interactive-story/backend/tests/test_branch_management.py

"""Phase 14 SP7 — naming a branch, and throwing one away.

SP5 gave the tree a fork and a switch. Neither of them ever removes anything,
and nothing in the design prunes a tree on its own, so an adventure that is
retried and forked enough grows without a ceiling. Delete is what stands
between the tree and that, which is why it ships with the view that first makes
a fork reachable rather than in some later subphase.

Two rules carry most of this file:

* **A name is chosen, so it is stored; a label is derived, so it is not.** An
  unnamed branch keeps NULL and the client draws it from its fork depth. A
  generated "branch 4" in the column would be a lie the moment branch 3 is
  deleted.
* **The delete may never take the ground under the reader.** Refusing the head
  is the obvious half; refusing an *ancestor* of the head is the same mistake
  wearing a disguise, and it is the one that would leave `head_branch_id`
  pointing at a row the cascade removed.

    python -m pytest tests/test_branch_management.py -v
"""
import os
import tempfile

_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
_tmp.close()
os.environ["AIDND_DB_PATH"] = _tmp.name
os.environ.pop("AIDND_DATABASE_URL", None)
os.environ.pop("DATABASE_URL", None)

import pytest
from fastapi import Depends
from fastapi.testclient import TestClient
from sqlalchemy import select

from app import auth, limits, models, schemas
from app.context import cursors, lineage
from app.database import Base, SessionLocal, engine, get_db
from app.main import app
from app.providers import PromptParts
from app.routers import adventures


class ScriptedProvider:
    replies: list = []
    calls = 0

    def __init__(self, *a, **k):
        pass

    async def generate(self, parts: PromptParts, *, temperature, max_tokens):
        index = min(ScriptedProvider.calls, len(ScriptedProvider.replies) - 1)
        ScriptedProvider.calls += 1
        yield ("text", ScriptedProvider.replies[index])


@pytest.fixture()
def client(monkeypatch):
    Base.metadata.create_all(bind=engine)
    setup = SessionLocal()
    user = models.User(is_guest=False, email="branches@example.com")
    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={}, world_state={},
    )
    setup.add(adv)
    setup.flush()
    setup.add(models.Action(
        adventure_id=adv.id, index=0, type="start", text="You enter a cave."))
    setup.commit()
    adv_id, user_id = adv.id, user.id
    setup.close()

    ScriptedProvider.replies = ["Attempt one.", "Attempt two.", "Next turn."]
    ScriptedProvider.calls = 0
    monkeypatch.setattr(adventures, "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)):
        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._active_turns.clear()
        Base.metadata.drop_all(bind=engine)


# ------------------------------------------------------------------ helpers

def _play(client, text="look around"):
    r = client.post(f"/api/adventures/{client.adv_id}/actions",
                    json={"type": "do", "text": text})
    assert r.status_code == 200, r.text


def _retry(client):
    r = client.post(f"/api/adventures/{client.adv_id}/retry")
    assert r.status_code == 200, r.text


def _branches(client) -> list[dict]:
    r = client.get(f"/api/adventures/{client.adv_id}/branches")
    assert r.status_code == 200, r.text
    return r.json()


def _rename(client, branch_id, name):
    return client.patch(f"/api/adventures/{client.adv_id}/branches/{branch_id}",
                        json={"name": name})


def _delete(client, branch_id):
    return client.delete(f"/api/adventures/{client.adv_id}/branches/{branch_id}")


def _switch(client, branch_id):
    return client.post(f"/api/adventures/{client.adv_id}/branches/{branch_id}/switch")


def _texts(client) -> list[str]:
    return [
        a["text"]
        for a in client.get(f"/api/adventures/{client.adv_id}").json()["actions"]
    ]


def _discarded_on(adv_id, branch_id=None) -> int:
    """An AI attempt nobody built on, optionally restricted to one branch."""
    db = SessionLocal()
    try:
        q = db.query(models.Action).filter(
            models.Action.adventure_id == adv_id,
            models.Action.type == "ai",
            models.Action.live.is_(False),
        )
        if branch_id is not None:
            q = q.filter(models.Action.branch_id == branch_id)
        return q.order_by(models.Action.id).first().id
    finally:
        db.close()


def _forked(client):
    """A story with one fork. Returns (root id, forked id); the fork is head.

        start · do · [attempt one | ATTEMPT TWO] · do · next turn
                          └── forked here
    """
    _play(client)
    _retry(client)
    _play(client, "go deeper")
    root = _branches(client)[0]["id"]
    r = client.post(
        f"/api/adventures/{client.adv_id}/actions/{_discarded_on(client.adv_id)}/fork")
    assert r.status_code == 200, r.text
    forked = [b for b in _branches(client) if b["id"] != root][0]["id"]
    return root, forked


def _counts(adv_id, branch_ids):
    db = SessionLocal()
    try:
        return (
            db.query(models.Action)
            .filter(models.Action.branch_id.in_(branch_ids)).count(),
            db.query(models.Memory)
            .filter(models.Memory.branch_id.in_(branch_ids)).count(),
        )
    finally:
        db.close()


# ------------------------------------------------------------------ naming

def test_a_branch_starts_unnamed(client):
    """NULL, not a generated label — the client draws one from the fork depth.

    A name written here would go stale the moment a branch before it is
    deleted and the ordinals shift under it.
    """
    root, forked = _forked(client)
    assert [b["name"] for b in _branches(client)] == [None, None]


def test_a_name_is_stored_and_read_back(client):
    root, forked = _forked(client)
    r = _rename(client, forked, "the cellar")
    assert r.status_code == 200, r.text
    assert r.json()["name"] == "the cellar"
    assert {b["id"]: b["name"] for b in _branches(client)} == {
        root: None, forked: "the cellar",
    }


def test_a_blank_name_goes_back_to_unnamed(client):
    """A name of spaces is not a name anyone chose.

    Storing one would give the client an empty label to draw where it would
    otherwise fall back to the fork depth — a branch that looks nameless and
    reads as broken.
    """
    root, forked = _forked(client)
    _rename(client, forked, "briefly named")
    assert _rename(client, forked, "   ").json()["name"] is None
    assert _rename(client, forked, None).json()["name"] is None


def test_a_name_longer_than_the_column_is_refused(client):
    """422 here rather than a 500 at INSERT: Postgres enforces VARCHAR(80)."""
    root, forked = _forked(client)
    assert _rename(client, forked, "x" * (schemas.BRANCH_NAME_MAX + 1)).status_code == 422
    assert _rename(client, forked, "x" * schemas.BRANCH_NAME_MAX).status_code == 200


def test_naming_a_branch_of_another_adventure_is_a_404(client):
    root, forked = _forked(client)
    db = SessionLocal()
    try:
        other = models.Adventure(
            user_id=db.get(models.Adventure, client.adv_id).user_id,
            title="Elsewhere", script_state={}, world_state={},
        )
        db.add(other)
        db.commit()
        other_id = other.id
    finally:
        db.close()
    r = client.patch(f"/api/adventures/{other_id}/branches/{forked}", json={"name": "x"})
    assert r.status_code == 404


# ----------------------------------------------------------------- deleting

def test_the_root_branch_cannot_be_deleted(client):
    """It holds the turns every other branch borrows."""
    root, forked = _forked(client)
    r = _delete(client, root)
    assert r.status_code == 400
    assert "adventure" in r.json()["detail"].lower()
    assert len(_branches(client)) == 2


def test_the_branch_being_read_cannot_be_deleted(client):
    root, forked = _forked(client)
    assert [b["is_head"] for b in _branches(client) if b["id"] == forked] == [True]
    r = _delete(client, forked)
    assert r.status_code == 400
    assert "switch" in r.json()["detail"].lower()


def test_an_ancestor_of_the_branch_being_read_cannot_be_deleted(client):
    """The same mistake as deleting the head, wearing a disguise.

    `parent_branch_id` cascades, so deleting a branch the head was forked from
    would take the head with it and leave `head_branch_id` pointing at nothing.
    """
    root, forked = _forked(client)
    # A fork of the fork, so `forked` is an ancestor of the head rather than
    # the head itself.
    _retry(client)
    _play(client, "press on")
    nested = _discarded_on(client.adv_id, branch_id=forked)
    r = client.post(f"/api/adventures/{client.adv_id}/actions/{nested}/fork")
    assert r.status_code == 200, r.text
    assert len(_branches(client)) == 3

    r = _delete(client, forked)
    assert r.status_code == 400
    assert "forked from it" in r.json()["detail"]
    assert len(_branches(client)) == 3


def test_deleting_a_branch_leaves_the_line_it_forked_from_untouched(client):
    root, forked = _forked(client)
    _switch(client, root)
    kept = _texts(client)

    assert _delete(client, forked).status_code == 204
    assert [b["id"] for b in _branches(client)] == [root]
    assert _texts(client) == kept, "the parent keeps every turn it had"


def test_deleting_a_branch_takes_its_nodes_and_its_descendants(client):
    """One statement, however deep the subtree — the cascade does the walking."""
    root, forked = _forked(client)
    _retry(client)
    _play(client, "press on")
    nested_attempt = _discarded_on(client.adv_id, branch_id=forked)
    client.post(f"/api/adventures/{client.adv_id}/actions/{nested_attempt}/fork")
    nested = [b["id"] for b in _branches(client) if b["id"] not in (root, forked)][0]

    doomed_actions, _ = _counts(client.adv_id, [forked, nested])
    assert doomed_actions > 0
    root_actions_before, _ = _counts(client.adv_id, [root])

    _switch(client, root)
    assert _delete(client, forked).status_code == 204

    assert [b["id"] for b in _branches(client)] == [root]
    assert _counts(client.adv_id, [forked, nested]) == (0, 0)
    assert _counts(client.adv_id, [root])[0] == root_actions_before


def test_deleting_a_branch_clears_a_cursor_that_stood_on_it(client):
    """Harmless on Postgres, a real bug on SQLite.

    Postgres never reuses a branch id, so a stale anchor simply never resolves.
    SQLite hands the freed id to the next fork, at which point the anchor
    resolves onto a branch it has never seen and reports a stretch of story as
    already summarized — which loses it from the memories for good.
    """
    root, forked = _forked(client)
    db = SessionLocal()
    try:
        adventure = db.get(models.Adventure, client.adv_id)
        cursors.MEMORY.anchor(adventure, forked, 3)
        cursors.SUMMARY.anchor(adventure, root, 1)
        db.commit()
    finally:
        db.close()

    _switch(client, root)
    assert _delete(client, forked).status_code == 204

    db = SessionLocal()
    try:
        adventure = db.get(models.Adventure, client.adv_id)
        assert cursors.MEMORY.stored(adventure) == (None, cursors.NO_DEPTH)
        # The one standing on ground that survived is left exactly where it was.
        assert cursors.SUMMARY.stored(adventure) == (root, 1)
    finally:
        db.close()


def test_deleting_an_unknown_branch_is_a_404(client):
    root, forked = _forked(client)
    assert _delete(client, forked + 9999).status_code == 404


# --------------------------------------------------------- the bank vs a path

def _memories(client) -> list[dict]:
    r = client.get(f"/api/adventures/{client.adv_id}/memories")
    assert r.status_code == 200, r.text
    return r.json()


def _add_memory(client, text):
    r = client.post(f"/api/adventures/{client.adv_id}/memories", json={"text": text})
    assert r.status_code == 201, r.text
    return r.json()["id"]


def test_a_hand_written_memory_is_anchored_where_it_was_written(client):
    """It takes the head, so it is a memory *of a story* rather than of an
    adventure. A NULL depth is a coordinate no fork can cap."""
    root, forked = _forked(client)
    memory_id = _add_memory(client, "Took the other door.")

    db = SessionLocal()
    try:
        memory = db.get(models.Memory, memory_id)
        adventure = db.get(models.Adventure, client.adv_id)
        assert memory.branch_id == forked, "the branch being read"
        assert memory.depth is not None, "never NULL again"
        assert memory.depth == adventure.head_depth
    finally:
        db.close()


def test_the_drawer_shows_the_path_being_read_and_nothing_else(client):
    """The bank you can see is the bank the model can see.

    An adventure-wide list would show memories from branches this story never
    went down — which are never retrieved — and a reader cannot tell those from
    the ones actually in play.
    """
    root, forked = _forked(client)
    on_the_fork = _add_memory(client, "Took the other door.")
    _switch(client, root)
    on_the_root = _add_memory(client, "Went the long way instead.")

    assert {m["id"] for m in _memories(client)} == {on_the_root}, \
        "the fork's memory is not on this story"

    # Switching to the fork shows its own memory — and the root's, because a
    # fork borrows its ancestors up to the point it left them. The relationship
    # is asymmetric on purpose; the parent never went down the fork.
    _switch(client, forked)
    listed = {m["id"] for m in _memories(client)}
    assert on_the_fork in listed
    assert on_the_root not in listed, "written after the fork left this branch"


def test_the_drawer_and_retrieval_agree_on_what_is_visible(client):
    """One predicate, so a memory can never be listed but unretrievable (or the
    reverse). Two spellings of "on this path" would eventually drift."""
    root, forked = _forked(client)
    _add_memory(client, "Took the other door.")
    _switch(client, root)
    _add_memory(client, "Went the long way instead.")

    db = SessionLocal()
    try:
        adventure = db.get(models.Adventure, client.adv_id)
        retrievable = {
            row[0] for row in db.execute(
                select(models.Memory.id).where(
                    models.Memory.adventure_id == adventure.id,
                    lineage.path_of(db, adventure).clause(models.Memory),
                )
            )
        }
    finally:
        db.close()

    assert {m["id"] for m in _memories(client)} == retrievable


def test_deleting_a_branch_deletes_the_memories_written_on_it(client):
    """Not merely out of view — the row goes with the branch, through the
    cascade. That is what keeps "the drawer shows only your path" from
    stranding anything: a memory you cannot see is on a branch you can still
    switch to, and deleting that branch takes it for good."""
    root, forked = _forked(client)
    doomed = _add_memory(client, "Took the other door.")
    _switch(client, root)

    db = SessionLocal()
    try:
        assert db.get(models.Memory, doomed) is not None, "still on its own branch"
    finally:
        db.close()

    assert _delete(client, forked).status_code == 204

    db = SessionLocal()
    try:
        assert db.get(models.Memory, doomed) is None, "gone with the branch"
    finally:
        db.close()


# ------------------------------------------------------------------- backup

def test_a_bundle_carries_the_name_a_player_chose(client):
    """A name is a decision, so it travels — the rule the v2 format is built on.

    `lineage` and the head depth stay out because they are computed from what
    the file already carries; a name is computed from nothing.
    """
    root, forked = _forked(client)
    _rename(client, root, "the long way")
    _rename(client, forked, "the cellar")

    exported = client.get(f"/api/adventures/{client.adv_id}/export").json()
    assert [b.get("name") for b in exported["branches"]] == ["the long way", "the cellar"]

    r = client.post("/api/adventures/import", json=exported)
    assert r.status_code == 201, r.text
    restored = client.get(f"/api/adventures/{r.json()['id']}/branches").json()
    assert [b["name"] for b in restored] == ["the long way", "the cellar"]


def test_an_unnamed_tree_exports_no_name_key(client):
    """Unchanged from the file SP6 wrote, for a tree nobody has named."""
    _forked(client)
    exported = client.get(f"/api/adventures/{client.adv_id}/export").json()
    assert all("name" not in b for b in exported["branches"])


def test_a_bundle_naming_a_branch_with_a_number_is_refused(client):
    """400 from the planner, not a database error three branches in."""
    _forked(client)
    exported = client.get(f"/api/adventures/{client.adv_id}/export").json()
    exported["branches"][1]["name"] = 7
    r = client.post("/api/adventures/import", json=exported)
    assert r.status_code == 400
    assert "not text" in r.json()["detail"]