Keep the local Claude test rig, and record what it found

`backend/tools/claude_shim.py` serves an OpenAI-compatible endpoint backed by
the local `claude` command line tool, so a demo can be played against a real
model with no 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.

Playing the Pokemon demo through it made all five of the world-state changes in
`plan/16` work, and the refusal loop ran end to end for the first time: turn 3
clamped to nothing, turn 4's assembled prompt carried the correction verbatim,
and the model's next delta was right. Two failures previously blamed on the
code were the demo model. One is a schema fault and is still open: Milo's three
Pokemon share one `active_hp` stat, so a switch leaves the newcomer at 0 HP.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PacdRuPXSkQQy4ZYdH32hF

plan/16-world-state-refusals.md

@@ -231,3 +231,95 @@ old cap made the reset unreachable in one turn.
 
 **Not fixed:** the `initial == max` shape itself. It is now loud rather than
 silent, and the wording removes the usual cause, but the shape is still there.
+
+---
+
+## Driven against Claude, 2026-08-28
+
+The four turns above ran on the free demo model, which ignored two instructions
+that were present and correct in the prompt. To separate model behavior from
+code, the same demo was played again through `backend/tools/claude_shim.py`, an
+OpenAI-compatible endpoint backed by the local `claude` command line tool. The
+model was `sonnet`. See the README for how to run it.
+
+Every one of the five changes worked:
+
+| Turn | Chips |
+|---|---|
+| 1 | `turn +1`, `active pokemon → Wartortle`, `wartortle hp -8`, `milo active hp -46`, dashed `type advantage used refused — no such flag` |
+| 2 | `turn +1`, `milo active hp -52`, `milo pokemon fainted +1`, `milo active pokemon → Onix`, `✓ graveler defeated` |
+| 3 | `turn +1 (limited)`, dashed `milo active hp no change — at its limit` |
+| 4 | `turn +1`, `milo active hp +32`, `✓ type advantage used` |
+
+`graveler_defeated` fired for the first time in five playtests, `world.turn`
+moved every turn, `pokemon_fainted` went 0 to 1 at the faint, and every HP number
+was a signed change rather than a total. The two failures left open above were
+the demo model, not the instructions.
+
+**The refusal loop is verified end to end.** Turn 3 clamped to nothing. Turn 4's
+assembled prompt, read from `GET /api/adventures/1/actions/9/context`, carried
+the correction verbatim:
+
+```
+[Part of your last state block was not applied. Correct it in this turn's block:
+- `npc.milo.active_hp` did not move. It is already at its minimum of 0 (it runs
+  from 0 to 98; it moves at most 98 per turn).]
+```
+
+The model's next delta was `{"world.turn": 1, "npc.milo.active_hp": 32,
+"milestones.type_advantage_used": true}`. That is the loop the whole change
+exists for, and it had never been observed running.
+
+### The one bug that is still a schema fault
+
+At the faint the model set `npc.milo.active_pokemon` to `Onix` and sent no
+positive `active_hp` change, so Onix arrived on the field at 0 of 98 and every
+later hit was refused. Sonnet followed the rest of the scenario closely, so this
+is the schema rather than the model: `active_hp` is one stat with one `max` of
+98, shared by Graveler at 98, Onix at 90, and Kabutops at 88. A switch has to
+raise it, and nothing in the schema can raise it on the referee's side.
+
+The fix is to give Milo's three Pokemon their own NPC entries, which also removes
+the `initial == max` shape from this demo. Not done: the session's remaining time
+went to the guest starter instead.
+
+### Cost
+
+About $0.04 a turn, billed against the Claude subscription rather than a card.
+Roughly 13k of each request's 20k prompt tokens is the command line tool's own
+overhead; the app's prompt is about 7k.
+
+---
+
+## What shipped alongside it, 2026-08-28
+
+**A permanent local test rig.** `backend/tools/claude_shim.py` is now in the
+repo. It finds the `claude` binary through `AIDND_CLAUDE_BIN`, then `PATH`, then
+the per-user install, and takes `--port` and `--claude`.
+
+**The demo says Pokemon in its title, and has a Pokeball for cover art.**
+`05-league-championship.json` is now `[Demo] Pokemon League Championship: Round
+One`. Renaming a seed exposed a fault: `seed.py` matches a seed to its row by
+title, so a rename inserted a second public scenario and stranded the first,
+which is the same failure this file records for "Road to the Champion". Seeds
+now carry `previous_titles`, and `_find_renamed` lands the rename on the
+existing row. The scenario kept its id, and no orphan appeared.
+
+The cover art is a 3.2 kB PNG data URI. An SVG one was tried first and stored as
+an empty `image_url`: `app/images.py` accepts raster formats only, on purpose,
+because SVG can carry script and these bytes are served from the app's own
+origin. `backend/tools/make_pokeball.py` draws the ball with `zlib` alone, so
+regenerating it needs no image library.
+
+**Every new guest gets the played adventure.** `app/starter.py` copies a shipped
+export bundle into each new guest account, from the guest mint in
+`routers/auth.py`. The bundle is this session's adventure trimmed to its first
+two exchanges, which ends on the knockout and shows an applied change, a refused
+one, and a milestone. It stops before the Onix bug above, and the state it
+leaves has Onix at its own 90 HP so a guest can play on from it.
+
+The row building that `POST /adventures/import` did inline moved into
+`bundle.materialize`, which both callers now use. The limit and rate checks
+stayed in the endpoint: the starter writes a file the server ships, so it has no
+untrusted list to cap. `tests/test_starter_adventure.py` covers the file, the
+copy, the chips, the playable end state, and the two failure paths.