local/docker-volume runs). REQUIRED when
-# AIDND_MULTI_USER is on — the app refuses to start without it, because a
-# regenerated secret on an ephemeral hosted filesystem would log out every
-# user on each deploy. Generate one:
-#   python -c "import secrets; print(secrets.token_urlsafe(48))"
-AIDND_SECRET_KEY=
-
-# Session cookie Secure flag (HTTPS-only). Defaults to on when
-# AIDND_MULTI_USER is on, off otherwise — set 0/1 only to override (e.g. 0
-# when testing multi-user mode over plain http on a LAN address).
-AIDND_COOKIE_SECURE=
-
-# --- Shared demo key (BYOK fallback; only active when AIDND_MULTI_USER=1) ---
-# Users with no API key of their own get this server-funded endpoint with a
-# model whitelist and a per-day turn cap. Unset = no demo, users must bring
-# their own key. Memory bank/auto-summarization are disabled on demo turns.
-AIDND_DEMO_API_KEY=
-# Default endpoint if unset: https://openrouter.ai/api/v1
-AIDND_DEMO_ENDPOINT_URL=
-# Comma-separated model whitelist. Default: google/gemma-4-26b-a4b-it:free
-AIDND_DEMO_MODELS=
-# Successful AI turns per user per day on the demo key. Default: 20
-AIDND_DEMO_TURNS_PER_DAY=
-# Comma-separated emails of "power users" (trusted testers) who bypass the daily
-# demo cap entirely — unmetered turns on the shared demo key — and get the AI Chat
-# page (a plain scratchpad for talking to a model, hidden from everyone else).
-# Registered accounts only (guests have no email). Matched case-insensitively.
-# Local (single-user) installs are always treated as power users.
-AIDND_POWER_USERS=
-
-# --- Visit analytics ---
-# Comma-separated emails allowed to see the Visitors dashboard (/analytics) and
-# its nav link. Deliberately separate from AIDND_POWER_USERS: a trusted tester
-# gets unmetered turns, which is no reason to hand them the traffic numbers.
-# Unset = nobody sees it in a hosted deploy. Local installs always can, and are
-# the only mode where the viewer's own visits are still counted (excluding them
-# would leave the page permanently empty on the machine it's developed on).
-# Collection itself is always on; only the dashboard is gated.
-AIDND_ANALYTICS_EMAILS=
-# Days to keep the one-row-per-visitor-per-day table that makes the funnel
-# count people rather than clicks. The daily counters are aggregate and kept
-# forever. Default: 400. Set 0 to keep visitor-days forever.
-AIDND_ANALYTICS_RETENTION_DAYS=
-
-# --- Guest retention (only active when AIDND_MULTI_USER=1) ---
-# Every first visit mints a guest account, so a public demo collects one row
-# per visitor. A guest with no activity for this many days is deleted along
-# with its scenarios, adventures and actions. Registered accounts are never
-# touched. Default: 5. Set 0 to keep guests forever.
-AIDND_GUEST_RETENTION_DAYS=
-# How often a running process re-checks. The sweep also runs once at startup,
-# which is what actually fires on hosts that sleep. Default: 6
-AIDND_CLEANUP_INTERVAL_HOURS=
-
-# The AI endpoint/API key/model are NOT env vars — they are configured at
-# runtime in the app's Settings page and stored (encrypted) in the database.
-#
-# Rate limits, request size limits, and per-user row caps are hardcoded with
-# generous values (see backend/app/limits.py) and active only in multi-user
-# mode — local installs are never throttled.

backend/app/accesslog.py

@@ -1,168 +0,0 @@
-"""The access log: who arrived, when, and from where.
-
-The deliberate opposite of analytics.py. That module counts and stores nothing
-that points at a person; this one records addresses, email addresses and
-devices, because an access log that cannot identify the access is not an access
-log. The two live in separate modules and separate tables on purpose, so that
-the anonymity of the counters is a property of the code rather than a convention
-someone has to remember.
-
-Owner-only, and never shown to the people it records.
-
-Four kinds of row:
-
-- `session`      A browser that has a session made a request. For a guest, this
-                 is their first visit.
-- `login`        An existing account signed in.
-- `register`     A guest upgraded to an account.
-- `login_failed` A password attempt that did not match, with the address tried.
-
-Session rows are the only ones that need thinning. `/auth/me` runs on every page
-load, and one row per load would be noise rather than a log. A row is written
-when the day or the address changes for that user. That is the granularity a log
-is read at, such as seen on the 3rd from 1.2.3.4, and it still records someone
-moving networks during a day.
-"""
-
-import logging
-import threading
-
-from sqlalchemy import desc, or_, select
-from sqlalchemy.orm import Session
-
-from . import analytics, models
-
-logger = logging.getLogger(__name__)
-
-SESSION = "session"
-LOGIN = "login"
-REGISTER = "register"
-LOGIN_FAILED = "login_failed"
-
-MAX_UA = 200
-
-# user id -> (day, ip) of the last session row written for them. Process-local
-# like the rate limiter's windows, and for the same reason: this is a single
-# process, and the worst case after a restart is one redundant row per user.
-_last_session: dict[int, tuple[str, str]] = {}
-_guard = threading.Lock()
-_MAX_TRACKED = 10_000
-
-
-def _client_ip(request) -> str:
-    # This import is deferred. `limits` imports `auth`, which the routers that
-    # call this function import, so a module-level import here would create a
-    # cycle. The spoof resistance lives in `limits` and must not be
-    # reimplemented. A second, looser answer to which address belongs to the
-    # client is how one of them ends up trusting a header it should not.
-    from . import limits
-
-    return limits.client_ip(request)
-
-
-def describe(user: models.User) -> str:
-    """Returns how a user is named in the log.
-
-    A guest has no email, and their id is the only handle anyone has for them.
-    The third case is a local install's implicit single user, who also has no
-    email but is the operator rather than a visitor. Naming that user "Guest #1"
-    would be wrong in the one row they are certain to read.
-    """
-    if user.email:
-        return user.email
-    return f"Guest #{user.id}" if user.is_guest else f"Local user #{user.id}"
-
-
-def _country(request) -> str:
-    """Returns the edge's country header, or "" when there is none.
-
-    The blank differs from the counters' "(unknown)" label. A table column reads
-    better as a dash than as a word, and an empty string is the correct value for
-    a country that is not known.
-    """
-    country = analytics.country_of(request.headers)
-    return "" if country == analytics.UNKNOWN else country
-
-
-def record(
-    db: Session,
-    kind: str,
-    request,
-    *,
-    user: models.User | None = None,
-    who: str | None = None,
-) -> None:
-    """Writes one row.
-
-    This function never raises. The log observes sign-in rather than guarding it,
-    and a logging failure must not lock anyone out.
-    """
-    try:
-        event = models.AccessEvent(
-            kind=kind,
-            user_id=user.id if user is not None else None,
-            who=(who if who is not None else describe(user) if user else "")[:320],
-            is_guest=bool(user.is_guest) if user is not None else False,
-            ip=_client_ip(request)[:45],
-            country=_country(request),
-            device=analytics.device_of(request.headers.get("user-agent", "")),
-            user_agent=(request.headers.get("user-agent") or "")[:MAX_UA],
-        )
-        db.add(event)
-        db.commit()
-    except Exception:  # pragma: no cover - defensive
-        db.rollback()
-        logger.exception("Access log write failed; continuing.")
-
-
-def note_session(db: Session, user: models.User, request) -> None:
-    """Records that a session made a request, at most one row per day per address."""
-    try:
-        today = analytics._today()
-        ip = _client_ip(request)
-        with _guard:
-            if _last_session.get(user.id) == (today, ip):
-                return
-            _last_session[user.id] = (today, ip)
-            if len(_last_session) > _MAX_TRACKED:
-                # Nothing here needs to persist. Clearing the map costs at most
-                # one extra row per active user.
-                _last_session.clear()
-                _last_session[user.id] = (today, ip)
-    except Exception:  # pragma: no cover - defensive
-        logger.exception("Access log session check failed; continuing.")
-        return
-    record(db, SESSION, request, user=user)
-
-
-def recent(
-    db: Session,
-    *,
-    limit: int = 50,
-    before_id: int | None = None,
-    kind: str | None = None,
-    query: str | None = None,
-) -> dict:
-    """Returns a page of the log, newest first.
-
-    The page is anchored on a row id rather than an offset, as the story pager
-    is. Rows keep arriving while the log is read, and an offset would shift the
-    page under whoever is reading it.
-    """
-    statement = select(models.AccessEvent).order_by(desc(models.AccessEvent.id))
-    if before_id is not None:
-        statement = statement.where(models.AccessEvent.id < before_id)
-    if kind:
-        statement = statement.where(models.AccessEvent.kind == kind)
-    if query:
-        like = f"%{query.strip()}%"
-        statement = statement.where(or_(
-            models.AccessEvent.who.ilike(like),
-            models.AccessEvent.ip.ilike(like),
-            models.AccessEvent.country.ilike(like),
-        ))
-    # Requesting one extra row reports whether more rows exist, without a
-    # second COUNT over the whole table.
-    rows = list(db.scalars(statement.limit(limit + 1)))
-    has_more = len(rows) > limit
-    return {"events": rows[:limit], "has_more": has_more}

backend/app/analytics.py

@@ -1,583 +0,0 @@
-"""Visit analytics for the hosted demo.
-
-This is a small self-hosted counter that answers whether anyone visited and
-whether they played. It is built into the app rather than added with a
-third-party script, because the CSP in `main.py` allows scripts from 'self'
-only, ad blockers block the popular trackers, and none of those trackers can see
-what is worth knowing here: turns taken, demo-key spend, and which seeded
-scenario people pick.
-
-Three rules shape the design:
-
-1. It stores nothing personal. It records no IP addresses, no user agents, no
-   user ids, and no title of anything a player wrote. A visitor appears only as
-   an HMAC of their user id, which is one-way and salted with the app's secret
-   key, so these tables cannot be joined back to an account even by someone
-   holding the database. Story content never reaches this module. What one
-   specific person did is unanswerable by design, and only totals are
-   available.
-2. Egress is the budget. Neon bills for bytes leaving the database, and this
-   project has already paid for forgetting that once. Counts are therefore
-   aggregated in memory and flushed as UPSERTs, so a visit is a write and never
-   a read, and every dashboard query is a GROUP BY that returns tens of rows
-   rather than per-visit rows. A month of traffic costs a few kilobytes to read
-   back.
-3. The numbers come from the server, not from the browser. The client reports
-   one thing, which is the page that was viewed. Everything with meaning, such
-   as a turn happening or an account being created, is recorded by the code that
-   performs it, where a stranger cannot fake it and an extension cannot block
-   it.
-
-Storage is two tables, both bounded. `analytics_daily` holds one counter row per
-day, metric, and label, which is a few dozen rows a day.
-`analytics_visitor_days` holds one row per visitor per day carrying the funnel
-flags, which is what makes the funnel count people rather than clicks. It is the
-only table that grows with traffic, and cleanup ages it out.
-"""
-
-import hmac
-import logging
-import os
-import re
-import threading
-from datetime import timedelta
-from hashlib import sha256
-from urllib.parse import urlsplit
-
-from sqlalchemy import case, func, or_, select
-from sqlalchemy.dialects.postgresql import insert as pg_insert
-from sqlalchemy.dialects.sqlite import insert as sqlite_insert
-from sqlalchemy.orm import Session
-
-from . import models, security
-
-logger = logging.getLogger(__name__)
-
-# ---------- Metrics ----------
-# `metric` is the family, and `label` is the bucket within it. One generic
-# counter table is better than a column per measurement, because adding a new
-# question later costs nothing rather than a migration.
-
-M_PAGE = "pageview"
-M_EVENT = "event"
-M_REFERRER = "referrer"
-M_DEVICE = "device"
-M_COUNTRY = "country"
-M_SCENARIO = "scenario"      # Which seeded or public scenario was played.
-M_ERROR = "error"            # "<status> <route>" for a 4xx or 5xx on /api.
-
-EV_SCENARIO_OPEN = "scenario_opened"
-EV_ADVENTURE = "adventure_created"
-EV_IMPORT = "adventure_imported"
-EV_TURN = "turn"
-EV_DEMO_TURN = "demo_turn"   # A turn billed to the shared demo key.
-EV_TURN_ERROR = "turn_error"
-EV_SIGNUP = "signup"
-EV_LOGIN = "login"
-
-# Events that are also funnel steps. Recording one sets a flag on the visitor's
-# row for the day, so the funnel counts distinct visitor-days rather than repeat
-# clicks. This name-to-column map is the whole definition of the funnel, and the
-# dashboard reads it back in this order.
-FUNNEL_FLAGS = {
-    EV_SCENARIO_OPEN: "opened",
-    EV_ADVENTURE: "created",
-    EV_TURN: "played",
-    EV_SIGNUP: "signed_up",
-}
-
-OTHER = "(other)"
-NONE_LABEL = "(direct)"
-UNKNOWN = "(unknown)"
-
-# ---------- Bounds ----------
-# These bounds exist so that a hostile visitor can add rows to these tables no
-# faster than an honest one. The only label a client can influence is the
-# referrer, and together these caps mean the worst it can do is fill one day's
-# referrer list and then be folded into "(other)".
-
-MAX_LABEL_LEN = 80
-MAX_LABELS_PER_METRIC = 200   # Distinct labels per metric per day, then OTHER.
-MAX_PENDING = 4000            # Buffered entries before an inline flush.
-FLUSH_INTERVAL_SECONDS = 60
-
-# How long the per-visitor-day rows are kept. The daily counters are small and
-# are kept indefinitely. These rows are the ones that scale with traffic. A
-# visitor whose last visit ages out counts as new again, which is an acceptable
-# trade at this horizon and keeps the table from being a permanent record of
-# anyone.
-RETENTION_DAYS = int(os.environ.get("AIDND_ANALYTICS_RETENTION_DAYS", "400") or 400)
-
-_HOST_OK = re.compile(r"^[a-z0-9.-]+$")
-_COUNTRY_OK = re.compile(r"^[A-Z]{2}$")
-_NUMERIC_SEGMENT = re.compile(r"^\d+$")
-
-# SPA routes, in the form the dashboard shows them. Any other path a client
-# reports becomes OTHER, so the page list cannot be filled with junk and cannot
-# record which adventure someone is reading.
-KNOWN_ROUTES = {
-    "/", "/adventures", "/scenarios", "/scenarios/:id", "/play/:id",
-    "/scripts", "/scripts/:id", "/settings", "/chat", "/analytics",
-}
-
-# ---------- In-process buffer ----------
-# The deployment is a single process, which is the same assumption `limits.py`
-# makes, so a plain dict under a lock is the whole design. Losing up to a minute
-# of counts to a hard restart is acceptable for traffic numbers, and the flusher
-# also runs on shutdown. On Render's free tier the service is idle when it
-# sleeps, so the buffer it sleeps on is empty.
-
-_counts: dict[tuple[str, str, str], int] = {}
-_visits: dict[tuple[str, str], set[str]] = {}       # (day, visitor) -> flags.
-_labels_seen: dict[tuple[str, str], set[str]] = {}  # (day, metric) -> labels.
-_guard = threading.Lock()
-
-
-def _today() -> str:
-    return models.utcnow().date().isoformat()
-
-
-def record(metric: str, label: str = "", *, n: int = 1) -> None:
-    """Adds `n` to one counter.
-
-    This function never raises. Analytics must not fail a request that it is
-    only observing.
-    """
-    try:
-        day = _today()
-        label = (label or "").strip()[:MAX_LABEL_LEN]
-        with _guard:
-            seen = _labels_seen.setdefault((day, metric), set())
-            if label not in seen:
-                if len(seen) >= MAX_LABELS_PER_METRIC:
-                    label = OTHER
-                else:
-                    seen.add(label)
-            key = (day, metric, label)
-            _counts[key] = _counts.get(key, 0) + n
-            pending = len(_counts) + len(_visits)
-    except Exception:  # pragma: no cover - defensive
-        logger.exception("Analytics counter failed; continuing.")
-        return
-    if pending >= MAX_PENDING:
-        flush()
-
-
-def visitor_id(user: models.User) -> str:
-    """Returns a stable, one-way handle for one visitor.
-
-    The handle is an HMAC of the user id under the app's secret key. It is
-    stable, so a returning visitor can be distinguished from a new one. It is
-    one-way, so nothing in the analytics tables points back at an account. It is
-    keyed, so a client cannot compute one and claim to be someone else. One
-    consequence follows: rotating `AIDND_SECRET_KEY` makes every returning
-    visitor look new.
-    """
-    digest = hmac.new(security.SECRET_KEY, f"visitor:{user.id}".encode(), sha256)
-    return digest.hexdigest()[:32]
-
-
-def record_visit(user: models.User | None, *, flag: str | None = None) -> None:
-    """Records that this visitor was here today, and optionally sets one funnel
-    flag.
-
-    Without a user the call does nothing. A page loaded before a session exists
-    still counts as a pageview, but not as a person.
-    """
-    if user is None:
-        return
-    try:
-        with _guard:
-            flags = _visits.setdefault((_today(), visitor_id(user)), set())
-            if flag:
-                flags.add(flag)
-    except Exception:  # pragma: no cover - defensive
-        logger.exception("Analytics visit failed; continuing.")
-
-
-def record_event(name: str, user: models.User | None = None) -> None:
-    """Records one event, and credits the visitor's day if it is a funnel step.
-
-    This is the whole interface the call sites use.
-    """
-    record(M_EVENT, name)
-    record_visit(user, flag=FUNNEL_FLAGS.get(name))
-
-
-# ---------- Normalizing what the browser reports ----------
-
-def normalize_route(path: str) -> str:
-    """Reduces a client-reported path to one of `KNOWN_ROUTES`.
-
-    Numeric segments become ":id". That bounds the label count, and it keeps
-    which adventure someone opened out of the statistics.
-    """
-    path = (path or "/").split("?")[0].split("#")[0]
-    if not path.startswith("/"):
-        path = "/" + path
-    if len(path) > 1:
-        path = path.rstrip("/")
-    parts = [":id" if _NUMERIC_SEGMENT.match(p) else p for p in path.split("/")]
-    route = "/".join(parts) or "/"
-    return route if route in KNOWN_ROUTES else OTHER
-
-
-def normalize_referrer(referrer: str, own_host: str = "") -> str:
-    """Returns the sending site as a bare host.
-
-    This app's own host means an internal navigation, which is not a referral.
-    In that case the function returns "", which tells the caller to skip it.
-    """
-    if not referrer:
-        return NONE_LABEL
-    host = (urlsplit(referrer).hostname or "").lower().lstrip(".")
-    if not host or not _HOST_OK.match(host) or len(host) > MAX_LABEL_LEN:
-        return OTHER
-    if host == (own_host or "").lower() or host in ("localhost", "127.0.0.1"):
-        return ""
-    return host[4:] if host.startswith("www.") else host
-
-
-def api_route_label(scope: dict, status: int) -> str:
-    """Returns an error bucket such as "500 /api/adventures/{adventure_id}".
-
-    The label uses the route template, never the request path. That keeps one
-    bucket per endpoint rather than one per adventure id. It also bounds the
-    table: an unmatched path is chosen entirely by the caller, so labeling by it
-    would let anyone create rows by requesting arbitrary paths.
-    """
-    template = getattr(scope.get("route"), "path", None)
-    return f"{status} {template}" if template else f"{status} (unmatched)"
-
-
-def device_of(user_agent: str) -> str:
-    """Returns "mobile", "tablet", or "desktop", and nothing more specific.
-
-    The user-agent string itself is never stored, because it is a fingerprint
-    and the useful answer is one word.
-    """
-    ua = (user_agent or "").lower()
-    if not ua:
-        return UNKNOWN
-    if any(bot in ua for bot in ("bot", "crawler", "spider", "headless", "preview")):
-        return "bot"
-    if "ipad" in ua or "tablet" in ua or ("android" in ua and "mobile" not in ua):
-        return "tablet"
-    if any(m in ua for m in ("mobi", "iphone", "ipod", "android", "phone")):
-        return "mobile"
-    return "desktop"
-
-
-# Geo headers an edge network may add. Render fronts services with a CDN that
-# can set `cf-ipcountry`, and the others cost nothing to check. A value is
-# trusted only if it looks like an ISO code, because a client can send any
-# header, so the worst case is a wrong country rather than an unbounded label.
-_GEO_HEADERS = ("cf-ipcountry", "x-vercel-ip-country", "x-geo-country", "x-country-code")
-
-
-def country_of(headers) -> str:
-    for name in _GEO_HEADERS:
-        value = (headers.get(name) or "").strip().upper()
-        if _COUNTRY_OK.match(value) and value != "XX":
-            return value
-    return UNKNOWN
-
-
-# ---------- Flushing ----------
-
-def _insert(db: Session):
-    return sqlite_insert if db.get_bind().dialect.name == "sqlite" else pg_insert
-
-
-def _drain() -> tuple[dict, dict]:
-    with _guard:
-        counts, visits = _counts.copy(), _visits.copy()
-        _counts.clear()
-        _visits.clear()
-        # The label sets bound cardinality within one day, so drop the
-        # previous day's rather than grow a map that never shrinks.
-        today = _today()
-        for key in [k for k in _labels_seen if k[0] != today]:
-            del _labels_seen[key]
-    return counts, visits
-
-
-def _restore(counts: dict, visits: dict) -> None:
-    """Returns a failed flush's work to the buffer, so the next flush retries it."""
-    with _guard:
-        for key, n in counts.items():
-            _counts[key] = _counts.get(key, 0) + n
-        for key, flags in visits.items():
-            _visits.setdefault(key, set()).update(flags)
-
-
-def flush(db: Session | None = None) -> None:
-    """Writes the buffer out. This is safe to call from anywhere and never raises."""
-    counts, visits = _drain()
-    if not counts and not visits:
-        return
-    own_session = db is None
-    if own_session:
-        from .database import SessionLocal
-        db = SessionLocal()
-    try:
-        _write_counts(db, counts)
-        _write_visits(db, visits)
-        db.commit()
-    except Exception:
-        db.rollback()
-        _restore(counts, visits)
-        logger.exception("Analytics flush failed; counts held for the next one.")
-    finally:
-        if own_session:
-            db.close()
-
-
-def _write_counts(db: Session, counts: dict) -> None:
-    if not counts:
-        return
-    table = models.AnalyticsDaily.__table__
-    rows = [
-        {"day": day, "metric": metric, "label": label, "hits": hits}
-        for (day, metric, label), hits in counts.items()
-    ]
-    stmt = _insert(db)(table).values(rows)
-    db.execute(stmt.on_conflict_do_update(
-        index_elements=["day", "metric", "label"],
-        set_={"hits": table.c.hits + stmt.excluded.hits},
-    ))
-
-
-def _write_visits(db: Session, visits: dict) -> None:
-    if not visits:
-        return
-    table = models.AnalyticsVisitorDay.__table__
-    ids = {visitor for _, visitor in visits}
-    # One indexed lookup decides new against returning for the whole batch. It
-    # is the only read this module makes outside the dashboard, and it returns
-    # short hashes for the visitors active right now, so the batch bounds it.
-    known = set(db.scalars(
-        select(models.AnalyticsVisitorDay.visitor)
-        .where(models.AnalyticsVisitorDay.visitor.in_(ids))
-        .distinct()
-    ))
-    rows = [
-        {
-            "day": day,
-            "visitor": visitor,
-            "is_new": visitor not in known,
-            **{column: column in flags for column in FUNNEL_FLAGS.values()},
-        }
-        for (day, visitor), flags in visits.items()
-    ]
-    stmt = _insert(db)(table).values(rows)
-    db.execute(stmt.on_conflict_do_update(
-        index_elements=["day", "visitor"],
-        # Flags only turn on, and `is_new` is absent on purpose. The first
-        # write of a visitor's first day is what decided it.
-        set_={
-            column: or_(table.c[column], stmt.excluded[column])
-            for column in FUNNEL_FLAGS.values()
-        },
-    ))
-
-
-def purge_old_visitor_days(db: Session) -> int:
-    """Deletes visitor-day rows past the retention horizon.
-
-    The cleanup sweeper calls this. The daily counters are never purged, because
-    they are aggregates, they are small, and this project keeps its history.
-    """
-    if RETENTION_DAYS <= 0:
-        return 0
-    cutoff = (models.utcnow().date() - timedelta(days=RETENTION_DAYS)).isoformat()
-    removed = db.query(models.AnalyticsVisitorDay).filter(
-        models.AnalyticsVisitorDay.day < cutoff
-    ).delete(synchronize_session=False)
-    db.commit()
-    return removed or 0
-
-
-# ---------- Reading it back ----------
-# Every query below is an aggregate. The database does the counting and returns
-# tens of rows, however much traffic is behind them. No query here can return a
-# row that belongs to one visitor.
-
-TOP_N = 12
-
-
-def _top(rows: list[dict], limit: int = TOP_N) -> list[dict]:
-    return rows[:limit]
-
-
-def summary(db: Session, days: int = 30) -> dict:
-    """Returns everything the dashboard shows for the last `days` days, including
-    today.
-
-    The function flushes first, so the numbers include the last minute.
-    """
-    flush(db)
-    today = models.utcnow().date()
-    since = (today - timedelta(days=days - 1)).isoformat()
-    daily = models.AnalyticsDaily
-    visitor = models.AnalyticsVisitorDay
-
-    # 1. Every counter in the window, reduced to (metric, label) totals. The
-    #    page, referrer, country, device, scenario, and error tables all come
-    #    from this one pass rather than from a query each.
-    by_metric: dict[str, list[dict]] = {}
-    for metric, label, hits in db.execute(
-        select(daily.metric, daily.label, func.sum(daily.hits))
-        .where(daily.day >= since)
-        .group_by(daily.metric, daily.label)
-    ):
-        by_metric.setdefault(metric, []).append({"label": label, "hits": int(hits)})
-    for rows in by_metric.values():
-        rows.sort(key=lambda row: -row["hits"])
-    events = {row["label"]: row["hits"] for row in by_metric.get(M_EVENT, [])}
-
-    # 2. The two per-day series the dashboard draws.
-    pageviews_by_day = {
-        day: int(hits)
-        for day, hits in db.execute(
-            select(daily.day, func.sum(daily.hits))
-            .where(daily.day >= since, daily.metric == M_PAGE)
-            .group_by(daily.day)
-        )
-    }
-    turns_by_day = {
-        day: int(hits)
-        for day, hits in db.execute(
-            select(daily.day, func.sum(daily.hits))
-            .where(daily.day >= since, daily.metric == M_EVENT, daily.label == EV_TURN)
-            .group_by(daily.day)
-        )
-    }
-
-    # 3. People, per day. There is one row per visitor per day, so COUNT(*) is
-    #    already the day's unique visitors and no DISTINCT is needed.
-    visitors_by_day: dict[str, dict] = {}
-    for day, total, fresh in db.execute(
-        select(
-            visitor.day,
-            func.count(),
-            func.sum(case((visitor.is_new, 1), else_=0)),
-        )
-        .where(visitor.day >= since)
-        .group_by(visitor.day)
-    ):
-        visitors_by_day[day] = {"visitors": int(total), "new": int(fresh or 0)}
-
-    # 4. The funnel over the whole window, counting each person once.
-    #    COUNT(DISTINCT CASE WHEN flag THEN visitor END) ignores the NULLs the
-    #    CASE leaves for everyone who did not reach that step.
-    unique, unique_new, *reached = db.execute(
-        select(
-            func.count(func.distinct(visitor.visitor)),
-            func.count(func.distinct(case((visitor.is_new, visitor.visitor)))),
-            *[
-                func.count(func.distinct(case((visitor.__table__.c[column], visitor.visitor))))
-                for column in FUNNEL_FLAGS.values()
-            ],
-        ).where(visitor.day >= since)
-    ).one()
-
-    series = []
-    for offset in range(days):
-        day = (today - timedelta(days=days - 1 - offset)).isoformat()
-        counted = visitors_by_day.get(day, {})
-        series.append({
-            "day": day,
-            "visitors": counted.get("visitors", 0),
-            "new": counted.get("new", 0),
-            "pageviews": pageviews_by_day.get(day, 0),
-            "turns": turns_by_day.get(day, 0),
-        })
-
-    visits = sum(row["visitors"] for row in series)
-    pageviews = sum(pageviews_by_day.values())
-    turns = events.get(EV_TURN, 0)
-    errors = by_metric.get(M_ERROR, [])
-    return {
-        "days": days,
-        "since": since,
-        "until": today.isoformat(),
-        "generated_at": models.utcnow().isoformat(),
-        "totals": {
-            # `visitors` counts each person once for the window. `visits`
-            # counts them once per day they returned, which is the closest
-            # measure to "sessions" that does not track sessions.
-            "visitors": int(unique),
-            "new_visitors": int(unique_new),
-            "visits": visits,
-            "pageviews": pageviews,
-            "turns": turns,
-            "demo_turns": events.get(EV_DEMO_TURN, 0),
-            "adventures": events.get(EV_ADVENTURE, 0),
-            "signups": events.get(EV_SIGNUP, 0),
-            "logins": events.get(EV_LOGIN, 0),
-            "turn_errors": events.get(EV_TURN_ERROR, 0),
-            "errors": sum(row["hits"] for row in errors),
-            "turns_per_visit": round(turns / visits, 1) if visits else 0,
-            "pages_per_visit": round(pageviews / visits, 1) if visits else 0,
-        },
-        "series": series,
-        # Step 0 is everyone who arrived, so the drop-off between it and
-        # "Opened a scenario" appears as a step like any other.
-        "funnel": [{"step": "Visited", "count": int(unique)}] + [
-            {"step": step, "count": int(count)}
-            for step, count in zip(
-                ["Opened a scenario", "Started an adventure", "Played a turn", "Signed up"],
-                reached,
-            )
-        ],
-        "pages": _top(by_metric.get(M_PAGE, [])),
-        "referrers": _top(by_metric.get(M_REFERRER, [])),
-        "countries": _top(by_metric.get(M_COUNTRY, [])),
-        "devices": by_metric.get(M_DEVICE, []),
-        "scenarios": _top(by_metric.get(M_SCENARIO, [])),
-        "errors": _top(errors),
-        "events": by_metric.get(M_EVENT, []),
-    }
-
-
-# ---------- Background flusher ----------
-# This matches the start and stop pair in `cleanup`, so the lifespan in
-# `main.py` reads the same way for both. The interval bounds how much a hard
-# restart can lose.
-
-async def _flush_loop() -> None:
-    import asyncio
-
-    from starlette.concurrency import run_in_threadpool
-
-    while True:
-        await asyncio.sleep(FLUSH_INTERVAL_SECONDS)
-        # This is blocking database work, so keep it off the event loop, which
-        # is also serving SSE turn streams.
-        await run_in_threadpool(flush)
-
-
-def start_flusher():
-    import asyncio
-
-    return asyncio.create_task(_flush_loop())
-
-
-async def stop_flusher(task) -> None:
-    """Cancels the loop and writes out whatever it was holding.
-
-    A deploy is the one restart that is both frequent and predictable, so it
-    should not be what loses a minute of counts.
-    """
-    import asyncio
-
-    from starlette.concurrency import run_in_threadpool
-
-    if task is not None:
-        task.cancel()
-        try:
-            await task
-        except asyncio.CancelledError:
-            pass
-    await run_in_threadpool(flush)

backend/app/attempts.py

@@ -41,11 +41,11 @@ from .context import lineage
 
 # The slices of a context snapshot that belong to one attempt rather than to the
 # turn. They are the world-state delta the attempt proposed and what the engine
-# did with it, the script report, the model's literal reply, and the endpoint's
+# did with it, the model's literal reply, and the endpoint's
 # token accounting. Each attempt is its own API call, and a retry is the call
 # most likely to read the prompt back out of cache. Everything else in a snapshot
 # is the prompt, which is assembled once per turn.
-ATTEMPT_KEYS = ("world_state", "script", "raw_output", "usage")
+ATTEMPT_KEYS = ("world_state", "raw_output", "usage")
 
 
 # ------------------------------------------------------------------ reading
@@ -152,7 +152,7 @@ def preceding(
 # ------------------------------------------------------------------ writing
 
 def restore_state(adventure: models.Adventure, node: models.Action | None) -> None:
-    """Restores the script state and world state that `node` left behind.
+    """Restores the world state that `node` left behind.
 
     A NULL snapshot means leave the live state as it is, never reset it. Rows
     written before SP4 that the migration could not derive an outcome for carry
@@ -161,17 +161,16 @@ def restore_state(adventure: models.Adventure, node: models.Action | None) -> No
     """
     if node is None:
         return
-    if isinstance(node.state_after, dict):
-        adventure.script_state = copy.deepcopy(node.state_after)
     if isinstance(node.world_state_after, dict):
         adventure.world_state = copy.deepcopy(node.world_state_after)
 
 
 def snapshot_outcome(adventure: models.Adventure, node: models.Action) -> None:
     """Records on `node` the state of the adventure now that the node has played."""
-    state = adventure.script_state if isinstance(adventure.script_state, dict) else {}
     world = adventure.world_state if isinstance(adventure.world_state, dict) else {}
-    node.state_after = copy.deepcopy(state)
+    # `state_after` held the scripting engine's shared state, which M2 removed.
+    # The column stays for schema compatibility and is written empty.
+    node.state_after = {}
     node.world_state_after = copy.deepcopy(world)
 
 

backend/app/auth.py

@@ -1,216 +1,44 @@
-"""Phase 8: user resolution, sessions, and the shared demo key.
+"""Resolving the one local user. **There is no authentication in this product.**
 
-The `AIDND_MULTI_USER` environment variable selects one of two modes:
+The module keeps its name so the dependency every router already depends on
+keeps working, but nothing here authenticates anybody. The Adventure
+Storyteller is a single-user application that binds to loopback: whoever can
+reach the API is the person who started it, and there is nobody else to tell
+them apart from.
 
-* Local mode, the default. Every request resolves to one automatically created
-  local user. There are no cookies and no login UI, so a clone or a
-  docker-compose run behaves like the single-user app from before Phase 8.
-* Multi-user mode, used for hosted deployments. Requests carry a signed session
-  cookie. `GET /api/auth/me` creates a guest user on the first visit, and
-  registering upgrades that guest in place so their data survives. A request
-  without a valid session gets a 401, and the frontend re-establishes the
-  session through `/me`.
+Upstream had two modes. `AIDND_MULTI_USER` selected a hosted deployment with
+signed session cookies, guest accounts, registration, login, a shared demo API
+key with a per-day cap, "power users", and an owner allowlist for the analytics
+dashboard. M2 removed all of it: this product has no hosted mode to protect, and
+every one of those surfaces was a way for the application to be reached by
+someone other than its owner.
 
-The shared demo key, which is the fallback when a user brings no key of their
-own, is also configured here. A user whose settings hold no API key is routed to
-a server-funded endpoint with a model allowlist and a per-day turn cap.
+What is left is the local path that upstream already had. Every request
+resolves to one automatically created user row.
+
+The `users` table and the `user_id` foreign keys on scenarios, adventures and
+settings stay. They are an **internal ownership detail**, not an account
+system: nothing creates a second user, nothing logs in, and no request carries
+an identity. They remain because rewriting them out would mean a migration
+across most of the schema to delete a column that costs nothing and keeps every
+existing M1 database readable.
 """
 
-import os
-from dataclasses import dataclass
 from datetime import timezone
 
-from fastapi import Depends, HTTPException, Request
+from fastapi import Depends, Request
 from sqlalchemy.orm import Session
 
-from . import models, security
+from . import models
 from .database import get_db
 
 
-def _env_flag(name: str) -> bool:
-    return os.environ.get(name, "").strip().lower() in ("1", "true", "yes", "on")
-
-
-MULTI_USER = _env_flag("AIDND_MULTI_USER")
-
-SESSION_COOKIE = "aidnd_session"
-# Secure cookies are on by default in multi-user mode, because a hosted
-# deployment serves HTTPS and browsers also accept Secure on http://localhost.
-# `AIDND_COOKIE_SECURE` overrides the default with 0 or 1. Use 0 when testing
-# multi-user mode over plain HTTP on a LAN address.
-_cookie_secure_env = os.environ.get("AIDND_COOKIE_SECURE", "").strip().lower()
-COOKIE_SECURE = (
-    _cookie_secure_env in ("1", "true", "yes", "on")
-    if _cookie_secure_env
-    else MULTI_USER
-)
-COOKIE_MAX_AGE = 60 * 60 * 24 * 365
-
-# ---------- Shared demo key (BYOK fallback) ----------
-
-DEMO_API_KEY = os.environ.get("AIDND_DEMO_API_KEY", "").strip()
-DEMO_ENDPOINT_URL = (
-    os.environ.get("AIDND_DEMO_ENDPOINT_URL", "").strip()
-    or "https://openrouter.ai/api/v1"
-)
-DEMO_MODELS = [
-    m.strip()
-    for m in os.environ.get("AIDND_DEMO_MODELS", "").split(",")
-    if m.strip()
-] or ["google/gemma-4-26b-a4b-it:free"]
-DEMO_TURNS_PER_DAY = int(os.environ.get("AIDND_DEMO_TURNS_PER_DAY", "20") or 20)
-
-# Trusted testers, listed by email, who bypass the daily demo cap and take
-# unmetered turns on the shared demo key. The list is comma-separated, and the
-# match ignores case.
-POWER_USERS = {
-    e.strip().lower()
-    for e in os.environ.get("AIDND_POWER_USERS", "").split(",")
-    if e.strip()
-}
-
-# Who can see the visit analytics. This is a separate list from `POWER_USERS` on
-# purpose. A trusted tester gets unmetered turns and the AI Chat page, which is
-# not a reason to give them the site's traffic numbers. An empty list, which is
-# the default, means nobody sees the dashboard in a hosted deployment.
-ANALYTICS_EMAILS = {
-    e.strip().lower()
-    for e in os.environ.get("AIDND_ANALYTICS_EMAILS", "").split(",")
-    if e.strip()
-}
-
-DEMO_CAP_MESSAGE = (
-    f"You've used all {DEMO_TURNS_PER_DAY} free demo turns for today. "
-    "Add your own API key in Settings to keep playing (it resets tomorrow)."
-)
-
-
-def demo_enabled() -> bool:
-    # The demo key is a hosted-deployment feature. A local install talks to
-    # whatever endpoint Settings points at, even with no API key, such as
-    # Ollama.
-    return MULTI_USER and bool(DEMO_API_KEY)
-
-
-@dataclass
-class ProviderConfig:
-    """What the turn engine connects with, after the decision between a
-    user-supplied key and the demo key.
-
-    Build one of these with `resolve_provider_config()`.
-    """
-
-    endpoint_url: str
-    api_key: str
-    model: str
-    using_demo: bool
-
-    def __post_init__(self) -> None:
-        # A second guard around server-funded turns. `resolve_provider_config()`
-        # already pins the model, and this makes the pin a property of the config
-        # object too, so a later caller cannot construct an unpinned one. This
-        # raise is unreachable by design. Reaching it means a new code path
-        # bypassed the pinning, which is worth failing on rather than billing
-        # for.
-        #
-        # The test is `using_demo`, not `api_key == DEMO_API_KEY`. Keying on the
-        # key value looks stricter and is wrong. The demo key is an ordinary
-        # OpenRouter key, so a user can legitimately paste that same key into
-        # their own Settings. Every resolution then raised, which returned a 500
-        # even from `GET /auth/me` and took the whole SPA down. `using_demo` is
-        # what means the server is paying, and only the demo branch below sets
-        # it.
-        if self.using_demo and self.model not in DEMO_MODELS:
-            raise ValueError(
-                f"Refusing to use the shared demo key with non-whitelisted model {self.model!r}"
-            )
-
-
-def resolve_provider_config(
-    settings: models.Settings, *, model_override: str | None = None
-) -> ProviderConfig:
-    """Returns the user's own key when they have one, and the shared demo key
-    otherwise.
-
-    The demo branch is the security-relevant one, and it is the only place the
-    allowlist rule lives. Every caller has to come through this function rather
-    than build a `ProviderConfig` itself. On the demo key:
-
-    * The model is pinned to `DEMO_MODELS`, so a caller-supplied override from
-      the AI Chat page, or a hand-edited Settings row, cannot point a
-      server-funded key at a paid model. An unrecognized model falls back to
-      `DEMO_MODELS[0]`.
-    * The endpoint is pinned to `DEMO_ENDPOINT_URL`, so the key cannot be
-      redirected to a URL the user controls and captured there.
-
-    `model_override` is a per-request preference and never a grant. It is used
-    verbatim with the user's own key, and on the demo key only when the model is
-    on the allowlist.
-    """
-    key = settings.api_key_plain
-    requested = (model_override or "").strip() or settings.model
-    if key or not demo_enabled():
-        return ProviderConfig(settings.endpoint_url, key, requested, False)
-    model = requested if requested in DEMO_MODELS else DEMO_MODELS[0]
-    return ProviderConfig(DEMO_ENDPOINT_URL, DEMO_API_KEY, model, True)
-
-
-def _today() -> str:
-    return models.utcnow().date().isoformat()
-
-
-def is_power_user(user: models.User) -> bool:
-    """Returns whether this user is a trusted tester.
-
-    A trusted tester gets unmetered demo turns, plus tooling that is not part of
-    the game, such as the AI Chat scratchpad. A local install is always trusted,
-    because it runs on the operator's own machine with their own API key. The
-    provider debug log is local-only for the same reason.
-    """
-    if not MULTI_USER:
-        return True
-    return bool(user.email) and user.email.lower() in POWER_USERS
-
-
-def is_owner(user: models.User) -> bool:
-    """Returns whether this user may see the visit analytics.
-
-    A local install always may, because it runs on the operator's own machine and
-    shows their own visits. The provider debug log follows the same reasoning. A
-    hosted deployment checks `AIDND_ANALYTICS_EMAILS`.
-    """
-    if not MULTI_USER:
-        return True
-    return bool(user.email) and user.email.lower() in ANALYTICS_EMAILS
-
-
-def demo_turns_left(user: models.User) -> int:
-    # A power user is never capped, so report the full cap and let the banner
-    # read "N of N" rather than count down.
-    if is_power_user(user):
-        return DEMO_TURNS_PER_DAY
-    used = user.demo_turns_used if user.demo_turns_date == _today() else 0
-    return max(0, DEMO_TURNS_PER_DAY - used)
-
-
-def count_demo_turn(user: models.User) -> None:
-    """Records one demo turn. The caller's commit stores it."""
-    if is_power_user(user):
-        return  # A power user's turns do not count against the cap.
-    today = _today()
-    if user.demo_turns_date != today:
-        user.demo_turns_date = today
-        user.demo_turns_used = 0
-    user.demo_turns_used += 1
-
-
-# ---------- User resolution ----------
-
 def local_user(db: Session) -> models.User:
-    """Returns the single implicit user used in local mode.
+    """Returns the single implicit user, creating it on first use.
 
-    A migration gives this user ownership of data written before Phase 8. On a
-    fresh database the user is created on first use.
+    A migration gives this user ownership of data written before per-user rows
+    existed, so an older database resolves to the row that already owns its
+    campaigns rather than to a fresh empty one.
     """
     user = (
         db.query(models.User)
@@ -237,27 +65,14 @@ def _touch(user: models.User, db: Session) -> None:
         db.commit()
 
 
-def resolve_session_user(request: Request, db: Session) -> models.User | None:
-    token = request.cookies.get(SESSION_COOKIE)
-    if not token:
-        return None
-    user_id = security.verify_session(token)
-    if user_id is None:
-        return None
-    return db.get(models.User, user_id)
+def get_current_user(
+    request: Request, db: Session = Depends(get_db)
+) -> models.User:
+    """The dependency every router uses. It always succeeds.
 
-
-def get_current_user(request: Request, db: Session = Depends(get_db)) -> models.User:
-    """The dependency every router uses to resolve the current user.
-
-    In multi-user mode a 401 means the frontend has to establish a session again
-    through `GET /api/auth/me`.
+    `request` is unused and kept so the signature stays a FastAPI dependency
+    the routers can depend on unchanged.
     """
-    if not MULTI_USER:
-        user = local_user(db)
-    else:
-        user = resolve_session_user(request, db)
-        if user is None:
-            raise HTTPException(401, "No session. Call GET /api/auth/me first.")
+    user = local_user(db)
     _touch(user, db)
     return user

backend/app/bundle.py

@@ -32,8 +32,19 @@ the import recomputes them:
 * `lineage` is a cache of `parent` plus `fork_depth`. Shipping it as well would
   put a second source of truth for one fact into a file anyone can hand-edit,
   and the two could then disagree without any read reporting it.
-* The head depth is the tip of the head branch, which is a fact about the nodes
-  that arrived with it.
+* The head depth used to be derived the same way — the tip of the head branch,
+  a fact about the nodes that arrived with it. M3 moved it to the other side of
+  the rule. Undo no longer deletes, so a story can be read at a position behind
+  its retained tip, and where the reader stopped is a decision nobody can
+  recompute from the rows: the same tree exports identically whether the user
+  undid three turns or none. `headDepth` is therefore written, and an import
+  that ignored it would silently Redo the story to its newest retained turn,
+  which is the Phase 0B export finding this milestone exists to close.
+
+A bundle written before M3 has no `headDepth` key, and there is nothing lost in
+that: at the time it was written the head could not sit behind the tip, so the
+derived answer *was* the recorded one. Such a file imports by deriving, exactly
+as it always did.
 
 Every hand-editable coordinate is therefore checked before a row is written, in
 `plan`, rather than repaired afterwards. An import that fails partway leaves an
@@ -109,7 +120,6 @@ def export(db: Session, adventure: models.Adventure) -> dict:
             "pronouns": adventure.persona_pronouns,
             "desc": adventure.persona_desc,
         },
-        "scriptState": adventure.script_state,
         "worldState": adventure.world_state,
         "autoSummarize": adventure.auto_summarize,
         "memoryBankEnabled": adventure.memory_bank_enabled,
@@ -118,23 +128,27 @@ def export(db: Session, adventure: models.Adventure) -> dict:
         # belongs to is the root. `_local` places its nodes there.
         "branches": [_exported_branch(b, local) for b in branches] or [_ROOT],
         "headBranch": local.get(adventure.head_branch_id, 0),
+        # M3. Where the story is being read, which is not always where it
+        # ends. See the head-depth rule at the top of this module.
+        "headDepth": adventure.head_depth,
         "memoryCursor": _exported_anchor(adventure, cursors.MEMORY, local),
         "summaryCursor": _exported_anchor(adventure, cursors.SUMMARY, local),
         "memories": [_exported_memory(m, local) for m in adventure.memories],
+        # M4. A Save Point is a decision — someone chose this position and gave
+        # it a name — so it goes in the file by the rule at the top of this
+        # module. Nothing here is derived: the coordinate is the one stored, not
+        # one recomputed from the rows, because the whole point of the pointer
+        # is that no amount of reading the turns can tell you which one somebody
+        # named. A bundle written before M4 has no key here and imports with no
+        # Save Points, which is what such a campaign had.
+        "checkpoints": [
+            _exported_checkpoint(c, local) for c in _checkpoints_of(db, adventure)
+        ],
         "storyCards": [
             {"type": c.type, "name": c.name, "keys": c.keys,
              "entry": c.entry, "notes": c.notes}
             for c in adventure.story_cards
         ],
-        "scripts": [
-            {
-                "position": s.position, "enabled": s.enabled,
-                "name": s.name, "description": s.description,
-                "library": s.library_js, "input": s.input_js,
-                "context": s.context_js, "output": s.output_js,
-            }
-            for s in adventure.scripts
-        ],
         "actions": [_exported_node(a, local) for a in nodes],
     }
 
@@ -161,6 +175,15 @@ def _exported_branch(branch: models.Branch, local: dict[int, int]) -> dict:
     # unnamed tree byte-identical to the one SP6 wrote.
     if branch.name:
         out["name"] = branch.name
+    # M3. A branch the story left behind is a decision too — the depth a
+    # divergent write departed at — so it goes in the file by the same rule that
+    # puts the fork points in it. A restored backup that could not tell abandoned
+    # history from active history would have lost the only thing distinguishing
+    # them, since every row of both arrives either way. Omitted when the branch
+    # is active, which keeps a file for a never-undone tree as it was.
+    if branch.superseded_at is not None:
+        out["supersededAt"] = branch.superseded_at.isoformat()
+        out["supersededDepth"] = branch.superseded_depth
     return out
 
 
@@ -202,6 +225,35 @@ def _exported_memory(memory: models.Memory, local: dict[int, int]) -> dict:
     }
 
 
+def _checkpoints_of(db: Session, adventure: models.Adventure) -> list[models.Checkpoint]:
+    """Returns the campaign's Save Points in creation order.
+
+    Read with a query rather than through a relationship, for the reason
+    `models.Branch` declares none: a relationship on `Adventure` would be loaded
+    by anything that touches an adventure, and the export is the only thing in
+    the application that wants every Save Point at once.
+    """
+    return (
+        db.query(models.Checkpoint)
+        .filter(models.Checkpoint.adventure_id == adventure.id)
+        .order_by(models.Checkpoint.id)
+        .all()
+    )
+
+
+def _exported_checkpoint(checkpoint: models.Checkpoint, local: dict[int, int]) -> dict:
+    return {
+        "name": checkpoint.name,
+        "note": checkpoint.note,
+        # The branch as a position in this file's list, like every other branch
+        # reference in the bundle. The depth is a coordinate along it and needs
+        # no translation.
+        "branch": _local(checkpoint.branch_id, local),
+        "depth": checkpoint.depth,
+        "createdAt": checkpoint.created_at.isoformat() if checkpoint.created_at else None,
+    }
+
+
 def _imported_persona(persona) -> dict:
     """Reads a bundle's `persona` block into `Adventure` keyword arguments.
 
@@ -262,11 +314,23 @@ def plan(bundle: dict, version: str) -> dict:
         _planned_nodes(bundle, len(branches)) if version == FORMAT
         else _planned_v1_nodes(bundle)
     )
+    head = _as_index(bundle.get("headBranch"), len(branches), default=0)
     return {
         "branches": branches,
         "nodes": nodes,
         "memories": _planned_memories(bundle, len(branches)),
-        "head": _as_index(bundle.get("headBranch"), len(branches), default=0),
+        # M4. Empty for a version 1 bundle and for any version 2 bundle written
+        # before Save Points existed, which is the same answer: no one had named
+        # a position in those campaigns.
+        "checkpoints": (
+            _planned_checkpoints(bundle, len(branches), nodes)
+            if version == FORMAT else []
+        ),
+        "head": head,
+        # None means the file does not say, which is every version 1 bundle and
+        # every version 2 bundle written before M3. `_point_the_head` derives it
+        # then, which is what those files were written expecting.
+        "headDepth": _planned_head_depth(bundle, branches, nodes, head),
         # Version 2 records where the derived work reached. Version 1 counted
         # it, and a count cannot become a node until the nodes exist. See
         # `settle`.
@@ -278,6 +342,58 @@ def plan(bundle: dict, version: str) -> dict:
     }
 
 
+def _derived_tip(branches: list[dict], nodes: list[dict], head: int) -> int:
+    """Returns where the head branch's story ends, which is where a file that
+    does not state a head depth is opened.
+
+    This is the rule `tree.refresh_head` applies and the one every bundle
+    written before M3 was exported under: the deepest node that arrived on the
+    head branch, or, for a branch that carries none of its own, the fork point
+    it inherits its story up to.
+    """
+    depths = [n["depth"] for n in nodes if n["branch"] == head]
+    if depths:
+        return max(depths)
+    fork_depth = branches[head].get("forkDepth")
+    return fork_depth if fork_depth is not None else lineage.NO_DEPTH
+
+
+def _planned_head_depth(
+    bundle: dict, branches: list[dict], nodes: list[dict], head: int
+) -> int | None:
+    """Returns the active head depth the file states, or None if it states none.
+
+    Checked here rather than repaired later, for the reason the module docstring
+    gives: a coordinate that disagrees with the rows is not a value any read can
+    be given, and an import that discovers it afterwards has already written
+    half a tree.
+
+    Two bounds. A head past the retained tip is a file claiming the story is
+    read somewhere it does not reach — the shape a truncated or hand-edited
+    export takes, and the one that would silently move the reader forward.
+    Below, `NO_DEPTH` is the floor, because an adventure with no story at all
+    sits one step in front of its first node.
+
+    A head *behind* the tip is not an error. It is the whole point: it is a
+    story the user undid and did not redo, and it must import undone.
+    """
+    stated = bundle.get("headDepth")
+    if stated is None:
+        return None
+    tip = _derived_tip(branches, nodes, head)
+    if not _is_int(stated) or stated < lineage.NO_DEPTH:
+        raise HTTPException(
+            400, f"The file gives the active head depth as {stated!r}."
+        )
+    if stated > tip:
+        raise HTTPException(
+            400,
+            f"The file reads its story at depth {stated}, but branch {head} "
+            f"ends at {tip}.",
+        )
+    return stated
+
+
 def _planned_branches(bundle: dict) -> list[dict]:
     raw = bundle.get("branches")
     entries = [b for b in raw if isinstance(b, dict)] if isinstance(raw, list) else []
@@ -287,8 +403,9 @@ def _planned_branches(bundle: dict) -> list[dict]:
     for i, entry in enumerate(entries):
         parent = entry.get("parent")
         name = _planned_branch_name(entry, i)
+        left = _planned_supersession(entry)
         if parent is None:
-            specs.append(dict(_ROOT, **({"name": name} if name else {})))
+            specs.append(dict(_ROOT, **({"name": name} if name else {}), **left))
             continue
         # A branch may fork only from a branch listed before it. The export
         # writes them that way, because branches are numbered in creation order
@@ -312,10 +429,27 @@ def _planned_branches(bundle: dict) -> list[dict]:
         specs.append({
             "parent": parent, "forkDepth": fork_depth,
             **({"name": name} if name else {}),
+            **left,
         })
     return specs
 
 
+def _planned_supersession(entry: dict) -> dict:
+    """Returns the branch's disposition as the file gives it, or nothing.
+
+    Both keys or neither. A time with no depth cannot say what was displaced and
+    a depth with no time is not a record of anything having happened, so a file
+    carrying one of them is treated as carrying neither rather than half of a
+    fact — no read depends on these columns, and inventing the missing half
+    would be the only way to get a wrong answer out of them.
+    """
+    at = _as_time(entry.get("supersededAt"))
+    depth = entry.get("supersededDepth")
+    if at is None or not _is_int(depth):
+        return {}
+    return {"supersededAt": at, "supersededDepth": depth}
+
+
 def _planned_branch_name(entry: dict, i: int) -> str | None:
     """Returns the name a branch entry carries, or `None` if nobody named it.
 
@@ -437,6 +571,57 @@ def _planned_memories(bundle: dict, branches: int) -> list[dict]:
     return out
 
 
+def _planned_checkpoints(
+    bundle: dict, branches: int, nodes: list[dict]
+) -> list[dict]:
+    """Returns the file's Save Points, checked against the tree it also carries.
+
+    A Save Point whose coordinate names no turn in the file is dropped rather
+    than imported, and dropped rather than raising. The two halves of that are
+    each deliberate:
+
+    * Dropped, because an imported pointer to a position the imported story does
+      not contain is a Save Point that can only ever refuse to restore. It would
+      be a row that exists to disappoint.
+    * Not a 400, unlike the head depth. The head is a position the campaign is
+      read at, so a file that misplaces it opens the story in the wrong place
+      and every read is affected. A Save Point is a bookmark, and a bad one
+      spoils nothing else in the file — refusing to import a whole campaign
+      because one bookmark is wrong would lose the story to save the bookmark.
+
+    A name that is blank once trimmed is dropped for the same reason the create
+    endpoint refuses one: an unnamed Save Point is not identifiable in a list.
+    """
+    # Every coordinate the file writes, not only the ones it marks live.
+    # `_write_nodes` makes exactly one attempt at each coordinate live whatever
+    # the file says, so a coordinate that exists is a coordinate that will
+    # resolve — and reading the flags here would drop a Save Point over a
+    # question the writer has already settled.
+    written = {(n["branch"], n["depth"]) for n in nodes}
+    raw = bundle.get("checkpoints")
+    out: list[dict] = []
+    for entry in raw if isinstance(raw, list) else []:
+        if not isinstance(entry, dict):
+            continue
+        name = str(entry.get("name") or "").strip()[:schemas.CHECKPOINT_NAME_MAX]
+        if not name:
+            continue
+        depth = entry.get("depth")
+        if not _is_int(depth):
+            continue
+        branch = _as_index(entry.get("branch"), branches, default=None)
+        if branch is None or (branch, depth) not in written:
+            continue
+        out.append({
+            "name": name,
+            "note": str(entry.get("note") or ""),
+            "branch": branch,
+            "depth": depth,
+            "createdAt": _as_time(entry.get("createdAt")),
+        })
+    return out
+
+
 def _planned_anchors(bundle: dict, branches: int) -> dict:
     anchors = {}
     for name in ("memory", "summary"):
@@ -462,6 +647,7 @@ def write(db: Session, adventure: models.Adventure, story: dict) -> None:
     _write_nodes(db, adventure, story["nodes"], ids)
     _write_memories(db, adventure, story["memories"], ids)
     _point_the_head(adventure, story, ids)
+    _write_checkpoints(db, adventure, story["checkpoints"], ids)
     _write_anchors(adventure, story, ids)
 
 
@@ -489,6 +675,8 @@ def _write_branches(
                 lineage=[],
                 name=spec.get("name"),
                 created_at=models.utcnow(),
+                superseded_at=spec.get("supersededAt"),
+                superseded_depth=spec.get("supersededDepth"),
             )
         ).inserted_primary_key[0]
         entries = [[new_id, None]]
@@ -575,25 +763,53 @@ def _write_memories(
         db.add(memory)
 
 
+def _write_checkpoints(
+    db: Session, adventure: models.Adventure, specs: list[dict], ids: list[int]
+) -> None:
+    """Writes the Save Points, and moves nothing.
+
+    Note what this function does not touch. The head is pointed by
+    `_point_the_head` from the file's own `headBranch`/`headDepth`, and importing
+    a Save Point must not disturb it — a campaign exported at turn 30 with a
+    Save Point at turn 12 opens at turn 30. The bundle records where the story
+    was being read and, separately, which positions someone named; restoring one
+    of them is a thing the user does afterwards, not a thing an import does for
+    them.
+    """
+    for spec in specs:
+        checkpoint = models.Checkpoint(
+            adventure_id=adventure.id,
+            name=spec["name"],
+            note=spec["note"],
+            branch_id=ids[spec["branch"]],
+            depth=spec["depth"],
+        )
+        if spec["createdAt"] is not None:
+            checkpoint.created_at = spec["createdAt"]
+        db.add(checkpoint)
+
+
 def _point_the_head(
     adventure: models.Adventure, story: dict, ids: list[int]
 ) -> None:
-    """Sets which branch the story is played on, and how deep it goes.
+    """Sets which branch the story is played on, and where it is being read.
 
-    The branch comes from the file and the depth does not. The tip of a branch is
-    whatever arrived on it, and a branch with no nodes of its own sits at its
-    fork point, which is the last node its story contains. That node is borrowed
-    but it is still the tip. This is the rule `tree.refresh_head` applies, run
-    here before a flush.
+    Both come from the file now (M3). A bundle that states its head depth is
+    opened exactly where its owner left it, undone turns and all, and the turns
+    past that point arrive as the retained future they were exported as.
+
+    A file that states none is opened at the tip of its head branch — whatever
+    arrived on it, or, for a branch carrying no nodes of its own, the fork point
+    that is the last node its story contains. That is the rule
+    `tree.refresh_head` applies and the only answer a pre-M3 bundle can be given,
+    because at the time it was written the head could not be anywhere else.
     """
     head = story["head"]
     adventure.head_branch_id = ids[head]
-    depths = [n["depth"] for n in story["nodes"] if n["branch"] == head]
-    if depths:
-        adventure.head_depth = max(depths)
+    if story["headDepth"] is not None:
+        adventure.head_depth = story["headDepth"]
         return
-    fork_depth = story["branches"][head].get("forkDepth")
-    adventure.head_depth = fork_depth if fork_depth is not None else lineage.NO_DEPTH
+    adventure.head_depth = _derived_tip(story["branches"], story["nodes"], head)
 
 
 def _write_anchors(
@@ -654,7 +870,6 @@ def materialize(
         authors_note=str(payload.get("authorsNote") or ""),
         ai_instructions=str(payload.get("aiInstructions") or ""),
         story_summary=str(payload.get("storySummary") or ""),
-        script_state=payload.get("scriptState") or {},
         world_state=payload.get("worldState") or {},
         auto_summarize=bool(payload.get("autoSummarize", False)),
         memory_bank_enabled=bool(payload.get("memoryBankEnabled", False)),
@@ -674,19 +889,10 @@ def materialize(
                 notes=str(card.get("notes") or ""),
             ))
 
-    for i, item in enumerate(payload.get("scripts") or []):
-        if isinstance(item, dict):
-            db.add(models.AdventureScript(
-                adventure_id=adventure.id,
-                position=int(item.get("position", i)),
-                enabled=bool(item.get("enabled", True)),
-                name=str(item.get("name") or "Imported Script")[:schemas.NAME_MAX],
-                description=str(item.get("description") or ""),
-                library_js=str(item.get("library") or ""),
-                input_js=str(item.get("input") or ""),
-                context_js=str(item.get("context") or ""),
-                output_js=str(item.get("output") or ""),
-            ))
+    # A bundle exported before M2 may carry "scripts" and "scriptState".
+    # Campaign scripting is gone, so both are ignored rather than rejected: the
+    # story, its tree, its cards and its memories still import intact, which is
+    # what the bundle is for.
 
     write(db, adventure, story)
     db.flush()

backend/app/cleanup.py

@@ -1,178 +0,0 @@
-"""Retention policy for throwaway guest accounts.
-
-In multi-user mode every first visit creates a `users` row through
-`GET /api/auth/me`, so a public demo accumulates one account per visitor. Most
-of those visitors never return, and each one leaves behind whatever scenarios,
-adventures, actions, and memories they generated. This module deletes guests
-that have been inactive for `AIDND_GUEST_RETENTION_DAYS`, which defaults to 5,
-along with everything they made.
-
-Why this is safe to run unattended:
-
-- Only rows with `is_guest` AND `email IS NULL` are ever touched, and both
-  clauses are checked rather than either alone. Registering upgrades the row
-  in place (is_guest -> False), so a guest who signs up keeps everything;
-  local mode's implicit single user is also is_guest=False.
-- Idle time is `COALESCE(last_seen_at, created_at)`. `auth._touch` writes
-  `last_seen_at` at most once an hour, and a guest created by `/auth/me` has
-  NULL there until its second request, so `created_at` is the correct floor for
-  a new visitor. Without the coalesce, those rows look arbitrarily old.
-- Nothing a guest owns is reachable by anyone else. `is_public` is an
-  output-only field, as `schemas.ScenarioBase` shows, so the only shared
-  scenarios are the seeded ones, which have a NULL `user_id` and are outside
-  this filter. Deleting a guest cannot remove content from another user.
-
-The sweep uses one Core DELETE rather than an ORM cascade. `db.delete(user)`
-would SELECT every adventure, action, memory, and story card into Python only to
-delete them, which on Neon is the egress pattern that has already cost this
-project once. Every foreign key from `users` downward is ON DELETE CASCADE, from
-users to scenarios, adventures, scripts, and settings, and from those to actions,
-memories, and cards, so the database deletes the whole graph in one statement and
-returns a row count.
-
-The scan gets no index. The sweep runs a few times a day against a table holding
-at most a few thousand rows, which does not justify a migration and the schema
-surface it adds.
-"""
-
-import asyncio
-import logging
-import os
-from datetime import datetime, timedelta
-
-from sqlalchemy import delete, func
-from sqlalchemy.orm import Session
-from starlette.concurrency import run_in_threadpool
-
-from . import analytics, auth, models
-from .database import SessionLocal
-
-logger = logging.getLogger(__name__)
-
-
-def _int_env(name: str, default: int) -> int:
-    try:
-        return int(os.environ.get(name, "").strip() or default)
-    except ValueError:
-        logger.warning("%s is not an integer; using %d.", name, default)
-        return default
-
-
-# Days of inactivity before a guest account is deleted. A value of 0 or less
-# disables the policy, for a deployment that keeps everything.
-RETENTION_DAYS = _int_env("AIDND_GUEST_RETENTION_DAYS", 5)
-
-# How often a long-lived process re-checks. Hours, not minutes: nothing here is
-# time-critical, and on Render's free tier the service sleeps and cold-starts
-# often enough that the startup sweep does most of the work by itself.
-SWEEP_INTERVAL_SECONDS = _int_env("AIDND_CLEANUP_INTERVAL_HOURS", 6) * 3600
-
-
-def enabled() -> bool:
-    """Guests only exist in multi-user mode, so local runs skip the sweep
-    rather than pointing a DELETE at a database that has nothing to collect."""
-    return auth.MULTI_USER and RETENTION_DAYS > 0
-
-
-def anything_to_sweep() -> bool:
-    """Whether the periodic task is worth starting at all. The two jobs it runs
-    are independent: a deployment can keep every guest forever and still want
-    its analytics rows aged out, and vice versa."""
-    return enabled() or analytics.RETENTION_DAYS > 0
-
-
-def delete_stale_guests(db: Session, *, now: datetime | None = None) -> int:
-    """Delete guests idle for RETENTION_DAYS or more. Returns the row count.
-
-    The caller owns error handling; `sweep` is the safe wrapper.
-    """
-    if RETENTION_DAYS <= 0:
-        return 0
-    # Stored timestamps are UTC without a timezone on both backends. SQLite
-    # drops the timezone, and the Postgres columns are TIMESTAMP WITHOUT TIME
-    # ZONE with the session pinned to UTC in `database.py`. Match that, so the
-    # comparison does not depend on how a dialect renders a value that carries a
-    # timezone.
-    reference = now or models.utcnow()
-    cutoff = reference.replace(tzinfo=None) - timedelta(days=RETENTION_DAYS)
-
-    stmt = (
-        delete(models.User)
-        .where(
-            models.User.is_guest.is_(True),
-            models.User.email.is_(None),
-            func.coalesce(models.User.last_seen_at, models.User.created_at) < cutoff,
-        )
-        # Without this option, the "auto" strategy cannot evaluate coalesce in
-        # Python and falls back to fetching every matching primary key first.
-        # That is a second round trip for no benefit, because this session holds
-        # no User objects to synchronize.
-        .execution_options(synchronize_session=False)
-    )
-    removed = db.execute(stmt).rowcount or 0
-    db.commit()
-    return removed
-
-
-def sweep() -> int:
-    """One pass, with its own session. Never raises: a failed cleanup must not
-    be able to take the app down (same rule as seeding). Returns the guest
-    count, which is the number worth logging about."""
-    if not anything_to_sweep():
-        return 0
-    db = SessionLocal()
-    try:
-        # Ages out the per-visitor analytics rows, on its own terms: it is not
-        # about guests, and it must still happen on a deployment that has
-        # chosen to keep every account it ever minted.
-        aged = analytics.purge_old_visitor_days(db)
-        if aged:
-            logger.info("Aged out %d analytics visitor-day row(s).", aged)
-        removed = delete_stale_guests(db) if enabled() else 0
-        if removed:
-            logger.info(
-                "Cleaned up %d guest account(s) idle for %d+ days.",
-                removed,
-                RETENTION_DAYS,
-            )
-        return removed
-    except Exception:
-        db.rollback()
-        logger.exception("Guest cleanup failed; continuing without it.")
-        return 0
-    finally:
-        db.close()
-
-
-async def _sweep_loop() -> None:
-    while True:
-        # Blocking DB work: keep it off the event loop, which is also serving
-        # SSE turn streams.
-        await run_in_threadpool(sweep)
-        await asyncio.sleep(SWEEP_INTERVAL_SECONDS)
-
-
-def start_sweeper() -> asyncio.Task | None:
-    """Kick off the periodic sweep; None when there is nothing to sweep."""
-    if not enabled():
-        logger.info("Guest cleanup disabled (multi_user=%s, retention_days=%d).",
-                    auth.MULTI_USER, RETENTION_DAYS)
-    else:
-        logger.info(
-            "Guest cleanup on: deleting guests idle %d+ days, every %d hour(s).",
-            RETENTION_DAYS,
-            SWEEP_INTERVAL_SECONDS // 3600,
-        )
-    if not anything_to_sweep():
-        return None
-    return asyncio.create_task(_sweep_loop())
-
-
-async def stop_sweeper(task: asyncio.Task | None) -> None:
-    if task is None:
-        return
-    task.cancel()
-    try:
-        await task
-    except asyncio.CancelledError:
-        pass

backend/app/context/lineage.py

@@ -78,7 +78,16 @@ class Path:
     """One story, expressed as a SQL clause and as a Python predicate.
 
     The object holds the lineage entries newest first, plus the depth of the
-    tip. The tip is used only to estimate how much story each entry covers.
+    head. Every entry is read as capped at the head, which is what makes the
+    active head a position the whole application honours (M3).
+
+    Before M3 the head was always the deepest node, so the cap never bit and the
+    tip was used only to estimate how much story each entry covers. Undo now
+    moves the head backward without deleting anything, so a path can have live
+    nodes past its head, and those nodes are not part of the story being told.
+    Capping here is what hides them, and it hides them from every read at once:
+    the transcript, the context builder, `attempts.preceding`, and memory
+    retrieval all funnel through `path_of`.
     """
 
     def __init__(self, entries: list[tuple[int, int | None]], tip: int | None = None):
@@ -91,6 +100,40 @@ class Path:
     def __len__(self) -> int:
         return len(self.entries)
 
+    # ------------------------------------------------------------- the head
+
+    def _cap(self, max_depth: int | None) -> int | None:
+        """Returns `max_depth` limited by the head, which no read may pass.
+
+        Three cases, and the third is the one M3 added:
+
+        * No head recorded (`tip is None`). The caller asked for the lineage
+          without a position, so the entry's own cap stands. `tree` builds such
+          a path when it resolves the node in front of a depth.
+        * An uncapped entry, which means "this branch through to its tip". The
+          head is the cap.
+        * A capped entry, which is an ancestor capped at the fork depth. The
+          head still wins when it sits behind that fork, because undoing below
+          a fork point is undoing into the shared prefix. Taking the smaller of
+          the two is what lets Undo walk back past a fork instead of stopping
+          there — safe now that it deletes nothing.
+        """
+        if self.tip is None:
+            return max_depth
+        if max_depth is None:
+            return self.tip
+        return min(max_depth, self.tip)
+
+    def uncapped(self) -> "Path":
+        """Returns the same lineage read through to its retained tip.
+
+        This is the retained history, head or no head: what Redo can still walk
+        forward into, and what a write below the head has to fork away from.
+        Only those two callers should use it. Every read of *the story* wants
+        the capped path.
+        """
+        return Path(self.entries, None)
+
     # ---------------------------------------------------------------- SQL
 
     def clause(
@@ -125,7 +168,9 @@ class Path:
         entries = self.entries if count is None else self.entries[:count]
         if not entries:
             return false()
-        on_path = or_(*[self._entry_clause(model, b, d) for b, d in entries])
+        on_path = or_(
+            *[self._entry_clause(model, b, self._cap(d)) for b, d in entries]
+        )
         if model is models.Action:
             return and_(on_path, models.Action.live.is_(True))
         return on_path
@@ -155,9 +200,10 @@ class Path:
         for branch_id, max_depth in self.entries:
             if node.branch_id != branch_id:
                 continue
-            if max_depth is None:
+            cap = self._cap(max_depth)
+            if cap is None:
                 return True
-            if node.depth is not None and node.depth <= max_depth:
+            if node.depth is not None and node.depth <= cap:
                 return True
         return False
 
@@ -187,7 +233,7 @@ class Path:
             return total
         covered = 0
         for i, (_, max_depth) in enumerate(self.entries):
-            top = self.tip if max_depth is None else max_depth
+            top = self._cap(max_depth)
             below = self.entries[i + 1][1] if i + 1 < total else NO_DEPTH
             if top is None or below is None:
                 # Either no tip was recorded, or a hand-written row is missing a
@@ -211,7 +257,8 @@ class Path:
         story has forked.
         """
         for i, (_, max_depth) in enumerate(self.entries):
-            if max_depth is not None and max_depth <= depth:
+            cap = self._cap(max_depth)
+            if cap is not None and cap <= depth:
                 return i
         return len(self.entries)
 
@@ -241,7 +288,8 @@ class Path:
             return depth
         for entry_branch, max_depth in self.entries:
             if entry_branch == branch_id:
-                return depth if max_depth is None else min(depth, max_depth)
+                cap = self._cap(max_depth)
+                return depth if cap is None else min(depth, cap)
         return NO_DEPTH
 
 

backend/app/database.py

@@ -4,10 +4,17 @@ from pathlib import Path
 from sqlalchemy import create_engine, event
 from sqlalchemy.orm import DeclarativeBase, sessionmaker
 
-# AIDND_DB_PATH lets deployments (Docker volume, hosted disk) relocate the
-# SQLite database; default stays backend/data.db for local runs. The parent
-# directory also hosts the auto-generated secret.key (see security.py), so
-# DB_PATH stays defined even when Postgres is in use.
+# The one database. It is SQLite, on this machine, in a file.
+#
+# Upstream could also point at a server database — `AIDND_DATABASE_URL` or the
+# platform-conventional `DATABASE_URL`, normalised onto psycopg3, with
+# pre-ping for a serverless Postgres that suspends when idle. That existed for
+# a hosted deployment. M2 removed it along with the deployment: a local
+# single-user storyteller has one reader, and a network database would be one
+# more thing that has to be running, and one more place the story lives.
+#
+# `AIDND_DB_PATH` stays. It is how the Docker image puts the database on a
+# volume, and how a test points at a throwaway file.
 _env_db_path = os.environ.get("AIDND_DB_PATH")
 DB_PATH = (
     Path(_env_db_path).resolve()
@@ -15,48 +22,20 @@ DB_PATH = (
     else Path(__file__).resolve().parent.parent / "data.db"
 )
 
-# `AIDND_DATABASE_URL`, or the conventional `DATABASE_URL`, switches the app to
-# a server database. Any SQLAlchemy URL works, and hosted deploys use Postgres,
-# which Phase 9 settled on Neon for. If neither variable is set, the app uses
-# SQLite.
-DATABASE_URL = (
-    os.environ.get("AIDND_DATABASE_URL", "").strip()
-    or os.environ.get("DATABASE_URL", "").strip()
+DB_PATH.parent.mkdir(parents=True, exist_ok=True)
+engine = create_engine(
+    f"sqlite:///{DB_PATH}",
+    connect_args={"check_same_thread": False},
 )
 
 
-def _normalize_url(url: str) -> str:
-    """Map the postgres:// / postgresql:// schemes hosts hand out to the
-    psycopg3 driver installed in requirements.txt."""
-    for prefix in ("postgres://", "postgresql://"):
-        if url.startswith(prefix):
-            return "postgresql+psycopg://" + url[len(prefix):]
-    return url
-
-
-if DATABASE_URL:
-    engine = create_engine(
-        _normalize_url(DATABASE_URL),
-        # Serverless Postgres (Neon) suspends idle databases; pre-ping
-        # replaces silently-dead pooled connections instead of erroring.
-        pool_pre_ping=True,
-        # Store/read naive UTC like SQLite does, regardless of server default.
-        connect_args={"options": "-c timezone=UTC"},
-    )
-else:
-    DB_PATH.parent.mkdir(parents=True, exist_ok=True)
-    engine = create_engine(
-        f"sqlite:///{DB_PATH}",
-        connect_args={"check_same_thread": False},
-    )
-
-    @event.listens_for(engine, "connect")
-    def _enable_sqlite_foreign_keys(dbapi_connection, _record):
-        # SQLite ships with foreign keys OFF per connection; without this every
-        # ondelete=CASCADE/SET NULL in models.py is silently ignored.
-        cursor = dbapi_connection.cursor()
-        cursor.execute("PRAGMA foreign_keys=ON")
-        cursor.close()
+@event.listens_for(engine, "connect")
+def _enable_sqlite_foreign_keys(dbapi_connection, _record):
+    # SQLite ships with foreign keys OFF per connection; without this every
+    # ondelete=CASCADE/SET NULL in models.py is silently ignored.
+    cursor = dbapi_connection.cursor()
+    cursor.execute("PRAGMA foreign_keys=ON")
+    cursor.close()
 
 
 SessionLocal = sessionmaker(bind=engine, autoflush=False, expire_on_commit=False)

backend/app/endpoints.py

@@ -0,0 +1,179 @@
+"""Which inference endpoints this product is willing to talk to.
+
+The Adventure Storyteller sends the player's prose, the assembled context, the
+retrieved memories, and the embedding inputs to whatever address the model
+endpoint names. That makes the endpoint the single most consequential setting
+in the application: point it somewhere else and the whole campaign goes there.
+
+The v1 rule (`planning/DECISIONS/002-ollama-only-v1.md`, ADR 004) is that
+inference runs on user-controlled local infrastructure. Two deployments are
+supported and no third is:
+
+* **same-host** — Ollama on loopback, the default;
+* **explicitly configured trusted LAN** — Ollama on another machine the user
+  controls, named by them, reached over HTTP or over HTTPS with a certificate
+  their machine trusts.
+
+Everything on the public Internet is refused. Not discouraged in the UI, not
+absent from a dropdown — refused, here, on the way out, so that a hand-edited
+database row or a hostname that starts resolving somewhere new cannot quietly
+turn a local install into an exfiltration path.
+
+## How the line is drawn
+
+By **address**, not by name, and against an explicit allowlist of networks:
+loopback, the three RFC1918 ranges, link-local, IPv6 unique-local, and
+carrier-grade NAT — the last of which is what a mesh VPN such as Tailscale
+hands out and is as user-controlled as a LAN.
+
+Every address the host resolves to must be in one of them. One address outside
+is enough to refuse the endpoint, so a name resolving to both a private and a
+public address does not squeak through.
+
+The networks are spelled out rather than inferred from `ipaddress`'s own
+classifications, which do not mean what this rule needs: `is_private` is true
+of the documentation ranges and of `0.0.0.0/8`, and `is_reserved` is true of
+IPv6 loopback — so a rule written around it refuses `http://[::1]:11434/v1`,
+which is an ordinary same-host Ollama. Naming the networks keeps the policy
+readable and makes anything unnamed refused by default.
+
+Checking addresses rather than hostnames is what makes the rule hard to talk
+around. A cloud provider cannot be reached by spelling its name differently,
+and `localhost.` or a DNS entry pointing at a public host is judged on where it
+actually goes.
+
+## What this is not
+
+It is not a general network-policy framework, and there is nothing to configure.
+There is one predicate, and it is applied in two places: when the endpoint is
+saved, so the user gets a clear error immediately, and again before every
+outbound request, because a name that resolved to `192.168.1.50` this morning
+can resolve to something else this afternoon.
+
+TLS is a separate matter and is never traded against this one. See
+`tlstrust.py`: certificates are verified in full, and no endpoint — however
+private its address — may skip that.
+"""
+
+import ipaddress
+import socket
+from urllib.parse import urlparse
+
+#: The networks an inference endpoint may live on. Anything else is refused.
+ALLOWED_NETWORKS = tuple(
+    ipaddress.ip_network(cidr)
+    for cidr in (
+        "127.0.0.0/8",      # this machine
+        "10.0.0.0/8",       # RFC1918
+        "172.16.0.0/12",    # RFC1918
+        "192.168.0.0/16",   # RFC1918
+        "169.254.0.0/16",   # link-local
+        "100.64.0.0/10",    # carrier-grade NAT, which mesh VPNs use
+        "::1/128",          # this machine, v6
+        "fc00::/7",         # unique-local, v6
+        "fe80::/10",        # link-local, v6
+    )
+)
+
+
+def _is_local(ip) -> bool:
+    return any(ip in net for net in ALLOWED_NETWORKS)
+
+#: Hosts that are only ever a cloud inference service. The address rule below
+#: already refuses every one of them, because they all resolve to public
+#: addresses; this list exists solely so the error says *why* rather than
+#: leaving the user to wonder whether their DNS is broken.
+CLOUD_HOSTS = (
+    "openrouter.ai",
+    "api.openai.com",
+    "api.anthropic.com",
+    "api.groq.com",
+    "api.mistral.ai",
+    "api.together.xyz",
+    "api.deepseek.com",
+    "generativelanguage.googleapis.com",
+    "api.cohere.ai",
+    "api.perplexity.ai",
+)
+
+_CLOUD_REASON = (
+    "this build talks to Ollama on your own machine or on your own network, "
+    "and has no cloud provider support"
+)
+
+
+def _cloud_host(host: str) -> bool:
+    host = host.lower().rstrip(".")
+    return any(host == h or host.endswith("." + h) for h in CLOUD_HOSTS)
+
+
+def rejection_reason(url: str) -> str | None:
+    """Why this endpoint may not be used, or None if it may.
+
+    The string is shown to the user, so it says what to do rather than what
+    went wrong internally.
+    """
+    parsed = urlparse((url or "").strip())
+    if parsed.scheme not in ("http", "https"):
+        return "the endpoint URL must start with http:// or https://"
+    host = parsed.hostname
+    if not host:
+        return "the endpoint URL has no host"
+    if _cloud_host(host):
+        return f"{host} is a cloud inference service — {_CLOUD_REASON}"
+
+    port = parsed.port or (443 if parsed.scheme == "https" else 80)
+    try:
+        infos = socket.getaddrinfo(host, port, type=socket.SOCK_STREAM)
+    except socket.gaierror:
+        return (
+            f"the host {host!r} could not be resolved — check the address, and "
+            "that the machine running Ollama is reachable from here"
+        )
+
+    for info in infos:
+        try:
+            ip = ipaddress.ip_address(info[4][0])
+        except ValueError:
+            return "the endpoint host resolved to an address that could not be read"
+        if _is_local(ip):
+            continue
+        if ip.is_global:
+            return (
+                f"{host} resolves to {ip}, which is a public Internet address — "
+                f"{_CLOUD_REASON}. Use Ollama on this machine "
+                "(http://127.0.0.1:11434/v1) or on a machine on your own network"
+            )
+        return (
+            f"{host} resolves to {ip}, which is not on this machine and not on "
+            "your own network. Use http://127.0.0.1:11434/v1, or the address of "
+            "a machine on your network"
+        )
+    return None
+
+
+def check(url: str) -> None:
+    """Raises `EndpointRejected` if this endpoint is outside the policy."""
+    reason = rejection_reason(url)
+    if reason is not None:
+        raise EndpointRejected(reason)
+
+
+class EndpointRejected(Exception):
+    """The configured endpoint is not one this product will send a story to."""
+
+
+def is_loopback(url: str) -> bool:
+    """Whether this endpoint is on this machine. Used for reporting, not for
+    gating: a trusted-LAN endpoint is equally allowed."""
+    host = urlparse((url or "").strip()).hostname
+    if not host:
+        return False
+    try:
+        infos = socket.getaddrinfo(host, None, type=socket.SOCK_STREAM)
+    except socket.gaierror:
+        return False
+    try:
+        return all(ipaddress.ip_address(i[4][0]).is_loopback for i in infos)
+    except ValueError:
+        return False

backend/app/head.py

@@ -0,0 +1,405 @@
+"""M3: where the story is being read, and what moving that point costs.
+
+Undo used to delete. It removed the trailing nodes, let `tree.refresh_head`
+recompute the tip from what survived, and the story was wherever the rows ended.
+That made the head a derived value and made Redo impossible, because the turns it
+would have moved forward into were gone.
+
+The head is now a stored position that can sit behind the retained tip. Nothing
+is deleted, so three things that used to be the same question are now three
+different ones:
+
+* **the active head** — `adventure.head_branch_id` and `adventure.head_depth`,
+  the end of the story being told. Every read of the story stops here, because
+  `lineage.Path` caps every entry at it.
+* **the retained tip** — the deepest live node still on the lineage. Redo walks
+  toward it. It is read through `Path.uncapped()`, and only this module and the
+  divergence check may look at it.
+* **the opening** — the shallowest node on the story, which is the floor Undo
+  may not pass.
+
+Everything that moves the head or asks a question about it lives here, so the
+turn engine, Retry, Add-take, Undo, Redo and Edit share one set of rules rather
+than four similar ones. The Phase 0B spike put the fork check in the write path
+and left Retry and Add-take on the old one, which is exactly the divergence this
+module exists to prevent.
+
+The state that belongs to a position is not recomputed. Every node carries the
+world state it left behind (`attempts.snapshot_outcome`), so moving the head is a
+row lookup plus `attempts.restore_state`, at any distance, in either direction.
+"""
+
+from sqlalchemy.orm import Session, undefer
+
+from . import attempts, models, tree
+from .context import lineage
+
+# The kinds of node a player writes. An undo or a redo steps over a whole turn,
+# which is one of these followed by the reply to it, so both ends need to agree
+# on what "a player's half of a turn" is.
+PLAYER_TYPES = ("do", "say", "story", "continue")
+
+
+# ------------------------------------------------------------------ reading
+
+def opening_depth(db: Session, adventure: models.Adventure) -> int | None:
+    """Returns the depth of the first node of the story, or None if there is none.
+
+    This is Undo's floor. The Phase 0B spike moved the head to -1 and rendered an
+    empty transcript, because its guard tested for a node of type `start` and an
+    adventure opened with a player-written `story` action has none. Asking the
+    path for its shallowest node needs no such special case: whatever the opening
+    is called, it is the node with the smallest depth, and the story keeps it.
+
+    The read is uncapped. The opening does not move when the head does, and
+    capping would make the floor depend on where the head already is.
+    """
+    return (
+        db.query(models.Action.depth)
+        .filter(
+            models.Action.adventure_id == adventure.id,
+            lineage.path_of(db, adventure).uncapped().clause(models.Action),
+        )
+        .order_by(models.Action.depth.asc(), models.Action.id.asc())
+        .limit(1)
+        .scalar()
+    )
+
+
+def retained_tip(db: Session, adventure: models.Adventure) -> int | None:
+    """Returns the depth of the deepest live node still retained on this lineage.
+
+    This is what the head would be if the story had never been undone, and it is
+    what Redo can reach. It is not the head, and no read of the story may use it.
+    """
+    return (
+        db.query(models.Action.depth)
+        .filter(
+            models.Action.adventure_id == adventure.id,
+            lineage.path_of(db, adventure).uncapped().clause(models.Action),
+        )
+        .order_by(models.Action.depth.desc(), models.Action.id.desc())
+        .limit(1)
+        .scalar()
+    )
+
+
+def behind_tip(db: Session, adventure: models.Adventure) -> bool:
+    """Returns whether retained story sits past the head.
+
+    This one predicate answers every "does this write need to fork?" question in
+    the application. It is true exactly when the user has undone and not redone,
+    which is the only situation in which writing can displace an accepted future.
+
+    It is also what makes "is this turn the tip?" answerable again. Retry,
+    Add-take and `stand_on` each decide between amending a turn in place and
+    giving it a branch, and each used to ask `last_action`, which reads the
+    *capped* path and therefore reports the node at the head as the newest one.
+    Under a moved-back head that answer is wrong in the dangerous direction: it
+    says a turn with an accepted future is a leaf, and amending it in place would
+    leave that future descending from a take that is no longer live.
+    """
+    tip = retained_tip(db, adventure)
+    return tip is not None and tip > adventure.head_depth
+
+
+def node_at(
+    db: Session, adventure: models.Adventure, depth: int
+) -> models.Action | None:
+    """Returns the live node at `depth` on the retained lineage, outcome loaded.
+
+    The read is uncapped on purpose: Redo asks for a node it is about to move the
+    head onto, which is by definition past the head at the time of asking. The
+    outcome columns are undeferred because the only reason to fetch this row is
+    to restore the state it left behind.
+    """
+    return (
+        db.query(models.Action)
+        .filter(
+            models.Action.adventure_id == adventure.id,
+            lineage.path_of(db, adventure).uncapped().clause(models.Action),
+            models.Action.depth == depth,
+        )
+        .options(
+            undefer(models.Action.state_after),
+            undefer(models.Action.world_state_after),
+        )
+        .order_by(models.Action.id)
+        .first()
+    )
+
+
+def redo_target(db: Session, adventure: models.Adventure) -> int | None:
+    """Returns the depth the head moves to on Redo, or None if there is nowhere.
+
+    Redo steps over a whole turn, the same unit Undo steps back over, so a
+    player's action and the reply to it move together. Landing between them would
+    show the story an input with no answer and would leave the next Undo undoing
+    half a turn.
+
+    The walk is along the retained lineage, which is what makes Redo follow the
+    continuation that was active rather than choosing among branches. After a
+    divergence the new branch *is* the lineage, and the displaced future is no
+    longer on it, so this returns None without having to know that a divergence
+    happened. That is `STORY-BRANCH-SEMANTICS.md` §8 falling out of the lineage
+    rather than being enforced by a flag.
+    """
+    ahead = (
+        db.query(models.Action)
+        .filter(
+            models.Action.adventure_id == adventure.id,
+            lineage.path_of(db, adventure).uncapped().clause(models.Action),
+            models.Action.depth > adventure.head_depth,
+        )
+        .order_by(models.Action.depth.asc(), models.Action.id.asc())
+        .limit(2)
+        .all()
+    )
+    if not ahead:
+        return None
+    first = ahead[0]
+    if (
+        first.type in PLAYER_TYPES
+        and len(ahead) > 1
+        and ahead[1].type == "ai"
+        and ahead[1].depth == (first.depth or 0) + 1
+    ):
+        return ahead[1].depth
+    return first.depth
+
+
+def can_redo(db: Session, adventure: models.Adventure) -> bool:
+    """Returns whether an ordinary Redo is available from where the head is."""
+    return redo_target(db, adventure) is not None
+
+
+def undo_target(
+    db: Session, adventure: models.Adventure
+) -> tuple[int, models.Action] | None:
+    """Returns where Undo moves the head, and the first node it steps back over.
+
+    None means there is nothing to undo, which is either an empty story or a head
+    already resting on the opening. The caller turns that into a 400; this
+    function does not raise, so that the same question can be asked without
+    committing to undoing.
+
+    A turn is the player's node plus the reply to it, and both move together for
+    the reason given in `redo_target`. The player half is only claimed when it is
+    directly in front of the reply, so a bare `continue`, which writes no player
+    node, steps back over the reply alone.
+    """
+    newest = (
+        db.query(models.Action)
+        .filter(
+            models.Action.adventure_id == adventure.id,
+            lineage.path_of(db, adventure).clause(models.Action),
+        )
+        .order_by(models.Action.depth.desc(), models.Action.id.desc())
+        .limit(2)
+        .all()
+    )
+    if not newest:
+        return None
+    last = newest[0]
+    first_stepped = last
+    before = newest[1] if len(newest) > 1 else None
+    if (
+        last.type == "ai"
+        and before is not None
+        and before.type in PLAYER_TYPES
+        and before.depth == (last.depth or 0) - 1
+    ):
+        first_stepped = before
+    floor = opening_depth(db, adventure)
+    if first_stepped.depth is None or floor is None:
+        return None
+    if first_stepped.depth <= floor:
+        # Stepping back over this turn would hide the opening of the campaign,
+        # which is the pre-campaign state `STORY-BRANCH-SEMANTICS.md` §4 stops
+        # at. The floor is the opening node itself rather than depth -1, so an
+        # adventure that opens on a player-written `story` action stops in the
+        # same place as one that opens on a `start` node.
+        return None
+    return first_stepped.depth - 1, first_stepped
+
+
+def can_undo(db: Session, adventure: models.Adventure) -> bool:
+    """Returns whether an ordinary Undo is available from where the head is."""
+    return undo_target(db, adventure) is not None
+
+
+def displaced_history_under(
+    db: Session, adventure: models.Adventure, node: models.Action
+) -> bool:
+    """Returns whether story the reader cannot see descends from `node`.
+
+    This is the question an in-place edit has to ask. Editing rewrites one row
+    and re-evaluates nothing, which is what makes it a correction rather than a
+    new continuation. That is harmless while everything descending from the row
+    is on screen: the reader can see what their correction has to stay
+    consistent with. It stops being harmless the moment a continuation descends
+    from the row and is *not* on screen, because the edit then silently changes
+    the words an invisible stretch of story was written from. That is the one
+    way M3's retained history can be made to contradict itself.
+
+    Refusing is deliberately the whole of the fix. Making such an edit fork, so
+    the original text and its future stay whole, is
+    `STORY-BRANCH-SEMANTICS.md` §14-15 — and §15 requires re-evaluating the
+    state the edited prose implies, which is M5's extraction pass. Neither is
+    started here.
+
+    The question is asked as one shape rather than two, because the two ways a
+    descendant becomes invisible turn out to be the same fact. An undone future
+    sits past the head on this very lineage; a displaced line sits past a fork
+    on a branch the story left. In both cases there is a live node, deeper than
+    this one, that descends from it and is not on the path being read — and the
+    departed branch is usually an *ancestor* of the branch now being read, which
+    is why "branches other than the active one" is the wrong set to look at.
+
+    Only the deepest live node on each descending branch is examined. Whether a
+    node is on the read path is monotone in depth: a branch is on the path with
+    a cap, and a node is visible when its depth is at or under that cap. So if
+    the deepest one is visible, every shallower one is too, and if it is not,
+    the answer is already yes.
+
+    A node that is not live has no descendants of its own — a take the story
+    moved past keeps a continuation only by being forked, and that fork is a
+    branch this loop asks about anyway — so editing one is always safe.
+    """
+    if not node.live or node.depth is None:
+        return False
+    read = lineage.path_of(db, adventure)
+    branches = (
+        db.query(models.Branch)
+        .filter(models.Branch.adventure_id == adventure.id)
+        .all()
+    )
+    for branch in branches:
+        # Uncapped: the question is what this branch's story descends from, not
+        # how much of it the reader is currently being shown.
+        if not lineage.Path(lineage.entries_of(branch)).contains(node):
+            continue
+        deepest = (
+            db.query(models.Action)
+            .filter(
+                models.Action.adventure_id == adventure.id,
+                models.Action.branch_id == branch.id,
+                models.Action.live.is_(True),
+                models.Action.depth > node.depth,
+            )
+            .order_by(models.Action.depth.desc(), models.Action.id.desc())
+            .first()
+        )
+        if deepest is not None and not read.contains(deepest):
+            return True
+    return False
+
+
+# ------------------------------------------------------------------ writing
+
+def move_to(db: Session, adventure: models.Adventure, depth: int) -> None:
+    """Moves the active head to `depth` and restores the state recorded there.
+
+    This is the whole of Undo and Redo. Nothing is deleted, nothing is
+    recomputed, and the direction of travel does not matter: the node at the
+    destination carries the world state it left behind, so arriving from in front
+    of it and arriving from behind it restore the same value.
+
+    A destination with no node — the head resting one step in front of the
+    opening — leaves the live state alone, which is `attempts.restore_state`'s
+    rule for a missing snapshot and the reason it is not this function's job to
+    invent an empty one.
+    """
+    adventure.head_depth = depth
+    attempts.restore_state(adventure, node_at(db, adventure, depth))
+
+
+def move_to_node(db: Session, adventure: models.Adventure, node: models.Action) -> bool:
+    """Moves the head onto `node`, changing line only if it is not on this one.
+
+    M4 restores a Save Point through this, and it adds no restoring of its own:
+    the depth half is `move_to` unchanged, so the state, the transcript, the
+    assembled context and memory eligibility all arrive exactly as they do for
+    Undo and Redo. Returns whether the line had to change as well as the depth,
+    which is the one thing about a restore a caller cannot work out afterwards.
+
+    The head is two values, and the two halves move for different reasons. A
+    Save Point almost always names a position on the story being read — its own
+    line, or the shared prefix that line inherits — and then only the depth
+    moves. Leaving the branch alone is what makes the restored position keep the
+    continuation it has: after a divergence, restoring to the shared prefix must
+    put the reader back on the *new* line, where Redo walks into the turns they
+    are still writing, not into the future they left. Reaching for the Save
+    Point's own branch there would quietly hand back the abandoned story.
+
+    The other case is real and has to work. A Save Point survives divergence
+    (`STORY-BRANCH-SEMANTICS.md` §19), so one can name a position on a line the
+    story has since left, and no amount of depth movement reaches a branch this
+    path does not contain. The line then moves as well — one assignment, the
+    same one `switch_branch` makes — and the depth still moves through
+    `move_to`. Nothing is created: a restore never forks, whichever case it
+    takes. The first write below the restored head does, through
+    `fork_if_behind_head`, like every other write.
+    """
+    switched = not lineage.path_of(db, adventure).uncapped().contains(node)
+    if switched:
+        adventure.head_branch_id = node.branch_id
+    move_to(db, adventure, node.depth)
+    return switched
+
+
+def fork_if_behind_head(db: Session, adventure: models.Adventure) -> bool:
+    """Gives the story a new branch when a write would displace a retained future.
+
+    Returns whether a branch was created, which is what a caller reports as a
+    divergence.
+
+    Called before every write that continues the story, and it does nothing on
+    the ordinary path where the head is already at the tip. That is the property
+    worth keeping: a story that is never undone forks exactly as often as it did
+    before M3, so the branch table does not fill up with one branch per turn.
+
+    Undo alone must not fork. Moving the head is not a decision to abandon
+    anything — the user may be reading, or about to Redo. Only the first write
+    below the head states which continuation they mean, which is
+    `STORY-BRANCH-SEMANTICS.md` §8 and §20 and what makes Redo survive an Undo.
+
+    `tree.branch_at` leaves the departed branch exactly as it is: its nodes stay
+    live, at their depths, on their branch. The new branch inherits the story up
+    to the head and owns everything written from here, so the displaced future
+    remains reachable through the branch it was written on.
+    """
+    if not behind_tip(db, adventure):
+        return False
+    departed = lineage.branch_of(db, adventure)
+    at_depth = adventure.head_depth
+    tree.branch_at(db, adventure, at_depth)
+    if departed is not None:
+        mark_superseded(departed, at_depth)
+    return True
+
+
+def mark_superseded(branch: models.Branch, depth: int) -> None:
+    """Records that this branch's story past `depth` was displaced.
+
+    `DATA-MODEL.md` §5 gives a branch a disposition of active, retained or
+    disposable. This is that disposition, stored as the fact that produced it
+    rather than as a word: the depth the story left at, and when. A branch with
+    no `superseded_at` is active; one with a value has retained history past that
+    depth which no active head is reading.
+
+    Nothing in the application reads these columns to make a decision, and that
+    is deliberate. Redo is decided by the lineage, not by a flag, so a stale or
+    hand-edited value here cannot make the story wrong. They exist so that the
+    cleanup and discarded-history features `STORY-BRANCH-SEMANTICS.md` §28 and
+    §29 leave to a later version have something to select on, and so that a
+    divergence is observable in a test.
+
+    The shallowest departure wins. A branch left at depth 9 and later left again
+    at depth 4 has retained history from 4 onward, and recording the later, deeper
+    value would understate what was displaced.
+    """
+    if branch.superseded_depth is None or depth < branch.superseded_depth:
+        branch.superseded_depth = depth
+    if branch.superseded_at is None:
+        branch.superseded_at = models.utcnow()

backend/app/limits.py

@@ -1,183 +1,35 @@
-"""Phase 9: abuse guards for hosted, multi-user deployments.
+"""Resource bounds on what a single request or a single story may cost.
 
-Rate limits and row caps do nothing in local mode, because a single local player
-should never be throttled by their own app. The values are hardcoded on purpose.
-They are generous enough that a legitimate player never notices them, and tight
-enough that a hostile visitor cannot exhaust the demo key, saturate the CPU, or
-fill the database.
+Upstream carried three things here, and only one of them belongs in a local
+single-user product. Per-IP and per-user **rate limiting**, the login-attempt
+throttle, and the per-user **quotas** were hosted-service policy: they existed
+to stop a hostile visitor exhausting a shared demo key or filling a shared
+database. M2 removed all of it. There are no visitors, and throttling the one
+person who started the application would be a bug rather than a guard.
+
+What is left is defensive programming, and it applies whatever the deployment:
+
+* a ceiling on the **request body**, so a malformed or hostile payload cannot
+  be read into memory before anything looks at it;
+* ceilings on how large **one adventure** may grow, in actions, memories,
+  story cards and branches. These bound storage and the cost of the queries
+  that walk them. They are per-story, not per-user: nothing here counts how
+  many campaigns a person may have.
+
+An import is checked against the same per-adventure ceilings that live creation
+uses, so a bundle cannot carry a story past a limit that play could not reach.
 """
 
 import json
-import os
-import threading
-import time
-from collections import defaultdict, deque
 
-from fastapi import HTTPException, Request
+from fastapi import HTTPException
 from sqlalchemy import func
 from sqlalchemy.orm import Session
 
-from . import auth, models
+from . import models
 
-# ---------- Rate limiting ----------
-# Fixed windows per scope and caller. The windows live in memory, which is
-# enough for the single-process deployment this app targets. The worst case
-# after a restart is a brief extra allowance.
+# ---------- Per-story row caps ----------
 
-# Maps a scope to (max requests, window seconds).
-RATE_LIMITS: dict[str, tuple[int, int]] = {
-    "turn": (10, 60),             # AI turn generation. The demo key also has a daily cap.
-    "chat": (30, 60),             # The AI Chat scratchpad, for power users.
-    "script-test": (30, 60),      # Sandboxed, but each run costs up to 2s of CPU.
-    "connection-test": (10, 60),  # Outbound HTTP to a user-supplied URL.
-    "import": (30, 60),           # Large writes.
-    "auth": (10, 300),            # Register and login attempts, per IP.
-    "guest": (30, 300),           # New guest users, per IP. Each one is a database row.
-    # Pageview beacons. The limit is generous, because a real reader clicking
-    # around a SPA sends a handful a minute, and it is low enough that nobody
-    # can inflate the traffic numbers faster than by reloading the page.
-    "analytics": (120, 60),
-}
-
-_windows: dict[tuple[str, str], deque] = defaultdict(deque)
-_windows_guard = threading.Lock()
-
-
-# How many proxy hops sit between the app and the real client. On Render, and on
-# most platforms, that is one, because the platform's edge appends the connecting
-# IP to the right of `X-Forwarded-For`. A client can prepend any value on the
-# left, but it cannot push a value past the edge's own append, so the trustworthy
-# client IP is the entry that many places from the right rather than uvicorn's
-# leftmost choice. Trusting the leftmost entry let anyone rotate
-# `X-Forwarded-For` to get a fresh rate-limit bucket per request and bypass the
-# auth and guest limits. If the deployment adds more hops, set
-# `AIDND_TRUSTED_PROXY_HOPS`.
-TRUSTED_PROXY_HOPS = max(1, int(os.environ.get("AIDND_TRUSTED_PROXY_HOPS", "1") or 1))
-
-
-def client_ip(request: Request) -> str:
-    """Returns the real client IP, resisting a spoofed `X-Forwarded-For`.
-
-    The function reads the hop the trusted edge appended, which is the rightmost
-    entry minus any extra trusted hops. If no forwarded header is present, which
-    happens locally, in development, and on a direct connection, it falls back to
-    the socket peer.
-
-    The function is public because the access log needs the same answer. Two
-    functions that each decide which address belongs to the caller is how one of
-    them ends up trusting a header it should not.
-    """
-    forwarded = request.headers.get("x-forwarded-for")
-    if forwarded:
-        parts = [p.strip() for p in forwarded.split(",") if p.strip()]
-        if parts:
-            return parts[-min(TRUSTED_PROXY_HOPS, len(parts))]
-    return request.client.host if request.client else "unknown"
-
-
-def rate_limit(scope: str, request: Request, user: models.User | None = None) -> None:
-    """Raises a 429 when the caller exceeds the scope's window.
-
-    The window is keyed per user when a user is known, because an account
-    survives an IP change, and per IP otherwise.
-    """
-    if not auth.MULTI_USER:
-        return
-    limit, window_seconds = RATE_LIMITS[scope]
-    key = (scope, f"u{user.id}" if user else f"ip{client_ip(request)}")
-    now = time.time()
-    with _windows_guard:
-        window = _windows[key]
-        while window and window[0] < now - window_seconds:
-            window.popleft()
-        if len(window) >= limit:
-            raise HTTPException(
-                429, "You're doing that too fast — wait a minute and try again."
-            )
-        window.append(now)
-        if len(_windows) > 10_000:
-            _prune(now)
-
-
-# ---------- Per-account login throttle ----------
-# This is defense in depth next to the per-IP `auth` limit. A botnet dilutes
-# that limit, because many real source IPs each get their own bucket, so it
-# cannot by itself stop a distributed guessing run against one account. This cap
-# keys on the target email rather than on the caller, so guessing one account's
-# password stays expensive however many addresses the guesses come from.
-#
-# Only failures count, and a correct password clears the record. The window
-# slides over a short period rather than locking the account, so a user who
-# mistypes a few times recovers within minutes. The trade-off is that an
-# attacker can keep a known account throttled, which is an inconvenience and is
-# preferable to letting the account be brute-forced.
-LOGIN_FAIL_LIMIT = 8          # Failed attempts per account.
-LOGIN_FAIL_WINDOW = 900       # The window in seconds, which is 15 minutes.
-
-_login_fails: dict[str, deque] = defaultdict(deque)
-_login_guard = threading.Lock()
-
-
-def check_login_allowed(email: str) -> None:
-    """Raises a 429 when an account has too many recent failed logins.
-
-    Call this before verifying the password, so that a guess never reaches the
-    hash.
-    """
-    if not auth.MULTI_USER:
-        return
-    now = time.time()
-    with _login_guard:
-        window = _login_fails[email]
-        while window and window[0] < now - LOGIN_FAIL_WINDOW:
-            window.popleft()
-        if len(window) >= LOGIN_FAIL_LIMIT:
-            raise HTTPException(
-                429,
-                "Too many failed sign-in attempts for this account — "
-                "wait a few minutes and try again.",
-            )
-
-
-def note_login_failure(email: str) -> None:
-    """Records one failed attempt against `email`."""
-    if not auth.MULTI_USER:
-        return
-    now = time.time()
-    with _login_guard:
-        _login_fails[email].append(now)
-        if len(_login_fails) > 10_000:  # Bound the map against a flood of unique emails.
-            stale = [
-                key for key, window in _login_fails.items()
-                if not window or window[-1] < now - LOGIN_FAIL_WINDOW
-            ]
-            for key in stale:
-                del _login_fails[key]
-
-
-def note_login_success(email: str) -> None:
-    """Clears the account's failure record after a correct password."""
-    with _login_guard:
-        _login_fails.pop(email, None)
-
-
-def _prune(now: float) -> None:
-    """Drops callers whose whole window has expired, so the per-IP dict stays bounded.
-
-    Call this with the guard held.
-    """
-    longest = max(seconds for _, seconds in RATE_LIMITS.values())
-    stale = [key for key, window in _windows.items()
-             if not window or window[-1] < now - longest]
-    for key in stale:
-        del _windows[key]
-
-
-# ---------- Per-user row caps ----------
-
-MAX_ADVENTURES_PER_USER = 100
-MAX_SCENARIOS_PER_USER = 200
-MAX_SCRIPTS_PER_USER = 200
 MAX_STORY_CARDS_PER_OWNER = 200   # Per scenario or per adventure.
 MAX_MEMORIES_PER_ADVENTURE = 1000
 MAX_ACTIONS_PER_ADVENTURE = 5000
@@ -200,28 +52,14 @@ def check_row_cap(
 ) -> None:
     """Raises a 409 when creating one more row of `kind` would exceed its cap.
 
-    The caller has already checked ownership of the scenario or adventure passed
-    in.
+    Only per-story kinds are capped. `adventures` and `scenarios` were per-user
+    quotas and are no longer checked; the callers still pass them, and they are
+    accepted and ignored so that adding a cap back is a change here rather than
+    at every call site.
     """
-    if not auth.MULTI_USER:
+    if kind in ("adventures", "scenarios"):
         return
-    if kind == "adventures":
-        count = _count(db, models.Adventure, models.Adventure.user_id == user.id)
-        cap, subject, hint = (
-            MAX_ADVENTURES_PER_USER, "adventures",
-            "delete one you no longer play to make room",
-        )
-    elif kind == "scenarios":
-        count = _count(db, models.Scenario, models.Scenario.user_id == user.id)
-        cap, subject, hint = (
-            MAX_SCENARIOS_PER_USER, "scenarios", "delete one to make room"
-        )
-    elif kind == "scripts":
-        count = _count(db, models.Script, models.Script.user_id == user.id)
-        cap, subject, hint = (
-            MAX_SCRIPTS_PER_USER, "scripts", "delete one to make room"
-        )
-    elif kind == "story_cards":
+    if kind == "story_cards":
         owner_filter = (
             models.StoryCard.scenario_id == scenario_id
             if scenario_id is not None
@@ -273,8 +111,6 @@ def check_bundle_lists(**lists) -> None:
     The keyword arguments are `story_cards`, `memories`, `actions`, and
     `branches`.
     """
-    if not auth.MULTI_USER:
-        return
     for name, value in lists.items():
         cap = _BUNDLE_LIST_CAPS[name]
         if isinstance(value, list) and len(value) > cap:
@@ -286,8 +122,8 @@ def check_bundle_lists(**lists) -> None:
 
 # ---------- Request body size ----------
 # The limit is generous enough for the largest legitimate payload, which is an
-# adventure export holding thousands of actions. It applies in every mode, and no
-# honest request approaches it.
+# adventure export holding thousands of actions. No honest request approaches
+# it.
 
 MAX_BODY_BYTES = 2 * 1024 * 1024
 MAX_IMPORT_BODY_BYTES = 20 * 1024 * 1024

backend/app/main.py

@@ -1,6 +1,5 @@
 import mimetypes
 import os
-from contextlib import asynccontextmanager
 from pathlib import Path
 
 from fastapi import FastAPI
@@ -8,15 +7,10 @@ from fastapi.middleware.cors import CORSMiddleware
 from fastapi.staticfiles import StaticFiles
 from starlette.exceptions import HTTPException as StarletteHTTPException
 
-from . import analytics, cleanup
-from .auth import MULTI_USER
 from .database import engine
 from .limits import BodySizeLimitMiddleware
 from .migrations import bootstrap
-from .routers import (
-    adventures, analytics as analytics_router, auth, chat, debug, scenarios, scripts,
-    settings, story_cards,
-)
+from .routers import adventures, chat, debug, scenarios, settings, story_cards
 from .seed import seed_public_scenarios
 
 bootstrap(engine)
@@ -24,37 +18,32 @@ seed_public_scenarios(engine)
 
 # Production serves the SPA same-origin, so CORS only matters for the Vite dev
 # server; AIDND_CORS_ORIGINS overrides for any other cross-origin setup.
+#
+# A wildcard is refused rather than honoured. This API is unauthenticated by
+# design and bound to loopback, so its only protection from a page the user
+# happens to have open in another tab is the same-origin policy. `*` would hand
+# every site on the Internet a write handle on the local campaign database. If the
+# value is wrong the app refuses to start, because a permissive CORS policy that
+# nobody notices is worse than one that fails loudly.
 CORS_ORIGINS = [
     o.strip()
     for o in os.environ.get("AIDND_CORS_ORIGINS", "").split(",")
     if o.strip()
 ] or ["http://localhost:5173", "http://127.0.0.1:5173"]
 
-@asynccontextmanager
-async def lifespan(_app: FastAPI):
-    # Sweeps once on boot, then on an interval. Booting is the reliable
-    # trigger on Render's free tier, where the service sleeps after ~15
-    # minutes and a long-running timer rarely gets to fire.
-    sweeper = cleanup.start_sweeper()
-    # Visit counters are buffered in memory and written in batches; this is
-    # what turns them into rows, and stop_flusher writes out the last batch so
-    # a deploy doesn't drop it.
-    flusher = analytics.start_flusher()
-    try:
-        yield
-    finally:
-        await cleanup.stop_sweeper(sweeper)
-        await analytics.stop_flusher(flusher)
+if any(o == "*" or o.strip() == "*" for o in CORS_ORIGINS):
+    raise RuntimeError(
+        "AIDND_CORS_ORIGINS must not contain '*'. The storyteller API is "
+        "unauthenticated and loopback-bound; a wildcard origin would let any "
+        "web page read and rewrite every campaign. List the exact origins "
+        "instead."
+    )
 
-
-# The interactive API docs stay local-only: in multi-user mode they just hand
-# strangers a map of the API surface.
 app = FastAPI(
-    title="AI D&D",
-    docs_url=None if MULTI_USER else "/docs",
+    title="Adventure Storyteller",
+    docs_url="/docs",
     redoc_url=None,
-    openapi_url=None if MULTI_USER else "/openapi.json",
-    lifespan=lifespan,
+    openapi_url="/openapi.json",
 )
 
 app.add_middleware(
@@ -117,50 +106,14 @@ class SecurityHeadersMiddleware:
         await self.app(scope, receive, send_with_headers)
 
 
-class ApiErrorMiddleware:
-    """Counts failed API responses for the analytics dashboard.
-
-    This is middleware rather than an exception handler, because it observes
-    what the client received. A 429 from a rate limiter, a 404 from routing, and
-    a 500 from a handler that never returned all reach it the same way. It is
-    pure ASGI for the same reason as the headers above: an SSE turn must not be
-    buffered on its way out. It watches `/api` only, because a 404 on the SPA
-    mount is a page load rather than a fault.
-    """
-
-    def __init__(self, app):
-        self.app = app
-
-    async def __call__(self, scope, receive, send):
-        if scope["type"] != "http" or not scope.get("path", "").startswith("/api"):
-            return await self.app(scope, receive, send)
-
-        async def send_counting(message):
-            if message["type"] == "http.response.start" and message["status"] >= 400:
-                # The router has already put the matched route on the scope by
-                # the time a response starts, so the label can name the
-                # endpoint rather than the caller's path.
-                analytics.record(
-                    analytics.M_ERROR,
-                    analytics.api_route_label(scope, message["status"]),
-                )
-            await send(message)
-
-        await self.app(scope, receive, send_counting)
-
-
-app.add_middleware(ApiErrorMiddleware)
 app.add_middleware(SecurityHeadersMiddleware)
 
-app.include_router(auth.router)
 app.include_router(scenarios.router)
 app.include_router(adventures.router)
 app.include_router(story_cards.router)
-app.include_router(scripts.router)
 app.include_router(settings.router)
 app.include_router(chat.router)
 app.include_router(debug.router)
-app.include_router(analytics_router.router)
 
 
 @app.get("/api/health")
@@ -171,7 +124,8 @@ def health():
 # In production, serve the built frontend (frontend/dist) as static files.
 class SPAStaticFiles(StaticFiles):
     """Serve index.html for unknown paths so client-side routes (/play/3)
-    survive a page reload. API routes are matched before this mount."""
+    survive a page reload. API routes are matched before this mount, and an
+    unmatched one 404s rather than falling through to the page."""
 
     async def get_response(self, path, scope):
         try:
@@ -179,11 +133,20 @@ class SPAStaticFiles(StaticFiles):
         except StarletteHTTPException as exc:
             if exc.status_code != 404:
                 raise
-            return await super().get_response("index.html", scope)
+            return await self._fallback(path, scope)
         if response.status_code == 404:
-            return await super().get_response("index.html", scope)
+            return await self._fallback(path, scope)
         return response
 
+    async def _fallback(self, path, scope):
+        # The mount is a catch-all, so an /api path no router claims — a typo,
+        # or an endpoint this build removed — used to come back as the SPA's
+        # HTML with status 200, and a client asking for JSON parsed a web page
+        # instead of seeing that the route is not there.
+        if path == "api" or path.startswith("api/"):
+            raise StarletteHTTPException(status_code=404)
+        return await super().get_response("index.html", scope)
+
 
 # Python's mimetypes table has no entry for woff2 on a slim Debian image, so
 # StaticFiles served the self-hosted fonts as application/octet-stream. Browsers

backend/app/memorybank.py

@@ -142,26 +142,22 @@ _running: set[int] = set()
 _tasks: set[asyncio.Task] = set()
 
 
-# Both factories below use the user's own key by construction. They read the
-# endpoint and key from `Settings` and never from `auth.DEMO_*`, so
-# summarization and embedding cannot spend the shared demo key. Their call sites
-# are also skipped when `using_demo` is true.
-#
-# Do not change these to accept a `ProviderConfig`. `summary_model` and
-# `embedding_model` are free-form user input and are not on the demo allowlist.
+# Both factories read the endpoint and the model names straight off `Settings`.
+# They used to also read an API key, which is gone: Ollama does not use one and
+# M2 removed cloud providers. `summary_model` and `embedding_model` fall back to
+# the narrator model when the user has not named a separate one.
 def summary_provider(settings: models.Settings) -> OpenAICompatibleProvider:
     return OpenAICompatibleProvider(
         settings.endpoint_url,
-        settings.api_key_plain,
         settings.summary_model or settings.model,
         settings.api_mode,
-        settings.reasoning_max_tokens,
+        settings.model_timeout_seconds,
     )
 
 
 def embedding_provider(settings: models.Settings) -> OpenAICompatibleProvider:
     return OpenAICompatibleProvider(
-        settings.endpoint_url, settings.api_key_plain, settings.embedding_model
+        settings.endpoint_url, settings.embedding_model
     )
 
 

backend/app/migrations.py

@@ -301,7 +301,8 @@ MIGRATIONS: list[tuple[int, str | dict[str, str]]] = [
     (63, "ALTER TABLE actions ADD COLUMN parent_id INTEGER REFERENCES actions(id) ON DELETE SET NULL"),
     (64, "CREATE INDEX IF NOT EXISTS ix_actions_parent ON actions (parent_id)"),
     # Phase 17: `Settings.stream` was dead state. Nothing ever read it, and every
-    # turn streams. This is item S1 in `docs/self-review.md`. The table holds one
+    # turn streams; upstream's self-review log flagged it as dead state. The
+    # table holds one
     # row per user, so the rewrite is small and needs no VACUUM FULL.
     (65, "ALTER TABLE settings DROP COLUMN stream"),
     # Phase 17, SP8: drop the eight columns the story tree replaced. Each one was
@@ -338,6 +339,28 @@ MIGRATIONS: list[tuple[int, str | dict[str, str]]] = [
     (74, "ALTER TABLE adventures ADD COLUMN persona_name VARCHAR(80) NOT NULL DEFAULT ''"),
     (75, "ALTER TABLE adventures ADD COLUMN persona_pronouns VARCHAR(40) NOT NULL DEFAULT ''"),
     (76, "ALTER TABLE adventures ADD COLUMN persona_desc TEXT NOT NULL DEFAULT ''"),
+    # M2: how long to wait for the model. Upstream hardcoded 120s in the HTTP
+    # client, which a cold model load on a CPU-only machine can exceed. The
+    # default matches `providers.openai_compatible.DEFAULT_READ_TIMEOUT`.
+    (77, "ALTER TABLE settings ADD COLUMN model_timeout_seconds INTEGER NOT NULL DEFAULT 300"),
+
+    # M3. A branch left behind by a divergent write records where the story left
+    # it. NULL means active, which is what every existing branch is: before M3
+    # the head could not sit behind the tip, so no branch had been superseded.
+    # No backfill.
+    (78, "ALTER TABLE branches ADD COLUMN superseded_at TIMESTAMP"),
+    (79, "ALTER TABLE branches ADD COLUMN superseded_depth INTEGER"),
+    # M4: Save Points. `create_all` creates the `checkpoints` table itself, on
+    # existing databases as well as fresh ones, exactly as it did for
+    # `memories` at version 2 and `branches` at version 46. What it does not
+    # create is the index every list and every cascade reads, so that is what
+    # this version is.
+    #
+    # No backfill. A Save Point records a decision someone made, and nobody has
+    # made one yet: an M3 database has no position a user chose to name, and
+    # inventing one would be inventing the decision.
+    (80, "CREATE INDEX IF NOT EXISTS ix_checkpoints_adventure "
+         "ON checkpoints (adventure_id)"),
 ]
 
 LATEST_VERSION = max((v for v, _ in MIGRATIONS), default=1)
@@ -1106,23 +1129,3 @@ def bootstrap(engine: Engine, through: int = LATEST_VERSION) -> None:
                     _backfill_parents(conn)
                 current = version
         _set_version(conn, current)
-        _encrypt_plaintext_api_keys(conn)
-
-
-def _encrypt_plaintext_api_keys(conn) -> None:
-    """Encrypts API keys saved before encryption at rest existed (Phase 8).
-
-    Those keys are stored in plain text, so this pass wraps them in Fernet. Plain
-    SQL cannot do it. The pass runs on every start, and it matches no rows once
-    every row carries the `enc:` prefix.
-    """
-    from . import security  # Deferred: security derives its key from DB_PATH setup.
-
-    rows = conn.execute(text(
-        "SELECT id, api_key FROM settings WHERE api_key != '' AND api_key NOT LIKE 'enc:%'"
-    )).all()
-    for row_id, plain in rows:
-        conn.execute(
-            text("UPDATE settings SET api_key = :key WHERE id = :id"),
-            {"key": security.encrypt_secret(plain), "id": row_id},
-        )

backend/app/models.py

@@ -1,8 +1,8 @@
 from datetime import datetime, timezone
 
 from sqlalchemy import (
-    JSON, Boolean, Column, DateTime, Float, ForeignKey, Index, Integer, LargeBinary,
-    String, Table, Text, UniqueConstraint, event,
+    JSON, Boolean, DateTime, Float, ForeignKey, Index, Integer, LargeBinary,
+    String, Text, event,
 )
 from sqlalchemy.orm import Mapped, Session, mapped_column, relationship
 
@@ -37,19 +37,12 @@ class User(Base):
     is_guest: Mapped[bool] = mapped_column(Boolean, default=True)
     created_at: Mapped[datetime] = mapped_column(DateTime, default=utcnow)
     last_seen_at: Mapped[datetime | None] = mapped_column(DateTime, nullable=True)
-    # Shared demo key usage (resets when the UTC date changes).
+    # Was the shared demo key's per-day tally. M2 removed the demo key; these
+    # columns stay so existing databases open unchanged and are never written.
     demo_turns_used: Mapped[int] = mapped_column(Integer, default=0)
     demo_turns_date: Mapped[str] = mapped_column(String(10), default="")
 
 
-scenario_scripts = Table(
-    "scenario_scripts",
-    Base.metadata,
-    Column("scenario_id", ForeignKey("scenarios.id", ondelete="CASCADE"), primary_key=True),
-    Column("script_id", ForeignKey("scripts.id", ondelete="CASCADE"), primary_key=True),
-)
-
-
 class Scenario(Base):
     __tablename__ = "scenarios"
 
@@ -89,7 +82,6 @@ class Scenario(Base):
         back_populates="scenario", cascade="all, delete-orphan"
     )
     adventures: Mapped[list["Adventure"]] = relationship(back_populates="scenario")
-    scripts: Mapped[list["Script"]] = relationship(secondary=scenario_scripts)
 
 
 class Adventure(Base):
@@ -121,6 +113,9 @@ class Adventure(Base):
     persona_name: Mapped[str] = mapped_column(String(80), default="")
     persona_pronouns: Mapped[str] = mapped_column(String(40), default="")
     persona_desc: Mapped[str] = mapped_column(Text, default="")
+    # Was the campaign scripting engine's shared `state` object. M2 removed
+    # scripting; the column stays so existing databases open unchanged, and it
+    # is never written with anything but an empty dict.
     script_state: Mapped[dict] = mapped_column(JSON, default=dict)
     # Phase 12: live RPG world state (world/player/npc stats + milestones),
     # instantiated from the scenario's stat_schema. Empty when there's no RPG layer.
@@ -177,11 +172,6 @@ class Adventure(Base):
         cascade="all, delete-orphan",
         order_by="Action.id",
     )
-    scripts: Mapped[list["AdventureScript"]] = relationship(
-        back_populates="adventure",
-        cascade="all, delete-orphan",
-        order_by="AdventureScript.position",
-    )
     memories: Mapped[list["Memory"]] = relationship(
         back_populates="adventure",
         cascade="all, delete-orphan",
@@ -238,6 +228,78 @@ class Branch(Base):
     # branch by its fork depth, which deleting a branch does not change.
     name: Mapped[str | None] = mapped_column(String(80), nullable=True)
     created_at: Mapped[datetime] = mapped_column(DateTime, default=utcnow)
+    # M3: the disposition `DATA-MODEL.md` §5 gives a branch, stored as the fact
+    # that produced it. NULL means active. A value means a divergent write left
+    # this branch at `superseded_depth`, so its nodes past that depth are
+    # retained history that no active head is reading.
+    #
+    # Nothing reads these to decide behaviour. Redo follows the lineage, so a
+    # wrong value here cannot make the story wrong; they exist for the cleanup
+    # and discarded-history features that `STORY-BRANCH-SEMANTICS.md` §28-29
+    # leave to a later version. See `head.mark_superseded`.
+    superseded_at: Mapped[datetime | None] = mapped_column(DateTime, nullable=True)
+    superseded_depth: Mapped[int | None] = mapped_column(Integer, nullable=True)
+
+
+class Checkpoint(Base):
+    """M4: a Save Point — a durable named pointer to a story position.
+
+    "Save Point" is what the user reads; `checkpoint` is what the code calls it
+    (`BROWSER-UX-SPEC.md` §23).
+
+    The row holds a name and a coordinate, and no story. `DATA-MODEL.md` §8
+    describes the pointer as naming a turn; the coordinate here is
+    `(branch_id, depth)`, which is what M3 made the head and what
+    `head.node_at` resolves. Restoring one is therefore head movement with a
+    bounds check rather than a restore system of its own — see ADR 012 and
+    `head.move_to_node`.
+
+    A coordinate rather than an action id, deliberately. One coordinate can
+    hold several attempts at a turn and exactly one of them is live, so a
+    retry replaces the row a Save Point would have pinned. "Turn 42 of this
+    line" survives a retry; "action 918" would point at a take the story no
+    longer tells.
+
+    `branch_id` is the branch the node itself sits on, not the branch that was
+    being read when the Save Point was made. Those differ whenever the head is
+    resting in a shared prefix, and the node's own branch is the one that still
+    names the position after the reader has moved elsewhere.
+
+    **Nothing removes a Save Point but the user.** They are not cleaned up for
+    going stale, for being behind the head, or for pointing into a future the
+    story has left (`STORY-BRANCH-SEMANTICS.md` §19).
+
+    That includes deleting a branch. `branch_id` carries `ON DELETE CASCADE` as
+    referential integrity — a Save Point must never point at a branch that is
+    gone — but the branch endpoint refuses to delete a branch any Save Point
+    names, so the cascade does not fire through the application
+    (`routers/adventures/branches.py`, `STORY-BRANCH-SEMANTICS.md` §19.1). The
+    user deletes the Save Point first, which deletes no story, and then the
+    branch. Deleting the whole campaign does cascade, and should: that is what
+    the user asked for.
+    """
+
+    __tablename__ = "checkpoints"
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    adventure_id: Mapped[int] = mapped_column(
+        ForeignKey("adventures.id", ondelete="CASCADE")
+    )
+    name: Mapped[str] = mapped_column(String(120), default="")
+    # `DATA-MODEL.md` §8's optional notes, and `BROWSER-UX-SPEC.md` §24's
+    # optional second field. Empty is the ordinary case.
+    note: Mapped[str] = mapped_column(Text, default="")
+    branch_id: Mapped[int] = mapped_column(
+        ForeignKey("branches.id", ondelete="CASCADE")
+    )
+    depth: Mapped[int] = mapped_column(Integer)
+    created_at: Mapped[datetime] = mapped_column(DateTime, default=utcnow)
+    # Bumped by a rename, which is the only edit a Save Point allows. The
+    # coordinate is never rewritten: `STORY-BRANCH-SEMANTICS.md` §24 keeps a
+    # Save Point's meaning auditable by making "move it" delete-and-recreate.
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime, default=utcnow, onupdate=utcnow
+    )
 
 
 class Memory(Base):
@@ -419,9 +481,10 @@ class Action(Base):
     # and for re-attaching the emit block when replaying history to the model.
     # Mirrors the active variant, same as text/reasoning/context_snapshot.
     world_delta: Mapped[dict | None] = mapped_column(JSON, nullable=True)
-    # Phase 14, SP4: the shared script state and the RPG world state as they
-    # stood after this node was played. These columns record the node's outcome
-    # rather than its starting position.
+    # Phase 14, SP4: the RPG world state as it stood after this node was
+    # played. These columns record the node's outcome rather than its starting
+    # position. (`state_after` held the scripting engine's state, which M2
+    # removed; it is now always written empty.)
     #
     # Two operations need this outcome, and neither can use a snapshot taken
     # before the turn. Switching between siblings must restore the state that
@@ -508,52 +571,6 @@ class Action(Base):
         return out
 
 
-class Script(Base):
-    __tablename__ = "scripts"
-
-    id: Mapped[int] = mapped_column(primary_key=True)
-    user_id: Mapped[int | None] = mapped_column(
-        ForeignKey("users.id", ondelete="CASCADE"), nullable=True
-    )
-    name: Mapped[str] = mapped_column(String(200), default="Untitled Script")
-    description: Mapped[str] = mapped_column(Text, default="")
-    library_js: Mapped[str] = mapped_column(Text, default="")
-    input_js: Mapped[str] = mapped_column(Text, default="")
-    context_js: Mapped[str] = mapped_column(Text, default="")
-    output_js: Mapped[str] = mapped_column(Text, default="")
-    created_at: Mapped[datetime] = mapped_column(DateTime, default=utcnow)
-    updated_at: Mapped[datetime] = mapped_column(DateTime, default=utcnow, onupdate=utcnow)
-
-
-class AdventureScript(Base):
-    """A script copied into an adventure at creation, so library edits don't
-    change running adventures unless the player explicitly re-syncs it from
-    `source_script_id`. `state` lives on Adventure.script_state (one shared
-    state per adventure, as in AI Dungeon)."""
-
-    __tablename__ = "adventure_scripts"
-
-    id: Mapped[int] = mapped_column(primary_key=True)
-    adventure_id: Mapped[int] = mapped_column(ForeignKey("adventures.id", ondelete="CASCADE"))
-    # The library Script that this copy was made from, which lets the player
-    # re-sync it on demand. The value is NULL for legacy copies that predate
-    # this column, and for demo-derived copies whose source the player does not
-    # own. Those copies fall back to matching by name, or cannot be synced.
-    source_script_id: Mapped[int | None] = mapped_column(
-        ForeignKey("scripts.id", ondelete="SET NULL"), nullable=True
-    )
-    position: Mapped[int] = mapped_column(Integer, default=0)
-    enabled: Mapped[bool] = mapped_column(Boolean, default=True)
-    name: Mapped[str] = mapped_column(String(200), default="Untitled Script")
-    description: Mapped[str] = mapped_column(Text, default="")
-    library_js: Mapped[str] = mapped_column(Text, default="")
-    input_js: Mapped[str] = mapped_column(Text, default="")
-    context_js: Mapped[str] = mapped_column(Text, default="")
-    output_js: Mapped[str] = mapped_column(Text, default="")
-
-    adventure: Mapped[Adventure] = relationship(back_populates="scripts")
-
-
 class Settings(Base):
     __tablename__ = "settings"
 
@@ -564,8 +581,10 @@ class Settings(Base):
         ForeignKey("users.id", ondelete="CASCADE"), nullable=True, unique=True
     )
     endpoint_url: Mapped[str] = mapped_column(String(500), default="http://localhost:11434/v1")
-    # Encrypted at rest with Fernet, which produces a value that starts with
-    # "enc:". See security.py. To read the key, use `api_key_plain`.
+    # Was a cloud provider's API key, encrypted at rest. Ollama does not use
+    # one and M2 removed cloud providers, so nothing reads or writes this now.
+    # The column stays so existing databases open unchanged; an old value is
+    # left where it is rather than migrated or decrypted.
     api_key: Mapped[str] = mapped_column(String(500), default="")
     model: Mapped[str] = mapped_column(String(200), default="")
     api_mode: Mapped[str] = mapped_column(String(20), default="chat")  # chat|completion
@@ -573,12 +592,17 @@ class Settings(Base):
     # 800 leaves room for a full scene; 400 tended to truncate mid-paragraph
     # and left reasoning models with nothing after their thinking.
     max_output_tokens: Mapped[int] = mapped_column(Integer, default=800)
-    # Separate thinking budget for reasoning models (OpenRouter-style
-    # `reasoning: {max_tokens}`); 0 = param not sent, -1 = reasoning explicitly
-    # off (`reasoning: {effort: none}`). Added on top of
-    # max_output_tokens so story output keeps its full budget.
+    # Was an OpenRouter-style thinking budget. Ollama's OpenAI-compatible
+    # endpoint ignores the field, so M2 stopped sending it and removed it from
+    # the Settings API and UI. The column stays so existing databases open
+    # unchanged and is never read.
     reasoning_max_tokens: Mapped[int] = mapped_column(Integer, default=0)
     context_token_budget: Mapped[int] = mapped_column(Integer, default=16384)
+    # How long to wait for the model, in seconds, before giving up on a turn.
+    # A cold load of a mid-sized model on a CPU-only machine can take minutes,
+    # while the same turn takes seconds once the model is resident. See
+    # `providers.openai_compatible.DEFAULT_READ_TIMEOUT`.
+    model_timeout_seconds: Mapped[int] = mapped_column(Integer, default=300)
     narrator_prompt: Mapped[str] = mapped_column(
         Text,
         default=(
@@ -599,120 +623,18 @@ class Settings(Base):
     memory_bank_capacity: Mapped[int] = mapped_column(Integer, default=80)
     memory_top_k: Mapped[int] = mapped_column(Integer, default=5)
 
-    @property
-    def has_api_key(self) -> bool:
-        return bool(self.api_key)
-
-    @property
-    def api_key_plain(self) -> str:
-        from . import security  # local import: models is imported before security
-
-        return security.decrypt_secret(self.api_key)
 
 
-# ---------- Visit analytics (see analytics.py) ----------
-# Two intentionally simple tables. Neither can hold text that a player wrote,
-# and neither can be joined back to a `users` row, because the visitor column
-# holds an HMAC and has no foreign key. When guest cleanup deletes an account,
-# the history that account contributed remains intact and anonymous.
-
-
-class AnalyticsDaily(Base):
-    """One counter: how many times `label` happened within `metric` on `day`.
-
-    The table stores a generic triple of metric, label, and hits rather than one
-    column per statistic. Measuring something new therefore costs a constant
-    rather than a migration. The only writer is an UPSERT that runs from a
-    buffer. See `analytics.flush`.
-    """
-
-    __tablename__ = "analytics_daily"
-
-    id: Mapped[int] = mapped_column(primary_key=True)
-    day: Mapped[str] = mapped_column(String(10), index=True)  # YYYY-MM-DD, UTC
-    metric: Mapped[str] = mapped_column(String(32))
-    label: Mapped[str] = mapped_column(String(80), default="")
-    hits: Mapped[int] = mapped_column(Integer, default=0)
-
-    # The upsert target: one row per bucket per day, created or incremented.
-    __table_args__ = (
-        UniqueConstraint("day", "metric", "label", name="uq_analytics_daily_bucket"),
-    )
-
-
-class AnalyticsVisitorDay(Base):
-    """One visitor, one day, and which funnel steps they reached on it.
-
-    This table exists so that the funnel counts people rather than clicks. A
-    player who starts six adventures counts as one person who started an
-    adventure. `is_new` is set when the visitor has no earlier row, which is why
-    the visitor column also has an index of its own.
-    """
-
-    __tablename__ = "analytics_visitor_days"
-
-    id: Mapped[int] = mapped_column(primary_key=True)
-    day: Mapped[str] = mapped_column(String(10))
-    # HMAC of the user id under the app secret; not reversible, not a key.
-    visitor: Mapped[str] = mapped_column(String(32))
-    is_new: Mapped[bool] = mapped_column(Boolean, default=False)
-    opened: Mapped[bool] = mapped_column(Boolean, default=False)
-    created: Mapped[bool] = mapped_column(Boolean, default=False)
-    played: Mapped[bool] = mapped_column(Boolean, default=False)
-    signed_up: Mapped[bool] = mapped_column(Boolean, default=False)
-
-    __table_args__ = (
-        UniqueConstraint("day", "visitor", name="uq_analytics_visitor_day"),
-        Index("ix_analytics_visitor", "visitor"),
-    )
-
-
-class AccessEvent(Base):
-    """One sign-in, registration, failed attempt, or session first-seen.
-
-    This table is the counterpart to the two above, and it is kept separate from
-    them on purpose. It identifies people by design, recording address, email,
-    and device. Keeping it in its own table and its own module means that the
-    structure enforces the anonymity of the counters rather than a convention.
-
-    `user_id` is a plain integer with no foreign key. An access log that
-    disappeared when the account did would not serve its purpose, and guest
-    cleanup deletes accounts on a schedule. `who` and `is_guest` are snapshots
-    for the same reason, so a row still reads correctly after the account is
-    gone.
-    """
-
-    __tablename__ = "access_events"
-
-    id: Mapped[int] = mapped_column(primary_key=True)
-    at: Mapped[datetime] = mapped_column(DateTime, default=utcnow, index=True)
-    # session | login | register | login_failed
-    kind: Mapped[str] = mapped_column(String(16))
-    user_id: Mapped[int | None] = mapped_column(Integer, nullable=True)
-    # The email for a registered account, or a label such as "Guest #12"
-    # otherwise. For a failed sign-in, this holds the address that was tried,
-    # which is the reason the row exists.
-    who: Mapped[str] = mapped_column(String(320), default="")
-    is_guest: Mapped[bool] = mapped_column(Boolean, default=False)
-    ip: Mapped[str] = mapped_column(String(45), default="")   # 45 = max IPv6
-    country: Mapped[str] = mapped_column(String(16), default="")
-    device: Mapped[str] = mapped_column(String(16), default="")
-    user_agent: Mapped[str] = mapped_column(String(200), default="")
-
-
-# Phase 14: the fallback under `tree.place_action`.
+# The hosted visitor dashboard's two counter tables and the access log that
+# recorded sign-ins, addresses and devices used to be mapped here. M2 removed
+# the hosted deployment they served.
 #
-# Since SP2, reads filter on `branch_id` and `depth`. A node written without
-# them is invisible to every page, every context build, and every memory pass.
-# The failure is silent, because nothing raises an error. Every current writer
-# places its nodes explicitly, but relying on that would also mean relying on
-# every fixture, script, and test written from now on. The session therefore
-# enforces the rule as rows travel to the database.
-#
-# This listener is registered here rather than in tree.py so that importing the
-# models is enough to enable it. The invariant belongs to the rows, not to the
-# module that usually writes them. The import sits inside the callback because
-# tree.py imports this module.
+# The tables are left in the database rather than dropped: they are inert,
+# nothing reads or writes them, and a destructive migration would risk an
+# existing campaign database for tidiness alone. They are not product
+# functionality.
+
+
 @event.listens_for(Session, "before_flush")
 def _place_new_nodes_on_the_tree(session, flush_context, instances):
     from . import tree

backend/app/netguard.py

@@ -1,52 +0,0 @@
-"""SSRF guard for the one place the server makes an outbound request to a
-user-supplied address: the BYOK `endpoint_url` (connection test + turns/chat).
-
-Without this guard, a hosted user could point `endpoint_url` at an internal
-service or at the cloud metadata endpoint, 169.254.169.254, and have the server
-fetch it. The connection test even returns part of the response. The guard
-therefore refuses any URL that resolves to a non-public address.
-
-The guard does nothing in local mode. A local install talking to
-http://localhost:11434, which is Ollama, is the intended case. The guard applies
-only to a hosted, multi-user deployment, where the endpoint comes from an
-untrusted visitor.
-"""
-
-import ipaddress
-import socket
-from urllib.parse import urlparse
-
-from . import auth
-
-
-def endpoint_block_reason(url: str) -> str | None:
-    """A human-readable reason this URL must NOT be fetched server-side, or None
-    if it's allowed. Resolves the host and rejects it if any resulting address
-    is non-public (private, loopback, link-local/metadata, reserved, …).
-
-    Checking at request time (not just on save) is deliberate: it resists a DNS
-    record that flips to a private IP after the value was stored.
-    """
-    if not auth.MULTI_USER:
-        return None
-    parsed = urlparse(url)
-    if parsed.scheme not in ("http", "https"):
-        return "the endpoint URL must start with http:// or https://"
-    host = parsed.hostname
-    if not host:
-        return "the endpoint URL has no host"
-    port = parsed.port or (443 if parsed.scheme == "https" else 80)
-    try:
-        infos = socket.getaddrinfo(host, port, type=socket.SOCK_STREAM)
-    except socket.gaierror:
-        return "the endpoint host could not be resolved"
-    for info in infos:
-        try:
-            ip = ipaddress.ip_address(info[4][0])
-        except ValueError:
-            return "the endpoint host resolved to an unrecognized address"
-        # is_global is the strict allowlist: private/loopback/link-local/CGNAT
-        # all report False, so this one check covers the metadata IP too.
-        if not ip.is_global or ip.is_multicast or ip.is_reserved:
-            return "the endpoint URL resolves to a non-public address"
-    return None

backend/app/providers/openai_compatible.py

@@ -3,32 +3,27 @@ from typing import AsyncIterator
 
 import httpx
 
-from .. import debuglog, netguard, tlstrust
+from .. import debuglog, endpoints, tlstrust
 from .base import PromptParts, Provider, ProviderError
 
 # Appended after the story text in chat mode, so a chat-tuned model continues
 # the prose rather than replying conversationally.
 CHAT_CONTINUE_HINT = "\n\n[Continue the story directly. Output only story text.]"
 
-# OpenRouter serves one model from whichever upstream is available, and every
-# upstream holds its own prompt cache, so a request routed somewhere new starts
-# with a cold cache however stable the prompt is. Naming a preferred upstream
-# makes routing deterministic, which is what allows a cache hit at all.
-#
-# `allow_fallbacks` stays at its default of true on purpose, because this is a
-# preference rather than a restriction. If the named upstream is down, the
-# request still goes elsewhere and only misses the cache, which is the behavior
-# without this setting.
-#
-# This is a list rather than a value derived from the model slug. The vendor half
-# of a slug is usually the provider slug, such as "deepseek/..." mapping to
-# "deepseek", which was verified against /api/v1/providers, but not reliably.
-# Google's models are served by "google-ai-studio" and "google-vertex", and there
-# is no "google". Look a vendor up on the model's Providers tab before adding it
-# here. A slug that does not exist is a routing preference that, at best, does
-# nothing.
-_OPENROUTER_HOST = "openrouter.ai"
-_PREFERRED_UPSTREAM = {"deepseek": "deepseek"}
+# A machine that is not listening refuses in milliseconds, so a slow connect
+# means the wrong address rather than a busy model.
+CONNECT_TIMEOUT = 10.0
+
+# How long to wait for generation when Settings names no value. Upstream
+# hardcoded 120s, and M1 measured a *cold* load of a 3B model on a GPU-less
+# four-core host exceeding it three times while the same turn took 6-9 seconds
+# once the model was resident. 300s covers a cold start on modest hardware and
+# is still a number: a wedged endpoint fails rather than hanging forever.
+DEFAULT_READ_TIMEOUT = 300.0
+
+# Embeddings are short and never cold-load a large model.
+EMBED_READ_TIMEOUT = 60.0
+
 
 
 # Completion endpoints have no roles, so a chat has to be flattened into one
@@ -44,74 +39,47 @@ def flatten_messages(messages: list[dict]) -> str:
 
 
 class OpenAICompatibleProvider(Provider):
-    """Adapter for any /v1-style endpoint.
+    """Adapter for Ollama's OpenAI-compatible `/v1` API.
 
-    This covers Ollama, LM Studio, OpenAI, OpenRouter, vLLM, and Groq, among
-    others.
+    The protocol is OpenAI's, which is what the module is named for; the
+    product speaks it to Ollama and to nothing else. `endpoints.py` decides
+    which addresses may be reached, and every request re-checks — the shape of
+    the wire format is not the same thing as permission to use it.
     """
 
     def __init__(
         self,
         endpoint_url: str,
-        api_key: str,
         model: str,
         api_mode: str = "chat",
-        reasoning_max_tokens: int = 0,
+        read_timeout: float | None = None,
     ):
         self.base_url = endpoint_url.rstrip("/")
-        self.api_key = api_key
         self.model = model
         self.api_mode = api_mode  # Either "chat" or "completion".
-        # The thinking budget for reasoning models, on top of `max_tokens`. A
-        # value of 0 means the `reasoning` parameter is not sent, because an
-        # endpoint that does not know the field may reject it. A negative value
-        # asks the endpoint to turn reasoning off.
-        self.reasoning_max_tokens = reasoning_max_tokens
+        # How long to wait for the model, in seconds. Cold-loading a model on a
+        # CPU-only machine can take minutes, and a fixed short timeout reports
+        # that as a failure. See `DEFAULT_READ_TIMEOUT`.
+        self.read_timeout = read_timeout or DEFAULT_READ_TIMEOUT
         # The token accounting from the last call, when the endpoint reported
-        # any. It holds the prompt and completion counts, plus, on OpenRouter,
-        # `prompt_tokens_details.cached_tokens`, which is the number of prompt
-        # tokens read from cache rather than billed in full. Every request method
-        # writes it, so a caller reads it after the call it made. One provider is
-        # built per request.
+        # any. Every request method writes it, so a caller reads it after the
+        # call it made. One provider is built per request.
         self.last_usage: dict | None = None
 
     def _headers(self) -> dict:
-        headers = {"Content-Type": "application/json"}
-        if self.api_key:
-            headers["Authorization"] = f"Bearer {self.api_key}"
-        return headers
+        # No Authorization header: Ollama does not use one, and this build has
+        # no cloud provider to carry a key for.
+        return {"Content-Type": "application/json"}
 
-    def _apply_reasoning_budget(self, body: dict) -> None:
-        """Gives reasoning models their own thinking budget, in the OpenRouter style.
+    def _timeout(self, seconds: float | None = None) -> httpx.Timeout:
+        """Short to connect, patient to read.
 
-        The method raises `max_tokens`, so the output keeps its full budget.
-
-        A negative budget does the opposite. It sends `effort: "none"` to turn
-        reasoning off on a model that reasons by default, such as DeepSeek V4
-        Flash. That differs from `exclude: true`, which still reasons and still
-        bills for it while hiding the trace. Zero still means send nothing, so an
-        endpoint that rejects unknown fields, such as Ollama, keeps working.
+        A machine that is not listening says so in milliseconds, so a slow
+        connect is a wrong address rather than a busy model and should fail
+        fast. Generation is the opposite: the first token can be minutes away
+        while a model loads.
         """
-        if self.api_mode != "chat":
-            return
-        if self.reasoning_max_tokens < 0:
-            body["reasoning"] = {"effort": "none"}
-        elif self.reasoning_max_tokens > 0:
-            body["reasoning"] = {"max_tokens": self.reasoning_max_tokens}
-            body["max_tokens"] += self.reasoning_max_tokens
-
-    def _apply_provider_routing(self, body: dict) -> None:
-        """Prefers one upstream on OpenRouter, so the prompt cache stays warm.
-
-        The method does nothing anywhere else. `provider` is an OpenRouter
-        extension, and Ollama and similar servers reject fields they do not know.
-        The `reasoning` parameter above is written around the same constraint.
-        """
-        if _OPENROUTER_HOST not in self.base_url:
-            return
-        upstream = _PREFERRED_UPSTREAM.get(self.model.split("/", 1)[0].lower())
-        if upstream:
-            body["provider"] = {"order": [upstream]}
+        return httpx.Timeout(seconds or self.read_timeout, connect=CONNECT_TIMEOUT)
 
     def _record_usage(self, payload: dict) -> None:
         """Records the endpoint's own token accounting, if it reported any.
@@ -147,8 +115,6 @@ class OpenAICompatibleProvider(Provider):
                 "max_tokens": max_tokens,
                 "stream": True,
             }
-        self._apply_reasoning_budget(body)
-        self._apply_provider_routing(body)
         return url, body
 
     @staticmethod
@@ -227,8 +193,6 @@ class OpenAICompatibleProvider(Provider):
                 "max_tokens": max_tokens,
                 "stream": True,
             }
-        self._apply_reasoning_budget(body)
-        self._apply_provider_routing(body)
         async for event in self._stream(url, body):
             yield event
 
@@ -238,17 +202,17 @@ class OpenAICompatibleProvider(Provider):
         The method POSTs a streaming request, yields `("text", chunk)` and
         `("reasoning", chunk)` pairs, and logs the exchange.
         """
-        # SSRF guard for hosted mode. A user-supplied `endpoint_url` must not
-        # point at an internal or metadata address. This does nothing for a
-        # local install.
-        reason = netguard.endpoint_block_reason(url)
+        # Re-checked on every request, not only when the endpoint was saved: a
+        # hostname that resolved to a LAN address yesterday can resolve
+        # somewhere else today, and a database row can be edited by hand.
+        reason = endpoints.rejection_reason(url)
         if reason:
             raise ProviderError(f"This endpoint can't be used — {reason}.")
         log = debuglog.start_entry(url, self.model, body)
         received: list[str] = []
         try:
             async with httpx.AsyncClient(
-                timeout=httpx.Timeout(120, connect=10), verify=tlstrust.ssl_context()
+                timeout=self._timeout(), verify=tlstrust.ssl_context()
             ) as client:
                 async with client.stream("POST", url, json=body, headers=self._headers()) as resp:
                     if resp.status_code != 200:
@@ -351,13 +315,16 @@ class OpenAICompatibleProvider(Provider):
                 "max_tokens": max_tokens,
                 "stream": False,
             }
-        self._apply_reasoning_budget(body)
-        self._apply_provider_routing(body)
 
+        # Same check as `_stream`: every outbound request re-tests the
+        # endpoint, so no path reaches an address the policy refuses.
+        reason = endpoints.rejection_reason(url)
+        if reason:
+            raise ProviderError(f"This endpoint can't be used — {reason}.")
         log = debuglog.start_entry(url, self.model, body)
         try:
             async with httpx.AsyncClient(
-                timeout=httpx.Timeout(120, connect=10), verify=tlstrust.ssl_context()
+                timeout=self._timeout(), verify=tlstrust.ssl_context()
             ) as client:
                 resp = await client.post(url, json=body, headers=self._headers())
         except httpx.HTTPError as exc:
@@ -383,10 +350,15 @@ class OpenAICompatibleProvider(Provider):
             raise ProviderError("No embedding model configured — set one in Settings.")
         url = f"{self.base_url}/embeddings"
         body = {"model": self.model, "input": texts}
+        # Same check as `_stream`: every outbound request re-tests the
+        # endpoint, so no path reaches an address the policy refuses.
+        reason = endpoints.rejection_reason(url)
+        if reason:
+            raise ProviderError(f"This endpoint can't be used — {reason}.")
         log = debuglog.start_entry(url, self.model, body)
         try:
             async with httpx.AsyncClient(
-                timeout=httpx.Timeout(60, connect=10), verify=tlstrust.ssl_context()
+                timeout=self._timeout(EMBED_READ_TIMEOUT), verify=tlstrust.ssl_context()
             ) as client:
                 resp = await client.post(url, json=body, headers=self._headers())
         except httpx.HTTPError as exc:

backend/app/routers/adventures/__init__.py

@@ -13,6 +13,7 @@ Read the modules in this order to follow a turn from end to end:
     turns          playing a turn, and the lock that allows only one at a time
     takes          retries and the attempts that collect at one coordinate
     branches       where a story splits
+    checkpoints    Save Points: durable names for positions the head can return to
 
 What this package re-exports, and what it deliberately does not:
 
@@ -31,8 +32,8 @@ from . import (  # noqa: F401
     turns,
     takes,
     branches,
+    checkpoints,
     bundle_io,
-    scripts,
     refresh,
     insights,
     memories,
@@ -41,7 +42,7 @@ from . import (  # noqa: F401
 from ... import limits  # noqa: F401  `adventures.limits` is patched by tests.
 from .crud import SNIPPET_MAX, _snippet
 from .paging import ACTION_PAGE
-from .takes import retry_action, undo_turn
+from .takes import redo_turn, retry_action, undo_turn
 from .turns import world_delta_of
 
 __all__ = [
@@ -49,6 +50,7 @@ __all__ = [
     "SNIPPET_MAX",
     "_snippet",
     "limits",
+    "redo_turn",
     "retry_action",
     "router",
     "undo_turn",

backend/app/routers/adventures/actions.py

@@ -8,7 +8,7 @@ coordinate through `nodes.delete_turn`.
 from fastapi import Depends, HTTPException
 from sqlalchemy.orm import Session
 
-from ... import attempts, models, schemas, tree
+from ... import attempts, head, models, schemas, tree
 from ...database import get_db
 
 from . import turns
@@ -41,6 +41,11 @@ def list_actions(
         ],
         total=total,
         has_more=has_more,
+        # Every page carries them, not just the newest window: the client reads
+        # the flags off whichever page arrived last, and scrolling up must not
+        # be able to grey out a Redo that is still available (M3).
+        can_undo=head.can_undo(db, adventure),
+        can_redo=head.can_redo(db, adventure),
     )
 
 
@@ -55,6 +60,27 @@ def update_action(
     action = db.get(models.Action, action_id)
     if action is None or action.adventure_id != adventure_id:
         raise HTTPException(404, "Action not found")
+    # An edit rewrites this row and re-evaluates nothing after it, which is what
+    # makes it a correction rather than a new continuation. That is safe while
+    # everything descending from the row is on screen, and unsafe the moment
+    # something descends from it that is not — an undone future, or a line a
+    # divergence left behind. The reader cannot see that story, so they cannot
+    # see what their correction has just contradicted (M3).
+    #
+    # Refusing is the whole of the fix, deliberately. Making the edit fork, so
+    # that the original text and its future stay whole, is
+    # `STORY-BRANCH-SEMANTICS.md` §14-15 — and §15 requires re-evaluating the
+    # state the edited prose implies, which is M5's extraction pass. Neither is
+    # started here. What is closed is the one case where the application could
+    # produce retained history that silently disagrees with itself.
+    if head.displaced_history_under(db, adventure, action):
+        raise HTTPException(
+            400,
+            "This turn has a later story that is not on screen — undone, or "
+            "left behind by a new continuation. Editing it here would change "
+            "the words that story was written from. Redo to bring it back "
+            "first, or play the turn again to start a new line from here.",
+        )
     # One row holds one text. Nothing mirrors it now, so nothing else has to be
     # updated. The edit used to have to be written into the live variant entry
     # as well, or paging away and back reverted it.
@@ -81,6 +107,7 @@ def delete_action(
         # This works like undo. The turn is deleted with all of its attempts,
         # and whatever it produced is withdrawn. The marks are depths, and a
         # depth does not move when an action before it is deleted.
+        was_at = adventure.head_depth
         delete_turn(db, adventure, action)
         db.flush()
         db.expire(adventure, ["actions"])
@@ -88,6 +115,13 @@ def delete_action(
         # middle leaves a gap in the depths, which is intended. See
         # `_backfill_tree`.
         tree.refresh_head(db, adventure)
+        # `refresh_head` recomputes the tip, which since M3 is not the head. A
+        # story sitting behind its retained tip must not be dragged forward to
+        # the tip by an unrelated delete — that would silently Redo it. Keep the
+        # head where the reader left it, unless the delete took the ground out
+        # from under it, in which case the new tip is as far as it can stay.
+        if was_at < adventure.head_depth:
+            adventure.head_depth = was_at
         # The script state and the world state belong to the adventure, not to
         # the node, so deleting the node does not take back what it did to
         # them. Put them back to what the story now ends with, which is the

backend/app/routers/adventures/branches.py

@@ -56,6 +56,19 @@ def list_branches(
         .group_by(models.Action.branch_id)
         .all()
     }
+    # M4 closeout: how many Save Points name a position on each line. Deleting a
+    # branch deletes them along with its story, and the panel has to be able to
+    # say so before the button is pressed (review §R B-2). One grouped query for
+    # the whole tree, like the one above it — never one per branch.
+    save_points = {
+        branch_id: count
+        for branch_id, count in db.query(
+            models.Checkpoint.branch_id, func.count(models.Checkpoint.id)
+        )
+        .filter(models.Checkpoint.adventure_id == adventure.id)
+        .group_by(models.Checkpoint.branch_id)
+        .all()
+    }
     out = []
     for branch in branches:
         count, tip = owned.get(branch.id, (0, None))
@@ -70,6 +83,7 @@ def list_branches(
                 branch.fork_depth if branch.fork_depth is not None else tree.NO_DEPTH
             ),
             own_actions=count,
+            save_points=save_points.get(branch.id, 0),
             is_head=(branch.id == adventure.head_branch_id),
             name=branch.name,
             created_at=branch.created_at,
@@ -151,15 +165,31 @@ def delete_branch(
     heavily retried adventure from growing without bound. That is why it ships
     with the view that first lets anyone create a fork rather than after it.
 
-    Two kinds of branch cannot be deleted. The root cannot, because it holds the
-    turns every other branch borrows, so deleting it deletes the whole story. The
-    branch currently being read cannot, and neither can any branch it was forked
-    from, because the cascade would remove the head under the player and leave
-    `head_branch_id` dangling. Switch branches first.
+    Three kinds of branch cannot be deleted. The root cannot, because it holds
+    the turns every other branch borrows, so deleting it deletes the whole story.
+    The branch currently being read cannot, and neither can any branch it was
+    forked from, because the cascade would remove the head under the player and
+    leave `head_branch_id` dangling. Switch branches first.
+
+    The third is M4's: **a branch a Save Point names cannot be deleted while that
+    Save Point exists.** `STORY-BRANCH-SEMANTICS.md` §19 says a named checkpoint
+    remains until explicitly deleted, and §28 says a future cleanup feature must
+    retain paths referenced by checkpoints. A cascade that removed Save Points
+    along with a branch would break both, and would break them silently: the
+    story the user asked to delete is the visible thing, and the named moments
+    would go without ever being named in the request. So the deletion is refused,
+    the Save Points are listed, and the user decides — delete the Save Point
+    first, then the branch. Deleting a Save Point still deletes no story (§25),
+    so the recovery costs nothing but a click.
+
+    The check covers the whole doomed subtree, not just this branch, because
+    deleting a branch takes everything forked from it.
 
     Nodes and memories are deleted by `ON DELETE CASCADE`, and descendants by the
     cascade on `branches.parent_branch_id`, so the delete is a single statement
-    however deep the subtree is.
+    however deep the subtree is. `checkpoints.branch_id` also carries a cascade,
+    as referential integrity — a Save Point must never point at a branch that is
+    gone — but the guard above means it does not fire through this endpoint.
     """
     branch = get_branch_or_404(adventure, branch_id, db)
     if branch.parent_branch_id is None:
@@ -178,6 +208,11 @@ def delete_branch(
             400, "You are reading this branch, or one forked from it. Switch to "
                  "another branch first.",
         )
+    # Refused before the lock is taken: this is a decision about the request, not
+    # a race with a turn.
+    protecting = _save_points_protecting(db, adventure, branch)
+    if protecting:
+        raise HTTPException(409, _protected_message(protecting))
     turns.acquire_turn_lock(adventure_id)
     try:
         # Collect the subtree before the delete, because afterwards there is no
@@ -199,6 +234,55 @@ def delete_branch(
     finally:
         turns._active_turns.discard(adventure_id)
 
+# How many Save Point names to spell out before the message starts summarising.
+# Enough to be actionable, few enough to stay a sentence.
+NAMED_IN_REFUSAL = 3
+
+
+def _save_points_protecting(
+    db: Session, adventure: models.Adventure, branch: models.Branch
+) -> list[models.Checkpoint]:
+    """Returns the Save Points that deleting `branch` would destroy.
+
+    The whole subtree, because deleting a branch takes everything forked from
+    it, and a check that looked only at this branch would let a Save Point on a
+    child be deleted without a word.
+    """
+    doomed = _branch_subtree(db, adventure, branch)
+    return (
+        db.query(models.Checkpoint)
+        .filter(
+            models.Checkpoint.adventure_id == adventure.id,
+            models.Checkpoint.branch_id.in_(doomed),
+        )
+        .order_by(models.Checkpoint.created_at, models.Checkpoint.id)
+        .all()
+    )
+
+
+def _protected_message(protecting: list[models.Checkpoint]) -> str:
+    """Says which Save Points stand in the way, and what to do about it.
+
+    Named rather than counted, because "2 Save Points" leaves the user hunting
+    for which ones. A long list is truncated so the message stays readable; the
+    Save Points panel shows the rest.
+    """
+    names = [f"“{c.name}”" for c in protecting[:NAMED_IN_REFUSAL]]
+    listed = ", ".join(names)
+    extra = len(protecting) - len(names)
+    if extra > 0:
+        listed += f" and {extra} more"
+    subject = "a Save Point" if len(protecting) == 1 else "Save Points"
+    return (
+        f"This branch, or a branch forked from it, is where {subject} "
+        f"{listed} {'is' if len(protecting) == 1 else 'are'} saved. Delete "
+        f"{'that Save Point' if len(protecting) == 1 else 'those Save Points'} "
+        f"first if you no longer need "
+        f"{'it' if len(protecting) == 1 else 'them'}, then delete the branch. "
+        f"Deleting a Save Point does not delete any story."
+    )
+
+
 def _branch_subtree(
     db: Session, adventure: models.Adventure, root: models.Branch
 ) -> set[int]:

backend/app/routers/adventures/bundle_io.py

@@ -7,7 +7,7 @@ only check ownership and hand the work over.
 from fastapi import Body, Depends, Request
 from sqlalchemy.orm import Session
 
-from ... import analytics, bundle, limits, models, schemas
+from ... import bundle, head, limits, models, schemas
 from ...database import get_db
 
 from .deps import CurrentUser, current_adventure, router
@@ -34,7 +34,6 @@ def import_adventure(
     user: models.User = CurrentUser,
 ):
     version = bundle.check_format(payload)
-    limits.rate_limit("import", request, user)
     limits.check_row_cap("adventures", db, user)
     limits.check_bundle_lists(
         story_cards=payload.get("storyCards"),
@@ -63,8 +62,14 @@ def import_adventure(
 
     db.commit()
     db.refresh(adventure)
+    # A campaign exported while undone imports undone (M3), so the history
+    # controls have to be right on the response that opens it — otherwise the
+    # first thing the reader sees about a story with a retained future is a
+    # greyed-out Redo.
+    out = schemas.AdventureOut.model_validate(adventure)
+    out.can_undo = head.can_undo(db, adventure)
+    out.can_redo = head.can_redo(db, adventure)
     # This is not a funnel step. A returning player imports a bundle, so it
     # says nothing about how far a first-time visitor got. It is counted anyway,
     # because it is the clearest evidence that anyone uses the export format.
-    analytics.record_event(analytics.EV_IMPORT, user)
-    return adventure
+    return out

backend/app/routers/adventures/checkpoints.py

@@ -0,0 +1,351 @@
+"""M4: Save Points — create, list, rename, delete, and restore.
+
+A Save Point is a durable named pointer to a story position and nothing else.
+It stores a coordinate, never a copy of any story, and restoring one moves the
+active head to that coordinate. That is the whole design, and it is what
+`BUILD-MILESTONES.md`'s note on M4 and ADR 012 ask for: M3 made the head a
+stored `(branch, depth)` and made arriving at one a row lookup plus a state
+restore, so a Save Point needs no restore machinery of its own.
+
+What is deliberately absent from this module, because a second copy of any of it
+would be the failure M4 is warned about:
+
+* no head fields are assigned here — `head.move_to_node` moves the head, and
+  `head.move_to` under it restores the state, exactly as Undo and Redo do;
+* nothing reconstructs state, prunes a memory, copies a turn, or deletes one;
+* nothing forks. Restore is not a decision to abandon anything, so it creates no
+  branch. The first write below the restored head forks, through the same
+  `fork_if_behind_head` every other write goes through, and the displaced future
+  stays retained (`STORY-BRANCH-SEMANTICS.md` §20).
+
+The user-facing word is "Save Point" and the internal one is `checkpoint`
+(`BROWSER-UX-SPEC.md` §23). Error strings here are read by a player, so they say
+Save Point.
+"""
+
+from dataclasses import dataclass
+
+from fastapi import Depends, HTTPException
+from sqlalchemy import and_, or_
+from sqlalchemy.orm import Session
+
+from ... import head, models, schemas
+from ...context import lineage
+from ...database import get_db
+
+from . import turns
+from .deps import current_adventure, router
+from .paging import current_window
+
+
+def _node_at(
+    db: Session, adventure: models.Adventure, branch_id: int, depth: int
+) -> models.Action | None:
+    """Returns the live turn a Save Point's coordinate names, or None.
+
+    The lookup is by coordinate and is not scoped to any path. That is the
+    point of it: a Save Point outlives the reader moving away, so the question
+    it has to answer is "is this position still in this campaign's retained
+    history", not "is it on the story being read now". Whether it is on the
+    current path is a separate question, and `head.move_to_node` is what acts on
+    the answer.
+
+    `live` is what makes the coordinate follow a retry. One coordinate can hold
+    several attempts at a turn, and a Save Point names the turn rather than the
+    attempt, so it lands on whichever take the story currently tells.
+    """
+    return (
+        db.query(models.Action)
+        .filter(
+            models.Action.adventure_id == adventure.id,
+            models.Action.branch_id == branch_id,
+            models.Action.depth == depth,
+            models.Action.live.is_(True),
+        )
+        .order_by(models.Action.id)
+        .first()
+    )
+
+
+@dataclass(frozen=True)
+class _Coordinate:
+    """The shape `lineage.Path` reads, without loading a story row.
+
+    `Path.contains` asks three things of a node: its branch, its depth, and
+    whether it is live. A coordinate already known to resolve has all three, so
+    the membership question can be put to the coordinate itself. That keeps the
+    single implementation of "is this on the path being read" in `lineage`,
+    where M3 put it, while costing no query and no prose.
+    """
+
+    branch_id: int
+    depth: int
+    live: bool = True
+
+
+def _live_coordinates(
+    db: Session, adventure: models.Adventure, checkpoints: list[models.Checkpoint]
+) -> set[tuple[int, int]]:
+    """Returns which of these Save Points' coordinates still name a live turn.
+
+    One query for the whole list, selecting two integer columns.
+
+    This replaces a resolution per Save Point (M4 review §R B-1), which cost one
+    query each and loaded whole `Action` entities — narration included — to
+    answer a question that is only ever "does a row exist here". `paging.py`
+    states the rule this now follows: a bulk read names the columns it needs, so
+    a new column costs nothing until someone adds it to the list.
+
+    The clause is an OR of exact `(branch, depth)` pairs rather than
+    `branch IN (…) AND depth IN (…)`, which would match the cross product and
+    report a Save Point as resolved because *some other* Save Point's depth
+    exists on *this* one's branch.
+    """
+    coordinates = {(c.branch_id, c.depth) for c in checkpoints}
+    if not coordinates:
+        return set()
+    rows = (
+        db.query(models.Action.branch_id, models.Action.depth)
+        .filter(
+            models.Action.adventure_id == adventure.id,
+            models.Action.live.is_(True),
+            or_(*[
+                and_(models.Action.branch_id == branch, models.Action.depth == depth)
+                for branch, depth in coordinates
+            ]),
+        )
+        .all()
+    )
+    return {(branch, depth) for branch, depth in rows}
+
+
+def _render_all(
+    db: Session, adventure: models.Adventure, checkpoints: list[models.Checkpoint]
+) -> list[schemas.CheckpointOut]:
+    """Reads Save Points out with the three facts the panel needs about them.
+
+    Bounded work whatever the length of the list: one query for the coordinates
+    and one lineage for the campaign, both computed before the loop. Rendering
+    one Save Point and rendering fifty differ in Python, not in round trips.
+    """
+    live = _live_coordinates(db, adventure, checkpoints)
+    # The path is a property of the campaign, not of any Save Point, so it is
+    # read once. Reading it per row was the other half of the N+1.
+    path = lineage.path_of(db, adventure).uncapped()
+    out = []
+    for checkpoint in checkpoints:
+        coordinate = (checkpoint.branch_id, checkpoint.depth)
+        resolved = coordinate in live
+        rendered = schemas.CheckpointOut.model_validate(checkpoint)
+        # The same `depth + 1` the branch list counts with, so a moment number
+        # means the same thing in both places.
+        rendered.turn = checkpoint.depth + 1
+        rendered.resolved = resolved
+        rendered.on_path = resolved and path.contains(
+            _Coordinate(checkpoint.branch_id, checkpoint.depth)
+        )
+        out.append(rendered)
+    return out
+
+
+def _rendered(
+    db: Session, adventure: models.Adventure, checkpoint: models.Checkpoint
+) -> schemas.CheckpointOut:
+    """Reads one Save Point out, through the same path the list uses."""
+    return _render_all(db, adventure, [checkpoint])[0]
+
+
+def _get_or_404(
+    db: Session, adventure: models.Adventure, checkpoint_id: int
+) -> models.Checkpoint:
+    """Resolves a Save Point id, refusing one that belongs to another campaign.
+
+    The ownership check is the reason this is a function rather than a `db.get`
+    at each call site. A Save Point names a position in one campaign's history,
+    and a coordinate from another campaign would name a different story's turn —
+    or, worse, resolve against this one by arithmetic coincidence. So the id is
+    matched against this adventure, and a Save Point belonging to another is a
+    404 rather than a restore of the wrong story.
+    """
+    checkpoint = db.get(models.Checkpoint, checkpoint_id)
+    if checkpoint is None or checkpoint.adventure_id != adventure.id:
+        raise HTTPException(404, "Save Point not found")
+    return checkpoint
+
+
+def _clean_name(raw: str) -> str:
+    """Returns the trimmed name, refusing one that is blank once trimmed."""
+    name = (raw or "").strip()
+    if not name:
+        raise HTTPException(400, "A Save Point needs a name.")
+    return name
+
+
+@router.get("/{adventure_id}/checkpoints", response_model=list[schemas.CheckpointOut])
+def list_checkpoints(
+    db: Session = Depends(get_db),
+    adventure: models.Adventure = Depends(current_adventure),
+):
+    """Returns the campaign's Save Points, newest first.
+
+    Newest first rather than in story order, because story order is not
+    something this list can honestly claim. Depths are positions along a path,
+    and two Save Points on lines that parted company are not comparable by depth
+    at all — ordering by it would draw a sequence that no reading of the story
+    passes through. When they were made is a fact about all of them.
+    """
+    rows = (
+        db.query(models.Checkpoint)
+        .filter(models.Checkpoint.adventure_id == adventure.id)
+        .order_by(models.Checkpoint.created_at.desc(), models.Checkpoint.id.desc())
+        .all()
+    )
+    return _render_all(db, adventure, rows)
+
+
+@router.post(
+    "/{adventure_id}/checkpoints",
+    response_model=schemas.CheckpointOut,
+    status_code=201,
+)
+def create_checkpoint(
+    adventure_id: int,
+    payload: schemas.CheckpointCreate,
+    db: Session = Depends(get_db),
+    adventure: models.Adventure = Depends(current_adventure),
+):
+    """Names the position the story is currently being read at.
+
+    The active head, not the retained tip. Creating a Save Point after two Undos
+    saves the undone position, because that is where the reader is and the
+    position they are looking at is the one they mean. The distinction only
+    exists at all because M3 stopped Undo from deleting.
+
+    The node at the head is resolved before the row is written, and its own
+    branch is what gets stored — which is not always the branch being read. A
+    head resting in a shared prefix sits on an ancestor's node, and the
+    ancestor is the branch that still names that position after the reader has
+    forked away from it.
+
+    **Held under the campaign's turn lock** (M4 closeout, review §S C-5). "Save
+    where I am" has to name one committed position, and the head is exactly what
+    a turn in flight is about to move. Without the lock this endpoint could read
+    `head_depth` while a turn was mid-commit and store a coordinate for a
+    position the story had already left — a Save Point silently naming the wrong
+    moment, which no later operation could detect. It is the same lock Undo,
+    Redo and Restore take, for the same reason, and not a new mechanism.
+
+    Rename and Delete deliberately do **not** take it: neither reads nor moves a
+    story position, so there is nothing for a turn in flight to race them over.
+    """
+    name = _clean_name(payload.name)
+    turns.acquire_turn_lock(adventure_id)
+    try:
+        node = head.node_at(db, adventure, adventure.head_depth)
+        if node is None:
+            raise HTTPException(400, "There is no turn here to save yet.")
+        checkpoint = models.Checkpoint(
+            adventure_id=adventure.id,
+            name=name,
+            note=payload.note or "",
+            branch_id=node.branch_id,
+            depth=node.depth,
+        )
+        db.add(checkpoint)
+        db.commit()
+        db.refresh(checkpoint)
+        return _rendered(db, adventure, checkpoint)
+    finally:
+        turns._active_turns.discard(adventure_id)
+
+
+@router.patch(
+    "/{adventure_id}/checkpoints/{checkpoint_id}",
+    response_model=schemas.CheckpointOut,
+)
+def rename_checkpoint(
+    checkpoint_id: int,
+    payload: schemas.CheckpointRename,
+    db: Session = Depends(get_db),
+    adventure: models.Adventure = Depends(current_adventure),
+):
+    """Changes a Save Point's label. Nothing else about it moves.
+
+    Not the coordinate, not the head, not a row of story. A Save Point that has
+    been renamed restores to exactly the position it did before, which is
+    `STORY-BRANCH-SEMANTICS.md` §23.
+    """
+    checkpoint = _get_or_404(db, adventure, checkpoint_id)
+    if payload.name is not None:
+        checkpoint.name = _clean_name(payload.name)
+    if payload.note is not None:
+        checkpoint.note = payload.note
+    db.commit()
+    db.refresh(checkpoint)
+    return _rendered(db, adventure, checkpoint)
+
+
+@router.delete("/{adventure_id}/checkpoints/{checkpoint_id}", status_code=204)
+def delete_checkpoint(
+    checkpoint_id: int,
+    db: Session = Depends(get_db),
+    adventure: models.Adventure = Depends(current_adventure),
+):
+    """Removes the named pointer, and only the pointer.
+
+    The turn it named stays, its branch stays, the future past it stays, and the
+    head does not move. This endpoint deletes one row of the `checkpoints`
+    table. `STORY-BRANCH-SEMANTICS.md` §25.
+    """
+    checkpoint = _get_or_404(db, adventure, checkpoint_id)
+    db.delete(checkpoint)
+    db.commit()
+    return None
+
+
+@router.post(
+    "/{adventure_id}/checkpoints/{checkpoint_id}/restore",
+    response_model=schemas.ActionPage,
+)
+def restore_checkpoint(
+    adventure_id: int,
+    checkpoint_id: int,
+    db: Session = Depends(get_db),
+    adventure: models.Adventure = Depends(current_adventure),
+):
+    """Returns the story to a Save Point, deleting nothing.
+
+    Four steps, and the last one is not this module's code: resolve the
+    coordinate, refuse it if it no longer names a live turn, hand it to
+    `head.move_to_node`, and answer with the window the head now caps. The
+    transcript, the world state, the assembled context and which memories can be
+    retrieved all move together, because all four already read through the one
+    path object the head caps — the same reason Undo needed no memory pruning.
+
+    The turns past the restored position are retained, exactly as they are after
+    an Undo, and ordinary Redo can still walk forward into them until the user
+    writes something different. Restore does not fork; the first write below the
+    head does.
+
+    A coordinate that no longer resolves is refused rather than approximated.
+    Moving the head to the nearest surviving turn would be the one outcome worse
+    than doing nothing: a Save Point that silently means somewhere else.
+    """
+    checkpoint = _get_or_404(db, adventure, checkpoint_id)
+    turns.acquire_turn_lock(adventure_id)
+    try:
+        node = _node_at(db, adventure, checkpoint.branch_id, checkpoint.depth)
+        if node is None:
+            raise HTTPException(
+                409,
+                "That Save Point's position is no longer part of this story.",
+            )
+        head.move_to_node(db, adventure, node)
+        adventure.updated_at = models.utcnow()
+        db.commit()
+        db.refresh(adventure)
+        # A window, not the whole story, for the reason Undo gives: the client
+        # replaces its transcript with this, and the transcript is a window.
+        return current_window(db, adventure)
+    finally:
+        turns._active_turns.discard(adventure_id)

backend/app/routers/adventures/crud.py

@@ -9,7 +9,9 @@ from sqlalchemy import func
 from sqlalchemy.orm import Session
 from sqlalchemy.orm.attributes import set_committed_value
 
-from ... import analytics, attempts, images, limits, memorybank, models, schemas, tree, worldstate
+from ... import (
+    attempts, head, images, limits, memorybank, models, schemas, tree, worldstate,
+)
 from ...database import get_db
 
 from .deps import CurrentUser, current_adventure, router
@@ -195,20 +197,6 @@ def create_adventure(
     if scenario:
         for ref, spec in scenario_card_specs(scenario, values).items():
             db.add(models.StoryCard(adventure_id=adventure.id, source_ref=ref, **spec))
-        for position, script in enumerate(scenario.scripts):
-            db.add(
-                models.AdventureScript(
-                    adventure_id=adventure.id,
-                    source_script_id=script.id,
-                    position=position,
-                    name=script.name,
-                    description=script.description,
-                    library_js=script.library_js,
-                    input_js=script.input_js,
-                    context_js=script.context_js,
-                    output_js=script.output_js,
-                )
-            )
         if scenario.prompt.strip():
             opening = models.Action(
                 adventure_id=adventure.id,
@@ -223,12 +211,6 @@ def create_adventure(
 
     db.commit()
     db.refresh(adventure)
-    analytics.record_event(analytics.EV_ADVENTURE, user)
-    # Track which shared scenarios players pick. This is the only content this
-    # module records, and it records only public scenarios. A player's own
-    # scenario titles stay private.
-    if scenario is not None and scenario.is_public:
-        analytics.record(analytics.M_SCENARIO, scenario.title)
     return adventure
 
 
@@ -259,23 +241,14 @@ def get_adventure(
     set_committed_value(adventure, "actions", actions)
     out = schemas.AdventureOut.model_validate(adventure)
     out.action_count = total
+    # M3. Opening a story has to render its history controls correctly, and a
+    # campaign whose head sits behind the retained tip — undone and then closed —
+    # must come back with Redo available.
+    out.can_undo = head.can_undo(db, adventure)
+    out.can_redo = head.can_redo(db, adventure)
     return out
 
 
-@router.get("/{adventure_id}/script-state")
-def get_script_state(
-    adventure: models.Adventure = Depends(current_adventure),
-):
-    """Returns the scripting `state` object.
-
-    The object holds every variable that scripts read and write through
-    `state.x`, persisted after each hook. It stays `{}` until a script sets a
-    variable.
-    """
-    state = adventure.script_state if isinstance(adventure.script_state, dict) else {}
-    return {"state": state}
-
-
 @router.get("/{adventure_id}/world-state")
 def get_world_state(
     adventure: models.Adventure = Depends(current_adventure),

backend/app/routers/adventures/insights.py

@@ -7,7 +7,7 @@ returns the prompt a turn was actually generated from. Neither writes anything.
 from fastapi import Depends, HTTPException
 from sqlalchemy.orm import Session
 
-from ... import auth, memorybank, models
+from ... import memorybank, models
 from ...context import build_context
 from ...database import get_db
 from ..settings import get_settings
@@ -23,14 +23,7 @@ async def dry_run_context(
 ):
     """Returns what the app would send to the AI if the player continued now."""
     settings = get_settings(db, user)
-    if auth.resolve_provider_config(settings).using_demo:
-        memories = (
-            {"used": [], "error": "Memory bank is unavailable on the shared demo key."}
-            if adventure.memory_bank_enabled
-            else None
-        )
-    else:
-        memories = await memorybank.retrieve_memories(adventure, settings, update_stats=False)
+    memories = await memorybank.retrieve_memories(adventure, settings, update_stats=False)
     _, _, report = build_context(adventure, settings, memories)
     return report
 

backend/app/routers/adventures/nodes.py

@@ -8,7 +8,7 @@ module in the package can import them.
 from fastapi import HTTPException
 from sqlalchemy.orm import Session, undefer
 
-from ... import attempts, memorybank, models, tree
+from ... import attempts, head, memorybank, models, tree
 from ...context import cursors
 from ...context import lineage
 
@@ -125,6 +125,10 @@ def stand_on(
         newest is not None
         and newest.branch_id == action.branch_id
         and newest.depth == action.depth
+        # A turn the head rests on is still not a leaf while a retained future
+        # descends from it. `last_action` reads the capped path and cannot see
+        # that future, so switching in place here would strand it (M3).
+        and not head.behind_tip(db, adventure)
     )
     if at_the_tip:
         # The story at this coordinate is about to change, so withdraw whatever

backend/app/routers/adventures/paging.py

@@ -8,7 +8,7 @@ columns and apply the same numbering, so both live here.
 from sqlalchemy import func
 from sqlalchemy.orm import Session, load_only
 
-from ... import models, schemas
+from ... import head, models, schemas
 from ...context import lineage
 
 
@@ -165,4 +165,6 @@ def current_window(db: Session, adventure: models.Adventure) -> schemas.ActionPa
         ],
         total=total,
         has_more=has_more,
+        can_undo=head.can_undo(db, adventure),
+        can_redo=head.can_redo(db, adventure),
     )

backend/app/routers/adventures/scripts.py

@@ -1,116 +0,0 @@
-"""The per-adventure copies of library scripts.
-
-An adventure snapshots a library `Script` when it starts, so editing the library
-does not change a story in progress. These endpoints report whether a snapshot
-has fallen behind its library original, and copy the original over on request.
-"""
-
-from fastapi import Depends, HTTPException
-from sqlalchemy.orm import Session
-
-from ... import models, schemas
-from ...database import get_db
-
-from .deps import CurrentUser, current_adventure, router
-
-
-# Fields that are copied from a library Script into its adventure-script
-# snapshot, and compared to decide whether a copy is out of date.
-SYNC_FIELDS = ("name", "description", "library_js", "input_js", "context_js", "output_js")
-
-
-def resolve_library_script(
-    adv_script: models.AdventureScript, db: Session, user: models.User
-) -> models.Script | None:
-    """Returns the library Script an adventure script can re-sync from.
-
-    The result is the script this copy was made from. For a legacy copy with no
-    link, it is one of the player's own scripts with the same name. Only the
-    player's own scripts are considered, so a copy derived from a demo scenario
-    has nothing to sync to.
-    """
-    if adv_script.source_script_id is not None:
-        script = db.get(models.Script, adv_script.source_script_id)
-        if script is not None and script.user_id == user.id:
-            return script
-    return (
-        db.query(models.Script)
-        .filter(models.Script.user_id == user.id, models.Script.name == adv_script.name)
-        .order_by(models.Script.updated_at.desc())
-        .first()
-    )
-
-
-def _mark_out_of_date(
-    adv_script: models.AdventureScript, db: Session, user: models.User
-) -> models.AdventureScript:
-    """Attaches a transient `out_of_date` flag, which `AdventureScriptOut` reads.
-
-    The flag is `True` or `False` when a syncable library version exists, and
-    `None` when none exists.
-    """
-    library = resolve_library_script(adv_script, db, user)
-    adv_script.out_of_date = (
-        None if library is None
-        else any(getattr(adv_script, f) != getattr(library, f) for f in SYNC_FIELDS)
-    )
-    return adv_script
-
-
-@router.get("/{adventure_id}/scripts", response_model=list[schemas.AdventureScriptOut])
-def list_adventure_scripts(
-    db: Session = Depends(get_db),
-    user: models.User = CurrentUser,
-    adventure: models.Adventure = Depends(current_adventure),
-):
-    return [_mark_out_of_date(s, db, user) for s in adventure.scripts]
-
-
-@router.post(
-    "/{adventure_id}/scripts/{adv_script_id}/sync",
-    response_model=schemas.AdventureScriptOut,
-)
-def sync_adventure_script(
-    adventure_id: int,
-    adv_script_id: int,
-    db: Session = Depends(get_db),
-    user: models.User = CurrentUser,
-    adventure: models.Adventure = Depends(current_adventure),
-):
-    """Overwrites this copy's code with the latest from its library script.
-
-    `enabled`, `position`, and the adventure's shared `script_state` are kept.
-    """
-    script = db.get(models.AdventureScript, adv_script_id)
-    if script is None or script.adventure_id != adventure_id:
-        raise HTTPException(404, "Script not found")
-    library = resolve_library_script(script, db, user)
-    if library is None:
-        raise HTTPException(404, "No library script to sync from")
-    for field in SYNC_FIELDS:
-        setattr(script, field, getattr(library, field))
-    # Store the link, so that a name-matched legacy copy syncs by id next
-    # time.
-    script.source_script_id = library.id
-    db.commit()
-    db.refresh(script)
-    return _mark_out_of_date(script, db, user)
-
-
-@router.patch(
-    "/{adventure_id}/scripts/{adv_script_id}", response_model=schemas.AdventureScriptOut
-)
-def update_adventure_script(
-    adventure_id: int,
-    adv_script_id: int,
-    payload: schemas.AdventureScriptUpdate,
-    db: Session = Depends(get_db),
-    adventure: models.Adventure = Depends(current_adventure),
-):
-    script = db.get(models.AdventureScript, adv_script_id)
-    if script is None or script.adventure_id != adventure_id:
-        raise HTTPException(404, "Script not found")
-    for field, value in payload.model_dump(exclude_unset=True).items():
-        setattr(script, field, value)
-    db.commit()
-    return script

backend/app/routers/adventures/takes.py

@@ -11,17 +11,16 @@ from fastapi import Depends, HTTPException, Request
 from fastapi.responses import StreamingResponse
 from sqlalchemy.orm import Session
 
-from ... import attempts, limits, memorybank, models, schemas, tree
+from ... import attempts, head, limits, memorybank, models, schemas, tree
 from ...context import cursors
 from ...context import lineage
 from ...database import get_db
-from ...scripting import ScriptPipeline
 from ...sse import SSE_HEADERS
 
 from . import turns
 from .deps import CurrentUser, current_adventure, router
-from .nodes import delete_turn, last_action, stand_on
-from .paging import action_window, annotate_takes, current_window
+from .nodes import last_action, stand_on
+from .paging import current_window
 
 
 @router.post("/{adventure_id}/retry")
@@ -34,26 +33,44 @@ def retry_action(
 ):
     """Regenerates the last AI action and keeps the discarded attempt.
 
-    The attempt on screen stays as it was written. The shared script state and
-    world state roll back to what the node before it left behind, and the new
-    attempt is stored as a sibling at the same coordinate. No text the AI wrote
-    is rewritten or deleted.
+    The attempt on screen stays as it was written. The world state rolls back to
+    what the node before it left behind, and the new attempt is stored as a
+    sibling at the same coordinate. No text the AI wrote is rewritten or deleted.
+
+    M3 added the one case that cannot be a sibling. Retrying the turn the head
+    rests on while a retained future still descends from it would leave that
+    future hanging off a take that is no longer live — the story after it was
+    written to continue the old text. So a retry from behind the tip takes a
+    branch instead, exactly as `add_take` does for a turn the story has moved
+    past. It is the same operation reached from a different button.
     """
-    limits.rate_limit("turn", request, user)
-    turns.check_demo_cap(db, user)
     turns.acquire_turn_lock(adventure_id)
     last_ai = None
     try:
         newest = last_action(adventure, db)
         if newest is not None and newest.type == "ai":
-            last_ai = newest
+            # Read this before anything moves, and note it is *not*
+            # `fork_if_behind_head`: this fork leaves the path just in front of
+            # the turn being retried rather than at the head, so the new take
+            # lands at the same depth under the same parent.
+            diverging = head.behind_tip(db, adventure)
+            if diverging:
+                departed = lineage.branch_of(db, adventure)
+                tree.branch_at(db, adventure, (newest.depth or 0) - 1)
+                if departed is not None:
+                    head.mark_superseded(departed, (newest.depth or 0) - 1)
+            else:
+                # Only a sibling attempt names the node it replaces. A branched
+                # take is a fresh node at the same coordinate, so `generate_turn`
+                # places it through the tree rather than through `add_attempt`.
+                last_ai = newest
             # Roll the state back to before this AI turn's hooks ran, so that
             # regenerating starts from a clean state rather than applying output
             # mutations on top of the attempt being replaced. If the preceding
             # node has no snapshot, which happens for a pre-SP4 row that the
             # migration could not derive one for, this call does nothing and
             # leaves the state as it is.
-            attempts.roll_back_before(db, adventure, last_ai)
+            attempts.roll_back_before(db, adventure, newest)
             db.commit()
             db.refresh(adventure)
     except BaseException:
@@ -62,9 +79,7 @@ def retry_action(
     return StreamingResponse(
         turns.with_turn_lock(
             adventure_id,
-            turns.generate_turn(
-                adventure, db, ScriptPipeline(adventure, db), user, retry_of=last_ai
-            ),
+            turns.generate_turn(adventure, db, user, retry_of=last_ai),
         ),
         media_type="text/event-stream",
         headers=SSE_HEADERS,
@@ -142,6 +157,17 @@ def select_variant(
             "Only the latest message can be switched — the story has already "
             "continued from this one.",
         )
+    if head.behind_tip(db, adventure):
+        # The head is behind the retained tip, so this turn reads as the newest
+        # one but still has an accepted future descending from it. Switching the
+        # live take in place would leave that future continuing text the story
+        # no longer tells. Forking is the operation that does this safely, and
+        # `/fork` is where it lives.
+        raise HTTPException(
+            400,
+            "This turn has a later story that was undone but kept. Redo first, "
+            "or use another take to start a new line from here.",
+        )
     turns.acquire_turn_lock(adventure_id)
     try:
         chosen = rows[payload.index]
@@ -254,9 +280,7 @@ def add_take(
     turn, so the new attempt is written at the same depth under the same parent,
     and the line it leaves is unchanged. No node below is copied.
     """
-    limits.rate_limit("turn", request, user)
     limits.check_row_cap("actions", db, user, adventure=adventure)
-    turns.check_demo_cap(db, user)
     action = db.get(models.Action, action_id)
     if action is None or action.adventure_id != adventure_id:
         raise HTTPException(404, "Action not found")
@@ -270,7 +294,15 @@ def add_take(
     retry_of = None
     try:
         newest = last_action(adventure, db)
-        at_the_tip = newest is not None and newest.id == action.id
+        # `last_action` reads the capped path, so under a moved-back head it
+        # reports the node at the head as the newest one. A turn with a retained
+        # future is not a leaf, whatever the capped read says, so ask the head
+        # module rather than trusting the depth comparison alone (M3).
+        at_the_tip = (
+            newest is not None
+            and newest.id == action.id
+            and not head.behind_tip(db, adventure)
+        )
         if at_the_tip and action.type == "ai":
             # Nothing was played after it, so its attempts are still leaves and
             # a branch would serve no purpose. This is the `retry` path.
@@ -281,7 +313,10 @@ def add_take(
             # text that is there now. The new attempt leaves the path just
             # before the turn, so that story keeps the attempt it was written
             # for.
+            departed = lineage.branch_of(db, adventure)
             tree.branch_at(db, adventure, action.depth - 1)
+            if departed is not None:
+                head.mark_superseded(departed, action.depth - 1)
             attempts.roll_back_before(db, adventure, action)
         adventure.updated_at = models.utcnow()
         db.commit()
@@ -292,9 +327,7 @@ def add_take(
     if action.type == "ai":
         # There is no player action to write. The action this turn answers is
         # already on the path, borrowed from the line being left.
-        stream = turns.generate_turn(
-            adventure, db, ScriptPipeline(adventure, db), user, retry_of=retry_of
-        )
+        stream = turns.generate_turn(adventure, db, user, retry_of=retry_of)
     else:
         stream = turns.run_player_turn(
             adventure,
@@ -318,71 +351,78 @@ def undo_turn(
     db: Session = Depends(get_db),
     adventure: models.Adventure = Depends(current_adventure),
 ):
-    """Deletes the last turn: the trailing AI action and its player action, if any.
+    """Moves the story back one turn. Deletes nothing (M3).
 
-    The endpoint also rolls the shared `script_state` back to before that turn
-    ran, and it prunes any memory that summarized the removed actions. The turn
-    lock prevents an undo while a turn is still generating.
+    This endpoint used to remove the trailing AI action and the player action in
+    front of it, prune the memories that covered them, and let the tip fall back
+    to whatever survived. Undoing was therefore the one operation in the
+    application that destroyed accepted story, and it was why there was no Redo:
+    the turns to move forward into no longer existed.
+
+    Now it moves `adventure.head_depth`. The rows stay exactly where they are,
+    still live, still on their branch, and `lineage.Path` stops every read at the
+    head instead. The transcript, the assembled context, `attempts.preceding` and
+    memory retrieval all narrow together, because all four already funnelled
+    through the same path object.
+
+    The memory bank needs no pruning for the same reason. A memory carries the
+    coordinate of the node its block ends on, so a memory derived from a turn
+    that is now past the head falls outside the capped clause and stops being
+    retrievable — and becomes eligible again on Redo, without having been deleted
+    and re-embedded. That is `STORY-BRANCH-SEMANTICS.md` §33 for free.
+
+    The state comes back from the node the story now ends on, which recorded what
+    it left behind when it played. See `head.move_to`.
     """
     turns.acquire_turn_lock(adventure_id)
     try:
-        # Only the last turn is removed, so fetch the two actions it can
-        # consist of rather than the whole story.
-        newest = (
-            db.query(models.Action)
-            .filter(
-                models.Action.adventure_id == adventure.id,
-                lineage.path_of(db, adventure).clause(models.Action),
-            )
-            .order_by(models.Action.depth.desc(), models.Action.id.desc())
-            .limit(2)
-            .all()
-        )
-        if not newest or newest[0].type == "start":
+        target = head.undo_target(db, adventure)
+        if target is None:
             raise HTTPException(400, "Nothing to undo")
-        last = newest[0]
-        before_that = newest[1] if len(newest) > 1 else None
-        # Undo only what this branch owns. Everything before the fork is
-        # borrowed from an ancestor and is part of that ancestor's story too, so
-        # an undo here must never delete a turn out of another branch. The test
-        # reads the row's own branch rather than the fork depth, because the
-        # branch is what decides the case.
-        if last.branch_id != adventure.head_branch_id:
-            raise HTTPException(
-                400, "Nothing to undo on this branch — the turns before it "
-                     "belong to the branch it was forked from.",
-            )
-        first_removed = last
-        if (last.type == "ai" and before_that is not None
-                and before_that.type in ("do", "say", "story")
-                and before_that.branch_id == adventure.head_branch_id):
-            first_removed = before_that
-        # The state the story returns to once the turn is gone, which is what
-        # the node before the earliest removed one left behind. Read it before
-        # the deletes, while those rows are still in the story.
-        restore_to = attempts.preceding(db, adventure, first_removed)
-        delete_turn(db, adventure, last)
-        if first_removed is not last:
-            delete_turn(db, adventure, first_removed)
-        attempts.restore_state(adventure, restore_to)
-        db.flush()  # Apply the deletes before anything reads the story back.
-        db.expire(adventure, ["actions"])
-        # The tip moves back with the deleted rows.
-        tree.refresh_head(db, adventure)
+        depth, _first_stepped = target
+        head.move_to(db, adventure, depth)
+        adventure.updated_at = models.utcnow()
         db.commit()
         db.refresh(adventure)
         # Return the newest window rather than the whole story. The client
         # replaces its transcript with this response, and the transcript is a
         # window. Returning everything would defeat the paging on the action a
         # player is most likely to repeat several times in a row.
-        actions, total, has_more = action_window(db, adventure)
-        return schemas.ActionPage(
-            actions=[
-            schemas.ActionOut.model_validate(a)
-            for a in annotate_takes(db, adventure.id, actions)
-        ],
-            total=total,
-            has_more=has_more,
-        )
+        return current_window(db, adventure)
+    finally:
+        turns._active_turns.discard(adventure_id)
+
+
+@router.post("/{adventure_id}/redo", response_model=schemas.ActionPage)
+def redo_turn(
+    adventure_id: int,
+    db: Session = Depends(get_db),
+    adventure: models.Adventure = Depends(current_adventure),
+):
+    """Moves the story forward again into the continuation Undo stepped out of.
+
+    Redo exists because Undo stopped deleting. It walks the head forward over one
+    whole turn along the retained lineage, and restores the state that turn left
+    behind.
+
+    It follows the lineage rather than choosing among branches, which is what
+    makes it invalidate itself correctly. Writing below a moved-back head forks,
+    and from the new branch the displaced future is no longer on the lineage at
+    all — so there is nothing ahead to walk into and this returns 400 without any
+    flag having to be set or cleared. `STORY-BRANCH-SEMANTICS.md` §8.
+
+    400 is also what a head already at the tip gets, which is the ordinary case
+    for a story that has never been undone.
+    """
+    turns.acquire_turn_lock(adventure_id)
+    try:
+        depth = head.redo_target(db, adventure)
+        if depth is None:
+            raise HTTPException(400, "Nothing to redo")
+        head.move_to(db, adventure, depth)
+        adventure.updated_at = models.utcnow()
+        db.commit()
+        db.refresh(adventure)
+        return current_window(db, adventure)
     finally:
         turns._active_turns.discard(adventure_id)

backend/app/routers/adventures/turns.py

@@ -3,8 +3,8 @@
 Everything a test needs to intercept lives here, and other modules reach it as
 `turns.<name>` rather than importing it by value. That matters twice. The turn
 lock guards one set only while one module owns it. And a test that replaces
-`OpenAICompatibleProvider`, `generate_turn`, or `check_demo_cap` patches this
-module, which every caller reads through.
+`OpenAICompatibleProvider` or `generate_turn` patches this module, which every
+caller reads through.
 """
 import threading
 
@@ -13,12 +13,11 @@ from fastapi.responses import StreamingResponse
 from sqlalchemy.orm import Session
 
 from ... import (
-    analytics, attempts, auth, limits, memorybank, models, schemas, tree, worldstate,
+    attempts, head, limits, memorybank, models, schemas, tree, worldstate,
 )
 from ...context import build_context, cursors
 from ...database import get_db
 from ...providers import OpenAICompatibleProvider, PromptParts, ProviderError
-from ...scripting import ScriptPipeline
 from ...sse import SSE_HEADERS, sse, turn_error
 from ..settings import get_settings
 
@@ -115,14 +114,11 @@ def action_json(action: models.Action, db: Session | None = None) -> dict:
 async def generate_turn(
     adventure: models.Adventure,
     db: Session,
-    pipeline: ScriptPipeline,
     user: models.User,
     retry_of: models.Action | None = None,
 ):
     """Streams the AI continuation as SSE, then stores the result.
 
-    The continuation passes through the `context` and `output` script hooks.
-
     If `retry_of` is set, the result is stored as a sibling of that AI action, at
     the same turn and the same coordinate, and the discarded attempt stays where
     it was written. Before calling, the caller must roll the adventure back to
@@ -132,15 +128,15 @@ async def generate_turn(
     """
     saved = False
     try:
-        async for event in _generate_turn(adventure, db, pipeline, user, retry_of):
+        async for event in _generate_turn(adventure, db, user, retry_of):
             if event is _SAVED:
                 saved = True
                 continue
             yield event
     finally:
         if retry_of is not None and not saved:
-            # The turn failed with a provider error, an empty reply, a script
-            # stop, or a disconnected client. No sibling was written, so the
+            # The turn failed with a provider error, an empty reply, or a
+            # disconnected client. No sibling was written, so the
             # attempt on screen is still the live one. Restore the state it
             # produced.
             attempts.restore_state(adventure, retry_of)
@@ -155,55 +151,27 @@ _SAVED = object()
 async def _generate_turn(
     adventure: models.Adventure,
     db: Session,
-    pipeline: ScriptPipeline,
     user: models.User,
     retry_of: models.Action | None = None,
 ):
     settings = get_settings(db, user)
-    cfg = auth.resolve_provider_config(settings)
     # On a retry, the attempt being replaced is still the live node of its turn,
     # because it stays live until a replacement exists. Filter it out of the
     # context. Otherwise the model reads the attempt it is replacing as
     # established story and writes a sequel to it.
     replacing_id = retry_of.id if retry_of is not None else None
-    if cfg.using_demo:
-        # The server-funded key makes no embedding or summarization calls, so
-        # memory retrieval is skipped. If the bank is on, return a note.
-        memories = (
-            {"used": [], "error": "Memory bank is unavailable on the shared demo key — add your own API key in Settings."}
-            if adventure.memory_bank_enabled
-            else None
-        )
-    else:
-        memories = await memorybank.retrieve_memories(
-            adventure, settings, update_stats=True, exclude_action_id=replacing_id
-        )
+    memories = await memorybank.retrieve_memories(
+        adventure, settings, update_stats=True, exclude_action_id=replacing_id
+    )
     system_text, story_text, snapshot = build_context(
         adventure, settings, memories, exclude_action_id=replacing_id
     )
 
-    # onModelContext: scripts read, and can rewrite, the whole assembled
-    # context.
-    combined = f"{system_text}\n\n{story_text}" if system_text else story_text
-    modified, stop = pipeline.run("context", combined)
-    if stop:
-        yield sse({"type": "stopped", "script": pipeline.report()})
-        return
-    context_changed = modified != combined
-    parts = (
-        PromptParts(system="", story=modified)
-        if context_changed
-        else PromptParts(system=system_text, story=story_text)
-    )
-    snapshot["script"] = pipeline.report() | {
-        "context_changed": context_changed,
-        "context_before": combined if context_changed else None,
-        "context_after": modified if context_changed else None,
-    }
+    parts = PromptParts(system=system_text, story=story_text)
 
     provider = OpenAICompatibleProvider(
-        cfg.endpoint_url, cfg.api_key, cfg.model, settings.api_mode,
-        settings.reasoning_max_tokens,
+        settings.endpoint_url, settings.model, settings.api_mode,
+        settings.model_timeout_seconds,
     )
     chunks: list[str] = []
     reasoning_chunks: list[str] = []
@@ -239,13 +207,6 @@ async def _generate_turn(
         yield turn_error(detail)
         return
 
-    # onOutput
-    text, _ = pipeline.run("output", text)
-    if not text.strip():
-        yield turn_error("A script's output modifier returned empty text.")
-        return
-    snapshot["script"] = snapshot["script"] | pipeline.report()
-
     # RPG world state (Phase 12): read the AI's state delta out of the reply,
     # apply it through the engine, and strip the block from the displayed text.
     #
@@ -304,39 +265,15 @@ async def _generate_turn(
         tree.place_action(db, adventure, ai_action)
         db.add(ai_action)
     adventure.updated_at = models.utcnow()
-    if cfg.using_demo:
-        # Successful demo turns count against the daily cap, which the endpoint
-        # checks before the turn starts. A failed provider call above returns
-        # before this line.
-        auth.count_demo_turn(user)
     db.commit()
-    # Count the turn here, after every path on which it could still have failed,
-    # so the number means "stories advanced" rather than "requests attempted".
-    # The demo tally counts those same turns as spend on the server-funded key.
-    analytics.record_event(analytics.EV_TURN, user)
-    if cfg.using_demo:
-        analytics.record(analytics.M_EVENT, analytics.EV_DEMO_TURN)
     db.refresh(ai_action)
     yield _SAVED
-    yield sse({"type": "done", "action": action_json(ai_action, db), "script": pipeline.report()})
+    yield sse({"type": "done", "action": action_json(ai_action, db)})
     # Phase 6: schedule summarization and embedding without waiting for them.
-    # The task opens its own database session. It is skipped on the demo key,
-    # because background AI calls are unmetered spend on the server-funded
-    # key.
-    if not cfg.using_demo:
-        memorybank.schedule_post_turn(adventure)
+    # The task opens its own database session.
+    memorybank.schedule_post_turn(adventure)
 
 
-def check_demo_cap(db: Session, user: models.User) -> None:
-    """Checks the demo cap before a turn starts.
-
-    Checking first avoids storing a capped player's input and then leaving it
-    without a reply.
-    """
-    settings = get_settings(db, user)
-    if auth.resolve_provider_config(settings).using_demo and auth.demo_turns_left(user) <= 0:
-        raise HTTPException(429, auth.DEMO_CAP_MESSAGE)
-
 
 async def run_player_turn(
     adventure: models.Adventure,
@@ -353,29 +290,20 @@ async def run_player_turn(
     formatted, and a plain edit puts that same text in the box and writes it back
     verbatim. Formatting it a second time produces `> You > You ...`.
     """
-    pipeline = ScriptPipeline(adventure, db)
-
     # An empty do, say, or story action behaves as a continue.
     if payload.type != "continue" and payload.text.strip():
-        # onInput reads the formatted text, as in AI Dungeon: "> You ...".
         formatted = (
             payload.text.strip() if preformatted
             else format_player_input(payload.type, payload.text)
         )
-        modified, stop = pipeline.run("input", formatted)
-        if not modified.strip():
-            yield turn_error("A script's input modifier returned empty text.",
-                             script=pipeline.report())
-            return
         player_action = models.Action(
             adventure_id=adventure.id,
             depth=next_depth(adventure),
             type=payload.type,
-            text=modified,
+            text=formatted,
         )
-        # The state after the input hook has run. The node leaves this state
-        # behind. The AI turn after it starts here, and a retry of that turn
-        # rolls back to here.
+        # The state this node leaves behind. The AI turn after it starts here,
+        # and a retry of that turn rolls back to here.
         attempts.snapshot_outcome(adventure, player_action)
         tree.place_action(db, adventure, player_action)
         db.add(player_action)
@@ -387,12 +315,8 @@ async def run_player_turn(
         # that was just saved.
         db.expire(adventure, ["actions"])
         yield sse({"type": "player", "action": action_json(player_action, db)})
-        if stop:
-            # If onInput returns `{ stop: true }`, skip the AI call.
-            yield sse({"type": "stopped", "script": pipeline.report()})
-            return
 
-    async for event in generate_turn(adventure, db, pipeline, user):
+    async for event in generate_turn(adventure, db, user):
         yield event
 
 
@@ -405,12 +329,18 @@ def create_action(
     user: models.User = CurrentUser,
     adventure: models.Adventure = Depends(current_adventure),
 ):
-    limits.rate_limit("turn", request, user)
     limits.check_row_cap("actions", db, user, adventure=adventure)
-    check_demo_cap(db, user)
     acquire_turn_lock(adventure_id)
     try:
         _move_to_after(db, adventure, payload.after_id)
+        # The first write below a moved-back head is where a divergence happens
+        # (M3). Undo alone does not fork — the user may be reading, or about to
+        # Redo — so this is the moment the story states which continuation it
+        # means. The displaced future keeps its rows on the branch being left.
+        # A head already at the tip, which is every ordinary turn, forks nothing.
+        if head.fork_if_behind_head(db, adventure):
+            db.commit()
+            db.refresh(adventure)
     except BaseException:
         _active_turns.discard(adventure_id)
         raise

backend/app/routers/analytics.py

@@ -1,140 +0,0 @@
-"""Visit analytics: one endpoint the browser writes to, one the owner reads.
-
-The split matters. `/collect` is public and accepts one fact, which page was
-viewed, because anything a stranger can POST is a number a stranger can invent.
-Everything the dashboard relies on, meaning turns, adventures, sign-ups, demo
-spend, and errors, is recorded on the server by the code that performs it, so
-those counts are as trustworthy as the app itself.
-
-The two reading endpoints are owner-only and 404 for everyone else, the same
-way the AI Chat router does: a feature nobody else can use is better off not
-appearing to exist. `/summary` serves the anonymous counters (analytics.py,
-which stores nothing that points at a person) and `/access` serves the access
-log (accesslog.py, which identifies people on purpose).
-"""
-
-from fastapi import APIRouter, Depends, HTTPException, Query, Request, Response
-from pydantic import BaseModel, Field
-from sqlalchemy.orm import Session
-
-from .. import accesslog, analytics, auth, limits, models
-from ..database import get_db
-
-router = APIRouter(prefix="/api/analytics", tags=["analytics"])
-
-
-def owner(
-    db: Session = Depends(get_db),
-    user: models.User = Depends(auth.get_current_user),
-) -> models.User:
-    """Gates the reading half. It returns 404 rather than 403. See the module
-    docstring."""
-    if not auth.is_owner(user):
-        raise HTTPException(404, "Not found")
-    return user
-
-
-Owner = Depends(owner)
-
-
-class Pageview(BaseModel):
-    """What the SPA reports on a page load or a route change.
-
-    `first` marks a real page load rather than a client-side navigation. The
-    facts that describe a visit rather than a view, which are where it came from,
-    on what kind of device, and from which country, are recorded only on a page
-    load, so a visitor who clicks through five pages is still one referral.
-    """
-
-    path: str = Field("", max_length=300)
-    referrer: str = Field("", max_length=500)
-    first: bool = False
-
-
-@router.post("/collect", status_code=204)
-def collect(
-    payload: Pageview,
-    request: Request,
-    db: Session = Depends(get_db),
-) -> Response:
-    """Record one pageview. Always 204, even when nothing was counted: the
-    browser has no business knowing whether it was."""
-    limits.rate_limit("analytics", request)
-    # Resolved by hand rather than through get_current_user: a pageview that
-    # arrives before /auth/me has minted a session should still be counted as a
-    # view, not turned into a 401 the SPA has to handle.
-    user = (
-        auth.resolve_session_user(request, db)
-        if auth.MULTI_USER
-        else auth.local_user(db)
-    )
-    # The operator's own clicks are not traffic. This applies only in
-    # multi-user mode. Locally every user is the owner, and excluding them would
-    # leave the dashboard empty on the machine the app is developed on.
-    if auth.MULTI_USER and user is not None and auth.is_owner(user):
-        return Response(status_code=204)
-
-    analytics.record(analytics.M_PAGE, analytics.normalize_route(payload.path))
-    analytics.record_visit(user)
-    if payload.first:
-        referrer = analytics.normalize_referrer(
-            payload.referrer, request.url.hostname or ""
-        )
-        if referrer:  # "" means same-origin, which is not a referral
-            analytics.record(analytics.M_REFERRER, referrer)
-        analytics.record(
-            analytics.M_DEVICE,
-            analytics.device_of(request.headers.get("user-agent", "")),
-        )
-        analytics.record(analytics.M_COUNTRY, analytics.country_of(request.headers))
-    return Response(status_code=204)
-
-
-@router.get("/summary")
-def summary(
-    days: int = Query(30, ge=1, le=365),
-    db: Session = Depends(get_db),
-    _user: models.User = Owner,
-) -> dict:
-    """Returns the whole dashboard in one aggregate response.
-
-    The response is a few kilobytes however much traffic is behind it.
-    """
-    return analytics.summary(db, days)
-
-
-@router.get("/access")
-def access_log(
-    limit: int = Query(50, ge=1, le=200),
-    before_id: int | None = Query(None),
-    kind: str | None = Query(None),
-    q: str | None = Query(None, max_length=120),
-    db: Session = Depends(get_db),
-    _user: models.User = Owner,
-) -> dict:
-    """A page of the access log, newest first.
-
-    Unlike `/summary`, this returns rows about people, which is what it is for.
-    It is therefore behind the same owner gate, it is paged rather than returned
-    in full, and the people it describes have no endpoint that reaches it.
-    """
-    page = accesslog.recent(
-        db, limit=limit, before_id=before_id, kind=kind, query=q
-    )
-    return {
-        "events": [
-            {
-                "id": event.id,
-                "at": event.at.isoformat(),
-                "kind": event.kind,
-                "who": event.who,
-                "is_guest": event.is_guest,
-                "ip": event.ip,
-                "country": event.country,
-                "device": event.device,
-                "user_agent": event.user_agent,
-            }
-            for event in page["events"]
-        ],
-        "has_more": page["has_more"],
-    }

backend/app/routers/auth.py

@@ -1,158 +0,0 @@
-import re
-
-from fastapi import APIRouter, Depends, HTTPException, Request, Response
-from sqlalchemy.orm import Session
-
-from .. import (accesslog, analytics, auth, cleanup, limits, models, schemas,
-                security, starter)
-from ..database import get_db
-from .settings import get_settings
-
-router = APIRouter(prefix="/api/auth", tags=["auth"])
-
-EMAIL_RE = re.compile(r"^[^@\s]+@[^@\s]+\.[^@\s]+$")
-
-
-def _set_session_cookie(response: Response, user_id: int) -> None:
-    response.set_cookie(
-        auth.SESSION_COOKIE,
-        security.sign_session(user_id),
-        max_age=auth.COOKIE_MAX_AGE,
-        httponly=True,
-        samesite="lax",
-        secure=auth.COOKIE_SECURE,
-        path="/",
-    )
-
-
-def me_payload(user: models.User, db: Session) -> dict:
-    settings = get_settings(db, user)
-    cfg = auth.resolve_provider_config(settings)
-    return {
-        "multi_user": auth.MULTI_USER,
-        "id": user.id,
-        "email": user.email,
-        "is_guest": user.is_guest,
-        # Trusted testers: unmetered demo turns, plus the AI Chat scratchpad.
-        "power_user": auth.is_power_user(user),
-        # Separate allowlist: shows the visit-analytics page and its nav link.
-        "analytics": auth.is_owner(user),
-        # How long an idle guest is kept before cleanup deletes it (None when
-        # the policy is off). Served rather than hardcoded in the UI so the
-        # number a guest is shown is the number actually enforced.
-        "guest_retention_days": cleanup.RETENTION_DAYS if cleanup.enabled() else None,
-        "demo": {
-            "enabled": auth.demo_enabled(),
-            "using_demo": cfg.using_demo,
-            "model": cfg.model if cfg.using_demo else None,
-            "turns_per_day": auth.DEMO_TURNS_PER_DAY,
-            "turns_left": auth.demo_turns_left(user) if auth.demo_enabled() else None,
-            "models": auth.DEMO_MODELS if auth.demo_enabled() else [],
-        },
-    }
-
-
-@router.get("/me")
-def me(request: Request, response: Response, db: Session = Depends(get_db)):
-    """Returns the current user.
-
-    In multi-user mode this also establishes the session. If the cookie is
-    missing or invalid, the endpoint creates a guest user and sets a cookie. The
-    frontend calls it on load and after any 401.
-    """
-    if not auth.MULTI_USER:
-        user = auth.local_user(db)
-    else:
-        user = auth.resolve_session_user(request, db)
-        if user is None:
-            # Each new guest is a database row, so cap how fast one IP can
-            # create them.
-            limits.rate_limit("guest", request)
-            user = models.User(is_guest=True)
-            db.add(user)
-            db.commit()
-            # The guest is committed first, so a failure while copying the
-            # starter adventure still leaves them with an account.
-            starter.give(db, user)
-            db.commit()
-            _set_session_cookie(response, user.id)
-    # This endpoint is the SPA's bootstrap call, so it is where a session first
-    # shows itself; accesslog thins the rows down to one per day per address.
-    accesslog.note_session(db, user, request)
-    return me_payload(user, db)
-
-
-@router.post("/register")
-def register(
-    payload: schemas.AuthCredentials,
-    request: Request,
-    db: Session = Depends(get_db),
-    user: models.User = Depends(auth.get_current_user),
-):
-    """Upgrades the current guest in place.
-
-    The `user_id` does not change, so every adventure, scenario, script, and
-    setting they created as a guest is kept.
-    """
-    if not auth.MULTI_USER:
-        raise HTTPException(400, "Accounts are disabled in local mode.")
-    limits.rate_limit("auth", request)
-    email = payload.email.strip().lower()
-    if not EMAIL_RE.match(email):
-        raise HTTPException(422, "Enter a valid email address.")
-    if len(payload.password) < 8:
-        raise HTTPException(422, "Password must be at least 8 characters.")
-    if not user.is_guest:
-        raise HTTPException(400, "This session is already registered.")
-    if db.query(models.User).filter(models.User.email == email).first():
-        raise HTTPException(409, "An account with this email already exists — log in instead.")
-    user.email = email
-    user.password_hash = security.hash_password(payload.password)
-    user.is_guest = False
-    db.commit()
-    analytics.record_event(analytics.EV_SIGNUP, user)
-    accesslog.record(db, accesslog.REGISTER, request, user=user)
-    return me_payload(user, db)
-
-
-@router.post("/login")
-def login(
-    payload: schemas.AuthCredentials,
-    request: Request,
-    response: Response,
-    db: Session = Depends(get_db),
-):
-    """Point this browser's session at an existing account. Any current guest
-    session is simply abandoned (its data stays under the guest user)."""
-    if not auth.MULTI_USER:
-        raise HTTPException(400, "Accounts are disabled in local mode.")
-    limits.rate_limit("auth", request)
-    email = payload.email.strip().lower()
-    # Per-account throttle: stops distributed guessing against one email even
-    # when the per-IP limit above is diluted across many source addresses.
-    limits.check_login_allowed(email)
-    user = db.query(models.User).filter(models.User.email == email).first()
-    if (
-        user is None
-        or not user.password_hash
-        or not security.verify_password(payload.password, user.password_hash)
-    ):
-        limits.note_login_failure(email)
-        # Logged with the address that was tried, not the account that owns it:
-        # a guessing run against an address that has no account is exactly the
-        # thing worth being able to see.
-        accesslog.record(db, accesslog.LOGIN_FAILED, request, who=email)
-        raise HTTPException(401, "Incorrect email or password.")
-    limits.note_login_success(email)
-    _set_session_cookie(response, user.id)
-    analytics.record_event(analytics.EV_LOGIN, user)
-    accesslog.record(db, accesslog.LOGIN, request, user=user)
-    return me_payload(user, db)
-
-
-@router.post("/logout")
-def logout(response: Response):
-    if not auth.MULTI_USER:
-        raise HTTPException(400, "Accounts are disabled in local mode.")
-    response.delete_cookie(auth.SESSION_COOKIE, path="/")
-    return {"ok": True}

backend/app/routers/chat.py

@@ -1,22 +1,23 @@
-"""AI Chat: a plain scratchpad for talking to a model directly.
+"""AI Chat: a plain scratchpad for talking to the configured model directly.
 
-Power users reach it, which means the `AIDND_POWER_USERS` email allowlist. It is
-deliberately thin. It adds no story context, no scripts, and no world state, and
-it persists nothing. The conversation lives in the browser and is posted in full
-on each turn. It exists for testing models, prompts, and endpoints without
-starting an adventure.
+Deliberately thin. It adds no story context and no world state, and it persists
+nothing. The conversation lives in the browser and is posted in full on each
+turn. It exists for checking a model, a prompt, or an endpoint without starting
+an adventure — which is exactly the kind of thing a local single-user install
+wants a page for.
 
-Model choice is free when the user brought their own API key. On the shared demo
-key the model stays pinned to the `AIDND_DEMO_MODELS` allowlist, exactly as it is
-for turns. The server funds that key, so this page must not let it reach paid
-models.
+Upstream gated this behind a "power user" email allowlist and pinned the model
+when a shared demo key was in play. M2 removed both: there is one local user,
+who owns the endpoint, and there is no server-funded key to protect. The model
+this page talks to is the one in Settings, or one the user names per request —
+either way it is their own Ollama.
 """
 
-from fastapi import APIRouter, Depends, HTTPException, Request
+from fastapi import APIRouter, Depends, HTTPException
 from fastapi.responses import StreamingResponse
 from sqlalchemy.orm import Session
 
-from .. import auth, limits, models, schemas
+from .. import auth, models, schemas
 from ..database import get_db
 from ..providers import OpenAICompatibleProvider, ProviderError
 from ..sse import SSE_HEADERS, sse
@@ -25,80 +26,41 @@ from .settings import get_settings, list_endpoint_models
 router = APIRouter(prefix="/api/chat", tags=["chat"])
 
 
-def power_user(
-    db: Session = Depends(get_db),
-    user: models.User = Depends(auth.get_current_user),
-) -> models.User:
-    """Gate for the whole router. 404 rather than 403 so the feature simply
-    doesn't appear to exist for everyone else."""
-    if not auth.is_power_user(user):
-        raise HTTPException(404, "Not found")
-    return user
-
-
-PowerUser = Depends(power_user)
-
-
-def _resolve_model(
-    settings: models.Settings, requested: str | None
-) -> tuple[auth.ProviderConfig, str | None]:
-    """Returns the provider config for this chat, plus a note when the requested
-    model was not used.
-
-    The pinning rule lives in `resolve_provider_config`. This function only
-    reports the substitution that call made, so one place decides what the demo
-    key may talk to.
-    """
-    cfg = auth.resolve_provider_config(settings, model_override=requested)
-    wanted = (requested or "").strip()
-    if wanted and wanted != cfg.model:
-        return cfg, (
-            f"'{wanted}' isn't available on the shared demo key — using "
-            f"{cfg.model}. Add your own API key in Settings to use any model."
-        )
-    return cfg, None
-
-
 @router.get("/config")
 async def chat_config(
     db: Session = Depends(get_db),
-    user: models.User = PowerUser,
+    user: models.User = Depends(auth.get_current_user),
 ):
     """Returns what this page can talk to.
 
-    The response holds the resolved endpoint and model, whether model choice is
-    pinned to the demo allowlist, and the endpoint's model listing. The listing
-    is best effort, and an unreachable endpoint returns an empty list.
+    The model listing is best effort: an unreachable endpoint returns an empty
+    list and the reason, rather than failing the page.
     """
     settings = get_settings(db, user)
-    cfg = auth.resolve_provider_config(settings)
-    listing = await list_endpoint_models(cfg)
+    listing = await list_endpoint_models(settings.endpoint_url)
     return {
-        "endpoint_url": cfg.endpoint_url,
-        "model": cfg.model,
-        "using_demo": cfg.using_demo,
+        "endpoint_url": settings.endpoint_url,
+        "model": settings.model,
         "api_mode": settings.api_mode,
         "temperature": settings.temperature,
         "max_tokens": settings.max_output_tokens,
-        # On the demo key the whitelist IS the list of choices; otherwise it's
-        # whatever the endpoint advertises (suggestions, not a restriction).
-        "models": auth.DEMO_MODELS if cfg.using_demo else listing.get("models", []),
+        # Suggestions from the endpoint, not a restriction.
+        "models": listing.get("models", []),
         "models_error": None if listing.get("ok") else listing.get("detail"),
     }
 
 
-async def run_chat(cfg: auth.ProviderConfig, settings: models.Settings, payload: schemas.ChatRequest,
-                   note: str | None, db: Session, user: models.User):
+async def run_chat(
+    settings: models.Settings, model: str, payload: schemas.ChatRequest
+):
     """Streams the reply as SSE, using the turn stream's event shape.
 
     The generator emits `reasoning` and `chunk` events while generating and then
     a `done` event, so the frontend reuses the same code.
     """
-    if note:
-        yield sse({"type": "note", "detail": note})
     provider = OpenAICompatibleProvider(
-        cfg.endpoint_url, cfg.api_key, cfg.model, settings.api_mode,
-        settings.reasoning_max_tokens,
+        settings.endpoint_url, model, settings.api_mode,
+        settings.model_timeout_seconds,
     )
     messages = [m.model_dump() for m in payload.messages]
     chunks: list[str] = []
@@ -106,7 +68,11 @@ async def run_chat(cfg: auth.ProviderConfig, settings: models.Settings, payload:
     try:
         async for kind, chunk in provider.chat(
             messages,
-            temperature=payload.temperature if payload.temperature is not None else settings.temperature,
+            temperature=(
+                payload.temperature
+                if payload.temperature is not None
+                else settings.temperature
+            ),
             max_tokens=payload.max_tokens or settings.max_output_tokens,
         ):
             if kind == "reasoning":
@@ -123,33 +89,26 @@ async def run_chat(cfg: auth.ProviderConfig, settings: models.Settings, payload:
     if not text:
         detail = (
             "The model used its entire token budget on reasoning and returned no "
-            "reply — raise max tokens, cap the reasoning budget in Settings, or "
-            "use a non-reasoning model."
+            "reply — raise max tokens or use a non-reasoning model."
             if reasoning_chunks
             else "The AI returned an empty response."
         )
         yield sse({"type": "error", "detail": detail})
         return
 
-    if cfg.using_demo:
-        # Unmetered for power users (count_demo_turn is a no-op for them), but
-        # keep the call so the accounting stays right if the gate ever widens.
-        auth.count_demo_turn(user)
-        db.commit()
     yield sse({
         "type": "done",
         "text": text,
         "reasoning": "".join(reasoning_chunks).strip() or None,
-        "model": cfg.model,
+        "model": model,
     })
 
 
 @router.post("/stream")
 def chat_stream(
     payload: schemas.ChatRequest,
-    request: Request,
     db: Session = Depends(get_db),
-    user: models.User = PowerUser,
+    user: models.User = Depends(auth.get_current_user),
 ):
     total = sum(len(m.content) for m in payload.messages)
     if total > schemas.CHAT_TOTAL_MAX:
@@ -157,13 +116,12 @@ def chat_stream(
             413, f"This conversation is too long to send ({total:,} characters) — "
                  "clear it or start a new one."
         )
-    limits.rate_limit("chat", request, user)
     settings = get_settings(db, user)
-    cfg, note = _resolve_model(settings, payload.model)
-    if not cfg.model:
+    model = (payload.model or "").strip() or settings.model
+    if not model:
         raise HTTPException(400, "No model configured — set one in Settings or pick one here.")
     return StreamingResponse(
-        run_chat(cfg, settings, payload, note, db, user),
+        run_chat(settings, model, payload),
         media_type="text/event-stream",
         headers=SSE_HEADERS,
     )

backend/app/routers/debug.py

@@ -1,19 +1,16 @@
-from fastapi import APIRouter, HTTPException
+from fastapi import APIRouter
 
-from .. import auth, debuglog
+from .. import debuglog
 
 router = APIRouter(prefix="/api/debug", tags=["debug"])
 
 
 @router.get("/requests")
 def recent_requests():
-    """Most-recent-first log of provider requests/responses (no API keys).
+    """Most-recent-first log of provider requests and responses.
 
-    The log is a single process-wide ring buffer with no per-user attribution,
-    so in multi-user mode, which is how a hosted deployment runs, it would expose
-    other players' prompts. It is disabled there and available on a local
-    install.
+    A single process-wide ring buffer. It holds the prompts this install sent
+    to its own Ollama, which is exactly what the person running it needs to
+    diagnose a turn, and there is nobody else it could expose them to.
     """
-    if auth.MULTI_USER:
-        raise HTTPException(403, "The debug log is only available on local installs.")
     return debuglog.recent()

backend/app/routers/scenarios.py

@@ -3,7 +3,7 @@ from fastapi.responses import Response
 from sqlalchemy import or_
 from sqlalchemy.orm import Session
 
-from .. import analytics, auth, images, limits, models, schemas
+from .. import auth, images, limits, models, schemas
 from ..database import get_db
 
 router = APIRouter(prefix="/api/scenarios", tags=["scenarios"])
@@ -54,12 +54,6 @@ def get_scenario(
     user: models.User = Depends(auth.get_current_user),
 ):
     scenario = get_scenario_or_404(scenario_id, db, user)
-    # A funnel step, recorded for shared scenarios only. Opening one is the
-    # first sign that a visitor is interested, and someone editing their own
-    # scenario is already past this point. Their titles are theirs rather than a
-    # statistic.
-    if scenario.is_public:
-        analytics.record_event(analytics.EV_SCENARIO_OPEN, user)
     return scenario
 
 
@@ -96,18 +90,8 @@ def update_scenario(
 ):
     scenario = get_scenario_or_404(scenario_id, db, user, edit=True)
     data = payload.model_dump(exclude_unset=True)
-    script_ids = data.pop("script_ids", None)
     for field, value in data.items():
         setattr(scenario, field, value)
-    if script_ids is not None:
-        scripts = (
-            db.query(models.Script)
-            .filter(models.Script.id.in_(script_ids), models.Script.user_id == user.id)
-            .all()
-        )
-        if len(scripts) != len(set(script_ids)):
-            raise HTTPException(404, "One or more scripts not found")
-        scenario.scripts = sorted(scripts, key=lambda s: script_ids.index(s.id))
     db.commit()
     return scenario
 
@@ -148,13 +132,6 @@ def export_scenario(
             {"type": c.type, "name": c.name, "keys": c.keys, "entry": c.entry, "notes": c.notes}
             for c in s.story_cards
         ],
-        "scripts": [
-            {
-                "name": sc.name, "description": sc.description, "library": sc.library_js,
-                "input": sc.input_js, "context": sc.context_js, "output": sc.output_js,
-            }
-            for sc in s.scripts
-        ],
     }
 
 
@@ -185,7 +162,6 @@ def import_scenario(
 ):
     """Accepts our export format and AI Dungeon scenario exports best-effort;
     reports any keys it didn't understand."""
-    limits.rate_limit("import", request, user)
     limits.check_row_cap("scenarios", db, user)
     fields: dict = {}
     unmapped: list[str] = []
@@ -250,21 +226,6 @@ def import_scenario(
             )
         )
 
-    for item in bundle.get("scripts") or []:
-        if not isinstance(item, dict):
-            continue
-        script = models.Script(
-            user_id=user.id,
-            name=str(item.get("name") or "Imported Script")[:schemas.NAME_MAX],
-            description=str(item.get("description") or ""),
-            library_js=str(item.get("library") or item.get("sharedLibrary") or ""),
-            input_js=str(item.get("input") or item.get("onInput") or ""),
-            context_js=str(item.get("context") or item.get("onModelContext") or ""),
-            output_js=str(item.get("output") or item.get("onOutput") or ""),
-        )
-        db.add(script)
-        db.flush()
-        scenario.scripts.append(script)
 
     db.commit()
     out = schemas.ScenarioOut.model_validate(scenario).model_dump(mode="json")

backend/app/routers/scripts.py

@@ -1,159 +0,0 @@
-from fastapi import APIRouter, Body, Depends, HTTPException, Request
-from sqlalchemy.orm import Session
-
-from .. import auth, limits, models, schemas
-from ..database import get_db
-from ..scripting import run_hook
-
-router = APIRouter(prefix="/api/scripts", tags=["scripts"])
-
-HOOK_FIELDS = {"input": "input_js", "context": "context_js", "output": "output_js"}
-
-
-def get_script_or_404(script_id: int, db: Session, user: models.User) -> models.Script:
-    script = db.get(models.Script, script_id)
-    if script is None or script.user_id != user.id:
-        raise HTTPException(404, "Script not found")
-    return script
-
-
-@router.get("", response_model=list[schemas.ScriptOut])
-def list_scripts(
-    db: Session = Depends(get_db),
-    user: models.User = Depends(auth.get_current_user),
-):
-    return (
-        db.query(models.Script)
-        .filter(models.Script.user_id == user.id)
-        .order_by(models.Script.updated_at.desc())
-        .all()
-    )
-
-
-@router.post("", response_model=schemas.ScriptOut, status_code=201)
-def create_script(
-    payload: schemas.ScriptCreate,
-    db: Session = Depends(get_db),
-    user: models.User = Depends(auth.get_current_user),
-):
-    limits.check_row_cap("scripts", db, user)
-    script = models.Script(**payload.model_dump(), user_id=user.id)
-    db.add(script)
-    db.commit()
-    return script
-
-
-@router.get("/{script_id}", response_model=schemas.ScriptOut)
-def get_script(
-    script_id: int,
-    db: Session = Depends(get_db),
-    user: models.User = Depends(auth.get_current_user),
-):
-    return get_script_or_404(script_id, db, user)
-
-
-@router.patch("/{script_id}", response_model=schemas.ScriptOut)
-def update_script(
-    script_id: int,
-    payload: schemas.ScriptUpdate,
-    db: Session = Depends(get_db),
-    user: models.User = Depends(auth.get_current_user),
-):
-    script = get_script_or_404(script_id, db, user)
-    for field, value in payload.model_dump(exclude_unset=True).items():
-        setattr(script, field, value)
-    db.commit()
-    return script
-
-
-@router.delete("/{script_id}", status_code=204)
-def delete_script(
-    script_id: int,
-    db: Session = Depends(get_db),
-    user: models.User = Depends(auth.get_current_user),
-):
-    db.delete(get_script_or_404(script_id, db, user))
-    db.commit()
-
-
-@router.post("/{script_id}/test")
-def test_script(
-    script_id: int,
-    payload: schemas.ScriptTestRequest,
-    request: Request,
-    db: Session = Depends(get_db),
-    user: models.User = Depends(auth.get_current_user),
-):
-    """Runs one hook against sample text, making no AI call and storing nothing."""
-    script = get_script_or_404(script_id, db, user)
-    limits.rate_limit("script-test", request, user)
-    result = run_hook(
-        script.library_js,
-        getattr(script, HOOK_FIELDS[payload.hook]),
-        payload.text,
-        payload.state,
-        history=[],
-        story_cards=[],
-        info={"actionCount": 0, "characterNames": [], "memoryLength": 0, "maxChars": 0},
-    )
-    return {
-        "text": result.text,
-        "stop": result.stop,
-        "state": result.state,
-        "storyCards": result.story_cards,
-        "logs": result.logs,
-        "error": result.error,
-    }
-
-
-# ---------- Import / Export ----------
-
-@router.get("/{script_id}/export")
-def export_script(
-    script_id: int,
-    db: Session = Depends(get_db),
-    user: models.User = Depends(auth.get_current_user),
-):
-    """JSON bundle matching how AI Dungeon scripts circulate."""
-    script = get_script_or_404(script_id, db, user)
-    return {
-        "name": script.name,
-        "description": script.description,
-        "library": script.library_js,
-        "input": script.input_js,
-        "context": script.context_js,
-        "output": script.output_js,
-    }
-
-
-@router.post("/import", response_model=schemas.ScriptOut, status_code=201)
-def import_script(
-    request: Request,
-    bundle: dict = Body(...),
-    db: Session = Depends(get_db),
-    user: models.User = Depends(auth.get_current_user),
-):
-    """Accepts our export bundle; tolerates *_js key names too."""
-    limits.rate_limit("import", request, user)
-    limits.check_row_cap("scripts", db, user)
-    def pick(*keys: str) -> str:
-        for key in keys:
-            value = bundle.get(key)
-            if isinstance(value, str):
-                return value
-        return ""
-
-    script = models.Script(
-        user_id=user.id,
-        # A raw-dict import bypasses the schemas, so truncate to the VARCHAR
-        # width.
-        name=(pick("name") or "Imported Script")[:schemas.NAME_MAX],
-        description=pick("description"),
-        library_js=pick("library", "library_js", "sharedLibrary"),
-        input_js=pick("input", "input_js", "onInput"),
-        context_js=pick("context", "context_js", "onModelContext"),
-        output_js=pick("output", "output_js", "onOutput"),
-    )
-    db.add(script)
-    db.commit()
-    return script

backend/app/routers/settings.py

@@ -1,20 +1,33 @@
+"""The model settings, and the connection test that tells you why they don't work.
+
+There is one settings row, belonging to the one local user. It describes an
+Ollama: where it is, which model to narrate with, which to embed with, and how
+long to wait for it.
+
+Upstream let this row name any OpenAI-compatible endpoint and carry an
+encrypted API key for it. M2 narrowed both: `endpoints.py` decides which
+addresses may be named, and there is no key field, because Ollama does not use
+one and this build has no cloud provider to carry a key for.
+"""
+
 import httpx
-from fastapi import APIRouter, Depends, Request
+from fastapi import APIRouter, Depends, HTTPException
 from sqlalchemy.orm import Session
 from starlette.concurrency import run_in_threadpool
 
-from .. import auth, limits, models, netguard, schemas, security, tlstrust
+from .. import auth, endpoints, models, schemas, tlstrust
 from ..database import get_db
+from ..providers.openai_compatible import CONNECT_TIMEOUT
 
 router = APIRouter(prefix="/api/settings", tags=["settings"])
 
+#: The connection test is a listing, not a generation, so it never waits on a
+#: model load and does not need the turn engine's patience.
+TEST_TIMEOUT = 15.0
+
 
 def get_settings(db: Session, user: models.User) -> models.Settings:
-    """Returns the user's settings row, creating it on first access.
-
-    Phase 8 made settings per user rather than global. They cover the endpoint,
-    the key, the models, and the memory configuration.
-    """
+    """Returns the settings row, creating it on first access."""
     settings = (
         db.query(models.Settings).filter(models.Settings.user_id == user.id).first()
     )
@@ -34,16 +47,24 @@ def read_settings(
 
 
 @router.put("", response_model=schemas.SettingsOut)
-def update_settings(
+async def update_settings(
     payload: schemas.SettingsUpdate,
     db: Session = Depends(get_db),
     user: models.User = Depends(auth.get_current_user),
 ):
     settings = get_settings(db, user)
     fields = payload.model_dump(exclude_unset=True)
-    # Write-only API key: absent = unchanged, "" = cleared, else encrypted.
-    if "api_key" in fields:
-        fields["api_key"] = security.encrypt_secret(fields["api_key"].strip())
+
+    if "endpoint_url" in fields:
+        # Refused here so the user finds out while they are looking at the
+        # field, rather than on their next turn. The provider re-checks before
+        # every request regardless; this is the friendly half of the same rule.
+        reason = await run_in_threadpool(
+            endpoints.rejection_reason, fields["endpoint_url"]
+        )
+        if reason is not None:
+            raise HTTPException(400, f"That endpoint can't be used — {reason}.")
+
     embedding_model_changed = (
         "embedding_model" in fields
         and fields["embedding_model"] != settings.embedding_model
@@ -53,8 +74,6 @@ def update_settings(
     if embedding_model_changed:
         # Vectors from the old model have a different dimensionality/space;
         # clear them so the post-turn task re-embeds with the new model.
-        # This covers only this user's adventures, because settings are per
-        # user now.
         #
         # Both columns, and the flag. This is the one place that clears vectors
         # in bulk rather than through memorybank.set_vector, and when the
@@ -80,28 +99,61 @@ def update_settings(
     return settings
 
 
-async def list_endpoint_models(cfg: auth.ProviderConfig) -> dict:
-    """Fetches the endpoint's /models listing.
+async def list_endpoint_models(endpoint_url: str) -> dict:
+    """Fetches the endpoint's `/models` listing, and doubles as the connection test.
 
-    The call also serves as a connectivity check, so a failure returns
-    `{"ok": False, "detail": ...}` rather than raising.
+    Returns `{"ok": False, "detail": ...}` rather than raising, because every
+    caller wants to show the reason rather than fail the page.
+
+    The failure cases are told apart on purpose. "Ollama isn't running", "that
+    address isn't allowed", "the certificate doesn't verify" and "it answered,
+    but with an error" need four different things done about them, and a single
+    "connection failed" leaves the user guessing which they have.
     """
-    # SSRF guard. Never probe a non-public address the user supplied.
-    reason = await run_in_threadpool(netguard.endpoint_block_reason, cfg.endpoint_url)
-    if reason:
-        return {"ok": False, "detail": f"Can't reach that endpoint — {reason}."}
-    url = cfg.endpoint_url.rstrip("/") + "/models"
-    headers = {}
-    if cfg.api_key:
-        headers["Authorization"] = f"Bearer {cfg.api_key}"
+    reason = await run_in_threadpool(endpoints.rejection_reason, endpoint_url)
+    if reason is not None:
+        return {
+            "ok": False, "kind": "rejected",
+            "detail": f"That endpoint can't be used — {reason}.",
+        }
+
+    url = endpoint_url.rstrip("/") + "/models"
     try:
-        async with httpx.AsyncClient(timeout=10, verify=tlstrust.ssl_context()) as client:
-            resp = await client.get(url, headers=headers)
+        async with httpx.AsyncClient(
+            timeout=httpx.Timeout(TEST_TIMEOUT, connect=CONNECT_TIMEOUT),
+            verify=tlstrust.ssl_context(),
+        ) as client:
+            resp = await client.get(url)
+    except httpx.ConnectError as exc:
+        # A TLS failure arrives as a ConnectError too, and it needs a different
+        # answer from "nothing is listening": install the CA, don't start Ollama.
+        if "CERTIFICATE_VERIFY" in str(exc).upper() or "SSL" in str(exc).upper():
+            return {
+                "ok": False, "kind": "tls",
+                "detail": (
+                    "The endpoint's TLS certificate could not be verified. If it "
+                    "uses a private or self-signed CA, install that CA on this "
+                    "machine so the system trusts it. Certificate checking is "
+                    "not optional."
+                ),
+            }
+        return {
+            "ok": False, "kind": "unreachable",
+            "detail": f"Could not connect to {endpoint_url} — is Ollama running there?",
+        }
+    except httpx.TimeoutException:
+        return {
+            "ok": False, "kind": "timeout",
+            "detail": f"{endpoint_url} did not answer within {TEST_TIMEOUT:.0f}s.",
+        }
     except httpx.HTTPError as exc:
-        return {"ok": False, "detail": f"Connection failed: {exc}"}
+        return {"ok": False, "kind": "error", "detail": f"Connection failed: {exc}"}
 
     if resp.status_code != 200:
-        return {"ok": False, "detail": f"HTTP {resp.status_code}: {resp.text[:300]}"}
+        return {
+            "ok": False, "kind": "http",
+            "detail": f"HTTP {resp.status_code}: {resp.text[:300]}",
+        }
 
     models_available: list[str] = []
     try:
@@ -115,15 +167,19 @@ async def list_endpoint_models(cfg: auth.ProviderConfig) -> dict:
 
 @router.post("/test")
 async def test_connection(
-    request: Request,
     db: Session = Depends(get_db),
     user: models.User = Depends(auth.get_current_user),
 ):
-    """Runs a cheap connectivity check against whatever the turn engine would use.
-
-    That includes the shared demo endpoint, when the user has no key of their
-    own.
-    """
-    limits.rate_limit("connection-test", request, user)
+    """Checks the endpoint the turn engine would use, and lists its models."""
     settings = get_settings(db, user)
-    return await list_endpoint_models(auth.resolve_provider_config(settings))
+    result = await list_endpoint_models(settings.endpoint_url)
+    if result.get("ok") and settings.model and settings.model not in result["models"]:
+        # Reachable, but pointed at a model that is not installed there — the
+        # commonest way for a correct endpoint to still fail every turn.
+        return result | {
+            "warning": (
+                f"{settings.endpoint_url} is reachable, but has no model named "
+                f"'{settings.model}'. Pull it there, or pick one from the list."
+            )
+        }
+    return result

backend/app/routers/story_cards.py

@@ -159,7 +159,6 @@ def import_story_cards(
         raise HTTPException(422, 'Expected a "cards" array of story cards.')
     cards_in = [c for c in cards_in if isinstance(c, dict)]
 
-    limits.rate_limit("import", request, user)
     limits.check_bundle_lists(story_cards=cards_in)
     existing = len(owner.story_cards)
     if auth.MULTI_USER and existing + len(cards_in) > limits.MAX_STORY_CARDS_PER_OWNER:

backend/app/schemas.py

@@ -14,7 +14,6 @@ NAME_MAX = 200          # Titles and names. VARCHAR(200).
 TAGS_MAX = 500          # VARCHAR(500).
 CARD_TYPE_MAX = 100     # VARCHAR(100).
 PROSE_MAX = 50_000      # Memory, author's note, prompts, entries, and notes.
-SCRIPT_MAX = 200_000    # One JavaScript source file.
 ACTION_MAX = 20_000     # One player action.
 MEMORY_TEXT_MAX = 5_000
 # A scenario cover image, stored inline as a base64 data URI. A 400x300 WebP at
@@ -26,17 +25,21 @@ ICON_MAX = 16           # One emoji or glyph. VARCHAR(16).
 BRANCH_NAME_MAX = 80    # What a player called one line of the story. VARCHAR(80).
 PERSONA_NAME_MAX = 80   # The protagonist's name. VARCHAR(80).
 PERSONA_PRONOUNS_MAX = 40   # "they/them" and the like. VARCHAR(40).
+# M4: what a player called a Save Point. VARCHAR(120). Wider than a branch name
+# because these are sentences rather than labels — "Before entering the abbey"
+# is the example the specification uses throughout.
+CHECKPOINT_NAME_MAX = 120
 
 Name = Annotated[str, Field(max_length=NAME_MAX)]
 Tags = Annotated[str, Field(max_length=TAGS_MAX)]
 CardType = Annotated[str, Field(max_length=CARD_TYPE_MAX)]
 Prose = Annotated[str, Field(max_length=PROSE_MAX)]
-ScriptSource = Annotated[str, Field(max_length=SCRIPT_MAX)]
 ActionText = Annotated[str, Field(max_length=ACTION_MAX)]
 Image = Annotated[str, Field(max_length=IMAGE_MAX)]
 Icon = Annotated[str, Field(max_length=ICON_MAX)]
 PersonaName = Annotated[str, Field(max_length=PERSONA_NAME_MAX)]
 PersonaPronouns = Annotated[str, Field(max_length=PERSONA_PRONOUNS_MAX)]
+CheckpointName = Annotated[str, Field(max_length=CHECKPOINT_NAME_MAX)]
 
 
 class ORMModel(BaseModel):
@@ -106,7 +109,6 @@ class ScenarioUpdate(BaseModel):
     image: Image | None = None
     icon: Icon | None = None
     stat_schema: dict | None = None
-    script_ids: list[int] | None = None
 
 
 class ScenarioOut(ORMModel, ScenarioBase):
@@ -115,7 +117,6 @@ class ScenarioOut(ORMModel, ScenarioBase):
     created_at: datetime
     updated_at: datetime
     story_cards: list[StoryCardOut] = []
-    scripts: list["ScriptOut"] = []
 
 
 class ScenarioListItem(ORMModel):
@@ -258,6 +259,10 @@ class BranchOut(ORMModel):
     fork_depth: int | None = None
     depth: int
     own_actions: int = 0
+    # M4: how many Save Points name a position on this line. Deleting the branch
+    # deletes them with its story, so the panel warns with a number rather than
+    # a vague caution. Zero for a line nobody has bookmarked, which is most.
+    save_points: int = 0
     is_head: bool = False
     # NULL for a branch nobody has named. The client labels those from the fork
     # depth rather than the server inventing a name. See the column comment.
@@ -271,6 +276,67 @@ class BranchRename(BaseModel):
     name: Annotated[str, Field(max_length=BRANCH_NAME_MAX)] | None = None
 
 
+# ---------- Save Points (M4) ----------
+#
+# "Save Point" is the user-facing term and `checkpoint` is the internal one
+# (`BROWSER-UX-SPEC.md` §23). The wire format uses the internal name, as the
+# rest of this module does.
+
+
+class CheckpointOut(ORMModel):
+    """One Save Point: a name and the position it names.
+
+    The position is reported three ways because the panel needs three different
+    things from it. `turn` is what a reader counts — the same `depth + 1` the
+    branch list shows. `depth` and `branch_id` are the coordinate itself.
+    `on_path` says whether the position lies on the story being read, which is
+    how the panel can tell a Save Point on this line from one naming a line the
+    story has left; restoring either works, but they are not the same offer.
+
+    `resolved` is false when the coordinate no longer names a live turn, which
+    an action deleted out of the middle of a story can do. Restore refuses such
+    a Save Point rather than moving the head somewhere approximate, so the list
+    says so before the button is pressed.
+    """
+
+    id: int
+    adventure_id: int
+    name: str
+    note: str = ""
+    branch_id: int
+    depth: int
+    turn: int = 0
+    on_path: bool = True
+    resolved: bool = True
+    created_at: datetime
+    updated_at: datetime
+
+
+class CheckpointCreate(BaseModel):
+    """A Save Point at wherever the story is being read.
+
+    The position is not a field. A Save Point is made at the campaign's active
+    head, which the server already knows, and accepting a coordinate from the
+    client would be the second way to name a position — the thing this milestone
+    exists not to build.
+    """
+
+    name: CheckpointName
+    note: Prose = ""
+
+
+class CheckpointRename(BaseModel):
+    """A new label, and nothing else.
+
+    There is deliberately no coordinate here. `STORY-BRANCH-SEMANTICS.md` §24
+    keeps a Save Point's meaning auditable by refusing to move one: rename it,
+    or delete it and make another where you are.
+    """
+
+    name: CheckpointName | None = None
+    note: Prose | None = None
+
+
 class ActionUpdate(BaseModel):
     text: ActionText
 
@@ -321,6 +387,12 @@ class AdventureOut(ORMModel):
     # story's length, which is how the client knows more actions exist above.
     actions: list[ActionOut] = []
     action_count: int = 0
+    # M3. Whether the history controls have anywhere to go from where the story
+    # is. The client cannot work either out for itself: `can_undo` needs the
+    # campaign opening, which may be off the top of the loaded window, and
+    # `can_redo` needs the retained future, which the client is never sent.
+    can_undo: bool = False
+    can_redo: bool = False
 
 
 class ActionPage(BaseModel):
@@ -331,6 +403,10 @@ class ActionPage(BaseModel):
     # Whether anything older than this slice exists. The server computes it, so
     # the client never has to do arithmetic on positions to find the end.
     has_more: bool = False
+    # The same two flags `AdventureOut` carries, so that the response to Undo,
+    # Redo or a turn updates the controls without a second request.
+    can_undo: bool = False
+    can_redo: bool = False
 
 
 # ---------- Memory bank (Phase 6) ----------
@@ -374,67 +450,6 @@ class AdventureListItem(ORMModel):
     icon: str = ""
 
 
-# ---------- Scripts ----------
-
-class ScriptBase(BaseModel):
-    name: Name = "Untitled Script"
-    description: Prose = ""
-    library_js: ScriptSource = ""
-    input_js: ScriptSource = ""
-    context_js: ScriptSource = ""
-    output_js: ScriptSource = ""
-
-
-class ScriptCreate(ScriptBase):
-    pass
-
-
-class ScriptUpdate(BaseModel):
-    name: Name | None = None
-    description: Prose | None = None
-    library_js: ScriptSource | None = None
-    input_js: ScriptSource | None = None
-    context_js: ScriptSource | None = None
-    output_js: ScriptSource | None = None
-
-
-class ScriptOut(ORMModel, ScriptBase):
-    id: int
-    created_at: datetime
-    updated_at: datetime
-
-
-class ScriptTestRequest(BaseModel):
-    hook: Literal["input", "context", "output"]
-    text: Prose = ""
-    state: dict = {}
-
-
-class AdventureScriptOut(ORMModel):
-    id: int
-    adventure_id: int
-    position: int
-    enabled: bool
-    name: str
-    description: str
-    library_js: str
-    input_js: str
-    context_js: str
-    output_js: str
-    # The router sets this field, which is not stored. It is `True` when a
-    # syncable library version exists whose code differs from this copy, and
-    # `None` when there is nothing to sync from.
-    out_of_date: bool | None = None
-
-
-class AdventureScriptUpdate(BaseModel):
-    enabled: bool | None = None
-    library_js: ScriptSource | None = None
-    input_js: ScriptSource | None = None
-    context_js: ScriptSource | None = None
-    output_js: ScriptSource | None = None
-
-
 # ---------- Auth (Phase 8) ----------
 
 class AuthCredentials(BaseModel):
@@ -448,15 +463,12 @@ class AuthCredentials(BaseModel):
 
 class SettingsOut(ORMModel):
     endpoint_url: str
-    # The key itself is never returned. It is encrypted at rest and
-    # write-only.
-    has_api_key: bool
     model: str
     api_mode: str
     temperature: float
     max_output_tokens: int
-    reasoning_max_tokens: int
     context_token_budget: int
+    model_timeout_seconds: int
     narrator_prompt: str
     summary_model: str
     embedding_model: str
@@ -491,18 +503,15 @@ class ChatRequest(BaseModel):
 
 class SettingsUpdate(BaseModel):
     endpoint_url: Annotated[str, Field(max_length=500)] | None = None  # VARCHAR(500).
-    # Encryption expands the stored value by about four thirds into the same
-    # VARCHAR(500), so 256 plaintext characters is the largest safe input. The
-    # stored form is "enc:" plus Fernet plus base64.
-    api_key: Annotated[str, Field(max_length=256)] | None = None
     model: Name | None = None
     api_mode: Annotated[str, Field(max_length=20)] | None = None
     temperature: Annotated[float, Field(ge=0, le=5)] | None = None
     max_output_tokens: Annotated[int, Field(ge=1, le=100_000)] | None = None
-    # A value of -1 turns reasoning off explicitly, which sends
-    # `reasoning: {effort: none}`. A value of 0 sends nothing.
-    reasoning_max_tokens: Annotated[int, Field(ge=-1, le=100_000)] | None = None
     context_token_budget: Annotated[int, Field(ge=256, le=200_000)] | None = None
+    # Seconds to wait for the model. The floor is high enough that a normal
+    # turn cannot trip it; the ceiling exists so that "wait longer" stays a
+    # number rather than becoming "wait forever".
+    model_timeout_seconds: Annotated[int, Field(ge=30, le=3600)] | None = None
     narrator_prompt: Prose | None = None
     summary_model: Name | None = None
     embedding_model: Name | None = None

backend/app/scripting/__init__.py

@@ -1,4 +0,0 @@
-from .engine import HookResult, run_hook
-from .pipeline import ScriptPipeline
-
-__all__ = ["HookResult", "ScriptPipeline", "run_hook"]

backend/app/scripting/engine.py

@@ -1,146 +0,0 @@
-"""AI Dungeon-compatible script execution in an embedded QuickJS sandbox.
-
-Each hook run is fully isolated (fresh Context), capped at 16 MB memory and
-2 seconds CPU, with no filesystem/network/process access (QuickJS has none by
-default). Scripts follow the AI Dungeon contract: define a `modifier(text)`
-and call it as the last line; its return value `{ text, stop }` is the result.
-"""
-
-import json
-from dataclasses import dataclass, field
-
-import quickjs
-
-MEMORY_LIMIT = 16 * 1024 * 1024
-TIME_LIMIT_SECONDS = 2
-HISTORY_WINDOW = 100  # recent actions exposed as `history`
-
-# Globals per the official docs: text, state, history, storyCards, info,
-# log/console.log, story card functions, plus legacy worldInfo aliases.
-PRELUDE = """
-"use strict";
-var __logs = [];
-var state = __DATA__.state;
-var text = __DATA__.text;
-var history = __DATA__.history;
-var storyCards = __DATA__.storyCards;
-var info = __DATA__.info;
-
-function log(msg) {
-  __logs.push(typeof msg === "string" ? msg : JSON.stringify(msg));
-}
-var console = { log: log };
-
-// Returns the new card's index, or false if a card with those keys exists —
-// matching real AI Dungeon. Note index 0 is falsy; that quirk is upstream's.
-function addStoryCard(keys, entry, type) {
-  for (var i = 0; i < storyCards.length; i++) {
-    if (storyCards[i].keys === keys) return false;
-  }
-  storyCards.push({ id: null, keys: keys || "", entry: entry || "", type: type || "" });
-  return storyCards.length - 1;
-}
-function updateStoryCard(index, keys, entry, type) {
-  var card = storyCards[index];
-  if (!card) throw new Error("Story card not found");
-  card.keys = keys;
-  card.entry = entry;
-  card.type = type;
-}
-function removeStoryCard(index) {
-  if (!storyCards[index]) throw new Error("Story card not found");
-  storyCards.splice(index, 1);
-}
-
-// Legacy aliases used by older AI Dungeon scripts.
-var worldInfo = storyCards;
-var worldEntries = storyCards;
-function addWorldEntry(keys, entry) { return addStoryCard(keys, entry, ""); }
-function updateWorldEntry(index, keys, entry) {
-  var card = storyCards[index];
-  if (!card) throw new Error("World entry not found");
-  card.keys = keys;
-  card.entry = entry;
-}
-function removeWorldEntry(index) { return removeStoryCard(index); }
-"""
-
-COLLECT = """
-JSON.stringify({
-  result: (typeof __result === "undefined" || __result === null) ? null : __result,
-  state: state,
-  storyCards: storyCards,
-  logs: __logs
-})
-"""
-
-
-@dataclass
-class HookResult:
-    text: str
-    stop: bool = False
-    state: dict = field(default_factory=dict)
-    story_cards: list = field(default_factory=list)
-    logs: list = field(default_factory=list)
-    error: str | None = None
-
-
-def run_hook(
-    library_js: str,
-    hook_js: str,
-    text: str,
-    state: dict,
-    history: list[dict],
-    story_cards: list[dict],
-    info: dict,
-) -> HookResult:
-    """Run one modifier hook. This function never raises. Failures return as
-    `.error` with text, state, and cards unchanged, so a bad script cannot
-    break a turn."""
-    unchanged = HookResult(text=text, state=state, story_cards=story_cards)
-    source = f"{library_js}\n;\n{hook_js}" if library_js.strip() else hook_js
-    if not source.strip():
-        return unchanged
-
-    data = {
-        "state": state,
-        "text": text,
-        "history": history[-HISTORY_WINDOW:],
-        "storyCards": story_cards,
-        "info": info,
-    }
-    try:
-        ctx = quickjs.Context()
-        ctx.set_memory_limit(MEMORY_LIMIT)
-        ctx.set_time_limit(TIME_LIMIT_SECONDS)
-        ctx.eval(f"var __DATA__ = {json.dumps(data)};")
-        ctx.eval(PRELUDE)
-        ctx.eval(f"var __SRC__ = {json.dumps(source)};")
-        # Indirect eval keeps the script in global scope, so `modifier(text)` as the
-        # script's final expression statement becomes the completion value.
-        ctx.eval("var __result = (0, eval)(__SRC__);")
-        collected = json.loads(ctx.eval(COLLECT))
-    except quickjs.JSException as exc:
-        unchanged.error = f"Script error: {exc}"
-        return unchanged
-    except Exception as exc:  # memory limit, invalid JSON state, engine faults
-        unchanged.error = f"Script execution failed: {exc}"
-        return unchanged
-
-    result = collected.get("result")
-    new_text, stop = text, False
-    if isinstance(result, dict):
-        if isinstance(result.get("text"), str):
-            new_text = result["text"]
-        stop = bool(result.get("stop"))
-    elif isinstance(result, str):
-        new_text = result
-
-    new_state = collected.get("state")
-    return HookResult(
-        text=new_text,
-        stop=stop,
-        state=new_state if isinstance(new_state, dict) else {},
-        story_cards=collected.get("storyCards") or [],
-        logs=collected.get("logs") or [],
-    )

backend/app/scripting/pipeline.py

@@ -1,112 +0,0 @@
-"""Runs an adventure's enabled scripts through a turn's hook points, applying
-state and story-card mutations back to the database after each hook."""
-
-from sqlalchemy.orm import Session
-
-from .. import models
-from ..context import history as context_history
-from .engine import run_hook
-
-MAX_STORY_CARDS = 5000  # AI Dungeon's per-adventure sanity cap
-
-
-class ScriptPipeline:
-    def __init__(self, adventure: models.Adventure, db: Session):
-        self.adventure = adventure
-        self.db = db
-        self.logs: list[str] = []
-        self.errors: list[str] = []
-
-    @property
-    def message(self) -> str | None:
-        state = self.adventure.script_state
-        msg = state.get("message") if isinstance(state, dict) else None
-        return msg if isinstance(msg, str) and msg.strip() else None
-
-    def _history(self) -> list[dict]:
-        # Read the path rather than `adventure.actions`. That collection holds
-        # every branch's actions, and this is the documented history API a user
-        # script reads. Giving a script the siblings of the turn it is running on
-        # would be the same bug as building a prompt from them, and visible to
-        # the user.
-        #
-        # `story_actions` also drops rows with blank text, which
-        # `adventure.actions` kept, so this array is shorter than it was for an
-        # adventure that has any such rows. `info.actionCount` counts the same
-        # way. That is intended. A row with no text is this app's bookkeeping, it
-        # has no counterpart in the AI Dungeon history a ported script was
-        # written against, and the prompt has never included one. A script keyed
-        # on every N actions lands on different turns than it did before phase
-        # 14, and no reading of this is compatible with both.
-        return [
-            {"text": a.text, "rawText": a.text, "type": a.type}
-            for a in context_history.story_actions(self.adventure)
-        ]
-
-    def _cards(self) -> list[dict]:
-        return [
-            {"id": c.id, "keys": c.keys, "entry": c.entry, "type": c.type}
-            for c in self.adventure.story_cards
-        ]
-
-    def _info(self) -> dict:
-        return {
-            "actionCount": context_history.count(self.adventure),
-            "characterNames": [],
-            "memoryLength": len(self.adventure.memory),
-            "maxChars": 0,
-        }
-
-    def _apply_cards(self, returned: list) -> None:
-        existing = {c.id: c for c in self.adventure.story_cards}
-        seen_ids = set()
-        added = 0
-        for item in returned:
-            if not isinstance(item, dict):
-                continue
-            card_id = item.get("id")
-            keys = str(item.get("keys") or "")
-            entry = str(item.get("entry") or "")
-            card_type = str(item.get("type") or "")
-            if card_id in existing:
-                seen_ids.add(card_id)
-                card = existing[card_id]
-                card.keys, card.entry, card.type = keys, entry, card_type
-            elif len(existing) + added < MAX_STORY_CARDS:
-                self.db.add(
-                    models.StoryCard(
-                        adventure_id=self.adventure.id,
-                        keys=keys, entry=entry, type=card_type,
-                    )
-                )
-                added += 1
-        for card_id, card in existing.items():
-            if card_id not in seen_ids:
-                self.db.delete(card)
-
-    def run(self, hook: str, text: str) -> tuple[str, bool]:
-        """Chain `hook` across all enabled scripts. Returns (text, stop)."""
-        state = self.adventure.script_state if isinstance(self.adventure.script_state, dict) else {}
-        for script in self.adventure.scripts:
-            hook_js = getattr(script, f"{hook}_js")
-            if not script.enabled or not hook_js.strip():
-                continue
-            result = run_hook(
-                script.library_js, hook_js, text, state,
-                self._history(), self._cards(), self._info(),
-            )
-            if result.error:
-                self.errors.append(f"{script.name} ({hook}): {result.error}")
-                continue  # a broken script never breaks the turn
-            self.logs.extend(f"[{script.name}/{hook}] {line}" for line in result.logs)
-            self._apply_cards(result.story_cards)
-            state = result.state
-            self.adventure.script_state = state
-            self.db.commit()
-            text = result.text
-            if result.stop:
-                return text, True
-        return text, False
-
-    def report(self) -> dict:
-        return {"logs": self.logs, "errors": self.errors, "message": self.message}

backend/app/security.py

@@ -1,131 +0,0 @@
-"""Phase 8: secrets and crypto primitives for optional accounts.
-
-Everything derives from one server-side secret:
-
-* Session cookies are HMAC-signed with it.
-* Stored LLM API keys are Fernet-encrypted with a key derived from it.
-
-The secret comes from `AIDND_SECRET_KEY`, or it is generated once into
-`secret.key` next to the database, so a local install and a Docker volume work
-with no configuration. Losing that file logs everyone out and makes the stored
-API keys unreadable, and users then re-enter them. A multi-user deployment has
-to set the environment variable, because a hosted filesystem is ephemeral and a
-`secret.key` regenerated on every deploy would log out every user each time.
-
-Passwords use `hashlib.scrypt`, which is in the standard library and backed by
-OpenSSL, so this needs no separate hashing dependency.
-"""
-
-import base64
-import hashlib
-import hmac
-import os
-import secrets
-
-from cryptography.fernet import Fernet, InvalidToken
-
-from .database import DB_PATH
-
-_SECRET_FILE = DB_PATH.parent / "secret.key"
-
-
-def _load_secret() -> bytes:
-    env = os.environ.get("AIDND_SECRET_KEY", "").strip()
-    if env:
-        return env.encode()
-    # Same flag parse as auth.MULTI_USER (auth imports this module, so it
-    # can't be imported from there).
-    if os.environ.get("AIDND_MULTI_USER", "").strip().lower() in ("1", "true", "yes", "on"):
-        raise RuntimeError(
-            "AIDND_SECRET_KEY must be set when AIDND_MULTI_USER is on: an "
-            "auto-generated secret.key on an ephemeral hosted filesystem would "
-            "rotate on every deploy, logging out every user and orphaning "
-            "their stored API keys. Generate one with: "
-            "python -c \"import secrets; print(secrets.token_urlsafe(48))\""
-        )
-    if _SECRET_FILE.exists():
-        return _SECRET_FILE.read_bytes().strip()
-    secret = secrets.token_urlsafe(48).encode()
-    _SECRET_FILE.write_bytes(secret)
-    return secret
-
-
-SECRET_KEY = _load_secret()
-_fernet = Fernet(base64.urlsafe_b64encode(hashlib.sha256(SECRET_KEY).digest()))
-
-
-# ---------- Password hashing (scrypt) ----------
-
-_SCRYPT_N, _SCRYPT_R, _SCRYPT_P = 2**14, 8, 1
-
-
-def hash_password(password: str) -> str:
-    salt = secrets.token_bytes(16)
-    key = hashlib.scrypt(
-        password.encode(), salt=salt, n=_SCRYPT_N, r=_SCRYPT_R, p=_SCRYPT_P
-    )
-    return f"scrypt${_SCRYPT_N}${_SCRYPT_R}${_SCRYPT_P}${salt.hex()}${key.hex()}"
-
-
-def verify_password(password: str, stored: str) -> bool:
-    try:
-        scheme, n, r, p, salt_hex, key_hex = stored.split("$")
-        if scheme != "scrypt":
-            return False
-        key = hashlib.scrypt(
-            password.encode(), salt=bytes.fromhex(salt_hex),
-            n=int(n), r=int(r), p=int(p),
-        )
-        return hmac.compare_digest(key, bytes.fromhex(key_hex))
-    except (ValueError, AttributeError):
-        return False
-
-
-# ---------- Session tokens ----------
-# The token is "v1.<user_id>.<hmac>". It does not expire, because a long-lived
-# guest session is what this is for.
-
-def sign_session(user_id: int) -> str:
-    payload = f"v1.{user_id}"
-    sig = hmac.new(SECRET_KEY, payload.encode(), hashlib.sha256).hexdigest()
-    return f"{payload}.{sig}"
-
-
-def verify_session(token: str) -> int | None:
-    try:
-        version, user_id, sig = token.split(".")
-        if version != "v1":
-            return None
-        payload = f"{version}.{user_id}"
-        expected = hmac.new(SECRET_KEY, payload.encode(), hashlib.sha256).hexdigest()
-        if not hmac.compare_digest(sig, expected):
-            return None
-        return int(user_id)
-    except (ValueError, AttributeError):
-        return None
-
-
-# ---------- API-key encryption at rest ----------
-# Stored values carry an "enc:" prefix so plaintext keys from pre-Phase-8
-# databases can be recognized and migrated.
-
-ENC_PREFIX = "enc:"
-
-
-def encrypt_secret(plain: str) -> str:
-    if not plain:
-        return ""
-    return ENC_PREFIX + _fernet.encrypt(plain.encode()).decode()
-
-
-def decrypt_secret(stored: str) -> str:
-    """Returns the plaintext key. Tolerates legacy plaintext values (returned
-    as-is) and undecryptable tokens (secret rotated → treated as unset)."""
-    if not stored:
-        return ""
-    if not stored.startswith(ENC_PREFIX):
-        return stored
-    try:
-        return _fernet.decrypt(stored[len(ENC_PREFIX):].encode()).decode()
-    except (InvalidToken, ValueError):
-        return ""

backend/app/seed.py

@@ -4,8 +4,7 @@ Every JSON file in ``seed_data/`` describes one demo scenario in the same
 model-native shape the export endpoint produces. Seeded scenarios have a NULL
 owner and ``is_public=True``, so every visitor (including guests) sees them and
 can start an adventure from them, while nobody can edit them. Starting an
-adventure copies the scenario's story cards and scripts into the adventure, so
-the seeded scripts run for guests too.
+adventure copies the scenario's story cards into the adventure.
 
 Seed files are the source of truth for demo content: a scenario is inserted if
 missing, reconciled in place when a seed file's content changes, and deleted
@@ -13,7 +12,7 @@ when no file claims its title any more, so an edit ships on the next deploy.
 Rename a seed by changing its `title` and listing the old one under
 `previous_titles`, which moves the rename onto the existing row. When a seed already matches, nothing is written, so
 this stays cheap to run on every boot. An adventure already started from a demo
-keeps its own copied cards and scripts and is unchanged. Only a new adventure
+keeps its own copied cards and is unchanged. Only a new adventure
 picks up the updated content.
 """
 
@@ -35,7 +34,6 @@ SEED_DIR = Path(__file__).resolve().parent / "seed_data"
 _SCALARS = ("title", "description", "prompt", "memory", "authors_note", "ai_instructions",
             "tags", "image", "icon")
 _CARD_FIELDS = ("type", "name", "keys", "entry", "notes")
-_SCRIPT_FIELDS = ("name", "library_js", "input_js", "context_js", "output_js")
 
 
 def seed_public_scenarios(engine: Engine) -> None:
@@ -98,7 +96,7 @@ def _sweep_unclaimed(db, claimed: set[str]) -> int:
     nothing anybody created can be reached from here.
 
     An adventure started from a deleted demo survives. `adventures.scenario_id`
-    is `ON DELETE SET NULL`, so the story, its cards, and its scripts are its
+    is `ON DELETE SET NULL`, so the story and its cards are its
     own copies and stay; the adventure loses the cover art it inherited.
 
     The caller skips this when a seed file failed to parse. A file that cannot
@@ -117,11 +115,6 @@ def _sweep_unclaimed(db, claimed: set[str]) -> int:
     )
     for scenario in stale:
         logger.info("Removing seeded scenario %r; no seed file claims it.", scenario.title)
-        # The scripts are joined through a secondary table, so nothing cascades
-        # to them. They have a NULL owner and no other reader.
-        for script in list(scenario.scripts):
-            db.delete(script)
-        scenario.scripts = []
         db.delete(scenario)
     return len(stale)
 
@@ -130,10 +123,6 @@ def _card_tuple(source, get) -> tuple:
     return tuple(get(source, f) for f in _CARD_FIELDS)
 
 
-def _script_tuple(source, get) -> tuple:
-    return tuple(get(source, f) for f in _SCRIPT_FIELDS)
-
-
 def find_seeded(db, title: str) -> models.Scenario | None:
     """Returns the seeded scenario with this exact title, if there is one."""
     return (
@@ -178,14 +167,7 @@ def _matches(scenario: models.Scenario, data: dict) -> bool:
         _card_tuple(c, lambda o, f: o.get(f, ""))
         for c in (data.get("story_cards") or []) if isinstance(c, dict)
     )
-    if have_cards != want_cards:
-        return False
-    have_scripts = sorted(_script_tuple(s, lambda o, f: getattr(o, f)) for s in scenario.scripts)
-    want_scripts = sorted(
-        _script_tuple(s, lambda o, f: (o.get(f, "") or ("Script" if f == "name" else "")))
-        for s in (data.get("scripts") or []) if isinstance(s, dict)
-    )
-    return have_scripts == want_scripts
+    return have_cards == want_cards
 
 
 def _insert_scenario(db, data: dict) -> None:
@@ -203,9 +185,6 @@ def _update_scenario(db, scenario: models.Scenario, data: dict) -> None:
     # adventure foreign keys that point at it, intact.
     for card in list(scenario.story_cards):
         db.delete(card)
-    for script in list(scenario.scripts):
-        db.delete(script)
-    scenario.scripts = []
     db.flush()
     _populate_children(db, scenario, data)
 
@@ -231,19 +210,3 @@ def _populate_children(db, scenario: models.Scenario, data: dict) -> None:
                 notes=card.get("notes", ""),
             )
         )
-
-    for item in data.get("scripts") or []:
-        if not isinstance(item, dict):
-            continue
-        script = models.Script(
-            user_id=None,
-            name=item.get("name", "Script"),
-            description=item.get("description", ""),
-            library_js=item.get("library_js", ""),
-            input_js=item.get("input_js", ""),
-            context_js=item.get("context_js", ""),
-            output_js=item.get("output_js", ""),
-        )
-        db.add(script)
-        db.flush()
-        scenario.scripts.append(script)

backend/app/sse.py

@@ -6,11 +6,9 @@ frames, so the format lives here rather than in either one.
 """
 import json
 
-from . import analytics
-
 # `no-cache` stops an intermediary from caching the stream. `X-Accel-Buffering`
-# makes nginx-style reverse proxies, which hosted deploys use, flush each event
-# immediately rather than buffer it.
+# makes an nginx-style reverse proxy flush each event immediately rather than
+# buffer it, which matters if anyone puts one in front of the app.
 SSE_HEADERS = {"Cache-Control": "no-cache", "X-Accel-Buffering": "no"}
 
 
@@ -20,11 +18,9 @@ def sse(obj: dict) -> str:
 
 
 def turn_error(detail: str, **extra) -> str:
-    """Returns an SSE error for a turn that could not be produced, and counts it.
+    """Returns an SSE error for a turn that could not be produced.
 
-    A failed turn is still an HTTP 200 response, so the middleware's status-code
-    tally cannot see it. This metric exists so that a demo whose model refuses
-    every request does not report as healthy.
+    A failed turn is still an HTTP 200 response, because the error is reported
+    inside the stream the client is already reading.
     """
-    analytics.record(analytics.M_EVENT, analytics.EV_TURN_ERROR)
     return sse({"type": "error", "detail": detail, **extra})

backend/requirements.lock

@@ -19,10 +19,8 @@ annotated-doc==0.0.5
 annotated-types==0.8.0
 anyio==4.14.2
 certifi==2026.7.22
-cffi==2.1.1
 charset-normalizer==3.5.1
 click==8.5.0
-cryptography==50.0.1
 fastapi==0.141.1
 greenlet==3.5.5
 h11==0.16.0
@@ -33,16 +31,12 @@ idna==3.19
 iniconfig==2.3.0
 packaging==26.3
 pluggy==1.6.0
-psycopg==3.3.5
-psycopg-binary==3.3.5
-pycparser==3.0
 pydantic==2.13.5
 pydantic_core==2.46.5
 Pygments==2.21.0
 pytest==9.1.1
 python-dotenv==1.2.3
 PyYAML==6.0.3
-quickjs==1.19.4
 regex==2026.9.3
 requests==2.34.2
 SQLAlchemy==2.0.52

backend/requirements.txt

@@ -8,6 +8,3 @@ httpx>=0.27
 # code imports it by name.
 certifi
 tiktoken>=0.7
-quickjs>=1.19
-cryptography>=42
-psycopg[binary]>=3.2

backend/tests/_restart_server.py

@@ -0,0 +1,63 @@
+"""The storyteller, run as a real OS process for `test_process_restart.py`.
+
+Not a test module, and named so pytest does not collect it: it is the program
+the test starts, twice, against one database file.
+
+The model is replaced with a deterministic fake before the app is imported, so
+the process needs no Ollama, no network and no configuration. Everything else —
+the engine, the migrations, the routers, the session lifecycle — is the real
+application, which is the whole point of spawning a process at all.
+
+    python _restart_server.py <db_path> <port>
+"""
+import itertools
+import os
+import sys
+from pathlib import Path
+
+HERE = Path(__file__).resolve().parent
+sys.path.insert(0, str(HERE.parent))   # backend/, so `app` imports
+sys.path.insert(0, str(HERE))          # tests/, so `fakes` imports
+
+db_path, port = sys.argv[1], int(sys.argv[2])
+os.environ["AIDND_DB_PATH"] = db_path
+# A developer's shell may point these at Postgres, and `app.database` prefers
+# either over the SQLite path. The suite's conftest clears them for the same
+# reason; a spawned process does not inherit that, so clear them here too.
+os.environ.pop("AIDND_DATABASE_URL", None)
+os.environ.pop("DATABASE_URL", None)
+
+from fakes import GOLD_PER_TURN, gold_reply  # noqa: E402
+
+_turn = itertools.count(1)
+
+
+class DeterministicProvider:
+    """Banks one turn's worth of gold per reply, numbered so text is checkable.
+
+    The same instrumentation `test_head_cursor.py` and `test_save_points.py`
+    use, for the same reason: it makes "the state at this position" a number the
+    test can assert rather than a paragraph it has to interpret. M5 replaces the
+    machinery underneath; what this measures is where the story is being read.
+    """
+
+    last_usage = None
+
+    def __init__(self, *a, **k):
+        pass
+
+    async def generate(self, parts, *, temperature, max_tokens):
+        yield ("text", gold_reply(f"Beat {next(_turn)}."))
+
+
+from app.routers.adventures import turns  # noqa: E402
+
+turns.OpenAICompatibleProvider = DeterministicProvider
+
+from app.main import app  # noqa: E402
+
+if __name__ == "__main__":
+    import uvicorn
+
+    # Loopback only, as every supported start path does.
+    uvicorn.run(app, host="127.0.0.1", port=port, log_level="warning")

backend/tests/fakes.py

@@ -39,3 +39,44 @@ class ScriptedProvider:
         if isinstance(reply, Exception):
             raise reply
         yield ("text", reply)
+
+
+# ---------------------------------------------------------------------------
+# Deterministic per-turn state instrumentation
+# ---------------------------------------------------------------------------
+# Several tests need a value that changes by a fixed amount on every turn, so
+# that a rollback failure is arithmetic rather than a judgement call: if a take
+# stacks instead of replacing, the total is off by exactly one turn's worth.
+#
+# That instrumentation used to be a JavaScript `output` hook doing
+# `state.gold += 10` in the QuickJS sandbox. M2 removed campaign scripting, and
+# the tests below are not about scripting — they are about the state snapshot,
+# rollback, and branch-isolation machinery in `attempts.py` and `tree.py`,
+# which is unchanged.
+#
+# The counter therefore moved to the world-state engine, which is a real
+# remaining product path: the model emits a ```state delta block, the referee
+# applies it, and the result lands in `adventure.world_state`. The fake
+# provider decides what the model "emits", so it is exactly as deterministic as
+# the script was, and it exercises production code rather than a test hook.
+
+#: A schema with a plain unbounded counter. No `max_delta_per_turn` and no
+#: `cooldown`, so every +10 is applied in full, every turn.
+GOLD_SCHEMA = {
+    "player": {
+        "hp": {"min": 0, "max": 100, "initial": 100},
+        "gold": {"min": 0, "max": 1_000_000, "initial": 0},
+    }
+}
+
+GOLD_PER_TURN = 10
+
+
+def gold_reply(text: str, amount: int = GOLD_PER_TURN) -> str:
+    """A model reply that narrates `text` and banks `amount` gold."""
+    return f'{text}\n```state\n{{"player.gold": {amount}}}\n```'
+
+
+def gold_replies(prefix: str = "Take", count: int = 40) -> list[str]:
+    """`count` numbered replies, each banking one turn's worth of gold."""
+    return [gold_reply(f"{prefix} {n}.") for n in range(1, count + 1)]

backend/tests/test_accesslog.py

@@ -1,208 +0,0 @@
-"""The access log: app/accesslog.py and GET /api/analytics/access.
-
-This is the half of the analytics work that identifies people on purpose,
-so these tests pin the details that would quietly make it wrong. The
-address recorded must be the hardened one, not a header a client chose.
-Session rows must be thinned instead of written on every page load. And a
-row must outlive the account it describes, because guest cleanup deletes
-accounts on a schedule, and a log that deletes itself is not a log.
-
-    python -m pytest tests/test_accesslog.py -v
-"""
-import pytest
-from fastapi import Depends
-from fastapi.testclient import TestClient
-
-from app import accesslog, auth, limits, models, security
-from app.database import Base, SessionLocal, engine, get_db
-from app.main import app
-
-EDGE = "198.51.100.77"      # what the trusted proxy appended
-SPOOF = "10.0.0.1"          # what a client put in front of it
-
-
-@pytest.fixture(autouse=True)
-def clean_state():
-    accesslog._last_session.clear()
-    yield
-    accesslog._last_session.clear()
-
-
-@pytest.fixture()
-def client(monkeypatch):
-    Base.metadata.create_all(bind=engine)
-    setup = SessionLocal()
-    owner = models.User(is_guest=False, email="owner@example.com")
-    member = models.User(
-        is_guest=False, email="player@example.com",
-        password_hash=security.hash_password("hunter2long"),
-    )
-    setup.add_all([owner, member])
-    setup.commit()
-    ids = {"owner": owner.id, "member": member.id}
-    setup.close()
-
-    monkeypatch.setattr(limits, "rate_limit", lambda *a, **k: None)
-    monkeypatch.setattr(limits, "check_login_allowed", lambda *a, **k: None)
-    monkeypatch.setattr(auth, "MULTI_USER", True)
-    monkeypatch.setattr(auth, "ANALYTICS_EMAILS", {"owner@example.com"})
-
-    # /auth/me resolves its own session, so the cookie flow below is the real
-    # one. Every other endpoint goes through get_current_user, and `act_as`
-    # decides who that is.
-    acting = {"id": ids["owner"]}
-
-    def _current(db=Depends(get_db)):
-        return db.get(models.User, acting["id"])
-
-    app.dependency_overrides[auth.get_current_user] = _current
-    try:
-        test_client = TestClient(app)
-        test_client.ids = ids
-        test_client.act_as = lambda user_id: acting.update(id=user_id)
-        yield test_client
-    finally:
-        app.dependency_overrides.clear()
-        Base.metadata.drop_all(bind=engine)
-
-
-def visit(client, ip=EDGE, ua="Mozilla/5.0 (Windows NT 10.0; Win64; x64)"):
-    return client.get(
-        "/api/auth/me",
-        headers={"x-forwarded-for": f"{SPOOF}, {ip}", "user-agent": ua},
-    )
-
-
-def rows(kind=None):
-    db = SessionLocal()
-    try:
-        query = db.query(models.AccessEvent).order_by(models.AccessEvent.id)
-        if kind:
-            query = query.filter_by(kind=kind)
-        return query.all()
-    finally:
-        db.close()
-
-
-def read_log(client, **params):
-    return client.get("/api/analytics/access", params=params)
-
-
-# ---------- Writing ----------
-
-def test_a_new_session_is_logged(client):
-    visit(client)
-    logged = rows()
-    assert len(logged) == 1
-    entry = logged[0]
-    assert entry.kind == accesslog.SESSION
-    assert entry.is_guest and entry.who.startswith("Guest #")
-    assert entry.device == "desktop"
-
-
-def test_the_address_is_the_hardened_one_not_the_clients(client):
-    visit(client)
-    # The client prepended its own value. Only the hop the edge appended counts.
-    # Recording the leftmost value would make every row forgeable, which is
-    # worse for a log than having no log at all.
-    assert rows()[0].ip == EDGE
-
-
-def test_session_rows_are_thinned_to_one_per_day_per_address(client):
-    for _ in range(4):
-        visit(client)
-    assert len(rows(accesslog.SESSION)) == 1
-
-
-def test_a_changed_address_writes_a_new_row(client):
-    visit(client)
-    visit(client, ip="203.0.113.9")
-    logged = rows(accesslog.SESSION)
-    assert [entry.ip for entry in logged] == [EDGE, "203.0.113.9"]
-    # Same session throughout, so both rows name the same visitor.
-    assert logged[0].who == logged[1].who
-
-
-def test_sign_in_and_failure_are_both_logged(client):
-    client.post("/api/auth/login", json={"email": "player@example.com", "password": "wrong"},
-                headers={"x-forwarded-for": EDGE})
-    client.post("/api/auth/login", json={"email": "player@example.com", "password": "hunter2long"},
-                headers={"x-forwarded-for": EDGE})
-    kinds = [entry.kind for entry in rows()]
-    assert accesslog.LOGIN_FAILED in kinds and accesslog.LOGIN in kinds
-
-    failure = rows(accesslog.LOGIN_FAILED)[0]
-    # This records the address that was tried, not the account it belongs to.
-    # A failed attempt against an address with no matching account is
-    # exactly what this row exists to capture.
-    assert failure.who == "player@example.com"
-    assert failure.user_id is None
-    assert rows(accesslog.LOGIN)[0].user_id == client.ids["member"]
-
-
-def test_registering_is_logged_against_the_upgraded_account(client):
-    visit(client)  # creates the guest whose session then registers
-    client.act_as(rows()[0].user_id)
-    client.post("/api/auth/register", json={"email": "new@example.com", "password": "hunter2long"})
-    entry = rows(accesslog.REGISTER)[0]
-    assert entry.who == "new@example.com" and not entry.is_guest
-
-
-def test_a_row_outlives_the_account_it_describes(client):
-    visit(client)
-    entry = rows()[0]
-    db = SessionLocal()
-    try:
-        db.delete(db.get(models.User, entry.user_id))
-        db.commit()
-    finally:
-        db.close()
-    # There is no foreign key, and `who` is a snapshot. Guest cleanup deletes
-    # accounts on a schedule, and a log that vanishes along with them is not
-    # a log.
-    survivor = rows()[0]
-    assert survivor.who == entry.who and survivor.ip == EDGE
-
-
-def test_a_long_user_agent_is_truncated(client):
-    visit(client, ua="Mozilla/" + "x" * 500)
-    assert len(rows()[0].user_agent) == accesslog.MAX_UA
-
-
-def test_a_logging_failure_does_not_break_the_request(client, monkeypatch):
-    monkeypatch.setattr(accesslog, "_client_ip", lambda request: 1 / 0)
-    # The log observes sign-in. A logging failure must not block the request.
-    assert visit(client).status_code == 200
-
-
-# ---------- Reading ----------
-
-def test_the_log_is_invisible_to_everyone_but_the_owner(client):
-    visit(client)
-    assert read_log(client).status_code == 200
-    client.act_as(client.ids["member"])
-    assert read_log(client).status_code == 404
-
-
-def test_the_log_reads_newest_first_and_pages_backwards(client):
-    for index in range(5):
-        visit(client, ip=f"203.0.113.{index}")
-    first = read_log(client, limit=2).json()
-    assert [event["ip"] for event in first["events"]] == ["203.0.113.4", "203.0.113.3"]
-    assert first["has_more"]
-
-    older = read_log(client, limit=2, before_id=first["events"][-1]["id"]).json()
-    assert [event["ip"] for event in older["events"]] == ["203.0.113.2", "203.0.113.1"]
-
-
-def test_the_log_filters_by_kind_and_searches(client):
-    visit(client)
-    client.post("/api/auth/login", json={"email": "player@example.com", "password": "hunter2long"},
-                headers={"x-forwarded-for": "203.0.113.44"})
-
-    assert len(read_log(client, kind="login").json()["events"]) == 1
-    by_email = read_log(client, q="player@example.com").json()["events"]
-    assert len(by_email) == 1 and by_email[0]["kind"] == "login"
-    by_ip = read_log(client, q="203.0.113.44").json()["events"]
-    assert len(by_ip) == 1
-    assert read_log(client, q="nobody@example.com").json()["events"] == []

backend/tests/test_action_paging.py

@@ -48,7 +48,6 @@ def client(monkeypatch):
     adv_id, user_id = adventure.id, user.id
     setup.close()
 
-    monkeypatch.setattr(limits, "rate_limit", lambda *a, **k: None)
     monkeypatch.setattr(limits, "check_row_cap", lambda *a, **k: None)
 
     def _current_user(db=Depends(get_db)):

backend/tests/test_analytics.py

@@ -1,385 +0,0 @@
-"""Visit analytics: app/analytics.py and the two endpoints in front of it.
-
-This file tests three things, and the rest is arithmetic. The counters must
-survive the buffer/UPSERT round trip: a flush adds to what is already
-stored instead of replacing it, or every number would show only the last
-minute. The funnel counts people rather than clicks, which is the only
-reason the visitor-day table exists. The gate holds: a stranger cannot read
-the dashboard, and cannot inflate what it reports beyond hitting the page.
-
-    python -m pytest tests/test_analytics.py -v
-"""
-from datetime import timedelta
-
-import pytest
-from fastapi import Depends
-from fastapi.testclient import TestClient
-
-from app import analytics, auth, limits, models
-from app.database import Base, SessionLocal, engine, get_db
-from app.main import app
-
-
-@pytest.fixture(autouse=True)
-def clean_buffer():
-    """The buffer is process-wide, so a test that leaves counts in it would
-    show up inside the next one's flush."""
-    analytics._counts.clear()
-    analytics._visits.clear()
-    analytics._labels_seen.clear()
-    yield
-    analytics._counts.clear()
-    analytics._visits.clear()
-    analytics._labels_seen.clear()
-
-
-@pytest.fixture()
-def db():
-    Base.metadata.create_all(bind=engine)
-    session = SessionLocal()
-    try:
-        yield session
-    finally:
-        session.close()
-        Base.metadata.drop_all(bind=engine)
-
-
-def counter(db, metric, label):
-    row = (
-        db.query(models.AnalyticsDaily)
-        .filter_by(metric=metric, label=label)
-        .one_or_none()
-    )
-    return row.hits if row else 0
-
-
-def make_user(db, email=None):
-    user = models.User(is_guest=email is None, email=email)
-    db.add(user)
-    db.commit()
-    return user
-
-
-# ---------- The buffer and its flush ----------
-
-def test_counts_accumulate_across_flushes(db):
-    analytics.record(analytics.M_PAGE, "/")
-    analytics.record(analytics.M_PAGE, "/")
-    analytics.flush(db)
-    analytics.record(analytics.M_PAGE, "/")
-    analytics.flush(db)
-    # The second flush has to find the existing row and add to it. Replacing it
-    # would leave every counter showing only the newest minute of traffic.
-    assert counter(db, analytics.M_PAGE, "/") == 3
-
-
-def test_flush_is_a_no_op_when_nothing_happened(db):
-    analytics.flush(db)
-    assert db.query(models.AnalyticsDaily).count() == 0
-
-
-def test_a_failed_flush_keeps_the_counts(db, monkeypatch):
-    analytics.record(analytics.M_PAGE, "/")
-    monkeypatch.setattr(analytics, "_write_counts", lambda *a: 1 / 0)
-    analytics.flush(db)  # must not raise
-    monkeypatch.undo()
-    analytics.flush(db)
-    assert counter(db, analytics.M_PAGE, "/") == 1
-
-
-def test_label_cardinality_is_capped(db):
-    for i in range(analytics.MAX_LABELS_PER_METRIC + 25):
-        analytics.record(analytics.M_REFERRER, f"host{i}.example")
-    analytics.flush(db)
-    labels = db.query(models.AnalyticsDaily).filter_by(metric=analytics.M_REFERRER).count()
-    # Everything past the cap is folded into one bucket, so a referrer flood
-    # cannot create unlimited rows.
-    assert labels == analytics.MAX_LABELS_PER_METRIC + 1
-    assert counter(db, analytics.M_REFERRER, analytics.OTHER) == 25
-
-
-# ---------- Visitors ----------
-
-def test_visitor_id_is_stable_and_keyed(db, monkeypatch):
-    user = make_user(db)
-    handle = analytics.visitor_id(user)
-    assert handle == analytics.visitor_id(user)               # a returning visitor
-    assert handle != analytics.visitor_id(make_user(db))      # is still one visitor
-    assert len(handle) == 32 and int(handle, 16) >= 0         # opaque hex, not an id
-    # Keyed on the app secret, not a bare hash of the user id. Otherwise
-    # anyone holding this table could rebuild the mapping by hashing
-    # sequential ids.
-    monkeypatch.setattr(analytics.security, "SECRET_KEY", b"a-different-secret")
-    assert analytics.visitor_id(user) != handle
-
-
-def test_a_repeat_visitor_is_new_only_once(db):
-    user = make_user(db)
-    analytics.record_visit(user)
-    analytics.flush(db)
-    rows = db.query(models.AnalyticsVisitorDay).all()
-    assert len(rows) == 1 and rows[0].is_new
-
-    # Same visitor, a later day: seen before, so not new. The row is not
-    # merged into the first day's row either.
-    tomorrow = (models.utcnow().date() + timedelta(days=1)).isoformat()
-    analytics._visits[(tomorrow, analytics.visitor_id(user))] = set()
-    analytics.flush(db)
-    rows = db.query(models.AnalyticsVisitorDay).order_by(models.AnalyticsVisitorDay.day).all()
-    assert [row.is_new for row in rows] == [True, False]
-
-
-def test_one_row_per_visitor_per_day_however_much_they_do(db):
-    user = make_user(db)
-    for _ in range(5):
-        analytics.record_event(analytics.EV_ADVENTURE, user)
-        analytics.flush(db)
-    assert db.query(models.AnalyticsVisitorDay).count() == 1
-    assert counter(db, analytics.M_EVENT, analytics.EV_ADVENTURE) == 5
-
-
-def test_funnel_flags_only_ever_turn_on(db):
-    user = make_user(db)
-    analytics.record_event(analytics.EV_TURN, user)
-    analytics.flush(db)
-    # A later visit that reaches no funnel step must not clear the earlier one.
-    analytics.record_visit(user)
-    analytics.flush(db)
-    row = db.query(models.AnalyticsVisitorDay).one()
-    assert row.played and not row.created
-
-
-def test_purge_drops_only_rows_past_the_horizon(db):
-    old = (models.utcnow().date() - timedelta(days=analytics.RETENTION_DAYS + 1)).isoformat()
-    db.add(models.AnalyticsVisitorDay(day=old, visitor="a" * 32))
-    db.add(models.AnalyticsVisitorDay(day=analytics._today(), visitor="b" * 32))
-    db.commit()
-    assert analytics.purge_old_visitor_days(db) == 1
-    assert [r.visitor for r in db.query(models.AnalyticsVisitorDay)] == ["b" * 32]
-
-
-# ---------- Normalizing what a browser claims ----------
-
-@pytest.mark.parametrize("path, expected", [
-    ("/", "/"),
-    ("/adventures", "/adventures"),
-    ("/adventures/", "/adventures"),
-    ("/play/12?x=1", "/play/:id"),
-    ("/scenarios/9#top", "/scenarios/:id"),
-    ("/wp-admin", "(other)"),
-    ("/play/../../etc", "(other)"),
-    ("", "/"),
-])
-def test_route_normalization(path, expected):
-    assert analytics.normalize_route(path) == expected
-
-
-@pytest.mark.parametrize("referrer, expected", [
-    ("", "(direct)"),
-    ("https://news.ycombinator.com/item?id=1", "news.ycombinator.com"),
-    ("https://www.google.com/", "google.com"),
-    ("https://ai-dnd.example/scenarios", ""),          # our own host: not a referral
-    ("javascript:alert(1)", "(other)"),
-    ("https://" + "x" * 200 + ".com", "(other)"),
-])
-def test_referrer_normalization(referrer, expected):
-    assert analytics.normalize_referrer(referrer, "ai-dnd.example") == expected
-
-
-@pytest.mark.parametrize("ua, expected", [
-    ("Mozilla/5.0 (iPhone; CPU iPhone OS 17_0) AppleWebKit", "mobile"),
-    ("Mozilla/5.0 (iPad; CPU OS 17_0) AppleWebKit", "tablet"),
-    ("Mozilla/5.0 (Windows NT 10.0; Win64; x64)", "desktop"),
-    ("Googlebot/2.1", "bot"),
-    ("", "(unknown)"),
-])
-def test_device_detection(ua, expected):
-    assert analytics.device_of(ua) == expected
-
-
-def test_only_iso_looking_country_headers_are_trusted():
-    assert analytics.country_of({"cf-ipcountry": "de"}) == "DE"
-    assert analytics.country_of({"cf-ipcountry": "Norway"}) == analytics.UNKNOWN
-    assert analytics.country_of({"cf-ipcountry": "XX"}) == analytics.UNKNOWN
-    assert analytics.country_of({}) == analytics.UNKNOWN
-
-
-def test_error_labels_use_the_route_not_the_path():
-    class Route:
-        path = "/api/adventures/{adventure_id}"
-
-    assert analytics.api_route_label({"route": Route()}, 500) == "500 /api/adventures/{adventure_id}"
-    # An unmatched path is entirely attacker-chosen, so it never becomes a label.
-    assert analytics.api_route_label({}, 404) == "404 (unmatched)"
-
-
-# ---------- The summary ----------
-
-def test_summary_counts_people_once_per_step(db):
-    one, two = make_user(db), make_user(db)
-    for _ in range(3):
-        analytics.record_event(analytics.EV_SCENARIO_OPEN, one)
-        analytics.record_event(analytics.EV_TURN, one)
-    analytics.record_event(analytics.EV_SCENARIO_OPEN, two)
-
-    result = analytics.summary(db, days=7)
-    steps = {row["step"]: row["count"] for row in result["funnel"]}
-    assert steps["Visited"] == 2
-    assert steps["Opened a scenario"] == 2
-    assert steps["Played a turn"] == 1      # not 3, because one person made three turns
-    assert steps["Signed up"] == 0
-    # Raw event totals still count every occurrence.
-    assert result["totals"]["turns"] == 3
-    assert result["totals"]["visitors"] == 2
-
-
-def test_summary_series_covers_every_day_including_empty_ones(db):
-    analytics.record(analytics.M_PAGE, "/")
-    result = analytics.summary(db, days=7)
-    assert len(result["series"]) == 7
-    assert result["series"][-1]["day"] == models.utcnow().date().isoformat()
-    assert result["series"][-1]["pageviews"] == 1
-    assert result["series"][0]["pageviews"] == 0
-
-
-def test_summary_flushes_before_reading(db):
-    analytics.record(analytics.M_EVENT, analytics.EV_TURN)
-    # Never flushed by hand: the dashboard must not be up to a minute stale.
-    assert analytics.summary(db, days=1)["totals"]["turns"] == 1
-
-
-def test_summary_reports_pages_referrers_and_errors(db):
-    analytics.record(analytics.M_PAGE, "/play/:id", n=4)
-    analytics.record(analytics.M_REFERRER, "news.ycombinator.com", n=2)
-    analytics.record(analytics.M_ERROR, "500 /api/adventures/{adventure_id}")
-    result = analytics.summary(db, days=30)
-    assert result["pages"][0] == {"label": "/play/:id", "hits": 4}
-    assert result["referrers"][0]["label"] == "news.ycombinator.com"
-    assert result["totals"]["errors"] == 1
-
-
-# ---------- The endpoints ----------
-
-@pytest.fixture()
-def client(monkeypatch):
-    Base.metadata.create_all(bind=engine)
-    setup = SessionLocal()
-    visitor = models.User(is_guest=True)
-    owner = models.User(is_guest=False, email="owner@example.com")
-    setup.add_all([visitor, owner])
-    setup.commit()
-    ids = {"visitor": visitor.id, "owner": owner.id}
-    setup.close()
-
-    monkeypatch.setattr(limits, "rate_limit", lambda *a, **k: None)
-    # Multi-user is what makes the gate mean anything: local mode trusts
-    # whoever is at the keyboard, because it is the operator's own machine.
-    monkeypatch.setattr(auth, "MULTI_USER", True)
-    monkeypatch.setattr(auth, "ANALYTICS_EMAILS", {"owner@example.com"})
-
-    current = {"id": ids["visitor"]}
-
-    def _current_user(db=Depends(get_db)):
-        return db.get(models.User, current["id"])
-
-    app.dependency_overrides[auth.get_current_user] = _current_user
-    monkeypatch.setattr(
-        auth, "resolve_session_user", lambda request, db: db.get(models.User, current["id"])
-    )
-    try:
-        client = TestClient(app)
-        client.ids, client.current = ids, current
-        yield client
-    finally:
-        app.dependency_overrides.clear()
-        Base.metadata.drop_all(bind=engine)
-
-
-def read_summary(client, days=30):
-    return client.get(f"/api/analytics/summary?days={days}")
-
-
-def test_dashboard_is_invisible_to_everyone_but_the_owner(client):
-    assert read_summary(client).status_code == 404
-    client.current["id"] = client.ids["owner"]
-    assert read_summary(client).status_code == 200
-
-
-def test_collect_records_a_pageview_and_the_visit(client):
-    resp = client.post("/api/analytics/collect", json={"path": "/play/7", "first": True,
-                                                       "referrer": "https://news.ycombinator.com/"})
-    assert resp.status_code == 204
-    client.current["id"] = client.ids["owner"]
-    body = read_summary(client).json()
-    assert body["pages"][0] == {"label": "/play/:id", "hits": 1}
-    assert body["referrers"][0]["label"] == "news.ycombinator.com"
-    assert body["totals"]["visitors"] == 1
-
-
-def test_referrer_and_device_are_recorded_once_per_visit_not_per_view(client):
-    for path in ("/", "/scenarios", "/adventures"):
-        client.post("/api/analytics/collect", json={"path": path, "first": path == "/"})
-    client.current["id"] = client.ids["owner"]
-    body = read_summary(client).json()
-    assert body["totals"]["pageviews"] == 3
-    # Three views, one visit: the referral and the device are facts about the
-    # visit, so counting them per view would multiply every one of them.
-    assert sum(row["hits"] for row in body["devices"]) == 1
-
-
-def test_the_owners_own_visits_are_not_traffic(client):
-    client.current["id"] = client.ids["owner"]
-    client.post("/api/analytics/collect", json={"path": "/", "first": True})
-    assert read_summary(client).json()["totals"]["pageviews"] == 0
-
-
-def test_a_client_cannot_invent_pages_or_events(client):
-    client.post("/api/analytics/collect", json={"path": "/../../admin", "first": True})
-    # There is no field for it, so a made-up event is not even expressible.
-    client.post("/api/analytics/collect", json={"path": "/", "event": "signup"})
-    client.current["id"] = client.ids["owner"]
-    body = read_summary(client).json()
-    assert {row["label"] for row in body["pages"]} == {"(other)", "/"}
-    assert body["totals"]["signups"] == 0
-
-
-def test_api_errors_are_counted_by_route(client):
-    client.get("/api/adventures/999999")
-    client.current["id"] = client.ids["owner"]
-    errors = read_summary(client).json()["errors"]
-    assert errors and errors[0]["label"].startswith("404 /api/adventures/")
-
-
-# ---------- The dialect the tests never run on ----------
-
-def test_the_upserts_compile_for_postgres():
-    """Prod runs on Neon, but these tests run on SQLite, and a failed flush
-    is caught and logged instead of raised. A dialect mistake would
-    therefore stay invisible until the dashboard quietly stayed empty. This
-    test compiles both statements against Postgres without connecting to
-    one.
-    """
-    from sqlalchemy import create_engine
-    from sqlalchemy.dialects import postgresql
-    from sqlalchemy.orm import sessionmaker
-
-    session = sessionmaker(bind=create_engine("postgresql+psycopg://u:p@localhost/db"))()
-    compiled = []
-
-    def capture(statement, *args, **kwargs):
-        compiled.append(str(statement.compile(dialect=postgresql.dialect())))
-
-    session.execute = capture
-    session.scalars = lambda *a, **k: []
-
-    analytics._write_counts(session, {("2026-01-01", "pageview", "/"): 2})
-    analytics._write_visits(session, {("2026-01-01", "f" * 32): {"played"}})
-
-    counts, visits = compiled
-    assert "ON CONFLICT (day, metric, label) DO UPDATE" in counts
-    assert "analytics_daily.hits + excluded.hits" in counts
-    assert "ON CONFLICT (day, visitor) DO UPDATE" in visits
-    assert "analytics_visitor_days.played OR excluded.played" in visits
-    # is_new is settled by the first write of a visitor's first day and must
-    # not be in the update clause at all.
-    assert "is_new" not in visits.split("DO UPDATE")[1]

backend/tests/test_attempt_siblings.py

@@ -19,17 +19,10 @@ from app.database import Base, SessionLocal, engine, get_db
 from app.main import app
 from app.routers import adventures
 
-from fakes import ScriptedProvider
+from fakes import GOLD_SCHEMA, ScriptedProvider, gold_replies, gold_reply
 
-SCHEMA = {"player": {"hp": {"min": 0, "max": 100, "initial": 100}}}
+SCHEMA = GOLD_SCHEMA
 
-GOLD_SCRIPT = """
-const modifier = (text) => {
-  state.gold = (state.gold || 0) + 10;
-  return { text };
-};
-modifier(text);
-"""
 
 
 @pytest.fixture()
@@ -45,14 +38,11 @@ def client(monkeypatch):
     setup.flush()
     adv = models.Adventure(
         user_id=user.id, title="Cave", scenario_id=scenario.id,
-        script_state={}, world_state={"player": {"hp": 100}},
+        world_state={"player": {"hp": 100, "gold": 0}},
     )
     setup.add(adv)
     setup.flush()
     setup.add(models.Action(adventure_id=adv.id, type="start", text="You enter a cave."))
-    setup.add(models.AdventureScript(
-        adventure_id=adv.id, position=0, enabled=True, name="Gold", output_js=GOLD_SCRIPT,
-    ))
     setup.commit()
     adv_id, user_id = adv.id, user.id
     setup.close()
@@ -61,9 +51,6 @@ def client(monkeypatch):
     ScriptedProvider.calls = 0
     ScriptedProvider.prompts = []
     monkeypatch.setattr(adventures.turns, "OpenAICompatibleProvider", ScriptedProvider)
-    monkeypatch.setattr(auth, "resolve_provider_config", lambda s: auth.ProviderConfig(
-        "http://fake", "k", "test-model", False))
-    monkeypatch.setattr(limits, "rate_limit", lambda *a, **k: None)
     monkeypatch.setattr(limits, "check_row_cap", lambda *a, **k: None)
 
     def _current_user(db=Depends(get_db)):
@@ -213,18 +200,40 @@ def test_the_assembled_prompt_is_stored_once_per_turn(client):
     assert len(moved) == 1 and moved != live_holder, "the prompt follows the story"
 
 
-# ------------------------------------------------------- removing the turn
+# ------------------------------------------------- stepping behind the turn
 
-def test_undo_takes_every_attempt_with_it(client):
+def test_undo_hides_every_attempt_and_keeps_them_all(client):
+    """M3 rewrote this test. Undo used to delete the turn, and the assertion was
+    that it took the whole sibling group with it rather than leaving orphaned
+    attempts at a coordinate the story no longer reached.
+
+    The group still moves as one, but it moves out of the story rather than out
+    of the database: one Undo steps behind the turn, so none of its three
+    attempts is in what the story tells, and all three are still on disk for the
+    Redo that walks back into them. The old assertion is kept as the second half
+    — what the story reads — and the row count is the new first half.
+    """
     ScriptedProvider.replies = ["One.", "Two.", "Three."]
     _play(client)
     _retry(client)
     _retry(client)
-    assert len([a for a in _rows(client.adv_id) if a.type == "ai"]) == 3
+    before = _rows(client.adv_id)
+    assert len([a for a in before if a.type == "ai"]) == 3
 
     r = client.post(f"/api/adventures/{client.adv_id}/undo")
     assert r.status_code == 200, r.text
-    assert [a.type for a in _rows(client.adv_id)] == ["start"]
+    # What the story tells: the opening, and none of the turn's attempts.
+    assert [a["type"] for a in r.json()["actions"]] == ["start"]
+    # What it holds: every row that was there before, attempts included.
+    after = _rows(client.adv_id)
+    assert len(after) == len(before)
+    assert {a.id for a in after} == {a.id for a in before}
+    assert len([a for a in after if a.type == "ai"]) == 3
+    # And the group is reachable again, whole, with the same take live.
+    live_before = [a.id for a in before if a.type == "ai" and a.live]
+    r = client.post(f"/api/adventures/{client.adv_id}/redo")
+    assert r.status_code == 200, r.text
+    assert [a.id for a in _rows(client.adv_id) if a.type == "ai" and a.live] == live_before
 
 
 def test_deleting_a_retried_turn_deletes_its_attempts(client):

backend/tests/test_branch_clause.py

@@ -30,7 +30,6 @@ from app import auth, limits, models, tree
 from app.context import history, lineage
 from app.database import Base, SessionLocal, engine, get_db
 from app.main import app
-from app.scripting import ScriptPipeline
 from tools import dbmeter
 
 
@@ -224,24 +223,11 @@ def test_an_already_loaded_collection_is_cut_down_to_the_path(forked):
     assert labels(history.tail(adventure, 3)) == ["B5", "C6", "C7"]
 
 
-def test_user_scripts_are_handed_the_path(forked):
-    """The same risk one layer up, in code visible to users:
-    `pipeline._history()` is the documented scripting history API."""
-    db, adventure, _ = forked
-    list(adventure.actions)  # the pipeline's caller has usually loaded these
-    pipeline = ScriptPipeline(adventure, db)
-    assert [h["text"] for h in pipeline._history()] == [
-        "A0", "A1", "A2", "A3", "B4", "B5", "C6", "C7"
-    ]
-    assert pipeline._info()["actionCount"] == 8
-
-
 # ------------------------------------------------------------ over the wire
 
 @pytest.fixture()
 def client(forked, monkeypatch):
     db, adventure, ids = forked
-    monkeypatch.setattr(limits, "rate_limit", lambda *a, **k: None)
     monkeypatch.setattr(limits, "check_row_cap", lambda *a, **k: None)
 
     def _current_user(session=Depends(get_db)):

backend/tests/test_branch_forking.py

@@ -22,7 +22,7 @@ from app.database import Base, SessionLocal, engine, get_db
 from app.main import app
 from app.routers import adventures
 
-from fakes import ScriptedProvider
+from fakes import GOLD_SCHEMA, ScriptedProvider, gold_replies, gold_reply
 
 # `hp` moves freely. `mana` has a cooldown of 2 turns, so an incorrect
 # advance shows up as a change the referee should have rejected.
@@ -30,16 +30,13 @@ SCHEMA = {
     "player": {
         "hp": {"min": 0, "max": 100, "initial": 100},
         "mana": {"min": 0, "max": 50, "initial": 50, "cooldown": 2},
+        # The per-turn counter these tests measure rollbacks with. Unbounded and
+        # uncapped on purpose, so every turn's +10 lands in full. See
+        # `fakes.gold_reply`.
+        "gold": {"min": 0, "max": 1_000_000, "initial": 0},
     }
 }
 
-GOLD_SCRIPT = """
-const modifier = (text) => {
-  state.gold = (state.gold || 0) + 10;
-  return { text };
-};
-modifier(text);
-"""
 
 
 @pytest.fixture()
@@ -55,14 +52,11 @@ def client(monkeypatch):
     setup.flush()
     adv = models.Adventure(
         user_id=user.id, title="Cave", scenario_id=scenario.id,
-        script_state={}, world_state={"player": {"hp": 100, "mana": 50}},
+        world_state={"player": {"hp": 100, "mana": 50, "gold": 0}},
     )
     setup.add(adv)
     setup.flush()
     setup.add(models.Action(adventure_id=adv.id, type="start", text="You enter a cave."))
-    setup.add(models.AdventureScript(
-        adventure_id=adv.id, position=0, enabled=True, name="Gold", output_js=GOLD_SCRIPT,
-    ))
     setup.commit()
     adv_id, user_id = adv.id, user.id
     setup.close()
@@ -71,9 +65,6 @@ def client(monkeypatch):
     ScriptedProvider.calls = 0
     ScriptedProvider.prompts = []
     monkeypatch.setattr(adventures.turns, "OpenAICompatibleProvider", ScriptedProvider)
-    monkeypatch.setattr(auth, "resolve_provider_config", lambda s: auth.ProviderConfig(
-        "http://fake", "k", "test-model", False))
-    monkeypatch.setattr(limits, "rate_limit", lambda *a, **k: None)
     monkeypatch.setattr(limits, "check_row_cap", lambda *a, **k: None)
 
     def _current_user(db=Depends(get_db)):
@@ -121,7 +112,7 @@ def _state(adv_id):
     db = SessionLocal()
     try:
         adv = db.get(models.Adventure, adv_id)
-        return adv.script_state, adv.world_state
+        return (adv.world_state or {}).get("player", {}), adv.world_state
     finally:
         db.close()
 
@@ -322,11 +313,13 @@ def test_forking_a_live_node_on_another_branch_is_refused(client):
 
 # -------------------------------------------------------------- the state
 
-def test_switching_restores_the_script_and_world_state(client):
+def test_switching_restores_the_state_a_branch_left_behind(client):
+    # Two stats move: hp differs per attempt, and gold counts turns. Between
+    # them, a switch that restored the wrong snapshot is visible either way.
     ScriptedProvider.replies = [
-        "A scratch.\n```state\n{\"player.hp\": -5}\n```",
-        "A beating.\n```state\n{\"player.hp\": -40}\n```",
-        "Onward.",
+        'A scratch.\n```state\n{"player.hp": -5, "player.gold": 10}\n```',
+        'A beating.\n```state\n{"player.hp": -40, "player.gold": 10}\n```',
+        gold_reply("Onward."),
     ]
     _play(client)
     _retry(client)
@@ -336,9 +329,9 @@ def test_switching_restores_the_script_and_world_state(client):
 
     discarded = [a.id for a in _rows(client.adv_id) if a.type == "ai" and not a.live][0]
     _fork(client, discarded)
-    script_state, world_state = _state(client.adv_id)
+    player, world_state = _state(client.adv_id)
     assert world_state["player"]["hp"] == 95, "the attempt this branch tells"
-    assert script_state == {"gold": 10}, "one turn of gold, not three"
+    assert player["gold"] == 10, "one turn of gold, not three"
 
     client.post(f"/api/adventures/{client.adv_id}/branches/{parent}/switch")
     assert _state(client.adv_id) == on_parent
@@ -439,26 +432,41 @@ def test_a_memory_on_the_line_left_behind_is_out_of_range_on_the_fork(client):
 
 # ------------------------------------------------------------------- undo
 
-def test_undo_stops_at_the_fork(client):
-    """Undoing a turn on a fork must never reach into the branch it forked
-    from. Those turns belong to that branch's story too."""
+def test_undo_walks_off_a_fork_into_the_story_it_inherits(client):
+    """M3 rewrote this test, and reversed half of it.
+
+    Undo used to refuse at a fork point, and it had to: it deleted the turns it
+    stepped over, and the turns before the fork belong to the parent branch's
+    story as well. Refusing was the only way to stop one branch's Undo from
+    removing rows another branch was reading.
+
+    Nothing is deleted now, so there is nothing to protect the parent from. A
+    forked branch inherits the story up to its fork, that inherited story is
+    part of what this branch tells, and Undo walks back through it like any
+    other retained history. The floor is the campaign opening, not the fork.
+    """
     discarded = _divergent_story(client)
     _fork(client, discarded)
     rows_before = len(_rows(client.adv_id))
 
     r = client.post(f"/api/adventures/{client.adv_id}/undo")
     assert r.status_code == 200, r.text
-    # The promoted attempt is removed, and the player action before it
-    # stays, because that action belongs to the parent and the parent
-    # still has it.
-    assert len(_rows(client.adv_id)) == rows_before - 1
-    assert _texts(client) == ["You enter a cave.", "> You look around."]
+    # One Undo steps over a whole turn, so it takes the player's action with the
+    # reply to it — and that player action is the parent's row, sitting in front
+    # of the fork. Stepping behind it is a read moving backwards, not a branch
+    # reaching into another branch's rows: nothing moved either way.
+    assert len(_rows(client.adv_id)) == rows_before
+    assert _texts(client) == ["You enter a cave."]
 
-    # Nothing is left of this branch's own turns, so undo must refuse
-    # instead of removing the parent's turns.
+    # The opening is the floor, and it is the parent's node too.
     r = client.post(f"/api/adventures/{client.adv_id}/undo")
     assert r.status_code == 400
-    assert "forked from" in r.json()["detail"]
+    assert "Nothing to undo" in r.json()["detail"]
+
+    # Redo walks back out to where the fork was left, taking the turn whole.
+    assert client.post(f"/api/adventures/{client.adv_id}/redo").status_code == 200
+    assert _texts(client) == ["You enter a cave.", "> You look around.", "Attempt one."]
+    assert len(_rows(client.adv_id)) == rows_before
 
 
 # ----------------------------------------------------------- the tree view

backend/tests/test_branch_management.py

@@ -55,9 +55,6 @@ def client(monkeypatch):
     ScriptedProvider.replies = ["Attempt one.", "Attempt two.", "Next turn."]
     ScriptedProvider.calls = 0
     monkeypatch.setattr(adventures.turns, "OpenAICompatibleProvider", ScriptedProvider)
-    monkeypatch.setattr(auth, "resolve_provider_config", lambda s: auth.ProviderConfig(
-        "http://fake", "k", "test-model", False))
-    monkeypatch.setattr(limits, "rate_limit", lambda *a, **k: None)
     monkeypatch.setattr(limits, "check_row_cap", lambda *a, **k: None)
 
     def _current_user(db=Depends(get_db)):

backend/tests/test_bundle_v2.py

@@ -33,19 +33,12 @@ from app.database import Base, SessionLocal, engine, get_db
 from app.main import app
 from app.routers import adventures
 
-from fakes import ScriptedProvider
+from fakes import GOLD_SCHEMA, ScriptedProvider, gold_replies, gold_reply
 
-SCHEMA = {"player": {"hp": {"min": 0, "max": 100, "initial": 100}}}
+SCHEMA = GOLD_SCHEMA
 
 # Ten gold a turn, so the stored gold total tells how many turns the
 # story behind it played. This makes an after-snapshot visible from outside.
-GOLD_SCRIPT = """
-const modifier = (text) => {
-  state.gold = (state.gold || 0) + 10;
-  return { text };
-};
-modifier(text);
-"""
 
 OPENING = "You enter a cave."
 
@@ -63,14 +56,11 @@ def client(monkeypatch):
     setup.flush()
     adv = models.Adventure(
         user_id=user.id, title="Cave", scenario_id=scenario.id,
-        script_state={}, world_state={"player": {"hp": 100}},
+        world_state={"player": {"hp": 100, "gold": 0}},
     )
     setup.add(adv)
     setup.flush()
     setup.add(models.Action(adventure_id=adv.id, type="start", text=OPENING))
-    setup.add(models.AdventureScript(
-        adventure_id=adv.id, position=0, enabled=True, name="Gold", output_js=GOLD_SCRIPT,
-    ))
     setup.commit()
     adv_id, user_id = adv.id, user.id
     setup.close()
@@ -78,9 +68,6 @@ def client(monkeypatch):
     ScriptedProvider.replies = ["A reply."]
     ScriptedProvider.calls = 0
     monkeypatch.setattr(adventures.turns, "OpenAICompatibleProvider", ScriptedProvider)
-    monkeypatch.setattr(auth, "resolve_provider_config", lambda s: auth.ProviderConfig(
-        "http://fake", "k", "test-model", False))
-    monkeypatch.setattr(limits, "rate_limit", lambda *a, **k: None)
     monkeypatch.setattr(limits, "check_row_cap", lambda *a, **k: None)
 
     def _current_user(db=Depends(get_db)):
@@ -186,7 +173,7 @@ def _branch_rows(adv_id) -> list[models.Branch]:
 def _script_state(adv_id) -> dict:
     db = SessionLocal()
     try:
-        return db.get(models.Adventure, adv_id).script_state
+        return (db.get(models.Adventure, adv_id).world_state or {}).get("player", {})
     finally:
         db.close()
 
@@ -272,7 +259,7 @@ def test_a_switch_in_the_copy_restores_what_that_branch_left_behind(client):
     # Play one more turn on the fork, so the two tips end up at
     # genuinely different totals. Turn for turn, both branches earn the
     # same gold, so a switch that restored nothing would still look right.
-    ScriptedProvider.replies = ["Further still."]
+    ScriptedProvider.replies = [gold_reply("Further still.")]
     _play(client, original, "press on")
 
     per_branch = []
@@ -398,7 +385,6 @@ def test_a_fork_with_no_depth_is_refused(client):
 
 
 def test_more_branches_than_the_cap_is_refused(client, monkeypatch):
-    monkeypatch.setattr(auth, "MULTI_USER", True)
     payload = {
         "format": bundle.FORMAT, "title": "Too many",
         "branches": [{"parent": None, "forkDepth": None}]
@@ -558,7 +544,6 @@ def test_the_action_cap_counts_the_rows_a_v1_file_expands_into(client, monkeypat
     multiple of it. The body-size limit does not help here: the text is
     tiny, and the row count is the actual cost.
     """
-    monkeypatch.setattr(auth, "MULTI_USER", True)
     monkeypatch.setattr(limits, "MAX_ACTIONS_PER_ADVENTURE", 6)
     monkeypatch.setattr(limits, "_BUNDLE_LIST_CAPS",
                         {**limits._BUNDLE_LIST_CAPS, "actions": 6})

backend/tests/test_chat.py

@@ -1,8 +1,14 @@
-"""HTTP tests for the AI Chat scratchpad (power users only).
+"""HTTP tests for the AI Chat scratchpad.
 
-Covers the access gate, the streamed reply, and the demo-key model pinning.
-This pinning must not let a public visitor reach paid models through this
-page.
+Most of this file used to be about the shared demo key: an access gate on a
+"power user" email allowlist, and a pinning rule that stopped a public visitor
+reaching paid models on a server-funded key. M2 removed the hosted deployment
+those defended, so the rules they tested no longer exist to be tested. See
+`planning/archive/milestone-reports/M2-*` for the accounting.
+
+What remains is what the page still does: stream a reply from the configured
+model, honour a system prompt and a per-request model override, and refuse a
+conversation too large to send.
 
     python -m pytest tests/test_chat.py -v
 """
@@ -10,25 +16,27 @@ import pytest
 from fastapi import Depends
 from fastapi.testclient import TestClient
 
-from app import auth, limits, models
+from app import auth, models
 from app.database import Base, SessionLocal, engine, get_db
 from app.main import app
 from app.routers import chat
 
 
 class FakeProvider:
-    """Records what it was constructed with, then streams a fixed reply. Stands
-    in for the real egress point, so asserting on last_key/last_model is
-    asserting on exactly what would have gone over the wire."""
+    """Records what it was constructed with, then streams a fixed reply.
+
+    It stands in for the real egress point, so asserting on `last_endpoint` and
+    `last_model` is asserting on exactly what would have gone over the wire.
+    There is no `last_key` any more: the provider takes no API key, because
+    Ollama does not use one.
+    """
     last_usage = None
     last_model = None
-    last_key = None
     last_endpoint = None
     last_messages = None
 
-    def __init__(self, endpoint_url, api_key, model, api_mode="chat", reasoning_max_tokens=0):
+    def __init__(self, endpoint_url, model, api_mode="chat", read_timeout=None):
         FakeProvider.last_model = model
-        FakeProvider.last_key = api_key
         FakeProvider.last_endpoint = endpoint_url
 
     async def chat(self, messages, *, temperature, max_tokens):
@@ -41,68 +49,35 @@ class FakeProvider:
 def client(monkeypatch):
     Base.metadata.create_all(bind=engine)
     setup = SessionLocal()
-    user = models.User(is_guest=False, email="power@example.com")
+    user = models.User(is_guest=False)
     setup.add(user)
     setup.flush()
-    setup.add(models.Settings(user_id=user.id, api_key="enc:dummy", model="test-model"))
+    setup.add(models.Settings(user_id=user.id, model="test-model"))
     setup.commit()
     user_id = user.id
     setup.close()
 
     monkeypatch.setattr(chat, "OpenAICompatibleProvider", FakeProvider)
-    monkeypatch.setattr(limits, "rate_limit", lambda *a, **k: None)
-    # Multi-user mode is what makes the power-user gate meaningful, because
-    # local mode trusts everyone. The allowlist is set per test.
-    monkeypatch.setattr(auth, "MULTI_USER", True)
-    monkeypatch.setattr(auth, "POWER_USERS", {"power@example.com"})
-    # These tests deliberately do not stub resolve_provider_config. The
-    # point is to exercise the real BYOK-vs-demo decision, since that
-    # decision is what keeps the shared key off paid models. Each test
-    # picks a mode with _byok/_demo below.
 
     def _current_user(db=Depends(get_db)):
         return db.get(models.User, user_id)
 
     app.dependency_overrides[auth.get_current_user] = _current_user
+    c = TestClient(app)
     try:
-        yield TestClient(app)
+        yield c
     finally:
         app.dependency_overrides.clear()
         Base.metadata.drop_all(bind=engine)
 
 
-def _send(client, **extra):
-    return client.post("/api/chat/stream", json={"messages": [{"role": "user", "content": "hi"}], **extra})
+def _send(client, **body):
+    payload = {"messages": [{"role": "user", "content": "hi"}]}
+    payload.update(body)
+    return client.post("/api/chat/stream", json=payload)
 
 
-def _byok(monkeypatch):
-    """The user brought their own key: no demo key in play, any model allowed."""
-    monkeypatch.setattr(auth, "demo_enabled", lambda: False)
-    db = SessionLocal()
-    try:
-        settings = db.query(models.Settings).first()
-        settings.api_key = "sk-my-own-key"  # legacy-plaintext path: used as-is
-        db.commit()
-    finally:
-        db.close()
-
-
-def _demo(monkeypatch, whitelist=("free/allowed",)):
-    """The user has no key, so turns run on the server-funded demo key."""
-    monkeypatch.setattr(auth, "demo_enabled", lambda: True)
-    monkeypatch.setattr(auth, "DEMO_API_KEY", "demo-key")
-    monkeypatch.setattr(auth, "DEMO_ENDPOINT_URL", "http://demo")
-    monkeypatch.setattr(auth, "DEMO_MODELS", list(whitelist))
-
-
-def test_non_power_user_gets_404(client, monkeypatch):
-    monkeypatch.setattr(auth, "POWER_USERS", set())
-    assert _send(client).status_code == 404
-    assert client.get("/api/chat/config").status_code == 404
-
-
-def test_power_user_streams_a_reply(client, monkeypatch):
-    _byok(monkeypatch)
+def test_the_page_streams_a_reply(client):
     resp = _send(client)
     assert resp.status_code == 200, resp.text
     assert '"type": "reasoning"' in resp.text
@@ -111,136 +86,39 @@ def test_power_user_streams_a_reply(client, monkeypatch):
     assert FakeProvider.last_messages == [{"role": "user", "content": "hi"}]
 
 
-def test_system_prompt_and_model_override_are_honoured(client, monkeypatch):
-    _byok(monkeypatch)
+def test_it_uses_the_configured_endpoint_and_model(client):
+    _send(client)
+    assert FakeProvider.last_model == "test-model"
+    # The default from `models.Settings`, and the only kind of address the
+    # endpoint policy allows without configuration.
+    assert FakeProvider.last_endpoint == "http://localhost:11434/v1"
+
+
+def test_system_prompt_and_model_override_are_honoured(client):
     resp = client.post("/api/chat/stream", json={
         "messages": [
             {"role": "system", "content": "Be terse."},
             {"role": "user", "content": "hi"},
         ],
-        "model": "some/other-model",
+        "model": "some-other-model",
     })
     assert resp.status_code == 200, resp.text
-    # BYOK: any model the user names is passed straight through, on their key.
-    assert FakeProvider.last_model == "some/other-model"
-    assert FakeProvider.last_key == "sk-my-own-key"
+    assert FakeProvider.last_model == "some-other-model"
     assert FakeProvider.last_messages[0] == {"role": "system", "content": "Be terse."}
 
 
-def test_demo_key_pins_model_to_whitelist(client, monkeypatch):
-    _demo(monkeypatch)
-    resp = _send(client, model="expensive/paid-model")
-    assert resp.status_code == 200, resp.text
-    # Refused visibly: the whitelisted model runs instead, with a note. The
-    # paid slug must never reach the wire alongside the server-funded key.
-    assert FakeProvider.last_model == "free/allowed"
-    assert FakeProvider.last_key == "demo-key"
-    assert '"type": "note"' in resp.text
-
-    # A whitelisted model is still selectable on the demo key.
-    _demo(monkeypatch, ["free/allowed", "free/second"])
-    resp = _send(client, model="free/second")
-    assert resp.status_code == 200, resp.text
-    assert FakeProvider.last_model == "free/second"
-
-
-def test_demo_key_ignores_an_off_whitelist_settings_model(client, monkeypatch):
-    """The override is not the only untrusted input. `Settings.model` is
-    also user-set, and it must be pinned the same way when there is no
-    BYOK key."""
-    _demo(monkeypatch)
-    db = SessionLocal()
-    try:
-        db.query(models.Settings).first().model = "expensive/paid-model"
-        db.commit()
-    finally:
-        db.close()
-    resp = _send(client)
-    assert resp.status_code == 200, resp.text
-    assert FakeProvider.last_model == "free/allowed"
-
-
-def test_demo_key_endpoint_cannot_be_redirected(client, monkeypatch):
-    """A user-controlled `endpoint_url` would leak the key itself, which is
-    worse than spending it. The demo branch pins the URL too."""
-    _demo(monkeypatch)
-    db = SessionLocal()
-    try:
-        db.query(models.Settings).first().endpoint_url = "http://attacker.example/v1"
-        db.commit()
-    finally:
-        db.close()
-    assert _send(client).status_code == 200
-    assert FakeProvider.last_endpoint == "http://demo"
-    assert FakeProvider.last_key == "demo-key"
-
-
-def test_provider_config_refuses_server_funded_paid_model(monkeypatch):
-    """The structural backstop: a hand-built config (a future code path that
-    forgets to go through resolve_provider_config) cannot run a
-    server-funded turn on an off-whitelist model."""
-    monkeypatch.setattr(auth, "DEMO_API_KEY", "demo-key")
-    monkeypatch.setattr(auth, "DEMO_MODELS", ["free/allowed"])
-    with pytest.raises(ValueError):
-        auth.ProviderConfig("http://demo", "demo-key", "expensive/paid-model", True)
-    auth.ProviderConfig("http://demo", "demo-key", "free/allowed", True)  # whitelisted: fine
-    # The user's own key with any model stays fine.
-    auth.ProviderConfig("http://any", "sk-mine", "expensive/paid-model", False)
-
-
-def test_byok_user_may_reuse_the_demo_keys_value(client, monkeypatch):
-    """Regression: the demo key is just an OpenRouter key, so a user can paste
-    that same value into their own Settings. That is still BYOK, because
-    the user is paying, and it must not trip the guard. It used to raise
-    on every resolution, which returned a 500 from `GET /auth/me` and
-    broke the entire SPA (no nav, no chat)."""
-    monkeypatch.setattr(auth, "demo_enabled", lambda: True)
-    monkeypatch.setattr(auth, "DEMO_API_KEY", "shared-key")
-    monkeypatch.setattr(auth, "DEMO_ENDPOINT_URL", "http://demo")
-    monkeypatch.setattr(auth, "DEMO_MODELS", ["free/allowed"])
+def test_a_request_with_no_model_anywhere_is_refused(client):
     db = SessionLocal()
     try:
         settings = db.query(models.Settings).first()
-        settings.api_key = "shared-key"          # same value, but supplied by the user
-        settings.model = "expensive/paid-model"  # their spend, their choice
+        settings.model = ""
         db.commit()
     finally:
         db.close()
-
-    assert client.get("/api/auth/me").status_code == 200
-    assert client.get("/api/chat/config").status_code == 200
-    resp = _send(client)
-    assert resp.status_code == 200, resp.text
-    assert FakeProvider.last_model == "expensive/paid-model"
-    assert FakeProvider.last_key == "shared-key"
+    assert _send(client).status_code == 400
 
 
-def test_resolve_provider_config_is_the_single_choke_point(monkeypatch):
-    """Turns, AI Chat, and the connection test all resolve through this one
-    function, so pinning it here pins every caller. No DB or HTTP needed."""
-    monkeypatch.setattr(auth, "demo_enabled", lambda: True)
-    monkeypatch.setattr(auth, "DEMO_API_KEY", "demo-key")
-    monkeypatch.setattr(auth, "DEMO_ENDPOINT_URL", "http://demo")
-    monkeypatch.setattr(auth, "DEMO_MODELS", ["free/allowed"])
-
-    # No key of their own: both endpoint and model are pinned, regardless
-    # of what they set.
-    no_key = models.Settings(endpoint_url="http://mine/v1", api_key="", model="expensive/paid")
-    assert auth.resolve_provider_config(no_key) == auth.ProviderConfig(
-        "http://demo", "demo-key", "free/allowed", True)
-    assert auth.resolve_provider_config(
-        no_key, model_override="expensive/paid").model == "free/allowed"
-    assert auth.resolve_provider_config(
-        no_key, model_override="free/allowed").model == "free/allowed"
-
-    # Their own key: their endpoint, their key, their choice of model.
-    byok = models.Settings(endpoint_url="http://mine/v1", api_key="sk-mine", model="expensive/paid")
-    assert auth.resolve_provider_config(byok) == auth.ProviderConfig(
-        "http://mine/v1", "sk-mine", "expensive/paid", False)
-
-
-def test_oversized_conversation_is_refused(client, monkeypatch):
-    _byok(monkeypatch)
+def test_oversized_conversation_is_refused(client):
     huge = "x" * 90_000
     resp = client.post("/api/chat/stream", json={
         "messages": [{"role": "user", "content": huge} for _ in range(5)],

backend/tests/test_delete_state.py

@@ -1,6 +1,6 @@
 """Deleting a turn puts the shared state back.
 
-`script_state` and `world_state` belong to the adventure, not to the node
+`world_state` belongs to the adventure, not to the node
 that changed them. Undo, retry, a take and a branch switch all restore them;
 the delete endpoint did not. Deleting an AI turn removed the text and left
 everything the turn did to the numbers standing.
@@ -23,7 +23,7 @@ from app import auth, limits, models
 from app.database import Base, SessionLocal, engine, get_db
 from app.main import app
 from app.routers import adventures
-from fakes import ScriptedProvider
+from fakes import GOLD_SCHEMA, ScriptedProvider, gold_replies, gold_reply
 
 # `mana` carries a cooldown, so a clock that was not rolled back shows up as
 # a refusal rather than as a number that is merely off.
@@ -31,20 +31,19 @@ SCHEMA = {
     "player": {
         "hp": {"min": 0, "max": 100, "initial": 100},
         "mana": {"min": 0, "max": 50, "initial": 50, "cooldown": 2},
+        # The per-turn counter these tests measure rollbacks with. Unbounded and
+        # uncapped on purpose, so every turn's +10 lands in full. See
+        # `fakes.gold_reply`.
+        "gold": {"min": 0, "max": 1_000_000, "initial": 0},
     }
 }
 
 # Ten gold a turn. A total that only ever climbs makes a missing rollback
 # obvious: it is off by exactly one turn's worth.
-GOLD_SCRIPT = """
-const modifier = (text) => {
-  state.gold = (state.gold || 0) + 10;
-  return { text };
-};
-modifier(text);
-"""
 
 DRAIN = 'Drained.\n```state\n{"player.mana": -10}\n```'
+# The same turn, also banking the per-turn counter the rollback tests measure.
+DRAIN_AND_GOLD = 'Drained.\n```state\n{"player.mana": -10, "player.gold": 10}\n```'
 
 
 @pytest.fixture()
@@ -60,24 +59,18 @@ def client(monkeypatch):
     setup.flush()
     adv = models.Adventure(
         user_id=user.id, title="Tower", scenario_id=scenario.id,
-        script_state={}, world_state={"player": {"hp": 100, "mana": 50}},
+        world_state={"player": {"hp": 100, "mana": 50, "gold": 0}},
     )
     setup.add(adv)
     setup.flush()
     setup.add(models.Action(adventure_id=adv.id, type="start", text="You begin."))
-    setup.add(models.AdventureScript(
-        adventure_id=adv.id, position=0, enabled=True, name="Gold", output_js=GOLD_SCRIPT,
-    ))
     setup.commit()
     adv_id, user_id = adv.id, user.id
     setup.close()
 
-    ScriptedProvider.replies = [DRAIN]
+    ScriptedProvider.replies = [DRAIN_AND_GOLD]
     ScriptedProvider.calls = 0
     monkeypatch.setattr(adventures.turns, "OpenAICompatibleProvider", ScriptedProvider)
-    monkeypatch.setattr(auth, "resolve_provider_config", lambda s: auth.ProviderConfig(
-        "http://fake", "k", "test-model", False))
-    monkeypatch.setattr(limits, "rate_limit", lambda *a, **k: None)
     monkeypatch.setattr(limits, "check_row_cap", lambda *a, **k: None)
 
     def _current_user(db=Depends(get_db)):
@@ -116,7 +109,7 @@ def _state(adv_id):
     db = SessionLocal()
     try:
         adv = db.get(models.Adventure, adv_id)
-        return adv.script_state, adv.world_state
+        return (adv.world_state or {}).get("player", {}), adv.world_state
     finally:
         db.close()
 
@@ -168,17 +161,17 @@ def test_the_next_turn_is_not_refused_for_a_deleted_turn_s_cooldown(client):
     assert [c for c in _last_changes(client.adv_id) if c["kind"] == "rejected"] == []
 
 
-def test_deleting_the_ai_turn_rewinds_the_script_state(client):
-    """The same restore, on the other half of the shared state. Without it a
-    replayed turn stacks its script run on top of the deleted one's."""
+def test_deleting_the_ai_turn_rewinds_the_counter(client):
+    """The same restore, seen through a value that only ever climbs. Without it
+    a replayed turn stacks its effects on top of the deleted one's."""
     _play(client)
-    assert _state(client.adv_id)[0] == {"gold": 10}
+    assert _state(client.adv_id)[0]["gold"] == 10
 
     _delete(client, _ai_rows(client.adv_id)[-1].id)
-    assert _state(client.adv_id)[0] == {}
+    assert _state(client.adv_id)[0]["gold"] == 0
 
     _continue(client)
-    assert _state(client.adv_id)[0] == {"gold": 10}, "one turn of gold, not two"
+    assert _state(client.adv_id)[0]["gold"] == 10, "one turn of gold, not two"
 
 
 # ------------------------------------------------- deleting further back
@@ -190,7 +183,7 @@ def test_deleting_a_turn_the_story_moved_past_leaves_the_tip_alone(client):
     _play(client)
     _play(client, "press on")
     before = _state(client.adv_id)
-    assert before[0] == {"gold": 20}
+    assert before[0]["gold"] == 20
 
     first_ai = _ai_rows(client.adv_id)[0]
     assert _delete(client, first_ai.id).status_code == 204

backend/tests/test_egress.py

@@ -99,7 +99,6 @@ def client(monkeypatch):
     adv_id, user_id = adventure.id, user.id
     setup.close()
 
-    monkeypatch.setattr(limits, "rate_limit", lambda *a, **k: None)
     monkeypatch.setattr(limits, "check_row_cap", lambda *a, **k: None)
 
     def _current_user(db=Depends(get_db)):

backend/tests/test_embedding_model_switch.py

@@ -57,7 +57,6 @@ def client(monkeypatch):
     adv_id, user_id = adventure.id, user.id
     setup.close()
 
-    monkeypatch.setattr(limits, "rate_limit", lambda *a, **k: None)
     monkeypatch.setattr(limits, "check_row_cap", lambda *a, **k: None)
 
     def _current_user(db=Depends(get_db)):

backend/tests/test_endpoint_policy.py

@@ -0,0 +1,224 @@
+"""Which inference endpoints the product will and will not talk to.
+
+The endpoint is where the whole campaign goes: prompts, narration, retrieved
+memories, embedding inputs. `app/endpoints.py` is the rule that keeps that on
+the user's own infrastructure, and these tests are what stops the rule quietly
+widening.
+
+Nothing here touches the network. Hostnames are resolved through a stub, so the
+tests are about the *policy*, run identically offline, and cannot be made to
+pass or fail by whatever DNS the machine happens to have.
+
+    python -m pytest tests/test_endpoint_policy.py -v
+"""
+import ipaddress
+import socket
+
+import pytest
+from fastapi import Depends
+from fastapi.testclient import TestClient
+
+from app import auth, endpoints, models
+from app.database import Base, SessionLocal, engine, get_db
+from app.main import app
+from app.providers import OpenAICompatibleProvider, ProviderError
+
+
+@pytest.fixture()
+def resolves(monkeypatch):
+    """Points every hostname at addresses the test names."""
+    table: dict[str, list[str]] = {}
+
+    def fake_getaddrinfo(host, port, *a, **k):
+        # An address literal resolves to itself, as the real resolver does.
+        try:
+            ipaddress.ip_address(host)
+        except ValueError:
+            if host not in table:
+                raise socket.gaierror(-2, "Name or service not known")
+            answers = table[host]
+        else:
+            answers = [host]
+        return [
+            (
+                socket.AF_INET6 if ":" in ip else socket.AF_INET,
+                socket.SOCK_STREAM, 6, "", (ip, port or 0),
+            )
+            for ip in answers
+        ]
+
+    monkeypatch.setattr(socket, "getaddrinfo", fake_getaddrinfo)
+    return table
+
+
+# --- allowed: the user's own machine, and the user's own network ----------
+
+@pytest.mark.parametrize("url", [
+    "http://127.0.0.1:11434/v1",
+    "http://[::1]:11434/v1",
+    "http://192.168.1.50:11434/v1",       # RFC1918
+    "http://10.0.0.7:11434/v1",           # RFC1918
+    "http://172.16.4.4:11434/v1",         # RFC1918
+    "https://192.168.1.50:8443/v1",       # TLS on the LAN
+    "http://100.100.5.6:11434/v1",        # CGNAT, which is what a mesh VPN hands out
+    "http://[fd00::1]:11434/v1",          # IPv6 unique-local
+])
+def test_local_and_lan_addresses_are_allowed(url, resolves):
+    assert endpoints.rejection_reason(url) is None
+
+
+def test_a_hostname_resolving_to_the_lan_is_allowed(resolves):
+    resolves["ollama.home.arpa"] = ["192.168.1.50"]
+    assert endpoints.rejection_reason("https://ollama.home.arpa:8443/v1") is None
+
+
+# --- refused: anywhere else ----------------------------------------------
+
+@pytest.mark.parametrize("url", [
+    "http://8.8.8.8:11434/v1",
+    "http://1.1.1.1:11434/v1",
+    "http://[2001:4860:4860::8888]:11434/v1",
+])
+def test_public_addresses_are_refused(url, resolves):
+    reason = endpoints.rejection_reason(url)
+    assert reason is not None
+    assert "public Internet address" in reason
+
+
+@pytest.mark.parametrize("url", [
+    "https://198.51.100.9/v1",     # TEST-NET-2, a documentation range
+    "http://0.0.0.0:11434/v1",     # "this host", not an address to dial
+])
+def test_addresses_that_are_neither_local_nor_public_are_refused(url, resolves):
+    """Deny by default. `ipaddress` calls both of these "private", which is why
+    the policy names the networks it allows instead of asking that question."""
+    assert endpoints.rejection_reason(url) is not None
+
+
+def test_a_hostname_resolving_to_the_public_internet_is_refused(resolves):
+    resolves["ollama.example.com"] = ["93.184.216.34"]
+    reason = endpoints.rejection_reason("https://ollama.example.com/v1")
+    assert reason is not None and "public Internet address" in reason
+
+
+def test_a_split_horizon_answer_is_refused(resolves):
+    """One public address among the answers is enough. A name that resolves to
+    both a LAN address and a public one must not be usable: which one the
+    request actually reaches is not ours to decide."""
+    resolves["sneaky.example"] = ["192.168.1.50", "93.184.216.34"]
+    assert endpoints.rejection_reason("http://sneaky.example:11434/v1") is not None
+
+
+@pytest.mark.parametrize("host", [
+    "openrouter.ai", "api.openai.com", "api.anthropic.com", "api.groq.com",
+])
+def test_known_cloud_providers_are_named_in_the_refusal(host, resolves):
+    """They would be refused by address anyway — every one resolves publicly.
+    Naming them turns 'your DNS might be broken' into 'this build has no cloud
+    provider support'."""
+    resolves[host] = ["192.168.1.50"]  # even if DNS said otherwise
+    reason = endpoints.rejection_reason(f"https://{host}/v1")
+    assert reason is not None
+    assert "cloud inference service" in reason
+
+
+def test_a_subdomain_of_a_cloud_provider_is_refused(resolves):
+    resolves["eu.api.openai.com"] = ["192.168.1.50"]
+    assert endpoints.rejection_reason("https://eu.api.openai.com/v1") is not None
+
+
+@pytest.mark.parametrize("url", [
+    "ftp://127.0.0.1/v1",
+    "file:///etc/passwd",
+    "127.0.0.1:11434",     # no scheme
+    "",
+    "http://",
+])
+def test_things_that_are_not_usable_urls_are_refused(url, resolves):
+    assert endpoints.rejection_reason(url) is not None
+
+
+def test_an_unresolvable_host_is_refused_with_advice(resolves):
+    reason = endpoints.rejection_reason("http://nope.invalid:11434/v1")
+    assert reason is not None and "could not be resolved" in reason
+
+
+# --- the rule is applied, not merely available ---------------------------
+
+@pytest.fixture()
+def client(monkeypatch):
+    Base.metadata.create_all(bind=engine)
+    setup = SessionLocal()
+    user = models.User(is_guest=False)
+    setup.add(user)
+    setup.flush()
+    setup.add(models.Settings(user_id=user.id, model="test-model"))
+    setup.commit()
+    user_id = user.id
+    setup.close()
+
+    def _current_user(db=Depends(get_db)):
+        return db.get(models.User, user_id)
+
+    app.dependency_overrides[auth.get_current_user] = _current_user
+    c = TestClient(app)
+    try:
+        yield c
+    finally:
+        app.dependency_overrides.clear()
+        Base.metadata.drop_all(bind=engine)
+
+
+def test_saving_a_public_endpoint_is_refused(client, resolves):
+    resolves["openrouter.ai"] = ["93.184.216.34"]
+    r = client.put("/api/settings", json={"endpoint_url": "https://openrouter.ai/api/v1"})
+    assert r.status_code == 400, r.text
+    assert "can't be used" in r.json()["detail"]
+    # And it was not written.
+    assert client.get("/api/settings").json()["endpoint_url"] != "https://openrouter.ai/api/v1"
+
+
+def test_saving_a_lan_endpoint_is_allowed(client, resolves):
+    r = client.put("/api/settings", json={"endpoint_url": "http://192.168.1.50:11434/v1"})
+    assert r.status_code == 200, r.text
+    assert client.get("/api/settings").json()["endpoint_url"] == "http://192.168.1.50:11434/v1"
+
+
+def test_the_connection_test_reports_a_refused_endpoint_as_such(client, resolves):
+    """A row edited by hand, or a name that has started resolving elsewhere,
+    must not simply look 'unreachable'."""
+    db = SessionLocal()
+    try:
+        db.query(models.Settings).first().endpoint_url = "https://openrouter.ai/api/v1"
+        db.commit()
+    finally:
+        db.close()
+    resolves["openrouter.ai"] = ["93.184.216.34"]
+    body = client.post("/api/settings/test").json()
+    assert body["ok"] is False
+    assert body["kind"] == "rejected"
+
+
+@pytest.mark.anyio
+async def test_the_provider_refuses_before_it_sends_anything(resolves):
+    """The check that actually matters. Whatever is stored, no request leaves
+    for an address outside the policy — so a database edited behind the app's
+    back cannot turn into an exfiltration path."""
+    resolves["openrouter.ai"] = ["93.184.216.34"]
+    provider = OpenAICompatibleProvider("https://openrouter.ai/api/v1", "m")
+    with pytest.raises(ProviderError) as exc:
+        async for _ in provider.generate(
+            _parts(), temperature=0.8, max_tokens=10
+        ):
+            pass
+    assert "can't be used" in str(exc.value)
+
+
+def _parts():
+    from app.providers.base import PromptParts
+    return PromptParts(system="s", story="t")
+
+
+@pytest.fixture
+def anyio_backend():
+    return "asyncio"

backend/tests/test_guest_cleanup.py

@@ -1,205 +0,0 @@
-"""Guest retention policy: app/cleanup.py.
-
-These tests cover the two things that matter. Idle guests and their whole
-data graph must actually be deleted, and nothing else must ever be
-deleted.
-
-    python -m pytest tests/test_guest_cleanup.py -v
-"""
-from datetime import timedelta
-
-
-import pytest
-from sqlalchemy import create_engine, event
-from sqlalchemy.orm import sessionmaker
-
-from app import cleanup, models
-from app.database import Base
-from app.migrations import bootstrap
-
-
-@pytest.fixture()
-def db(tmp_path):
-    engine = create_engine(f"sqlite:///{tmp_path/'t.db'}", connect_args={"check_same_thread": False})
-
-    @event.listens_for(engine, "connect")
-    def _fk(dbapi_connection, _record):
-        # The whole policy relies on ON DELETE CASCADE. SQLite ignores every
-        # one of them unless this is set, the same as database.py does.
-        cur = dbapi_connection.cursor()
-        cur.execute("PRAGMA foreign_keys=ON")
-        cur.close()
-
-    bootstrap(engine)
-    Base.metadata.create_all(bind=engine)
-    session = sessionmaker(bind=engine, autoflush=False, expire_on_commit=False)()
-    yield session
-    session.close()
-
-
-NOW = models.utcnow().replace(tzinfo=None)
-
-
-def make_user(db, *, days_idle=None, days_old=0, guest=True, email=None):
-    """A user last seen `days_idle` ago (None = never seen, only created)."""
-    user = models.User(
-        is_guest=guest,
-        email=email,
-        password_hash=None if email is None else "x",
-        created_at=NOW - timedelta(days=days_old),
-        last_seen_at=None if days_idle is None else NOW - timedelta(days=days_idle),
-    )
-    db.add(user)
-    db.commit()
-    return user
-
-
-def sweep(db):
-    return cleanup.delete_stale_guests(db, now=NOW)
-
-
-def alive(db, user_id):
-    # A count, not db.get: the sweep deletes with synchronize_session=False, so
-    # the session's identity map still holds the object and db.get would answer
-    # from memory without ever asking the database.
-    return db.query(models.User).filter(models.User.id == user_id).count() == 1
-
-
-# ---------- what goes ----------
-
-def test_deletes_guest_idle_past_the_window(db):
-    user = make_user(db, days_idle=6)
-    assert sweep(db) == 1
-    assert not alive(db, user.id)
-
-
-def test_keeps_guest_inside_the_window(db):
-    user = make_user(db, days_idle=4)
-    assert sweep(db) == 0
-    assert alive(db, user.id)
-
-
-def test_boundary_is_not_yet_stale(db):
-    # Exactly 5 days survives. The comparison is strict.
-    user = make_user(db, days_idle=cleanup.RETENTION_DAYS)
-    assert sweep(db) == 0
-    assert alive(db, user.id)
-
-
-def test_never_seen_guest_falls_back_to_created_at(db):
-    """last_seen_at is NULL until a guest's second request (auth._touch runs
-    hourly), so a coalesce-less query would delete brand-new visitors."""
-    fresh = make_user(db, days_idle=None, days_old=0)
-    stale = make_user(db, days_idle=None, days_old=9)
-    assert sweep(db) == 1
-    assert alive(db, fresh.id)
-    assert not alive(db, stale.id)
-
-
-def test_recent_visit_beats_an_old_created_at(db):
-    # A long-standing guest who came back yesterday stays.
-    user = make_user(db, days_idle=1, days_old=90)
-    assert sweep(db) == 0
-    assert alive(db, user.id)
-
-
-# ---------- what must never go ----------
-
-def test_spares_registered_users(db):
-    """Registering upgrades the guest row in place. An idle account here is
-    a real user with real data, which is what signing up is meant to
-    protect."""
-    user = make_user(db, days_idle=400, guest=False, email="a@b.com")
-    assert sweep(db) == 0
-    assert alive(db, user.id)
-
-
-def test_spares_the_local_mode_user(db):
-    # email NULL but is_guest False: local mode's implicit owner of everything.
-    user = make_user(db, days_idle=400, guest=False)
-    assert sweep(db) == 0
-    assert alive(db, user.id)
-
-
-def test_spares_a_guest_flagged_row_that_has_an_email(db):
-    # This row should not exist, but both clauses are checked so it cannot be collected.
-    user = make_user(db, days_idle=400, guest=True, email="odd@b.com")
-    assert sweep(db) == 0
-    assert alive(db, user.id)
-
-
-def test_leaves_seeded_public_scenarios_alone(db):
-    """Seeded demo content has user_id NULL, so it is outside the filter."""
-    seeded = models.Scenario(user_id=None, is_public=True, title="Demo")
-    db.add(seeded)
-    make_user(db, days_idle=30)
-    db.commit()
-    assert sweep(db) == 1
-    assert db.query(models.Scenario).filter(models.Scenario.id == seeded.id).count() == 1
-
-
-def test_disabled_when_retention_is_zero(db, monkeypatch):
-    monkeypatch.setattr(cleanup, "RETENTION_DAYS", 0)
-    user = make_user(db, days_idle=999)
-    assert sweep(db) == 0
-    assert alive(db, user.id)
-
-
-def test_enabled_requires_multi_user(monkeypatch):
-    from app import auth
-    monkeypatch.setattr(auth, "MULTI_USER", False)
-    assert cleanup.enabled() is False
-    monkeypatch.setattr(auth, "MULTI_USER", True)
-    monkeypatch.setattr(cleanup, "RETENTION_DAYS", 5)
-    assert cleanup.enabled() is True
-    monkeypatch.setattr(cleanup, "RETENTION_DAYS", 0)
-    assert cleanup.enabled() is False
-
-
-# ---------- the cascade ----------
-
-def test_deletes_the_whole_data_graph(db):
-    """One DELETE must remove the adventure, its actions and memories, the
-    story cards, and the settings row. Nothing is loaded into Python, so if
-    the FK cascade does not reach a table, its rows are silently orphaned,
-    or the statement fails, instead of being removed."""
-    user = make_user(db, days_idle=30)
-    scenario = models.Scenario(user_id=user.id, title="S")
-    db.add(scenario)
-    db.commit()
-    adventure = models.Adventure(user_id=user.id, scenario_id=scenario.id, title="A")
-    db.add(adventure)
-    db.commit()
-    db.add_all([
-        models.Action(adventure_id=adventure.id, type="ai", text="t"),
-        models.Memory(adventure_id=adventure.id, text="m", source_start=0, source_end=0),
-        models.StoryCard(adventure_id=adventure.id, name="c"),
-        models.Settings(user_id=user.id),
-    ])
-    db.commit()
-
-    assert sweep(db) == 1
-
-    for model in (models.Scenario, models.Adventure, models.Action,
-                  models.Memory, models.StoryCard, models.Settings):
-        assert db.query(model).count() == 0, f"{model.__name__} rows survived"
-
-
-def test_one_users_cleanup_does_not_touch_another(db):
-    keeper = make_user(db, days_idle=1)
-    keep_adv = models.Adventure(user_id=keeper.id, title="mine")
-    goner = make_user(db, days_idle=30)
-    db.add_all([keep_adv, models.Adventure(user_id=goner.id, title="theirs")])
-    db.commit()
-
-    assert sweep(db) == 1
-    remaining = db.query(models.Adventure).all()
-    assert [a.title for a in remaining] == ["mine"]
-
-
-def test_sweep_swallows_errors(monkeypatch):
-    """A broken cleanup must not take the app down (same rule as seeding)."""
-    monkeypatch.setattr(cleanup.auth, "MULTI_USER", True)
-    monkeypatch.setattr(cleanup, "delete_stale_guests",
-                        lambda *a, **k: (_ for _ in ()).throw(RuntimeError("boom")))
-    assert cleanup.sweep() == 0

backend/tests/test_head_cursor.py

@@ -0,0 +1,873 @@
+"""M3: the active head, and what moving it costs.
+
+This file is the acceptance contract for the milestone that stopped Undo from
+deleting. Its subject is one invariant and the behaviour that follows from it:
+
+    Undo deletes zero accepted turns.
+
+Everything else here is a consequence. Redo exists because the turns are still
+there. Divergence retires a future rather than removing it. Memory and summary
+coverage narrow and widen again as the head moves, without anything being
+re-embedded. Export carries where the reader stopped, because that is now a
+decision rather than a fact about the newest row.
+
+The tests are named for the acceptance items they discharge — D01-D10, E01-E04,
+I01-I03, I07, L01-L02 in `planning/V1-ACCEPTANCE-TESTS.md` — so a reader can go
+from a failing test to the requirement it belongs to without a map.
+
+The world state is instrumentation here, not the subject. Each scripted reply
+banks ten gold, which makes "the state at this position" a number a test can
+assert instead of a paragraph it has to interpret. M5 replaces that machinery
+with genre-neutral narrative state; these tests then need the *instrumentation*
+moved, not the assertions removed, because what they measure is where the story
+is being read.
+
+    python -m pytest tests/test_head_cursor.py -v
+"""
+import pytest
+from fastapi import Depends
+from fastapi.testclient import TestClient
+
+from app import limits, models
+from app.providers import ProviderError
+from app.context import cursors, lineage
+from app.database import Base, SessionLocal, engine, get_db
+from app.main import app
+from app import auth, tree
+from app.routers import adventures
+
+from fakes import GOLD_PER_TURN, GOLD_SCHEMA, ScriptedProvider, gold_replies
+
+
+@pytest.fixture()
+def client(monkeypatch):
+    Base.metadata.create_all(bind=engine)
+    setup = SessionLocal()
+    user = models.User(is_guest=False, email="head@example.com")
+    setup.add(user)
+    setup.flush()
+    setup.add(models.Settings(user_id=user.id, api_key="enc:dummy", model="test-model"))
+    scenario = models.Scenario(user_id=user.id, title="S", stat_schema=GOLD_SCHEMA)
+    setup.add(scenario)
+    setup.flush()
+    adv = models.Adventure(
+        user_id=user.id, title="Tavern", scenario_id=scenario.id,
+        world_state={"player": {"hp": 100, "gold": 0}},
+    )
+    setup.add(adv)
+    setup.flush()
+    setup.add(models.Action(adventure_id=adv.id, type="start", text="You enter the tavern."))
+    setup.commit()
+    adv_id, user_id = adv.id, user.id
+    setup.close()
+
+    ScriptedProvider.replies = gold_replies()
+    monkeypatch.setattr(adventures.turns, "OpenAICompatibleProvider", ScriptedProvider)
+    monkeypatch.setattr(limits, "check_row_cap", lambda *a, **k: None)
+
+    def _current_user(db=Depends(get_db)):
+        return db.get(models.User, user_id)
+
+    app.dependency_overrides[auth.get_current_user] = _current_user
+    c = TestClient(app)
+    c.adv_id = adv_id
+    try:
+        yield c
+    finally:
+        app.dependency_overrides.clear()
+        adventures.turns._active_turns.clear()
+        Base.metadata.drop_all(bind=engine)
+
+
+# ------------------------------------------------------------------ helpers
+
+def _play(client, text="look around", type="do", after_id=None):
+    payload = {"type": type, "text": text}
+    if after_id is not None:
+        payload["after_id"] = after_id
+    r = client.post(f"/api/adventures/{client.adv_id}/actions", json=payload)
+    assert r.status_code == 200, r.text
+    return r
+
+
+def _turns(client, count):
+    for n in range(count):
+        _play(client, f"turn {n}")
+
+
+def _undo(client):
+    return client.post(f"/api/adventures/{client.adv_id}/undo")
+
+
+def _redo(client):
+    return client.post(f"/api/adventures/{client.adv_id}/redo")
+
+
+def _adventure(client) -> dict:
+    r = client.get(f"/api/adventures/{client.adv_id}")
+    assert r.status_code == 200, r.text
+    return r.json()
+
+
+def _texts(client) -> list[str]:
+    return [a["text"] for a in _adventure(client)["actions"]]
+
+
+def _rows(adv_id) -> list[models.Action]:
+    """Every action row, story or not, live or not, head or no head."""
+    db = SessionLocal()
+    try:
+        return (
+            db.query(models.Action)
+            .filter(models.Action.adventure_id == adv_id)
+            .order_by(models.Action.branch_id, models.Action.depth, models.Action.id)
+            .all()
+        )
+    finally:
+        db.close()
+
+
+def _gold(adv_id) -> int:
+    db = SessionLocal()
+    try:
+        adv = db.get(models.Adventure, adv_id)
+        return (adv.world_state or {}).get("player", {}).get("gold", 0)
+    finally:
+        db.close()
+
+
+def _head(adv_id) -> tuple[int, int]:
+    db = SessionLocal()
+    try:
+        adv = db.get(models.Adventure, adv_id)
+        return adv.head_branch_id, adv.head_depth
+    finally:
+        db.close()
+
+
+# ------------------------------------------------------- D01, D02, D03: undo
+
+def test_d01_one_undo_returns_the_transcript_and_the_state(client):
+    _turns(client, 2)
+    assert _gold(client.adv_id) == 2 * GOLD_PER_TURN
+    told = _texts(client)
+
+    page = _undo(client)
+    assert page.status_code == 200, page.text
+
+    # Both halves of the turn step back together: a player's action and the
+    # reply to it are one accepted story step.
+    assert [a["text"] for a in page.json()["actions"]] == told[:-2]
+    assert _gold(client.adv_id) == 1 * GOLD_PER_TURN
+
+
+def test_d02_five_consecutive_undos_each_land_where_they_should(client):
+    _turns(client, 7)
+    assert _gold(client.adv_id) == 7 * GOLD_PER_TURN
+
+    for step in range(1, 6):
+        assert _undo(client).status_code == 200
+        assert _gold(client.adv_id) == (7 - step) * GOLD_PER_TURN
+        # Two rows per turn, plus the opening.
+        assert len(_texts(client)) == 1 + 2 * (7 - step)
+
+
+def test_d03_undo_walks_back_to_the_campaign_opening_and_stops(client):
+    _turns(client, 7)
+
+    for _ in range(7):
+        assert _undo(client).status_code == 200
+
+    assert _texts(client) == ["You enter the tavern."]
+    assert _gold(client.adv_id) == 0
+    # The opening is the floor. There is no pre-campaign position to reach.
+    refused = _undo(client)
+    assert refused.status_code == 400
+    assert "Nothing to undo" in refused.json()["detail"]
+    assert _adventure(client)["can_undo"] is False
+
+
+def test_the_m3_invariant_undo_deletes_zero_accepted_turns(client):
+    """The row count is the milestone. Everything else in this file is a
+    consequence of it, so it is asserted on its own, over the whole retained
+    tree rather than over the story being told."""
+    _turns(client, 5)
+    before = [a.id for a in _rows(client.adv_id)]
+
+    for _ in range(5):
+        assert _undo(client).status_code == 200
+
+    after = [a.id for a in _rows(client.adv_id)]
+    assert after == before
+    assert len(_texts(client)) == 1  # and yet the story is back at its opening
+
+
+# -------------------------------------------------------------- D04, L02: redo
+
+def test_d04_redo_restores_the_continuation_and_its_state(client):
+    _turns(client, 4)
+    whole = _texts(client)
+
+    _undo(client)
+    _undo(client)
+    assert _gold(client.adv_id) == 2 * GOLD_PER_TURN
+
+    assert _redo(client).status_code == 200
+    assert _gold(client.adv_id) == 3 * GOLD_PER_TURN
+    assert _redo(client).status_code == 200
+    assert _gold(client.adv_id) == 4 * GOLD_PER_TURN
+    assert _texts(client) == whole
+    # Nowhere further forward to go, and the control says so.
+    assert _adventure(client)["can_redo"] is False
+    assert _redo(client).status_code == 400
+
+
+def test_l02_state_matches_the_position_in_both_directions(client):
+    """Each position's state is the snapshot the node left behind, so arriving
+    from in front of it and arriving from behind it must agree."""
+    _turns(client, 5)
+    going_back = []
+    for _ in range(5):
+        _undo(client)
+        going_back.append(_gold(client.adv_id))
+
+    coming_forward = []
+    for _ in range(5):
+        _redo(client)
+        coming_forward.append(_gold(client.adv_id))
+
+    assert going_back == [40, 30, 20, 10, 0]
+    assert coming_forward == [10, 20, 30, 40, 50]
+
+
+# ------------------------------------------------- D05, E01, E04: divergence
+
+def test_d05_a_new_turn_below_the_head_retires_redo_and_keeps_the_future(client):
+    _turns(client, 4)
+    abandoned = {a.id for a in _rows(client.adv_id)}
+
+    _undo(client)
+    _undo(client)
+    assert _adventure(client)["can_redo"] is True
+
+    ScriptedProvider.replies = ["A different road.\n```state\n{\"player.gold\": 1}\n```"]
+    _play(client, "go the other way")
+
+    # Ordinary Redo cannot walk into the old future any more...
+    assert _adventure(client)["can_redo"] is False
+    assert _redo(client).status_code == 400
+    # ...and not one row of it was deleted to achieve that.
+    kept = {a.id for a in _rows(client.adv_id)}
+    assert abandoned <= kept
+    # The story now tells the new continuation.
+    assert _texts(client)[-1].startswith("A different road.")
+
+
+def test_the_departed_branch_records_where_the_story_left_it(client):
+    """`DATA-MODEL.md` §5 gives a branch a disposition. It is stored as the fact
+    that produced it — the depth the story left at — and nothing reads it to
+    decide behaviour, so this test is what makes a divergence observable."""
+    _turns(client, 3)
+    _undo(client)
+    left_at = _head(client.adv_id)[1]
+
+    _play(client, "elsewhere")
+
+    db = SessionLocal()
+    try:
+        superseded = (
+            db.query(models.Branch)
+            .filter(
+                models.Branch.adventure_id == client.adv_id,
+                models.Branch.superseded_at.isnot(None),
+            )
+            .all()
+        )
+        assert len(superseded) == 1
+        assert superseded[0].superseded_depth == left_at
+    finally:
+        db.close()
+
+
+def test_e01_e04_a_fact_from_the_abandoned_future_is_not_current(client):
+    """E01 and E04 are the same mechanism measured twice: the state that is
+    current is the one belonging to the position the story is read at, so a
+    number only the abandoned future ever reached cannot survive a divergence."""
+    ScriptedProvider.replies = [
+        "You find a purse.\n```state\n{\"player.gold\": 10}\n```",
+        "You find the hoard.\n```state\n{\"player.gold\": 500}\n```",
+    ]
+    _play(client, "search")
+    _play(client, "keep searching")
+    assert _gold(client.adv_id) == 510
+
+    _undo(client)
+    assert _gold(client.adv_id) == 10
+
+    ScriptedProvider.replies = ["You leave empty-handed.\n```state\n{\"player.gold\": 1}\n```"]
+    _play(client, "go home")
+
+    assert _gold(client.adv_id) == 11, "the hoard belonged to a story this one is not"
+
+
+# ------------------------------------------------------ E02, E03: derived work
+
+def _attach_memory(adv_id, text, at_depth):
+    """Writes a memory ending on the live node at `at_depth`, the way the
+    summarizer would, and anchors the memory cursor there."""
+    db = SessionLocal()
+    try:
+        adventure = db.get(models.Adventure, adv_id)
+        node = (
+            db.query(models.Action)
+            .filter(
+                models.Action.adventure_id == adv_id,
+                models.Action.depth == at_depth,
+                models.Action.live.is_(True),
+            )
+            .first()
+        )
+        memory = models.Memory(
+            adventure_id=adv_id, text=text, source_start=0, source_end=node.depth,
+        )
+        tree.attach_memory(memory, node)
+        db.add(memory)
+        cursors.MEMORY.anchor_at(adventure, node)
+        cursors.SUMMARY.anchor_at(adventure, node)
+        db.commit()
+    finally:
+        db.close()
+
+
+def _retrievable(adv_id) -> set[str]:
+    """The memories the story can reach, through the clause `memorybank`
+    retrieves with."""
+    db = SessionLocal()
+    try:
+        adventure = db.get(models.Adventure, adv_id)
+        rows = (
+            db.query(models.Memory)
+            .filter(
+                models.Memory.adventure_id == adv_id,
+                lineage.path_of(db, adventure).clause(models.Memory),
+            )
+            .all()
+        )
+        return {m.text for m in rows}
+    finally:
+        db.close()
+
+
+def test_e02_an_abandoned_memory_is_unreachable_and_still_on_disk(client):
+    _turns(client, 3)
+    tip_depth = _head(client.adv_id)[1]
+    _attach_memory(client.adv_id, "Mara reveals she is a spy.", tip_depth)
+    assert _retrievable(client.adv_id) == {"Mara reveals she is a spy."}
+
+    _undo(client)
+    # Negative control: undone, the revelation is not retrievable...
+    assert _retrievable(client.adv_id) == set()
+    _play(client, "talk about the weather")
+    # ...and after diverging it stays unreachable, on a line the story left.
+    assert _retrievable(client.adv_id) == set()
+    db = SessionLocal()
+    try:
+        assert db.query(models.Memory).count() == 1, "unreachable, not deleted"
+    finally:
+        db.close()
+
+
+def test_e02_positive_control_the_memory_returns_on_the_line_it_belongs_to(client):
+    """The negative control alone would pass if memories were simply broken.
+    Redo puts the head back on the lineage the memory was written for, and it
+    must be retrievable again — without having been re-embedded."""
+    _turns(client, 3)
+    _attach_memory(client.adv_id, "Mara reveals she is a spy.", _head(client.adv_id)[1])
+
+    _undo(client)
+    assert _retrievable(client.adv_id) == set()
+    _redo(client)
+    assert _retrievable(client.adv_id) == {"Mara reveals she is a spy."}
+
+
+def test_e03_a_summary_anchor_cannot_claim_coverage_past_the_head(client):
+    """E03 without redesigning the summarizer. The anchor says how far the
+    derived work has read; resolved against a head-capped path it can never
+    report a stretch in the abandoned future as already covered, so that content
+    is re-derived for the new line rather than carried into it."""
+    _turns(client, 3)
+    tip_depth = _head(client.adv_id)[1]
+    _attach_memory(client.adv_id, "Everything up to the reveal.", tip_depth)
+
+    db = SessionLocal()
+    try:
+        adventure = db.get(models.Adventure, client.adv_id)
+        assert cursors.SUMMARY.depth(db, adventure) == tip_depth
+    finally:
+        db.close()
+
+    _undo(client)
+    _play(client, "a different question")
+
+    db = SessionLocal()
+    try:
+        adventure = db.get(models.Adventure, client.adv_id)
+        covered = cursors.SUMMARY.depth(db, adventure)
+        assert covered < tip_depth, "coverage from the abandoned line was claimed"
+    finally:
+        db.close()
+
+
+# ------------------------------------------------ D06-D08: retry and takes
+
+def test_d06_d08_retry_keeps_the_earlier_take_and_reuses_the_parent_state(client):
+    ScriptedProvider.replies = gold_replies("Take")
+    _play(client, "knock")
+    first = [a for a in _rows(client.adv_id) if a.type == "ai"][0]
+
+    r = client.post(f"/api/adventures/{client.adv_id}/retry")
+    assert r.status_code == 200, r.text
+
+    ai_rows = [a for a in _rows(client.adv_id) if a.type == "ai"]
+    assert len(ai_rows) == 2, "the earlier take is retained"
+    assert first.id in {a.id for a in ai_rows}
+    # Both takes sit at the same coordinate, which is what makes them takes
+    # rather than turns, and the state is one turn's worth either way.
+    assert {a.depth for a in ai_rows} == {first.depth}
+    assert _gold(client.adv_id) == GOLD_PER_TURN
+
+
+def test_d07_a_retry_from_behind_the_tip_branches_instead_of_amending(client):
+    """A turn with an accepted future is not a leaf, whatever the capped read
+    says. Retrying it has to leave that future on the line it was written for,
+    which is a branch — the same operation `add_take` performs for a turn the
+    story has already moved past."""
+    _turns(client, 3)
+    _undo(client)
+    before = {a.id for a in _rows(client.adv_id)}
+
+    r = client.post(f"/api/adventures/{client.adv_id}/retry")
+    assert r.status_code == 200, r.text
+
+    after = {a.id for a in _rows(client.adv_id)}
+    assert before <= after, "the retained future kept every row"
+    db = SessionLocal()
+    try:
+        assert db.query(models.Branch).filter_by(adventure_id=client.adv_id).count() == 2
+    finally:
+        db.close()
+
+
+def test_switching_a_take_is_refused_while_a_kept_future_hangs_off_it(client):
+    """The one operation that cannot be made safe by branching, because it
+    changes which take is live in place. It reports rather than guesses."""
+    ScriptedProvider.replies = gold_replies()
+    _play(client, "knock")
+    client.post(f"/api/adventures/{client.adv_id}/retry")
+    _play(client, "go in")
+    _undo(client)
+
+    newest = [a for a in _rows(client.adv_id) if a.type == "ai" and a.live][0]
+    r = client.post(
+        f"/api/adventures/{client.adv_id}/actions/{newest.id}/variant", json={"index": 0}
+    )
+    assert r.status_code == 400
+    assert "undone but kept" in r.json()["detail"]
+
+
+# ---------------------------------------------------------- D09, D10: editing
+
+def test_d09_d10_replaying_a_turn_forks_and_keeps_the_old_line(client):
+    """D09 and D10 through the operation the product actually offers. Editing
+    an earlier turn and replaying it is one endpoint — `takes` — and it is
+    already the "return to the parent state, then continue differently" shape
+    the semantics ask for. The plain text edit beside it is a correction to
+    prose that creates no continuation, and M3 does not change it.
+    """
+    ScriptedProvider.replies = [
+        "You accuse her.\n```state\n{\"player.gold\": 10}\n```",
+        "She draws a knife.\n```state\n{\"player.gold\": 20}\n```",
+    ]
+    _play(client, "I accuse Mara of stealing the key.")
+    _play(client, "wait")
+    accusation = [a for a in _rows(client.adv_id) if a.type == "do"][0]
+    old_future = {a.id for a in _rows(client.adv_id)}
+
+    ScriptedProvider.replies = ["She shakes her head.\n```state\n{\"player.gold\": 1}\n```"]
+    r = client.post(
+        f"/api/adventures/{client.adv_id}/actions/{accusation.id}/takes",
+        json={"text": "I quietly ask Mara whether she has seen the key."},
+    )
+    assert r.status_code == 200, r.text
+
+    # The old future is retained whole...
+    assert old_future <= {a.id for a in _rows(client.adv_id)}
+    # ...the edited input is what the story now tells...
+    told = _texts(client)
+    assert any("quietly ask Mara" in t for t in told)
+    assert not any("accuse her" in t for t in told)
+    # ...and no state from the abandoned line leaked into it.
+    assert _gold(client.adv_id) == 1
+
+
+# ------------------------------------------------------------------ L01
+
+def test_l01_a_failed_turn_accepts_no_narration_and_strands_no_state(client):
+    """A provider that fails must not leave the story half-advanced.
+
+    The head does move, by exactly one node, and that is deliberate rather than
+    a gap in the guarantee: A05 keeps the player's submitted text so it can be
+    tried again, and the head sits on it. What L01 forbids is an *accepted*
+    narration with half-written state behind it, a head that has moved past a
+    turn that did not happen, or earlier story becoming unreachable — so those
+    are what this asserts.
+    """
+    _turns(client, 2)
+    branch, depth = _head(client.adv_id)
+    told = _texts(client)
+    banked = _gold(client.adv_id)
+    ai_before = [a.id for a in _rows(client.adv_id) if a.type == "ai"]
+
+    ScriptedProvider.replies = [ProviderError("the model refused")]
+    client.post(f"/api/adventures/{client.adv_id}/actions",
+                json={"type": "do", "text": "the turn that fails"})
+
+    # One step, onto the retained player action, on the same branch.
+    assert _head(client.adv_id) == (branch, depth + 1)
+    # No narration was accepted, and no state moved with a turn that did not
+    # finish.
+    assert [a.id for a in _rows(client.adv_id) if a.type == "ai"] == ai_before
+    assert _gold(client.adv_id) == banked
+    # Every earlier turn is still readable, in order, unchanged.
+    assert _texts(client)[:len(told)] == told
+
+    # And the story still moves: one Undo steps back over the stranded input
+    # and the position is a complete turn again.
+    ScriptedProvider.replies = gold_replies()
+    assert _undo(client).status_code == 200
+    assert _texts(client) == told
+    assert _gold(client.adv_id) == banked
+
+
+# ------------------------------------------------- I01, I02, I03, I07: bundles
+
+def _export(client) -> dict:
+    r = client.get(f"/api/adventures/{client.adv_id}/export")
+    assert r.status_code == 200, r.text
+    return r.json()
+
+
+def _import(client, bundle) -> dict:
+    """Imports a bundle and returns the new adventure.
+
+    "A fresh data directory" is an adventure this file has never touched: the
+    import allocates its own branch rows and its own nodes, and resolves the
+    file's local branch numbers against them, which is the whole of what the
+    round trip has to get right. Sharing a database with the original does not
+    weaken that — the two adventures share no row.
+    """
+    r = client.post("/api/adventures/import", json=bundle)
+    assert r.status_code == 201, r.text
+    return r.json()
+
+
+def _story_of(adv_id) -> list[str]:
+    """The story an imported adventure tells, read through its own head."""
+    db = SessionLocal()
+    try:
+        adventure = db.get(models.Adventure, adv_id)
+        rows = (
+            db.query(models.Action)
+            .filter(
+                models.Action.adventure_id == adv_id,
+                lineage.path_of(db, adventure).clause(models.Action),
+            )
+            .order_by(models.Action.depth, models.Action.id)
+            .all()
+        )
+        return [a.text for a in rows]
+    finally:
+        db.close()
+
+
+def test_i01_i02_a_campaign_round_trips(client):
+    _turns(client, 3)
+    told = _texts(client)
+
+    imported = _import(client, _export(client))
+
+    assert _story_of(imported["id"]) == told
+    assert _gold(imported["id"]) == 3 * GOLD_PER_TURN
+
+
+def test_i03_the_bundle_carries_the_history_the_story_no_longer_tells(client):
+    """A backup that keeps only the active line is not a backup: the retained
+    future is what Redo and every later recovery feature read."""
+    _turns(client, 3)
+    _undo(client)
+    _play(client, "another way")
+    active = _texts(client)
+
+    bundle = _export(client)
+    assert len(bundle["branches"]) == 2
+    imported = _import(client, bundle)
+
+    assert _story_of(imported["id"]) == active
+    # Every row of the abandoned line arrived too, on its own branch.
+    db = SessionLocal()
+    try:
+        assert (
+            db.query(models.Action).filter_by(adventure_id=imported["id"]).count()
+            == len(_rows(client.adv_id))
+        )
+        assert db.query(models.Branch).filter_by(adventure_id=imported["id"]).count() == 2
+    finally:
+        db.close()
+
+
+def test_i07_an_undone_head_survives_export_and_import(client):
+    """The Phase 0B finding this milestone exists to close. Before M3 the head
+    depth was derived on import from the newest retained row, so a campaign
+    exported after two Undos came back silently redone to its tip."""
+    _turns(client, 5)
+    whole = _texts(client)
+    _undo(client)
+    _undo(client)
+    undone = _texts(client)
+    assert len(undone) == len(whole) - 4
+
+    bundle = _export(client)
+    assert bundle["headDepth"] == _head(client.adv_id)[1]
+
+    imported = _import(client, bundle)
+
+    # It opens exactly where it was left...
+    assert _story_of(imported["id"]) == undone
+    assert imported["can_redo"] is True
+    # ...the later turns arrived as retained history...
+    db = SessionLocal()
+    try:
+        assert (
+            db.query(models.Action).filter_by(adventure_id=imported["id"]).count()
+            == len(_rows(client.adv_id))
+        )
+    finally:
+        db.close()
+    # ...and Redo still walks forward into them, twice, to the same story.
+    for _ in range(2):
+        r = client.post(f"/api/adventures/{imported['id']}/redo")
+        assert r.status_code == 200, r.text
+    assert _story_of(imported["id"]) == whole
+
+
+def test_a_bundle_written_before_m3_opens_at_its_tip(client):
+    """Backward compatibility. A file with no `headDepth` is one written when
+    the head could not be anywhere but the tip, so deriving it is not a
+    fallback — it is the position that file recorded."""
+    _turns(client, 3)
+    told = _texts(client)
+    bundle = _export(client)
+    del bundle["headDepth"]
+
+    imported = _import(client, bundle)
+
+    assert _story_of(imported["id"]) == told
+
+
+def test_a_bundle_that_reads_past_its_own_story_is_refused(client):
+    """Checked in `plan`, before a row is written, for the reason the module
+    docstring gives: an import that discovers a bad coordinate afterwards has
+    already written half a tree."""
+    _turns(client, 2)
+    bundle = _export(client)
+    bundle["headDepth"] = 999
+
+    r = client.post("/api/adventures/import", json=bundle)
+    assert r.status_code == 400
+    assert "ends at" in r.json()["detail"]
+
+
+def test_the_bundle_carries_which_branches_the_story_left(client):
+    """Every row of an abandoned line arrives on an import either way, so the
+    disposition is the only thing that distinguishes it from an active one.
+    Losing it on a round trip would leave a restored backup unable to tell them
+    apart — which is what the later cleanup and recovery features select on."""
+    _turns(client, 3)
+    _undo(client)
+    _play(client, "another way")
+
+    imported = _import(client, _export(client))
+
+    db = SessionLocal()
+    try:
+        left = (
+            db.query(models.Branch)
+            .filter(
+                models.Branch.adventure_id == imported["id"],
+                models.Branch.superseded_at.isnot(None),
+            )
+            .all()
+        )
+        origin = (
+            db.query(models.Branch)
+            .filter(
+                models.Branch.adventure_id == client.adv_id,
+                models.Branch.superseded_at.isnot(None),
+            )
+            .all()
+        )
+        assert len(left) == len(origin) == 1
+        assert left[0].superseded_depth == origin[0].superseded_depth
+    finally:
+        db.close()
+
+
+def test_a_bundle_with_half_a_disposition_imports_as_active(client):
+    """Neither column is read to decide anything, so a file carrying one of them
+    is taken as carrying neither rather than having its missing half invented."""
+    _turns(client, 3)
+    _undo(client)
+    _play(client, "another way")
+    bundle = _export(client)
+    for branch in bundle["branches"]:
+        branch.pop("supersededDepth", None)
+
+    imported = _import(client, bundle)
+
+    db = SessionLocal()
+    try:
+        assert (
+            db.query(models.Branch)
+            .filter(
+                models.Branch.adventure_id == imported["id"],
+                models.Branch.superseded_at.isnot(None),
+            )
+            .count()
+            == 0
+        )
+    finally:
+        db.close()
+
+
+# ------------------------------------- the narrator-edit guard (M3 closeout)
+
+def _edit(client, action_id, text):
+    return client.patch(
+        f"/api/adventures/{client.adv_id}/actions/{action_id}", json={"text": text}
+    )
+
+
+def _live_ai_at(adv_id, depth):
+    return [
+        a for a in _rows(adv_id)
+        if a.type == "ai" and a.live and a.depth == depth
+    ][0]
+
+
+def test_editing_a_turn_with_nothing_after_it_is_still_allowed(client):
+    """The guard has to stay out of the way of the operation it protects. A
+    correction to the newest turn contradicts nothing, and that is the case the
+    edit control exists for."""
+    _turns(client, 2)
+    newest = [a for a in _rows(client.adv_id) if a.type == "ai"][-1]
+
+    r = _edit(client, newest.id, "Corrected.")
+
+    assert r.status_code == 200, r.text
+    assert _texts(client)[-1] == "Corrected."
+
+
+def test_editing_a_turn_on_the_visible_story_is_still_allowed(client):
+    """Mid-story is not by itself unsafe: everything descending from the turn is
+    on screen, so the reader can see what their correction has to agree with.
+    Making that case fork is `STORY-BRANCH-SEMANTICS.md` §14-15 and belongs to
+    M5 with the state re-evaluation it needs."""
+    _turns(client, 3)
+    older = [a for a in _rows(client.adv_id) if a.type == "ai"][0]
+
+    r = _edit(client, older.id, "Mara wears a green cloak.")
+
+    assert r.status_code == 200, r.text
+    assert "Mara wears a green cloak." in _texts(client)
+
+
+def test_editing_a_turn_with_an_undone_future_is_refused(client):
+    """The first unsafe case: the story past the head is not on screen, so an
+    edit here would silently change the words it was written from."""
+    _turns(client, 3)
+    _undo(client)
+    at_head = [a for a in _rows(client.adv_id) if a.type == "ai" and a.live]
+    target = sorted(at_head, key=lambda a: a.depth)[-2]
+    before = target.text
+
+    r = _edit(client, target.id, "Something else entirely.")
+
+    assert r.status_code == 400
+    assert "not on screen" in r.json()["detail"]
+    # Refused, not partially applied.
+    assert _rows(client.adv_id)[0].adventure_id == client.adv_id
+    assert [a.text for a in _rows(client.adv_id) if a.id == target.id] == [before]
+
+
+def test_editing_a_turn_a_divergence_left_behind_is_refused(client):
+    """The second unsafe case, and the one a head check alone would miss: after
+    a divergence the head is back at a tip, but a displaced line still runs on
+    past the shared turn."""
+    _turns(client, 3)
+    shared = [a for a in _rows(client.adv_id) if a.type == "ai"][0]
+    _undo(client)
+    _undo(client)
+    _play(client, "a different road")
+    assert _adventure(client)["can_redo"] is False, "the head is at a tip again"
+
+    r = _edit(client, shared.id, "Rewritten under both lines.")
+
+    assert r.status_code == 400
+    assert "left behind by a new continuation" in r.json()["detail"]
+
+
+def test_a_turn_the_displaced_line_does_not_descend_from_is_still_editable(client):
+    """The guard must be narrow. A branch that forked *before* a turn does not
+    descend from it, so a correction there contradicts nothing on that line."""
+    _turns(client, 2)
+    _undo(client)
+    _play(client, "a different road")          # forks below turn 1
+    _turns(client, 2)                          # and continues past the fork
+    newest = [a for a in _rows(client.adv_id) if a.type == "ai" and a.live]
+    target = sorted(newest, key=lambda a: a.depth)[-1]
+
+    r = _edit(client, target.id, "Corrected on the live line.")
+
+    assert r.status_code == 200, r.text
+
+
+def test_a_take_that_is_not_live_stays_editable(client):
+    """A take the story is not telling has no continuation of its own — keeping
+    one is what forking is for — so correcting its text cannot contradict
+    anything."""
+    ScriptedProvider.replies = gold_replies()
+    _play(client, "knock")
+    client.post(f"/api/adventures/{client.adv_id}/retry")
+    discarded = [a for a in _rows(client.adv_id) if a.type == "ai" and not a.live][0]
+
+    r = _edit(client, discarded.id, "The take nobody chose, corrected.")
+
+    assert r.status_code == 200, r.text
+
+
+def test_the_guard_lifts_when_the_story_is_brought_back(client):
+    """Refusal is a redirection, not a dead end: the error names Redo, so Redo
+    has to make the edit possible again."""
+    _turns(client, 3)
+    _undo(client)
+    live = sorted(
+        [a for a in _rows(client.adv_id) if a.type == "ai" and a.live],
+        key=lambda a: a.depth,
+    )
+    target = live[-2]
+    assert _edit(client, target.id, "x").status_code == 400
+
+    _redo(client)
+
+    r = _edit(client, target.id, "Corrected once the story was whole again.")
+    assert r.status_code == 200, r.text

backend/tests/test_local_only_surface.py

@@ -0,0 +1,269 @@
+"""What M2 removed stays removed, and what it must not break stays working.
+
+A subtractive milestone needs tests that fail if the surface grows back. These
+are cheap, blunt, and deliberately not clever: they assert against the running
+app's route table, the shipped configuration files, and the settings API.
+
+    python -m pytest tests/test_local_only_surface.py -v
+"""
+import re
+from pathlib import Path
+
+import pytest
+from fastapi import Depends
+from fastapi.testclient import TestClient
+
+from app import auth, models
+from app.database import Base, SessionLocal, engine, get_db
+from app.main import app
+from app.providers.openai_compatible import (
+    CONNECT_TIMEOUT, DEFAULT_READ_TIMEOUT, OpenAICompatibleProvider,
+)
+
+REPO = Path(__file__).resolve().parents[2]
+
+
+def _paths() -> set[str]:
+    """Every path the app serves, including those inside included routers."""
+    found = set()
+
+    def walk(routes):
+        for r in routes:
+            path = getattr(r, "path", None)
+            if path:
+                found.add(path)
+            walk(getattr(r, "routes", []) or [])
+
+    walk(app.routes)
+    return found
+
+
+@pytest.fixture()
+def client():
+    Base.metadata.create_all(bind=engine)
+    setup = SessionLocal()
+    user = models.User(is_guest=False)
+    setup.add(user)
+    setup.flush()
+    setup.add(models.Settings(user_id=user.id, model="test-model"))
+    setup.commit()
+    user_id = user.id
+    setup.close()
+
+    def _current_user(db=Depends(get_db)):
+        return db.get(models.User, user_id)
+
+    app.dependency_overrides[auth.get_current_user] = _current_user
+    c = TestClient(app)
+    try:
+        yield c
+    finally:
+        app.dependency_overrides.clear()
+        Base.metadata.drop_all(bind=engine)
+
+
+# --- the removed surfaces ------------------------------------------------
+
+@pytest.mark.parametrize("prefix", ["/api/auth", "/api/analytics", "/api/scripts"])
+def test_no_route_serves_a_removed_subsystem(prefix):
+    """Accounts, the visitor dashboard, and campaign scripting are gone as
+    routes, not merely hidden behind a flag."""
+    assert not [p for p in _paths() if p.startswith(prefix)], prefix
+
+
+@pytest.mark.parametrize("path", [
+    "/api/auth/me", "/api/auth/login", "/api/auth/register", "/api/auth/logout",
+    "/api/analytics/summary", "/api/analytics/collect", "/api/analytics/access",
+    "/api/scripts", "/api/adventures/1/scripts", "/api/adventures/1/script-state",
+])
+def test_a_removed_endpoint_answers_404(client, path):
+    assert client.get(path).status_code == 404, path
+
+
+def test_the_application_has_no_scripting_engine():
+    with pytest.raises(ImportError):
+        __import__("app.scripting")
+
+
+def test_no_module_imports_quickjs():
+    """The dependency is gone from requirements; this catches an import that
+    would put it back."""
+    for py in (REPO / "backend" / "app").rglob("*.py"):
+        assert "import quickjs" not in py.read_text(), py
+
+
+def test_requirements_carry_no_hosted_dependencies():
+    text = (REPO / "backend" / "requirements.txt").read_text()
+    for gone in ("quickjs", "psycopg", "cryptography"):
+        assert gone not in text, gone
+
+
+def test_no_render_deployment_config():
+    assert not (REPO / "render.yaml").exists()
+
+
+# --- no cloud provider, no key ------------------------------------------
+
+def test_settings_expose_no_api_key_field(client):
+    body = client.get("/api/settings").json()
+    assert "api_key" not in body
+    assert "has_api_key" not in body
+
+
+def test_an_api_key_cannot_be_set_through_the_api(client):
+    """Pydantic ignores unknown fields, so this asserts the value does not
+    land rather than that the request is refused."""
+    client.put("/api/settings", json={"api_key": "sk-should-not-stick"})
+    db = SessionLocal()
+    try:
+        assert db.query(models.Settings).first().api_key == ""
+    finally:
+        db.close()
+
+
+def test_the_provider_sends_no_authorization_header():
+    provider = OpenAICompatibleProvider("http://127.0.0.1:11434/v1", "m")
+    assert "Authorization" not in provider._headers()
+
+
+# --- the model timeout ---------------------------------------------------
+
+def test_the_default_timeout_is_generous_but_finite():
+    """M1 measured a cold model load exceeding the inherited hardcoded 120s on
+    a CPU-only host. It must be longer than that, and it must be a number."""
+    assert DEFAULT_READ_TIMEOUT > 120
+    assert DEFAULT_READ_TIMEOUT <= 3600
+
+
+def test_connect_stays_short_while_reading_stays_patient():
+    """A wrong address should fail in seconds; a loading model should not."""
+    provider = OpenAICompatibleProvider("http://127.0.0.1:11434/v1", "m")
+    timeout = provider._timeout()
+    assert timeout.connect == CONNECT_TIMEOUT <= 30
+    assert timeout.read == DEFAULT_READ_TIMEOUT
+
+
+def test_the_timeout_is_configurable(client):
+    r = client.put("/api/settings", json={"model_timeout_seconds": 900})
+    assert r.status_code == 200, r.text
+    assert client.get("/api/settings").json()["model_timeout_seconds"] == 900
+
+
+@pytest.mark.parametrize("value", [0, 29, 3601, -1])
+def test_an_unusable_timeout_is_refused(client, value):
+    """Not zero, not negative, and not "wait forever" spelled as a big number."""
+    assert client.put(
+        "/api/settings", json={"model_timeout_seconds": value}
+    ).status_code == 422
+
+
+def test_the_provider_honours_the_configured_timeout():
+    provider = OpenAICompatibleProvider("http://127.0.0.1:11434/v1", "m", read_timeout=45)
+    assert provider._timeout().read == 45
+
+
+# --- the storyteller stays on loopback -----------------------------------
+
+def test_the_native_start_scripts_bind_loopback():
+    for script in ("start.sh", "start.ps1"):
+        text = (REPO / script).read_text(errors="ignore")
+        assert "--host 127.0.0.1" in text, script
+        assert "--host 0.0.0.0" not in text, script
+
+
+def test_compose_publishes_to_loopback_only():
+    """The container listens on 0.0.0.0 because a published port cannot reach
+    anything else. What must stay loopback is the *host* side of the mapping."""
+    text = (REPO / "docker-compose.yml").read_text()
+    published = re.findall(r'^\s*-\s*"([^"]+)"', text, re.M)
+    assert published, "no published ports found — has the file moved?"
+    for mapping in published:
+        assert mapping.startswith("127.0.0.1:"), mapping
+
+
+# --- every provider factory must actually build ---------------------------
+
+def test_every_provider_factory_builds_from_a_real_settings_row(client):
+    """M2 shipped with a defect this test would have caught.
+
+    `Settings.api_key_plain` was removed with the API key, but `memorybank`'s
+    two provider factories still read it. Nothing failed at import, and no test
+    noticed, because every memory test stubs those factories out — so the break
+    only appeared at runtime, in a background task, as a swallowed
+    `AttributeError` that silently stopped summaries and embeddings.
+
+    Constructing each factory from a real row is the cheapest thing that would
+    have caught it, and it catches the same shape of mistake next time a
+    Settings column moves.
+    """
+    from app import memorybank
+
+    db = SessionLocal()
+    try:
+        settings = db.query(models.Settings).first()
+        settings.embedding_model = "nomic-embed-text:latest"
+        settings.summary_model = ""
+        db.commit()
+
+        summary = memorybank.summary_provider(settings)
+        assert summary.model == settings.model  # falls back to the narrator
+        assert summary.base_url == settings.endpoint_url.rstrip("/")
+
+        embed = memorybank.embedding_provider(settings)
+        assert embed.model == "nomic-embed-text:latest"
+
+        turn = OpenAICompatibleProvider(
+            settings.endpoint_url, settings.model, settings.api_mode,
+            settings.model_timeout_seconds,
+        )
+        assert turn.read_timeout == settings.model_timeout_seconds
+    finally:
+        db.close()
+
+
+def test_the_configured_timeout_reaches_every_generating_client(client, monkeypatch):
+    """The second defect this review caught. The setting was stored, validated
+    and exposed, and then not passed to the provider — so the turn engine kept
+    using the module default and "configurable" was a claim rather than a fact.
+
+    Each generating path is driven for real and the constructed provider is
+    recorded. Embeddings are deliberately excluded: they are short, never
+    cold-load a large model, and keep their own shorter constant.
+    """
+    from app import memorybank
+    from app.routers import chat as chat_router
+    from app.routers.adventures import turns as turns_router
+
+    seen = []
+
+    class Recorder:
+        last_usage = None
+
+        def __init__(self, endpoint_url, model, api_mode="chat", read_timeout=None):
+            seen.append(read_timeout)
+
+        async def generate(self, *a, **k):
+            yield ("text", "narration")
+
+        async def chat(self, *a, **k):
+            yield ("text", "reply")
+
+    monkeypatch.setattr(turns_router, "OpenAICompatibleProvider", Recorder)
+    monkeypatch.setattr(chat_router, "OpenAICompatibleProvider", Recorder)
+    monkeypatch.setattr(memorybank, "OpenAICompatibleProvider", Recorder)
+
+    assert client.put("/api/settings", json={"model_timeout_seconds": 777}).status_code == 200
+
+    adv = client.post("/api/adventures", json={"title": "T"}).json()["id"]
+    client.post(f"/api/adventures/{adv}/actions", json={"type": "story", "text": "hello"})
+    assert seen and seen[-1] == 777, f"turn engine used {seen[-1]!r}"
+
+    client.post("/api/chat/stream", json={"messages": [{"role": "user", "content": "hi"}]})
+    assert seen[-1] == 777, f"chat used {seen[-1]!r}"
+
+    db = SessionLocal()
+    try:
+        memorybank.summary_provider(db.query(models.Settings).first())
+    finally:
+        db.close()
+    assert seen[-1] == 777, f"summarizer used {seen[-1]!r}"

backend/tests/test_memory_rewrite.py

@@ -128,7 +128,7 @@ def fill_bank(db, adventure, *, count=2):
 def options(**overrides):
     args = dict(write=False, adventure=None, email=None, limit=None,
                 include_forgotten=False, embed=False, endpoint=None,
-                model=None, api_key=None)
+                model=None)
     args.update(overrides)
     return argparse.Namespace(**args)
 
@@ -248,23 +248,6 @@ def test_the_rewrite_prompt_is_the_one_the_app_sends(db):
 
 # --------------------------------------------------------------------- the tool
 
-def test_the_database_line_carries_no_password():
-    """The report names the database it is about to rewrite. That line ends up
-    in a console, a screenshot or a pasted bug report."""
-    shown = rewrite_memories.safe_dsn(
-        "postgresql://parth:hunter2@ep-cool-frost.us-east-1.aws.neon.tech/aidnd"
-        "?sslmode=require")
-    assert "hunter2" not in shown
-    assert "sslmode" not in shown  # a password can be passed there too
-    assert shown == ("postgresql://parth@ep-cool-frost.us-east-1.aws.neon.tech"
-                     "/aidnd")
-
-
-def test_an_unparseable_database_url_shows_nothing_at_all():
-    assert rewrite_memories.safe_dsn("not-a-url") == "(configured)"
-
-
-
 def test_without_write_nothing_changes(db, monkeypatch):
     adventure = make_adventure(db)
     first, _ = fill_bank(db, adventure)
@@ -316,9 +299,12 @@ def test_a_hand_written_memory_is_left_alone(db, monkeypatch):
     assert typed.text == "Kaelen owes a debt."
 
 
-def test_an_owner_with_no_api_key_is_skipped(db, monkeypatch):
-    """Summarization spends the user's own key and never the shared demo key."""
-    adventure = make_adventure(db, key="")
+def test_an_adventure_with_no_model_configured_is_skipped(db, monkeypatch):
+    """Nothing to summarize with, so the memory is reported rather than
+    silently left as it was. This used to be about the owner's API key; after
+    M2 the thing that can be missing is the model name."""
+    adventure = make_adventure(db)
+    _blank_model(db, adventure)
     first, _ = fill_bank(db, adventure)
     stub = StubSummarizer()
     monkeypatch.setattr(memorybank, "summary_provider", lambda s: stub)
@@ -328,10 +314,10 @@ def test_an_owner_with_no_api_key_is_skipped(db, monkeypatch):
     assert first.text == "You entered the crypt 1."
 
 
-def test_an_api_key_on_the_command_line_covers_that_owner(db, monkeypatch):
-    """The way to summarize for an owner who has no key of their own, and the
-    way to point a run at the local Claude shim instead of a paid endpoint."""
-    adventure = make_adventure(db, key="")
+def test_a_model_on_the_command_line_covers_that_adventure(db, monkeypatch):
+    """How to run the rewrite against a model other than the configured one."""
+    adventure = make_adventure(db)
+    _blank_model(db, adventure)
     first, _ = fill_bank(db, adventure)
     built: list[tuple] = []
 
@@ -340,11 +326,22 @@ def test_an_api_key_on_the_command_line_covers_that_owner(db, monkeypatch):
         return StubSummarizer()
 
     monkeypatch.setattr("app.providers.OpenAICompatibleProvider", build)
-    assert run_tool(options(write=True, api_key="sk-cli", model="sonnet",
+    assert run_tool(options(write=True, model="other-model",
                             endpoint="http://127.0.0.1:8787/v1")) == 0
     db.expire_all()
     assert first.text == "Kaelen entered the crypt 1."
-    assert built[0][:3] == ("http://127.0.0.1:8787/v1", "sk-cli", "sonnet")
+    assert built[0][:2] == ("http://127.0.0.1:8787/v1", "other-model")
+
+
+def _blank_model(db, adventure) -> None:
+    settings = (
+        db.query(models.Settings)
+        .filter(models.Settings.user_id == adventure.user_id)
+        .first()
+    )
+    settings.model = ""
+    settings.summary_model = ""
+    db.commit()
 
 
 def test_limit_stops_early(db, monkeypatch):

backend/tests/test_netguard.py

@@ -1,60 +0,0 @@
-"""Tests for the SSRF guard on the user-supplied BYOK endpoint_url.
-
-    python -m pytest tests/test_netguard.py -v
-"""
-import pytest
-
-from app import auth, netguard
-
-
-@pytest.fixture
-def hosted(monkeypatch):
-    monkeypatch.setattr(auth, "MULTI_USER", True)
-
-
-def _resolves_to(monkeypatch, ip: str):
-    """Pin `getaddrinfo` so the test exercises the address decision, not real DNS."""
-    monkeypatch.setattr(
-        netguard.socket, "getaddrinfo",
-        lambda *a, **k: [(2, 1, 6, "", (ip, 443))],
-    )
-
-
-@pytest.mark.parametrize("ip", [
-    "127.0.0.1",          # loopback
-    "169.254.169.254",    # cloud metadata (link-local)
-    "10.0.0.5",           # RFC1918
-    "192.168.1.1",        # RFC1918
-    "172.16.0.9",         # RFC1918
-    "0.0.0.0",            # unspecified
-    "100.64.0.1",         # carrier-grade NAT
-    "::1",                # IPv6 loopback
-    "fd00::1",            # IPv6 unique-local
-])
-def test_blocks_non_public_addresses(hosted, monkeypatch, ip):
-    _resolves_to(monkeypatch, ip)
-    assert netguard.endpoint_block_reason("https://evil.example.com/v1") is not None
-
-
-def test_allows_public_address(hosted, monkeypatch):
-    _resolves_to(monkeypatch, "104.18.0.1")  # a public IP
-    assert netguard.endpoint_block_reason("https://openrouter.ai/api/v1") is None
-
-
-def test_rejects_non_http_scheme(hosted):
-    assert netguard.endpoint_block_reason("file:///etc/passwd") is not None
-    assert netguard.endpoint_block_reason("gopher://x/") is not None
-
-
-def test_unresolvable_host_is_blocked(hosted, monkeypatch):
-    def boom(*a, **k):
-        raise netguard.socket.gaierror("no such host")
-    monkeypatch.setattr(netguard.socket, "getaddrinfo", boom)
-    assert netguard.endpoint_block_reason("https://nope.invalid/v1") is not None
-
-
-def test_noop_in_local_mode(monkeypatch):
-    monkeypatch.setattr(auth, "MULTI_USER", False)
-    # Local installs must reach localhost (Ollama). The guard never blocks local mode.
-    assert netguard.endpoint_block_reason("http://localhost:11434/v1") is None
-    assert netguard.endpoint_block_reason("http://127.0.0.1:11434/v1") is None

backend/tests/test_persona.py

@@ -275,7 +275,6 @@ def client(monkeypatch):
     user_id = user.id
     setup.close()
 
-    monkeypatch.setattr(limits, "rate_limit", lambda *a, **k: None)
     monkeypatch.setattr(limits, "check_row_cap", lambda *a, **k: None)
 
     def _current_user(db=Depends(get_db)):

backend/tests/test_process_restart.py

@@ -0,0 +1,325 @@
+"""D11 and L03 across a genuine OS process boundary.
+
+The rest of the suite runs the app in-process through `TestClient`, which is the
+right tool for almost everything and the wrong one for exactly one claim:
+*durability*. A Save Point that survived only because a Python object was still
+alive would pass a same-process test and fail a user's restart. `TestClient`
+cannot tell those apart, so the M4 review recorded the shipped D11/L03 tests as
+weaker than the acceptance items they were named for (§R B-3).
+
+This module closes that. It starts the real application as a **subprocess**,
+plays a story over HTTP, kills the process, starts a **second** process against
+the same database file, and only then asks whether the Save Point is still
+there. Everything crossing the boundary crosses it as bytes on disk.
+
+Deterministic and local: the spawned server replaces the model with a scripted
+provider (`_restart_server.py`), so there is no Ollama, no network and no
+sleep-and-hope — readiness is probed, not waited for.
+
+    python -m pytest tests/test_process_restart.py -v
+"""
+import json
+import os
+import socket
+import subprocess
+import sys
+import tempfile
+import time
+import urllib.error
+import urllib.request
+from pathlib import Path
+
+import pytest
+
+from fakes import GOLD_PER_TURN
+
+HERE = Path(__file__).resolve().parent
+SERVER = HERE / "_restart_server.py"
+
+# How long a spawned server may take to answer before the test gives up. The
+# process imports the app and runs migrations on a fresh file, which is well
+# under a second on this project; the ceiling is for a loaded machine.
+STARTUP_TIMEOUT = 60.0
+
+
+def _free_port() -> int:
+    """Returns a port nothing is listening on.
+
+    Bind, read, release. There is a race between releasing and the server
+    claiming it, which is why the caller probes for readiness rather than
+    assuming success — a lost race shows up as a startup timeout, not as a
+    silent pass.
+    """
+    with socket.socket() as s:
+        s.bind(("127.0.0.1", 0))
+        return s.getsockname()[1]
+
+
+class Server:
+    """One storyteller process, and the HTTP calls the test makes against it."""
+
+    def __init__(self, db_path: str, port: int):
+        self.port = port
+        self.proc = subprocess.Popen(
+            [sys.executable, str(SERVER), db_path, str(port)],
+            stdout=subprocess.PIPE,
+            stderr=subprocess.STDOUT,
+            # Never inherit the parent's database redirection; the child is told
+            # which file to open on its command line.
+            env={**os.environ, "AIDND_DB_PATH": db_path},
+        )
+
+    # ------------------------------------------------------------ lifecycle
+
+    def wait_until_ready(self) -> None:
+        deadline = time.monotonic() + STARTUP_TIMEOUT
+        while time.monotonic() < deadline:
+            if self.proc.poll() is not None:
+                raise AssertionError(
+                    f"server exited early ({self.proc.returncode}):\n{self._output()}"
+                )
+            try:
+                self.call("GET", "/settings")
+                return
+            except (urllib.error.URLError, ConnectionError, OSError):
+                time.sleep(0.05)
+        raise AssertionError(f"server never became ready:\n{self._output()}")
+
+    def stop(self) -> None:
+        """Ends the process, and does not return until it is actually gone."""
+        if self.proc.poll() is None:
+            self.proc.terminate()
+            try:
+                self.proc.wait(timeout=15)
+            except subprocess.TimeoutExpired:
+                self.proc.kill()
+                self.proc.wait(timeout=15)
+        if self.proc.stdout is not None:
+            self.proc.stdout.close()
+
+    def _output(self) -> str:
+        if self.proc.stdout is None:
+            return "(no output captured)"
+        try:
+            return self.proc.stdout.read().decode(errors="replace")[-2000:]
+        except Exception:
+            return "(output unreadable)"
+
+    def is_listening(self) -> bool:
+        try:
+            self.call("GET", "/settings")
+            return True
+        except Exception:
+            return False
+
+    # ---------------------------------------------------------------- HTTP
+
+    def call(self, method: str, path: str, payload=None, expect: int | None = None):
+        data = json.dumps(payload).encode() if payload is not None else None
+        request = urllib.request.Request(
+            f"http://127.0.0.1:{self.port}/api{path}",
+            data=data,
+            method=method,
+            headers={"Content-Type": "application/json"},
+        )
+        try:
+            with urllib.request.urlopen(request, timeout=60) as response:
+                body, status = response.read(), response.status
+        except urllib.error.HTTPError as exc:          # a real answer, not a failure
+            body, status = exc.read(), exc.code
+        if expect is not None and status != expect:
+            raise AssertionError(f"{method} {path} -> {status}: {body[:400]!r}")
+        return json.loads(body) if body and status != 204 else None
+
+    def play(self, adventure_id: int, text: str) -> None:
+        """Plays one turn through the streaming endpoint, to completion."""
+        request = urllib.request.Request(
+            f"http://127.0.0.1:{self.port}/api/adventures/{adventure_id}/actions",
+            data=json.dumps({"type": "do", "text": text}).encode(),
+            method="POST",
+            headers={"Content-Type": "application/json"},
+        )
+        with urllib.request.urlopen(request, timeout=120) as response:
+            response.read()
+
+    # ------------------------------------------------------------- reading
+
+    def transcript(self, adventure_id: int) -> list[str]:
+        page = self.call("GET", f"/adventures/{adventure_id}", expect=200)
+        return [a["text"] for a in page["actions"]]
+
+    def gold(self, adventure_id: int) -> int:
+        state = self.call("GET", f"/adventures/{adventure_id}/world-state", expect=200)
+        return state["state"]["player"]["gold"]
+
+    def total_rows(self, adventure_id: int) -> int:
+        """Every row of the whole tree, head or no head.
+
+        `action_count` is scoped to the path being read, so it falls when the
+        head moves back — which is the feature, not a deletion. The export
+        carries the entire tree whatever the head is doing, so it is what
+        "nothing was deleted" has to be measured against.
+        """
+        bundle = self.call("GET", f"/adventures/{adventure_id}/export", expect=200)
+        return len(bundle["actions"])
+
+
+@pytest.fixture()
+def workspace():
+    """A database file, and whichever servers a test starts against it."""
+    directory = tempfile.mkdtemp(prefix="m4-restart-")
+    db_path = os.path.join(directory, "campaign.db")
+    started: list[Server] = []
+
+    def start() -> Server:
+        server = Server(db_path, _free_port())
+        started.append(server)
+        server.wait_until_ready()
+        return server
+
+    try:
+        yield start
+    finally:
+        # Every child dies even if the test failed part way through, and each
+        # stop() waits, so a later test cannot inherit a live listener.
+        for server in started:
+            server.stop()
+
+
+def _campaign_with_a_save_point(server: Server):
+    """Three turns, a Save Point on the third, then four more turns.
+
+    Returns everything the second process has to be able to reproduce.
+    """
+    scenario = server.call("POST", "/scenarios", {
+        "title": "Abbey",
+        "stat_schema": {"player": {"gold": {"initial": 0, "min": 0, "max": 9999}}},
+    }, expect=201)
+    adventure = server.call("POST", "/adventures", {
+        "title": "The abbey", "scenario_id": scenario["id"],
+    }, expect=201)
+    adventure_id = adventure["id"]
+
+    for n in range(3):
+        server.play(adventure_id, f"turn {n}")
+    at_save = {
+        "transcript": server.transcript(adventure_id),
+        "gold": server.gold(adventure_id),
+    }
+    save_point = server.call("POST", f"/adventures/{adventure_id}/checkpoints",
+                             {"name": "Before entering the abbey"}, expect=201)
+
+    for n in range(4):
+        server.play(adventure_id, f"later {n}")
+    at_tip = {
+        "transcript": server.transcript(adventure_id),
+        "gold": server.gold(adventure_id),
+        "rows": server.total_rows(adventure_id),
+    }
+    return adventure_id, save_point, at_save, at_tip
+
+
+def test_d11_l03_a_save_point_survives_a_real_process_restart(workspace):
+    """D11 and L03 together, across a boundary a same-process test cannot cross.
+
+    The first process writes the campaign and exits. The second process is a
+    different interpreter with an empty session, an empty identity map and no
+    memory of anything — everything it knows, it reads off the disk.
+    """
+    first = workspace()
+    adventure_id, save_point, at_save, at_tip = _campaign_with_a_save_point(first)
+
+    assert at_tip["gold"] == at_save["gold"] + 4 * GOLD_PER_TURN
+    assert len(at_tip["transcript"]) == len(at_save["transcript"]) + 8
+
+    # --- the boundary -----------------------------------------------------
+    first.stop()
+    assert first.proc.poll() is not None, "the first server did not actually exit"
+    assert not first.is_listening(), "the first server is still answering"
+
+    second = workspace()
+    assert second.proc.pid != first.proc.pid
+
+    # --- D11: the Save Point is still there -------------------------------
+    listed = second.call("GET", f"/adventures/{adventure_id}/checkpoints", expect=200)
+    assert [c["id"] for c in listed] == [save_point["id"]]
+    assert listed[0]["name"] == "Before entering the abbey"
+    assert (listed[0]["branch_id"], listed[0]["depth"]) == (
+        save_point["branch_id"], save_point["depth"]
+    )
+    assert listed[0]["resolved"] is True
+    # The story came back too, at the position the first process left it.
+    assert second.transcript(adventure_id) == at_tip["transcript"]
+
+    rows_before_restore = second.total_rows(adventure_id)
+    assert rows_before_restore == at_tip["rows"]
+
+    # --- L03: restoring reconstructs the historical position --------------
+    page = second.call(
+        "POST", f"/adventures/{adventure_id}/checkpoints/{save_point['id']}/restore",
+        expect=200,
+    )
+    assert [a["text"] for a in page["actions"]] == at_save["transcript"]
+    assert second.transcript(adventure_id) == at_save["transcript"]
+    assert second.gold(adventure_id) == at_save["gold"]
+
+    # --- restore deleted nothing, and Redo is still available -------------
+    assert second.total_rows(adventure_id) == rows_before_restore
+    assert page["can_redo"] is True
+    assert second.call("GET", f"/adventures/{adventure_id}", expect=200)["can_redo"] is True
+
+
+def test_the_retained_continuation_is_reachable_after_a_restart(workspace):
+    """The later history is not merely present in the database after a restart —
+    it is still the continuation the story tells, walkable by ordinary Redo."""
+    first = workspace()
+    adventure_id, save_point, at_save, at_tip = _campaign_with_a_save_point(first)
+    first.stop()
+
+    second = workspace()
+    second.call("POST",
+                f"/adventures/{adventure_id}/checkpoints/{save_point['id']}/restore",
+                expect=200)
+    assert second.transcript(adventure_id) == at_save["transcript"]
+
+    steps = 0
+    while second.call("GET", f"/adventures/{adventure_id}", expect=200)["can_redo"]:
+        second.call("POST", f"/adventures/{adventure_id}/redo", expect=200)
+        steps += 1
+        assert steps <= 10, "Redo never stopped"
+
+    assert steps == 4
+    assert second.transcript(adventure_id) == at_tip["transcript"]
+    assert second.gold(adventure_id) == at_tip["gold"]
+    assert second.total_rows(adventure_id) == at_tip["rows"]
+
+
+def test_a_divergent_write_after_a_restart_keeps_the_displaced_future(workspace):
+    """D13's second half, across the boundary: the fork still happens on the
+    write rather than on the restore, and the displaced turns keep their rows."""
+    first = workspace()
+    adventure_id, save_point, at_save, at_tip = _campaign_with_a_save_point(first)
+    first.stop()
+
+    second = workspace()
+    second.call("POST",
+                f"/adventures/{adventure_id}/checkpoints/{save_point['id']}/restore",
+                expect=200)
+    branches_before = second.call("GET", f"/adventures/{adventure_id}/branches",
+                                  expect=200)
+    assert len(branches_before) == 1, "restore must not fork"
+
+    second.play(adventure_id, "go around the back")
+
+    branches_after = second.call("GET", f"/adventures/{adventure_id}/branches",
+                                 expect=200)
+    assert len(branches_after) == 2, "the write should have forked"
+    # Nothing was deleted to achieve it: the tree grew by the new turn only.
+    assert second.total_rows(adventure_id) == at_tip["rows"] + 2
+    # Ordinary Redo no longer offers the displaced future.
+    assert second.call("GET", f"/adventures/{adventure_id}", expect=200)["can_redo"] is False
+    # And the Save Point still names the position it always did.
+    listed = second.call("GET", f"/adventures/{adventure_id}/checkpoints", expect=200)
+    assert (listed[0]["branch_id"], listed[0]["depth"]) == (
+        save_point["branch_id"], save_point["depth"]
+    )

backend/tests/test_prompt_caching.py

@@ -17,10 +17,10 @@ Three things must hold, and each is easy to undo by accident:
 * Moving a section out of the system block does not drop it from the
   token budget. It is still in the prompt.
 
-This file also covers two request-level concerns: preferring one
-OpenRouter upstream, since each upstream holds its own cache, and reading
-back the usage the endpoint reports, so the hit rate is measurable rather
-than assumed.
+This file also covers one request-level concern: reading back the usage
+the endpoint reports, so the hit rate is measurable rather than assumed.
+It covered OpenRouter upstream pinning too, until M2 removed cloud
+provider support.
 
     python -m pytest tests/test_prompt_caching.py -v
 """
@@ -40,50 +40,11 @@ SCHEMA = {
 }
 
 
-# ------------------------------------------------- preferring one upstream
-
-def _routed(endpoint, model):
-    provider = OpenAICompatibleProvider(endpoint, "k", model, "chat", 0)
-    body = {"max_tokens": 100}
-    provider._apply_provider_routing(body)
-    return body
-
-
-def test_openrouter_deepseek_pins_the_upstream():
-    """Each upstream has its own cache, so routing has to be deterministic."""
-    body = _routed("https://openrouter.ai/api/v1", "deepseek/deepseek-v4-flash-0731")
-    assert body["provider"] == {"order": ["deepseek"]}
-
-
-def test_fallbacks_stay_on():
-    """A preference, not a restriction: if deepseek is down the turn still runs
-    somewhere else and merely misses the cache."""
-    body = _routed("https://openrouter.ai/api/v1", "deepseek/deepseek-v4-flash-0731")
-    assert "allow_fallbacks" not in body["provider"]
-
-
-def test_non_openrouter_endpoints_get_no_provider_field():
-    """Ollama and other providers reject fields they do not know. This is
-    the same problem the `reasoning` param works around."""
-    body = _routed("http://localhost:11434/v1", "deepseek/deepseek-v4-flash-0731")
-    assert "provider" not in body
-
-
-def test_unknown_vendors_are_left_alone():
-    """The vendor half of a slug is not reliably a provider slug: Google's
-    models are served by "google-ai-studio", and there is no "google". A guess
-    would be a routing preference naming an upstream that does not exist."""
-    body = _routed("https://openrouter.ai/api/v1", "google/gemma-4-26b-a4b-it:free")
-    assert "provider" not in body
-
-
-# ------------------------------------------------------ reading usage back
-
 def test_usage_is_recorded_from_a_final_chunk():
     """In a stream, the usage block arrives in a final chunk that carries
     no choices, which is why it is read separately from the text
     extraction."""
-    provider = OpenAICompatibleProvider("https://openrouter.ai/api/v1", "k", "m")
+    provider = OpenAICompatibleProvider("http://127.0.0.1:11434/v1", "m")
     assert provider.last_usage is None
     provider._record_usage({"choices": [{"delta": {"content": "hi"}}]})
     assert provider.last_usage is None
@@ -95,7 +56,7 @@ def test_usage_is_recorded_from_a_final_chunk():
 
 
 def test_a_later_chunk_without_usage_does_not_erase_it():
-    provider = OpenAICompatibleProvider("https://openrouter.ai/api/v1", "k", "m")
+    provider = OpenAICompatibleProvider("http://127.0.0.1:11434/v1", "m")
     provider._record_usage({"usage": {"prompt_tokens": 5}})
     provider._record_usage({"choices": [{"delta": {"content": "x"}}]})
     provider._record_usage({"usage": {}})

backend/tests/test_ratelimit_hardening.py

@@ -1,99 +0,0 @@
-"""Regression tests for the X-Forwarded-For rate-limit bypass and the
-per-account login throttle added to close it.
-
-Background: uvicorn's `--forwarded-allow-ips "*"` trusted the leftmost
-`X-Forwarded-For` entry. The client controls that entry, so rotating the
-header issued a fresh rate-limit bucket on every request. `client_ip` now
-reads the hop the trusted edge appends, which is the rightmost one. Login
-also has an email-keyed throttle that no IP trick can weaken.
-
-    python -m pytest tests/test_ratelimit_hardening.py -v
-"""
-import pytest
-
-from app import auth, limits
-
-
-class _Req:
-    """Minimal stand-in for starlette's Request: a header lookup and a peer."""
-
-    def __init__(self, xff: str | None, peer: str | None = "10.0.0.1"):
-        self.headers = {} if xff is None else {"x-forwarded-for": xff}
-        self.client = None if peer is None else type("C", (), {"host": peer})()
-
-
-# ---------- client_ip: the spoof-resistant hop ----------
-
-def test_client_ip_takes_appended_rightmost_hop(monkeypatch):
-    monkeypatch.setattr(limits, "TRUSTED_PROXY_HOPS", 1)
-    # An attacker prepends a fake IP. The edge appends the real one on the right.
-    req = _Req("203.0.113.9, 198.51.100.77")
-    assert limits.client_ip(req) == "198.51.100.77"
-
-
-def test_client_ip_ignores_spoofed_leftmost(monkeypatch):
-    monkeypatch.setattr(limits, "TRUSTED_PROXY_HOPS", 1)
-    # The keyed IP stays the real hop regardless of what the client adds on
-    # the left, so rotating that value no longer creates a new bucket.
-    a = limits.client_ip(_Req("1.1.1.1, 198.51.100.77"))
-    b = limits.client_ip(_Req("2.2.2.2, 198.51.100.77"))
-    c = limits.client_ip(_Req("evil, junk, 198.51.100.77"))
-    assert a == b == c == "198.51.100.77"
-
-
-def test_client_ip_honours_extra_trusted_hops(monkeypatch):
-    monkeypatch.setattr(limits, "TRUSTED_PROXY_HOPS", 2)
-    # Two trusted hops: real client is second from the right.
-    req = _Req("9.9.9.9, 203.0.113.5, 198.51.100.77")
-    assert limits.client_ip(req) == "203.0.113.5"
-
-
-def test_client_ip_falls_back_to_socket_peer():
-    assert limits.client_ip(_Req(None, peer="172.16.0.4")) == "172.16.0.4"
-    assert limits.client_ip(_Req(None, peer=None)) == "unknown"
-
-
-# ---------- per-account login throttle ----------
-
-@pytest.fixture(autouse=True)
-def _multi_user(monkeypatch):
-    monkeypatch.setattr(auth, "MULTI_USER", True)
-    # Isolate the module-level failure map for each test.
-    from collections import defaultdict, deque
-    monkeypatch.setattr(limits, "_login_fails", defaultdict(deque))
-
-
-def test_login_throttle_blocks_after_limit():
-    email = "victim@example.com"
-    # Each attempt up to the limit is allowed and recorded as a failure.
-    for _ in range(limits.LOGIN_FAIL_LIMIT):
-        limits.check_login_allowed(email)      # does not raise
-        limits.note_login_failure(email)
-    # One more failure exceeds the limit.
-    with pytest.raises(limits.HTTPException) as exc:
-        limits.check_login_allowed(email)
-    assert exc.value.status_code == 429
-
-
-def test_login_throttle_is_per_account():
-    for _ in range(limits.LOGIN_FAIL_LIMIT):
-        limits.note_login_failure("a@example.com")
-    with pytest.raises(limits.HTTPException):
-        limits.check_login_allowed("a@example.com")
-    # A different account is unaffected because the throttle keys on email, not IP.
-    limits.check_login_allowed("b@example.com")  # must not raise
-
-
-def test_successful_login_clears_the_streak():
-    email = "typo@example.com"
-    for _ in range(limits.LOGIN_FAIL_LIMIT):
-        limits.note_login_failure(email)
-    limits.note_login_success(email)
-    limits.check_login_allowed(email)  # failure streak cleared, must not raise
-
-
-def test_throttle_is_noop_in_local_mode(monkeypatch):
-    monkeypatch.setattr(auth, "MULTI_USER", False)
-    for _ in range(limits.LOGIN_FAIL_LIMIT * 3):
-        limits.note_login_failure("solo@example.com")
-    limits.check_login_allowed("solo@example.com")  # never throttled locally

backend/tests/test_reasoning_param.py

@@ -1,45 +0,0 @@
-"""What the provider puts in the `reasoning` request field for each budget
-setting: a positive budget asks for thinking, 0 stays silent, -1 turns it off.
-
-    python -m pytest tests/test_reasoning_param.py -v
-"""
-from app.providers.openai_compatible import OpenAICompatibleProvider
-
-
-def _body(reasoning_max_tokens, api_mode="chat", max_tokens=1000):
-    provider = OpenAICompatibleProvider(
-        "https://openrouter.ai/api/v1", "k", "deepseek/deepseek-v4-flash-0731",
-        api_mode, reasoning_max_tokens,
-    )
-    body = {"max_tokens": max_tokens}
-    provider._apply_reasoning_budget(body)
-    return body
-
-
-def test_zero_sends_nothing():
-    """Ollama and other providers reject unknown fields. Sending 0 must not add a `reasoning` field."""
-    assert "reasoning" not in _body(0)
-
-
-def test_positive_budget_adds_thinking_tokens():
-    body = _body(500)
-    assert body["reasoning"] == {"max_tokens": 500}
-    # the story output keeps its own full budget on top of the thinking budget
-    assert body["max_tokens"] == 1500
-
-
-def test_negative_turns_reasoning_off():
-    body = _body(-1)
-    assert body["reasoning"] == {"effort": "none"}
-    # "off" must not inflate the output budget
-    assert body["max_tokens"] == 1000
-
-
-def test_off_is_not_merely_excluded():
-    """`exclude: true` still generates and bills for reasoning tokens. The off setting must omit the field entirely instead of relying on `exclude`."""
-    assert _body(-1)["reasoning"].get("exclude") is None
-
-
-def test_completion_mode_never_sends_reasoning():
-    for budget in (-1, 0, 500):
-        assert "reasoning" not in _body(budget, api_mode="completion")

backend/tests/test_retry_variants.py

@@ -14,18 +14,11 @@ from app.main import app
 from app.providers import ProviderError
 from app.routers import adventures
 
-from fakes import ScriptedProvider
+from fakes import GOLD_SCHEMA, ScriptedProvider, gold_replies, gold_reply
 
-SCHEMA = {"player": {"hp": {"min": 0, "max": 100, "initial": 100}}}
+SCHEMA = GOLD_SCHEMA
 
 # Each turn spends 10 gold, so a double-applied or un-rolled-back attempt shows.
-GOLD_SCRIPT = """
-const modifier = (text) => {
-  state.gold = (state.gold || 0) + 10;
-  return { text };
-};
-modifier(text);
-"""
 
 
 @pytest.fixture()
@@ -41,14 +34,11 @@ def client(monkeypatch):
     setup.flush()
     adv = models.Adventure(
         user_id=user.id, title="Cave", scenario_id=scenario.id,
-        script_state={}, world_state={"player": {"hp": 100}},
+        world_state={"player": {"hp": 100, "gold": 0}},
     )
     setup.add(adv)
     setup.flush()
     setup.add(models.Action(adventure_id=adv.id, type="start", text="You enter a cave."))
-    setup.add(models.AdventureScript(
-        adventure_id=adv.id, position=0, enabled=True, name="Gold", output_js=GOLD_SCRIPT,
-    ))
     setup.commit()
     adv_id, user_id = adv.id, user.id
     setup.close()
@@ -57,9 +47,6 @@ def client(monkeypatch):
     ScriptedProvider.calls = 0
     ScriptedProvider.prompts = []
     monkeypatch.setattr(adventures.turns, "OpenAICompatibleProvider", ScriptedProvider)
-    monkeypatch.setattr(auth, "resolve_provider_config", lambda s: auth.ProviderConfig(
-        "http://fake", "k", "test-model", False))
-    monkeypatch.setattr(limits, "rate_limit", lambda *a, **k: None)
     monkeypatch.setattr(limits, "check_row_cap", lambda *a, **k: None)
 
     def _current_user(db=Depends(get_db)):
@@ -80,7 +67,7 @@ def _adv(adv_id):
     db = SessionLocal()
     try:
         adv = db.get(models.Adventure, adv_id)
-        return adv.script_state, adv.world_state
+        return (adv.world_state or {}).get("player", {}), adv.world_state
     finally:
         db.close()
 
@@ -177,15 +164,15 @@ def test_three_attempts_all_kept_in_order(client):
 
 def test_switching_back_restores_that_attempt_state(client):
     ScriptedProvider.replies = [
-        "You take a scratch.\n```state\n{\"player.hp\": -5}\n```",
-        "You take a beating.\n```state\n{\"player.hp\": -40}\n```",
+        'You take a scratch.\n```state\n{"player.hp": -5, "player.gold": 10}\n```',
+        'You take a beating.\n```state\n{"player.hp": -40, "player.gold": 10}\n```',
     ]
     _play(client)
     assert _adv(client.adv_id)[1]["player"]["hp"] == 95
     _retry(client)
-    script_state, world_state = _adv(client.adv_id)
+    player, world_state = _adv(client.adv_id)
     assert world_state["player"]["hp"] == 60
-    assert script_state == {"gold": 10}  # rolled back, not stacked to 20
+    assert player["gold"] == 10  # rolled back, not stacked to 20
 
     last = _actions(client)[-1]
     r = client.post(
@@ -194,9 +181,9 @@ def test_switching_back_restores_that_attempt_state(client):
     assert r.json()["text"].startswith("You take a scratch")
     assert r.json()["take_index"] == 0
     # The stats follow the narration back.
-    script_state, world_state = _adv(client.adv_id)
+    player, world_state = _adv(client.adv_id)
     assert world_state["player"]["hp"] == 95
-    assert script_state == {"gold": 10}
+    assert player["gold"] == 10
 
     # And forward again.
     client.post(f"/api/adventures/{client.adv_id}/actions/{last['id']}/variant",
@@ -251,26 +238,26 @@ def test_switching_to_a_missing_index_is_rejected(client):
 def test_failed_retry_leaves_the_previous_attempt_in_charge(client):
     """A provider error mid-retry must undo the rollback, or the stats on
     screen would silently disagree with the text still shown."""
-    ScriptedProvider.replies = ["Attempt one.", ProviderError("upstream is down")]
+    ScriptedProvider.replies = [gold_reply("Attempt one."), ProviderError("upstream is down")]
     _play(client)
-    assert _adv(client.adv_id)[0] == {"gold": 10}
+    assert _adv(client.adv_id)[0]["gold"] == 10
 
     client.post(f"/api/adventures/{client.adv_id}/retry")
 
     actions = _actions(client)
     assert actions[-1]["text"] == "Attempt one."  # text never lost
-    assert _adv(client.adv_id)[0] == {"gold": 10}  # and the state still matches it
+    assert _adv(client.adv_id)[0]["gold"] == 10  # and the state still matches it
 
 
 def test_undo_removes_the_action_and_its_history(client):
-    ScriptedProvider.replies = ["One.", "Two."]
+    ScriptedProvider.replies = [gold_reply(t) for t in ["One.", "Two."]]
     _play(client)
     _retry(client)
     r = client.post(f"/api/adventures/{client.adv_id}/undo")
     assert r.status_code == 200, r.text
     # Undo returns the newest window now, not the whole story.
     assert [a["type"] for a in r.json()["actions"]] == ["start"]
-    assert _adv(client.adv_id)[0] == {}
+    assert _adv(client.adv_id)[0]["gold"] == 0
 
 
 def test_editing_the_text_updates_the_live_variant(client):

backend/tests/test_scenario_art.py

@@ -125,7 +125,6 @@ def client(monkeypatch):
     user_id = user.id
     setup.close()
 
-    monkeypatch.setattr(limits, "rate_limit", lambda *a, **k: None)
     monkeypatch.setattr(limits, "check_row_cap", lambda *a, **k: None)
 
     def _current_user(db=Depends(get_db)):

backend/tests/test_scenario_refresh.py

@@ -34,7 +34,6 @@ def client(monkeypatch):
     user_id = user.id
     setup.close()
 
-    monkeypatch.setattr(limits, "rate_limit", lambda *a, **k: None)
     monkeypatch.setattr(limits, "check_row_cap", lambda *a, **k: None)
 
     def _current_user(db=Depends(get_db)):

backend/tests/test_state_revert.py

@@ -1,5 +1,10 @@
-"""Tests for undo and retry rolling back the shared `script_state`
-(plan/11-state-revert-and-retry-fix.md).
+"""Tests for undo and retry rolling back the shared `world_state`.
+
+The state being rolled back was the scripting engine's `script_state` until
+M2 removed campaign scripting. The machinery under test — `attempts.restore_state`,
+`roll_back_before`, and the per-node outcome snapshot — is unchanged; only the
+column it moves has. `world_state`/`world_state_after` is now the shared state
+an adventure carries, so that is what these tests exercise.
 
 Phase 14 SP4 reversed the snapshots. An action used to carry the state as
 it stood before it ran, and rolling back read the snapshot off the action
@@ -36,11 +41,11 @@ def db():
         adventures.turns._active_turns.clear()
 
 
-def _make_adventure(db, script_state):
+def _make_adventure(db, world_state):
     user = models.User(is_guest=False)
     db.add(user)
     db.flush()
-    adv = models.Adventure(user_id=user.id, title="T", script_state=script_state)
+    adv = models.Adventure(user_id=user.id, title="T", world_state=world_state)
     db.add(adv)
     db.flush()
     return user, adv
@@ -49,13 +54,46 @@ def _make_adventure(db, script_state):
 def _add(db, adv, index, type_, text="x", state_after=None):
     a = models.Action(
         adventure_id=adv.id, type=type_, text=text,
-        state_after=state_after,
+        world_state_after=state_after,
     )
     db.add(a)
     db.flush()
     return a
 
 
+def _row_count(db, adv):
+    """Every action row the adventure holds, live or not, head or no head."""
+    return db.query(models.Action).filter_by(adventure_id=adv.id).count()
+
+
+def _all_types(db, adv):
+    """The retained story in depth order, which is not the same as the story
+    being told once the head has moved back behind the tip."""
+    rows = (
+        db.query(models.Action)
+        .filter_by(adventure_id=adv.id)
+        .order_by(models.Action.depth, models.Action.id)
+        .all()
+    )
+    return [a.type for a in rows]
+
+
+def _retrievable(db, adv):
+    """The memories the story can currently reach, read through the same clause
+    `memorybank` retrieves with — which is capped at the active head."""
+    from app.context import lineage
+
+    rows = (
+        db.query(models.Memory)
+        .filter(
+            models.Memory.adventure_id == adv.id,
+            lineage.path_of(db, adv).clause(models.Memory),
+        )
+        .all()
+    )
+    return {m.text for m in rows}
+
+
 def _forget_snapshots(db, adv):
     """Blank every outcome, the way a row written before SP4 looks.
 
@@ -72,19 +110,34 @@ def _forget_snapshots(db, adv):
 # ---------------------------------------------------------------- undo
 
 def test_undo_reverts_state_to_before_the_turn(db):
-    # A turn moved script_state from {gold:0} to {gold:10}. The node in
+    # A turn moved world_state from {gold:0} to {gold:10}. The node in
     # front of the turn records where it started. The current state is
     # the mutated one.
+    #
+    # M3 rewrote what the second half of this test asserts. Undo used to delete
+    # the turn, so the story was short afterwards because the rows were gone.
+    # It now moves the head, so the story is short because it is being read
+    # from somewhere earlier — and the rows are all still there. The state
+    # assertion is unchanged, because `attempts.restore_state` is unchanged:
+    # the state still comes off the node the story now ends on.
     user, adv = _make_adventure(db, {"gold": 10})
     _add(db, adv, 0, "start", state_after={"gold": 0})
     _add(db, adv, 1, "do", state_after={"gold": 0})
     _add(db, adv, 2, "ai", state_after={"gold": 10})
     db.commit()
+    before = _row_count(db, adv)
 
-    adventures.undo_turn(adv.id, db=db, adventure=adv)
+    page = adventures.undo_turn(adv.id, db=db, adventure=adv)
 
-    assert adv.script_state == {"gold": 0}
-    assert [a.type for a in adv.actions] == ["start"]
+    assert adv.world_state == {"gold": 0}
+    # What the story now tells.
+    assert [a.type for a in page.actions] == ["start"]
+    assert adv.head_depth == 0
+    # What it still holds. Zero accepted turns deleted, which is the M3
+    # invariant this file is the closest test to.
+    assert _row_count(db, adv) == before
+    assert _all_types(db, adv) == ["start", "do", "ai"]
+    assert page.can_redo is True
 
 
 def test_undo_of_bare_continue_uses_the_node_in_front(db):
@@ -95,10 +148,30 @@ def test_undo_of_bare_continue_uses_the_node_in_front(db):
     _add(db, adv, 1, "ai", state_after={"gold": 5})
     db.commit()
 
-    adventures.undo_turn(adv.id, db=db, adventure=adv)
+    page = adventures.undo_turn(adv.id, db=db, adventure=adv)
 
-    assert adv.script_state == {"gold": 0}
-    assert [a.type for a in adv.actions] == ["start"]
+    assert adv.world_state == {"gold": 0}
+    assert [a.type for a in page.actions] == ["start"]
+    assert _all_types(db, adv) == ["start", "ai"]
+
+
+def test_redo_puts_back_the_state_the_turn_left_behind(db):
+    """The other half of the same mechanism: undo and redo restore the same
+    snapshot from opposite directions, because it belongs to the node rather
+    than to the direction of travel."""
+    user, adv = _make_adventure(db, {"gold": 10})
+    _add(db, adv, 0, "start", state_after={"gold": 0})
+    _add(db, adv, 1, "do", state_after={"gold": 0})
+    _add(db, adv, 2, "ai", state_after={"gold": 10})
+    db.commit()
+
+    adventures.undo_turn(adv.id, db=db, adventure=adv)
+    page = adventures.redo_turn(adv.id, db=db, adventure=adv)
+
+    assert adv.world_state == {"gold": 10}
+    assert [a.type for a in page.actions] == ["start", "do", "ai"]
+    assert adv.head_depth == 2
+    assert page.can_redo is False
 
 
 def test_undo_leaves_state_untouched_when_snapshot_missing(db):
@@ -112,7 +185,7 @@ def test_undo_leaves_state_untouched_when_snapshot_missing(db):
 
     adventures.undo_turn(adv.id, db=db, adventure=adv)
 
-    assert adv.script_state == {"gold": 10}
+    assert adv.world_state == {"gold": 10}
 
 
 def test_undo_raises_when_nothing_to_undo(db):
@@ -141,20 +214,45 @@ def test_undo_blocked_by_active_turn_lock(db):
         adventures.turns._active_turns.discard(adv.id)
 
 
-def test_undo_prunes_memory_covering_removed_actions(db):
+def test_undo_stops_retrieving_a_memory_without_deleting_it(db):
+    """M3 rewrote this test. Undo used to prune the memories covering the turns
+    it deleted, because those turns were gone and a summary of them described
+    story the adventure no longer had.
+
+    Nothing is deleted now, and nothing needs pruning either. A memory carries
+    the coordinate of the node its block ends on, so one derived from a turn
+    that is now past the head falls outside the head-capped path clause and
+    stops being retrievable — and becomes eligible again on Redo, without having
+    been deleted and re-embedded. That is `STORY-BRANCH-SEMANTICS.md` §33
+    holding as a consequence of the head rather than as its own mechanism.
+    """
     user, adv = _make_adventure(db, {})
     for i in range(4):
         _add(db, adv, i, "ai" if i % 2 else "do", state_after={})
-    # A memory summarizing actions up to index 3, which undo will delete.
-    covering = models.Memory(adventure_id=adv.id, text="m", source_start=0, source_end=3)
-    keep = models.Memory(adventure_id=adv.id, text="k", source_start=0, source_end=1)
+    db.commit()
+    # A memory ending on the turn undo will step behind, and one ending before
+    # it. The coordinate is what the clause reads; `source_*` only says which
+    # stretch the summarizer covered.
+    covering = models.Memory(
+        adventure_id=adv.id, text="m", source_start=0, source_end=3,
+        branch_id=adv.head_branch_id, depth=3,
+    )
+    keep = models.Memory(
+        adventure_id=adv.id, text="k", source_start=0, source_end=1,
+        branch_id=adv.head_branch_id, depth=1,
+    )
     db.add_all([covering, keep])
     db.commit()
 
-    adventures.undo_turn(adv.id, db=db, adventure=adv)  # removes indexes 2 & 3
+    adventures.undo_turn(adv.id, db=db, adventure=adv)  # head moves to depth 1
 
-    texts = {m.text for m in adv.memories}
-    assert texts == {"k"}
+    assert _retrievable(db, adv) == {"k"}
+    # Still on disk, still embedded, still attached to the adventure.
+    assert {m.text for m in adv.memories} == {"k", "m"}
+
+    adventures.redo_turn(adv.id, db=db, adventure=adv)
+
+    assert _retrievable(db, adv) == {"k", "m"}
 
 
 # -------------------------------------------------------- withdrawing a node
@@ -188,24 +286,24 @@ def test_snapshot_outcome_is_an_independent_deep_copy(db):
     _, adv = _make_adventure(db, {"nested": {"n": 1}})
     node = models.Action(adventure_id=adv.id, type="ai", text="x")
     attempts.snapshot_outcome(adv, node)
-    adv.script_state["nested"]["n"] = 99
-    assert node.state_after == {"nested": {"n": 1}}  # unaffected by later mutation
+    adv.world_state["nested"]["n"] = 99
+    assert node.world_state_after == {"nested": {"n": 1}}  # unaffected by later mutation
 
 
 def test_snapshot_outcome_handles_non_dict(db):
     _, adv = _make_adventure(db, {})
-    adv.script_state = None
+    adv.world_state = None
     node = models.Action(adventure_id=adv.id, type="ai", text="x")
     attempts.snapshot_outcome(adv, node)
-    assert node.state_after == {}
+    assert node.world_state_after == {}
 
 
 def test_restore_state_ignores_a_node_with_no_outcome(db):
     _, adv = _make_adventure(db, {"gold": 7})
     attempts.restore_state(adv, models.Action(adventure_id=adv.id, type="ai"))
-    assert adv.script_state == {"gold": 7}
+    assert adv.world_state == {"gold": 7}
     attempts.restore_state(adv, None)
-    assert adv.script_state == {"gold": 7}
+    assert adv.world_state == {"gold": 7}
 
 
 # ---------------------------------------------------------------- retry
@@ -220,8 +318,6 @@ def test_retry_restores_the_state_the_turn_started_from(db, monkeypatch):
     _add(db, adv, 2, "ai", state_after={"gold": 20})
     db.commit()
 
-    monkeypatch.setattr(adventures.limits, "rate_limit", lambda *a, **k: None)
-    monkeypatch.setattr(adventures.turns, "check_demo_cap", lambda *a, **k: None)
 
     async def _noop(*a, **k):
         if False:
@@ -230,12 +326,12 @@ def test_retry_restores_the_state_the_turn_started_from(db, monkeypatch):
 
     adventures.retry_action(adv.id, request=None, db=db, user=user, adventure=adv)
 
-    assert adv.script_state == {"gold": 10}
+    assert adv.world_state == {"gold": 10}
     # Nothing is written until a replacement actually arrives: the attempt on
     # screen is left exactly as it was, and stays the live one.
     assert [a.type for a in adv.actions] == ["start", "do", "ai"]
     last = adv.actions[-1]
     assert last.live is True
     assert len(attempts.group(db, last)) == 1  # no sibling was filed
-    assert last.state_after == {"gold": 20}  # its own outcome, untouched
+    assert last.world_state_after == {"gold": 20}  # its own outcome, untouched
     adventures.turns._active_turns.discard(adv.id)

backend/tests/test_story_tree_baseline.py

@@ -15,7 +15,7 @@ This file must pass unmodified through SP1 (schema), SP2 (branch clause),
 and SP3 (memories on nodes). If a change here looks necessary in one of
 those subphases, the change is wrong, not the test. SP4 is the first
 subphase allowed to move it, and only for the variant-count semantics
-called out in plan/14.
+the story-tree migration changed.
 """
 import pytest
 from fastapi import Depends
@@ -26,20 +26,13 @@ from app.database import Base, SessionLocal, engine, get_db
 from app.main import app
 from app.routers import adventures
 
-from fakes import ScriptedProvider
+from fakes import GOLD_SCHEMA, ScriptedProvider, gold_replies, gold_reply
 
 # A world-state schema, so the RPG layer is exercised rather than skipped.
-SCHEMA = {"player": {"hp": {"min": 0, "max": 100, "initial": 100}}}
+SCHEMA = GOLD_SCHEMA
 
 # Ten gold a turn. A turn that double-applies its hooks, or one that fails to
 # roll back on retry, shows up here as a wrong total rather than as nothing.
-GOLD_SCRIPT = """
-const modifier = (text) => {
-  state.gold = (state.gold || 0) + 10;
-  return { text };
-};
-modifier(text);
-"""
 
 OPENING = "You enter a cave."
 
@@ -59,7 +52,7 @@ def _make_world(monkeypatch, *, seeded_actions: int = 0):
     setup.flush()
     adv = models.Adventure(
         user_id=user.id, title="Cave", scenario_id=scenario.id,
-        script_state={}, world_state={"player": {"hp": 100}},
+        world_state={"player": {"hp": 100, "gold": 0}},
     )
     setup.add(adv)
     setup.flush()
@@ -70,20 +63,14 @@ def _make_world(monkeypatch, *, seeded_actions: int = 0):
             type="ai" if i % 2 else "do",
             text=f"Seeded turn {i}.",
         ))
-    setup.add(models.AdventureScript(
-        adventure_id=adv.id, position=0, enabled=True, name="Gold", output_js=GOLD_SCRIPT,
-    ))
     setup.commit()
     adv_id, user_id = adv.id, user.id
     setup.close()
 
-    ScriptedProvider.replies = ["A reply."]
+    ScriptedProvider.replies = [gold_reply(t) for t in ["A reply."]]
     ScriptedProvider.calls = 0
     ScriptedProvider.prompts = []
     monkeypatch.setattr(adventures.turns, "OpenAICompatibleProvider", ScriptedProvider)
-    monkeypatch.setattr(auth, "resolve_provider_config", lambda s: auth.ProviderConfig(
-        "http://fake", "k", "test-model", False))
-    monkeypatch.setattr(limits, "rate_limit", lambda *a, **k: None)
     monkeypatch.setattr(limits, "check_row_cap", lambda *a, **k: None)
 
     def _current_user(db=Depends(get_db)):
@@ -145,7 +132,7 @@ def _state(adv_id):
     db = SessionLocal()
     try:
         adv = db.get(models.Adventure, adv_id)
-        return adv.script_state, adv.world_state
+        return (adv.world_state or {}).get("player", {}), adv.world_state
     finally:
         db.close()
 
@@ -172,7 +159,7 @@ def test_short_adventure_returns_everything(client):
 # --------------------------------------------------------------- the turn
 
 def test_a_turn_appends_the_player_action_then_the_ai_action(client):
-    ScriptedProvider.replies = ["The dark presses in."]
+    ScriptedProvider.replies = [gold_reply(t) for t in ["The dark presses in."]]
     _play(client, "light a torch")
     actions = _actions(client)
     assert [a["type"] for a in actions] == ["start", "do", "ai"]
@@ -181,7 +168,7 @@ def test_a_turn_appends_the_player_action_then_the_ai_action(client):
 
 
 def test_say_and_story_and_continue_all_work(client):
-    ScriptedProvider.replies = ["One.", "Two.", "Three."]
+    ScriptedProvider.replies = [gold_reply(t) for t in ["One.", "Two.", "Three."]]
     _play(client, "hello", type="say")
     _play(client, "The wind rises.", type="story")
     _play(client, "", type="continue")
@@ -190,7 +177,7 @@ def test_say_and_story_and_continue_all_work(client):
 
 
 def test_the_story_so_far_is_replayed_into_the_prompt(client):
-    ScriptedProvider.replies = ["First.", "Second."]
+    ScriptedProvider.replies = [gold_reply(t) for t in ["First.", "Second."]]
     _play(client, "go north")
     _play(client, "go south")
     story = ScriptedProvider.prompts[-1][1]
@@ -201,7 +188,7 @@ def test_the_story_so_far_is_replayed_into_the_prompt(client):
 
 def test_scripts_run_once_per_turn(client):
     """The gold script adds ten a turn. Two turns is twenty — not forty."""
-    ScriptedProvider.replies = ["One.", "Two."]
+    ScriptedProvider.replies = [gold_reply(t) for t in ["One.", "Two."]]
     _play(client)
     _play(client)
     script_state, _ = _state(client.adv_id)
@@ -211,7 +198,7 @@ def test_scripts_run_once_per_turn(client):
 # ------------------------------------------------------------------ retry
 
 def test_retry_replaces_the_text_and_keeps_the_attempt(client):
-    ScriptedProvider.replies = ["Attempt one.", "Attempt two."]
+    ScriptedProvider.replies = [gold_reply(t) for t in ["Attempt one.", "Attempt two."]]
     _play(client)
     assert _texts(client)[-1] == "Attempt one."
 
@@ -233,7 +220,7 @@ def test_retry_replaces_the_text_and_keeps_the_attempt(client):
 def test_retry_does_not_stack_script_effects(client):
     """The discarded attempt's ten gold is rolled back, so one turn plus one
     retry is still ten, not twenty."""
-    ScriptedProvider.replies = ["Attempt one.", "Attempt two."]
+    ScriptedProvider.replies = [gold_reply(t) for t in ["Attempt one.", "Attempt two."]]
     _play(client)
     client.post(f"/api/adventures/{client.adv_id}/retry")
     script_state, _ = _state(client.adv_id)
@@ -241,7 +228,7 @@ def test_retry_does_not_stack_script_effects(client):
 
 
 def test_switching_back_to_an_earlier_attempt_restores_it(client):
-    ScriptedProvider.replies = ["Attempt one.", "Attempt two."]
+    ScriptedProvider.replies = [gold_reply(t) for t in ["Attempt one.", "Attempt two."]]
     _play(client)
     client.post(f"/api/adventures/{client.adv_id}/retry")
     action_id = _actions(client)[-1]["id"]
@@ -259,7 +246,7 @@ def test_switching_back_to_an_earlier_attempt_restores_it(client):
 def test_only_the_newest_turn_can_be_switched(client):
     """An older turn's alternatives stay readable but not selectable. The
     story after it continues from what is live."""
-    ScriptedProvider.replies = ["One.", "Again.", "Two."]
+    ScriptedProvider.replies = [gold_reply(t) for t in ["One.", "Again.", "Two."]]
     _play(client)
     client.post(f"/api/adventures/{client.adv_id}/retry")
     older_id = _actions(client)[-1]["id"]
@@ -274,7 +261,7 @@ def test_only_the_newest_turn_can_be_switched(client):
 # ------------------------------------------------------------------- undo
 
 def test_undo_removes_the_whole_turn_and_rolls_state_back(client):
-    ScriptedProvider.replies = ["One.", "Two."]
+    ScriptedProvider.replies = [gold_reply(t) for t in ["One.", "Two."]]
     _play(client, "go north")
     _play(client, "go south")
     assert len(_actions(client)) == 5
@@ -365,7 +352,7 @@ def test_paging_past_the_start_reports_the_end(long_client):
 # ------------------------------------------------------- editing and deleting
 
 def test_editing_an_action_sticks(client):
-    ScriptedProvider.replies = ["Original."]
+    ScriptedProvider.replies = [gold_reply(t) for t in ["Original."]]
     _play(client)
     action_id = _actions(client)[-1]["id"]
     r = client.patch(f"/api/adventures/{client.adv_id}/actions/{action_id}",
@@ -380,7 +367,7 @@ def test_editing_an_action_sticks(client):
 def test_editing_a_retried_action_survives_a_reload(client):
     """The edit has to reach the live attempt too, or paging away and back
     reverts it."""
-    ScriptedProvider.replies = ["One.", "Two."]
+    ScriptedProvider.replies = [gold_reply(t) for t in ["One.", "Two."]]
     _play(client)
     client.post(f"/api/adventures/{client.adv_id}/retry")
     action_id = _actions(client)[-1]["id"]
@@ -390,7 +377,7 @@ def test_editing_a_retried_action_survives_a_reload(client):
 
 
 def test_deleting_an_action_removes_it(client):
-    ScriptedProvider.replies = ["One."]
+    ScriptedProvider.replies = [gold_reply(t) for t in ["One."]]
     _play(client)
     action_id = _actions(client)[-1]["id"]
     r = client.delete(f"/api/adventures/{client.adv_id}/actions/{action_id}")
@@ -431,7 +418,7 @@ def test_export_carries_the_whole_story(client):
     same fact: a bundle that stores coordinates has no use for a repeating
     group. Everything else here still passes unmodified.
     """
-    ScriptedProvider.replies = ["One.", "Two."]
+    ScriptedProvider.replies = [gold_reply(t) for t in ["One.", "Two."]]
     _play(client, "go north")
     _play(client, "go south")
 
@@ -446,7 +433,7 @@ def test_export_carries_the_whole_story(client):
 
 
 def test_export_round_trips_through_import(client):
-    ScriptedProvider.replies = ["One."]
+    ScriptedProvider.replies = [gold_reply(t) for t in ["One."]]
     _play(client, "go north")
     bundle = client.get(f"/api/adventures/{client.adv_id}/export").json()
 
@@ -461,7 +448,7 @@ def test_export_round_trips_through_import(client):
 
 
 def test_export_keeps_retry_attempts(client):
-    ScriptedProvider.replies = ["Attempt one.", "Attempt two."]
+    ScriptedProvider.replies = [gold_reply(t) for t in ["Attempt one.", "Attempt two."]]
     _play(client)
     client.post(f"/api/adventures/{client.adv_id}/retry")
 
@@ -474,7 +461,7 @@ def test_export_keeps_retry_attempts(client):
 # -------------------------------------------------------------- world state
 
 def test_world_state_is_readable_and_survives_a_turn(client):
-    ScriptedProvider.replies = ["Nothing changes."]
+    ScriptedProvider.replies = [gold_reply(t) for t in ["Nothing changes."]]
     _play(client)
     r = client.get(f"/api/adventures/{client.adv_id}/world-state")
     assert r.status_code == 200, r.text

backend/tests/test_take_edit.py

@@ -57,9 +57,6 @@ def client(monkeypatch):
     ScriptedProvider.replies = [f"Take {n}." for n in range(1, 40)]
     ScriptedProvider.calls = 0
     monkeypatch.setattr(adventures.turns, "OpenAICompatibleProvider", ScriptedProvider)
-    monkeypatch.setattr(auth, "resolve_provider_config", lambda s: auth.ProviderConfig(
-        "http://fake", "k", "test-model", False))
-    monkeypatch.setattr(limits, "rate_limit", lambda *a, **k: None)
     monkeypatch.setattr(limits, "check_row_cap", lambda *a, **k: None)
 
     def _current_user(db=Depends(get_db)):

backend/tests/test_take_parentage.py

@@ -58,12 +58,6 @@ def client(monkeypatch):
     ScriptedProvider.replies = [f"Take {n}." for n in range(1, 40)]
     ScriptedProvider.calls = 0
     monkeypatch.setattr(adventures.turns, "OpenAICompatibleProvider", ScriptedProvider)
-    monkeypatch.setattr(
-        auth,
-        "resolve_provider_config",
-        lambda s: auth.ProviderConfig("http://fake", "k", "test-model", False),
-    )
-    monkeypatch.setattr(limits, "rate_limit", lambda *a, **k: None)
     monkeypatch.setattr(limits, "check_row_cap", lambda *a, **k: None)
 
     def _current_user(db=Depends(get_db)):

backend/tests/test_take_state.py

@@ -24,20 +24,14 @@ from app.database import Base, SessionLocal, engine, get_db
 from app.main import app
 from app.routers import adventures
 
-from fakes import ScriptedProvider
+from fakes import GOLD_SCHEMA, ScriptedProvider, gold_replies, gold_reply
 
-SCHEMA = {"player": {"hp": {"min": 0, "max": 100, "initial": 100}}}
+SCHEMA = GOLD_SCHEMA
 
-# Ten gold a turn, every turn. A number that only ever increases makes a
-# rollback failure obvious: if a take stacks instead of replacing, the gold
-# total is off by exactly one turn's worth.
-GOLD_SCRIPT = """
-const modifier = (text) => {
-  state.gold = (state.gold || 0) + 10;
-  return { text };
-};
-modifier(text);
-"""
+# Ten gold a turn, every turn, banked through the world-state engine. A number
+# that only ever increases makes a rollback failure obvious: if a take stacks
+# instead of replacing, the gold total is off by exactly one turn's worth. See
+# `fakes.gold_reply` for why this is not a script any more.
 
 
 @pytest.fixture()
@@ -53,24 +47,18 @@ def client(monkeypatch):
     setup.flush()
     adv = models.Adventure(
         user_id=user.id, title="Vault", scenario_id=scenario.id,
-        script_state={}, world_state={"player": {"hp": 100}},
+        world_state={"player": {"hp": 100, "gold": 0}},
     )
     setup.add(adv)
     setup.flush()
     setup.add(models.Action(adventure_id=adv.id, type="start", text="You begin."))
-    setup.add(models.AdventureScript(
-        adventure_id=adv.id, position=0, enabled=True, name="Gold", output_js=GOLD_SCRIPT,
-    ))
     setup.commit()
     adv_id, user_id = adv.id, user.id
     setup.close()
 
-    ScriptedProvider.replies = [f"Take {n}." for n in range(1, 40)]
+    ScriptedProvider.replies = gold_replies("Take", 39)
     ScriptedProvider.calls = 0
     monkeypatch.setattr(adventures.turns, "OpenAICompatibleProvider", ScriptedProvider)
-    monkeypatch.setattr(auth, "resolve_provider_config", lambda s: auth.ProviderConfig(
-        "http://fake", "k", "test-model", False))
-    monkeypatch.setattr(limits, "rate_limit", lambda *a, **k: None)
     monkeypatch.setattr(limits, "check_row_cap", lambda *a, **k: None)
 
     def _current_user(db=Depends(get_db)):
@@ -107,7 +95,7 @@ def _take(client, action_id, text=""):
 def _gold(adv_id) -> int:
     db = SessionLocal()
     try:
-        return (db.get(models.Adventure, adv_id).script_state or {}).get("gold", 0)
+        return (db.get(models.Adventure, adv_id).world_state or {}).get("player", {}).get("gold", 0)
     finally:
         db.close()
 

backend/tests/test_tree_migration.py

@@ -31,8 +31,7 @@ from app.main import app
 # The three tables as they stood at schema 45, frozen. This is a snapshot
 # of a past schema. It must not be updated to track `models.py`, because
 # the whole point is that it lacks what SP1 adds. This DDL uses SQLite
-# syntax only. The migration's Postgres half is exercised against a real
-# server at deploy time (see plan/14).
+# syntax only.
 PRE_TREE_DDL = (
     """
     CREATE TABLE adventures (
@@ -120,7 +119,12 @@ def pre_tree():
         # Dropping the tables is the only way to remove the columns.
         # SQLite refuses to drop a column that a foreign key references,
         # and that is exactly the case for `branch_id`.
-        for table in ("actions", "memories", "branches", "adventures"):
+        #
+        # `checkpoints` (M4) is dropped first and for a different reason: it
+        # references both `branches` and `adventures`, and SQLite refuses to
+        # drop a table another table still points at. Any future table that
+        # references these four has to be added to the front of this list.
+        for table in ("checkpoints", "actions", "memories", "branches", "adventures"):
             conn.execute(text(f"DROP TABLE IF EXISTS {table}"))
         for ddl in PRE_TREE_DDL:
             conn.execute(text(ddl))
@@ -397,7 +401,6 @@ def client(monkeypatch):
     user_id, scenario_id = user.id, scenario.id
     setup.close()
 
-    monkeypatch.setattr(limits, "rate_limit", lambda *a, **k: None)
     monkeypatch.setattr(limits, "check_row_cap", lambda *a, **k: None)
 
     def _current_user(db=Depends(get_db)):
@@ -594,7 +597,7 @@ def pre_split():
     Base.metadata.drop_all(bind=engine)
     Base.metadata.create_all(bind=engine)
     with engine.begin() as conn:
-        for table in ("actions", "memories", "branches", "adventures"):
+        for table in ("checkpoints", "actions", "memories", "branches", "adventures"):
             conn.execute(text(f"DROP TABLE IF EXISTS {table}"))
         for ddl in PRE_TREE_DDL:
             conn.execute(text(ddl))

backend/tests/test_turn_flow_integration.py

@@ -1,9 +1,11 @@
 """End-to-end HTTP tests for undo and retry state revert. These tests drive
-real turns through the actual routes and scripting engine, with only the LLM
-provider mocked.
+real turns through the actual routes and the world-state engine, with only the
+LLM provider mocked.
 
-A script's output hook adds 10 gold each turn. These tests confirm that the
-adventure's stored gold total stays correct across play, undo, and retry.
+The model banks 10 gold each turn through its ```state delta block. These tests
+confirm that the adventure's stored gold total stays correct across play, undo,
+and retry. It was a JavaScript output hook that added the gold until M2 removed
+campaign scripting; the state machinery under test is the same either way.
 
     python -m pytest tests/test_turn_flow_integration.py -v
 """
@@ -16,15 +18,8 @@ from app.database import Base, SessionLocal, engine, get_db
 from app.main import app
 from app.routers import adventures
 
-from fakes import ScriptedProvider
+from fakes import GOLD_SCHEMA, ScriptedProvider, gold_replies, gold_reply
 
-GOLD_SCRIPT = """
-const modifier = (text) => {
-  state.gold = (state.gold || 0) + 10;
-  return { text };
-};
-modifier(text);
-"""
 
 
 AI_REPLY = "The torch flickers as you press onward."
@@ -38,24 +33,21 @@ def client(monkeypatch):
     setup.add(user)
     setup.flush()
     setup.add(models.Settings(user_id=user.id, api_key="enc:dummy", model="test-model"))
-    adv = models.Adventure(user_id=user.id, title="Cave", script_state={})
+    scenario = models.Scenario(user_id=user.id, title="S", stat_schema=GOLD_SCHEMA)
+    setup.add(scenario)
+    setup.flush()
+    adv = models.Adventure(user_id=user.id, title="Cave", scenario_id=scenario.id,
+                           world_state={"player": {"hp": 100, "gold": 0}})
     setup.add(adv)
     setup.flush()
     setup.add(models.Action(adventure_id=adv.id, type="start", text="You enter a cave."))
-    setup.add(models.AdventureScript(
-        adventure_id=adv.id, position=0, enabled=True, name="Gold",
-        output_js=GOLD_SCRIPT,
-    ))
     setup.commit()
     adv_id, user_id = adv.id, user.id
     setup.close()
 
     # Force a real, non-demo turn that uses the fake provider.
-    ScriptedProvider.replies = [AI_REPLY]
+    ScriptedProvider.replies = [gold_reply(AI_REPLY)]
     monkeypatch.setattr(adventures.turns, "OpenAICompatibleProvider", ScriptedProvider)
-    monkeypatch.setattr(auth, "resolve_provider_config", lambda s: auth.ProviderConfig(
-        "http://fake", "k", "test-model", False))
-    monkeypatch.setattr(limits, "rate_limit", lambda *a, **k: None)
     monkeypatch.setattr(limits, "check_row_cap", lambda *a, **k: None)
 
     def _current_user(db=Depends(get_db)):
@@ -73,10 +65,13 @@ def client(monkeypatch):
         Base.metadata.drop_all(bind=engine)
 
 
-def _state(adv_id):
+def _gold(adv_id) -> int:
+    """The banked total. Reading one stat rather than the whole section keeps
+    these assertions about the rollback, not about the schema's shape."""
     db = SessionLocal()
     try:
-        return db.get(models.Adventure, adv_id).script_state
+        player = (db.get(models.Adventure, adv_id).world_state or {}).get("player", {})
+        return player.get("gold", 0)
     finally:
         db.close()
 
@@ -88,38 +83,38 @@ def _play(client, type_="do", text="look around"):
 
 
 def test_play_then_undo_reverts_gold(client):
-    assert _state(client.adv_id) == {}
+    assert _gold(client.adv_id) == 0
     _play(client)
-    assert _state(client.adv_id) == {"gold": 10}
+    assert _gold(client.adv_id) == 10
 
     r = client.post(f"/api/adventures/{client.adv_id}/undo")
     assert r.status_code == 200, r.text
-    assert _state(client.adv_id) == {}  # gold reverted to zero
+    assert _gold(client.adv_id) == 0  # gold reverted to zero
 
 
 def test_two_turns_then_undo_reverts_only_last(client):
     _play(client)
     _play(client)
-    assert _state(client.adv_id) == {"gold": 20}
+    assert _gold(client.adv_id) == 20
 
     client.post(f"/api/adventures/{client.adv_id}/undo")
-    assert _state(client.adv_id) == {"gold": 10}  # back to after turn 1, not 0
+    assert _gold(client.adv_id) == 10  # back to after turn 1, not 0
 
 
 def test_retry_does_not_double_apply_gold(client):
     _play(client)
-    assert _state(client.adv_id) == {"gold": 10}
+    assert _gold(client.adv_id) == 10
 
-    # Before the fix, this produced 20 because the output hook ran twice.
+    # Before the fix, this produced 20 because the turn's effects ran twice.
     # Now it stays 10.
     r = client.post(f"/api/adventures/{client.adv_id}/retry")
     assert r.status_code == 200, r.text
-    assert _state(client.adv_id) == {"gold": 10}
+    assert _gold(client.adv_id) == 10
 
 
 def test_retry_then_undo_still_clean(client):
     _play(client)
     client.post(f"/api/adventures/{client.adv_id}/retry")
-    assert _state(client.adv_id) == {"gold": 10}
+    assert _gold(client.adv_id) == 10
     client.post(f"/api/adventures/{client.adv_id}/undo")
-    assert _state(client.adv_id) == {}
+    assert _gold(client.adv_id) == 0

backend/tests/test_worldstate_integration.py

@@ -63,9 +63,6 @@ def client(monkeypatch):
 
     ScriptedProvider.replies = [AI_REPLY]
     monkeypatch.setattr(adventures.turns, "OpenAICompatibleProvider", ScriptedProvider)
-    monkeypatch.setattr(auth, "resolve_provider_config", lambda s: auth.ProviderConfig(
-        "http://fake", "k", "test-model", False))
-    monkeypatch.setattr(limits, "rate_limit", lambda *a, **k: None)
     monkeypatch.setattr(limits, "check_row_cap", lambda *a, **k: None)
 
     def _current_user(db=Depends(get_db)):

backend/tools/memory_ab.py

@@ -4,10 +4,9 @@ Reviewing a prompt tells you what it asks for. It does not tell you what a model
 does with it. This runs the real pipeline twice over the *same* blocks of the
 *same* story, changing only the prompt, and prints the memories side by side.
 
-What it showed the first time it was run, and why `MEMORY_MAX_WORDS` exists, is
-written up in `plan/18-persona-and-memory-quality.md`. Two consecutive memories
-from one story came back in two different persons, and the same model wrote 34
-words for one block and 105 for the next.
+Why `MEMORY_MAX_WORDS` exists is what it showed the first time it was run: two
+consecutive memories from one story came back in two different persons, and the
+same model wrote 34 words for one block and 105 for the next.
 
 Three things make it a fair test rather than a demonstration:
 

backend/tools/rewrite_memories.py

@@ -56,66 +56,22 @@ Usage, from `backend/`:
     python -m tools.rewrite_memories --write --limit 3   # try three of them
     python -m tools.rewrite_memories --write --embed     # the whole backfill
 
-Without `--write` it makes no model calls, spends nothing, and only reports the
-scope. Every run reads the database the app reads: `AIDND_DB_PATH`, or
-`DATABASE_URL` for a hosted Postgres. Take a copy of it first — the old text is
-overwritten and is not kept anywhere.
+Without `--write` it makes no model calls and only reports the scope. Every run
+reads the database the app reads, at `AIDND_DB_PATH`. Take a copy of it first —
+the old text is overwritten and is not kept anywhere.
 
-**On the hosted deploy, name whose adventures you mean.** That database holds
-other people's stories, and each adventure is summarized with *its owner's* key,
-so an unfiltered `--write` spends other people's money on memories they did not
-ask to have rewritten. `--email` restricts the run to the accounts you name and
-`--adventure` to single adventures; a dry run costs nothing and lists both, with
-the owner of each. Guests have no email and can only be reached by id.
-
-Two environment variables reach that database from a checkout. In PowerShell,
-which is where this project is developed, they are set first and then persist
-for the rest of the session:
-
-    $env:AIDND_DATABASE_URL = Read-Host 'Neon URL'
-    $env:AIDND_SECRET_KEY = Read-Host 'Secret key'
-    .venv\Scripts\python.exe -m tools.rewrite_memories --email you@example.com
-
-`Read-Host` keeps both values out of the PowerShell history file. On a POSIX
-shell the same thing is one line:
-
-    AIDND_DATABASE_URL=... AIDND_SECRET_KEY=... \
-        python -m tools.rewrite_memories --email you@example.com
-
-`AIDND_SECRET_KEY` is not optional there. Stored API keys are encrypted with it,
-and with the wrong one `decrypt_secret` returns "" and every adventure is skipped
-as having no key (see `security.py`). The deployed image does not carry this
-directory — the Dockerfile copies `backend/app` alone — so run it from a
-checkout against the hosted database rather than from a shell on the box.
+`--adventure` restricts the run to single adventures, and a dry run lists what
+would change. The deployed image does not carry this directory — the Dockerfile
+copies `backend/app` alone — so run it from a checkout.
 """
 import argparse
 import asyncio
 import sys
 from pathlib import Path
 
-from urllib.parse import urlsplit
-
 from sqlalchemy import func, inspect as sa_inspect, select
 
 
-def safe_dsn(url: str) -> str:
-    """A connection string with the credentials taken out.
-
-    The report says which database it is about to rewrite, which is worth
-    printing. The password in a Neon URL is not: this output goes to a console,
-    a screenshot, or a pasted bug report, and the operator has no way to know
-    the line carried a credential until it is somewhere else.
-    """
-    parsed = urlsplit(url)
-    if not parsed.hostname:
-        return "(configured)"
-    who = f"{parsed.username}@" if parsed.username else ""
-    port = f":{parsed.port}" if parsed.port else ""
-    # The query string is dropped whole. `sslmode` is the only part anyone
-    # wants to see, and some drivers accept a password there too.
-    return f"{parsed.scheme}://{who}{parsed.hostname}{port}{parsed.path}"
-
-
 def words(text: str) -> int:
     return len(text.split())
 
@@ -127,16 +83,16 @@ def one_line(text: str, width: int = 96) -> str:
 
 async def main(args) -> int:
     from app import memorybank, models
-    from app.database import DB_PATH, DATABASE_URL, SessionLocal
+    from app.database import DB_PATH, SessionLocal
     from app.providers import OpenAICompatibleProvider, ProviderError
 
     db = SessionLocal()
-    print(f"database: {safe_dsn(DATABASE_URL) if DATABASE_URL else DB_PATH}")
+    print(f"database: {DB_PATH}")
     if not sa_inspect(db.get_bind()).has_table(models.Adventure.__tablename__):
         # A mistyped path creates an empty SQLite file rather than failing, so
         # say what is wrong instead of raising "no such table: adventures".
-        print("There are no tables here. Point AIDND_DB_PATH, or DATABASE_URL "
-              "for a hosted deploy, at the database the app uses.")
+        print("There are no tables here. Point AIDND_DB_PATH at the database "
+              "the app uses.")
         return 2
 
     adventures = db.query(models.Adventure).order_by(models.Adventure.id)
@@ -177,14 +133,13 @@ async def main(args) -> int:
 
     def provider_for(settings: models.Settings) -> OpenAICompatibleProvider:
         """The adventure owner's own summarizer, unless the run overrides it."""
-        if not (args.endpoint or args.model or args.api_key):
+        if not (args.endpoint or args.model):
             return memorybank.summary_provider(settings)
         return OpenAICompatibleProvider(
             args.endpoint or settings.endpoint_url,
-            args.api_key or settings.api_key_plain,
             args.model or settings.summary_model or settings.model,
             settings.api_mode,
-            settings.reasoning_max_tokens,
+            settings.model_timeout_seconds,
         )
 
     totals = {"rewritten": 0, "would rewrite": 0, "no source": 0,
@@ -205,11 +160,11 @@ async def main(args) -> int:
             continue
 
         settings = settings_for(adventure.user_id)
-        # An adventure whose owner has no key is reported rather than skipped
-        # silently: it is the one reason a memory this tool can rewrite is left
-        # alone, and the operator can fix it with --api-key.
+        # An adventure with no model configured is reported rather than
+        # skipped silently: it is the one reason a memory this tool can rewrite
+        # is left alone, and the operator can fix it with --model.
         usable = settings is not None and bool(
-            args.api_key or args.endpoint or settings.api_key_plain
+            args.model or settings.summary_model or settings.model
         )
         owner = db.get(models.User, adventure.user_id)
         who = (owner.email if owner and owner.email
@@ -333,7 +288,6 @@ if __name__ == "__main__":
                         help="re-embed here. Stop the app first; see the docstring.")
     parser.add_argument("--endpoint", help="override the owner's endpoint URL.")
     parser.add_argument("--model", help="override the owner's summary model.")
-    parser.add_argument("--api-key", help="override the owner's API key.")
     args = parser.parse_args()
 
     # A Windows console defaults to cp1252, which cannot encode the arrow this