phase: 02_level_content_and_validation

Phase `02_level_content_and_validation` — final verification **green**.

- **Gate:** `bash .agents/validate.sh` → ruff ✅ · pyright 0 errors ✅ · `undercooked-levels validate` OK (2 levels) ✅ · **668 passed** (incl. 10 Playwright e2e) ✅ · coverage **100%** ✅ · repo hygiene ✅
- **Criteria:** `validate` exit 0, one line per level; `list` = `01_first_kitchen`, `02_double_shift` in campaign order; live `:8000` `/healthz` 200, `/api/levels` (+detail) carries both levels with numeric `target_score`/`time_limit` and no grid/station leakage, `/api/config` correct, unknown id → 404, startup log `content loaded: 2 level(s), 4 recipe(s)`; `validate --dir tests/fixtures/levels/_bad/` → exit 1 with named `RECIPE_STATION_MISSING` / `SERVE_REACHABLE` / `TARGET_IMPLAUSIBLE`; A8 lock test proves a YAML-only level reaches loader+API+CLI.
- **Defect fixed (pre-existing path, phase-02-triggered):** `undercooked` with unusable content printed the report then a raw traceback and exited `1`. `src/undercooked/__main__.py` now catches `ContentError` → one closing line, exit `2` (like a bad setting); 2 new tests in `tests/unit/test_main.py` (incl. non-content failures still propagate).
- **Docs pass (full, project-wide):** README (content gate + exit `2`, config section), AGENTS.md §3, `docs/LEVELS.md` (startup refusal + exact CLI exit codes), `docs/DEPLOYMENT.md` (crash-loop diagnosis bullet); DESIGN/TESTING re-read, consistent.
- **Container re-verified (no phase-01 regression):** `podman build -f Containerfile` succeeds; the image ships `levels/` and serves `/healthz` 200, `/api/levels` (2 levels), `/` 200 as non-root.
- **Deviation to note:** the phase overview names `tests/fixtures/levels/bad/`; the actual broken-fixture dir is `tests/fixtures/levels/_bad/` (the `_` prefix is what keeps it out of normal discovery). Overview files are read-only to me — README/LEVELS.md document the real path.
- No git index/history commands run; all changes left unstaged for the harness. ntfy notification sent.

AGENTS.md

@@ -16,9 +16,10 @@
 - Execution is owned by the `phased-execution` skill (`run-task.sh`, `run-phase.sh`,
   `auto-phase.sh`). Each task runs in a fresh subprocess and must pass
   `.agents/validate.sh` before it moves to `complete/`. That gate fails fast in this
-  order: `ruff check .` → `pyright` → `undercooked-levels validate` (skipped with a
-  notice until phase 02 creates the loader) → the **full** `pytest` suite with the
-  coverage floor → repo-hygiene checks. It runs from the repo root or from `.agents/`.
+  order: `ruff check .` → `pyright` → `undercooked-levels validate` (unconditional:
+  the same loader + PLAN §8 rules `create_app` runs at startup, over
+  `$UNDERCOOKED_LEVELS_DIR`) → the **full** `pytest` suite with the coverage floor →
+  repo-hygiene checks. It runs from the repo root or from `.agents/`.
 - New work is authored by the `phase-authoring` skill as a phase directory — not
   implemented straight from chat.
 - **Never** modify `.agents/PLAN.md` or anything under `.agents/phases/complete/`.
@@ -37,6 +38,17 @@
   deviation from the default FastAPI stack.
 - **Data-driven content.** Levels/recipes/hazards come from YAML in `levels/` loaded
   through validated Pydantic models. No hard-coded level or recipe lists in Python.
+  `create_app()` loads the bundle once (`routes_content.load_validated_content`) and
+  **refuses to start** when content fails to load or violates a PLAN §8 rule — the
+  named-rule report goes to stderr, `ContentError` propagates and the `undercooked`
+  command exits `2` like it does for an impossible setting. The content API
+  projects through `extra="forbid"` response models: grids, station ids and spawn
+  coordinates never leave the server. `undercooked-levels` (`tools/levels.py`, its
+  author CLI) obeys the same rule: it prints whatever the loaded directory holds.
+  `tests/unit/test_content_not_hardcoded.py` is the lock — it adds a level YAML to a
+  copy of `levels/` and expects the loader, `/api/levels` and the CLI to carry it with
+  no Python edited, and fails if any `src/undercooked/**.py` or browser asset names a
+  shipped level or recipe id as a literal.
 - **Client: Canvas 2D + vanilla ES modules + this repo's own SVG art.** No bundler,
   no framework, no CDN, no analytics, no external fonts.
 - **Tests: pytest + Playwright.** One Playwright suite per user story; multi-player
@@ -52,7 +64,8 @@
 - [ ] **Full** project suite passes (`uv run pytest`), coverage gate met — including
       failures the task did not cause: fix them, do not skip, xfail, or delete tests.
 - [ ] `uv run ruff check .` and `uv run pyright` report zero errors.
-- [ ] `uv run undercooked-levels validate` passes if any level/content file changed.
+- [ ] `uv run undercooked-levels validate` passes — `.agents/validate.sh` runs it for
+      every task, whether or not any content file changed.
 - [ ] `README.md` and `AGENTS.md` updated when the change is user-visible
       (setup, commands, config, protocol, features, conventions). Every phase's final
       pass re-reviews both **in full, project-wide** and fixes inconsistencies,
@@ -115,8 +128,10 @@
 - **Protocol changes need a version bump**: editing a wire message means editing
   `src/undercooked/server/protocol.py`, `docs/PROTOCOL.md`, and the client in the same task,
   and bumping `PROTOCOL_VERSION` (PLAN §11).
-- **Determinism is a contract.** `sim/step.py` must produce identical state given the
-  same seed and input script — the replay tests in `tests/sim/` are the guard.
+- **Determinism is a contract.** `sim/step.py` (phase 03) must produce identical state
+  given the same seed and input script — the replay tests in `tests/sim/` are the guard
+  once the tick exists; until then `tests/sim/test_purity.py` holds the A5 boundary that
+  determinism depends on.
 - **ntfy is outbound-only.** Never use it to ask questions or wait for approval.
   If a task is ambiguous, make the best judgment consistent with PLAN.md, or stop
   and let the user rewrite the task.
@@ -134,9 +149,12 @@
 | Configuration (env vars → typed `Settings`), debugpy bootstrap | `src/undercooked/config.py`, `.env.example`, `src/undercooked/debug.py` |
 | Pure game rules (movement, stations, orders, scoring, hazards) | `src/undercooked/sim/` |
 | Level/recipe content | `levels/*.yaml` |
+| Content schema, ASCII-grid parser, content loader, playability validator (contract: `docs/LEVELS.md`) | `src/undercooked/sim/recipe.py`, `level.py`, `content.py`, `validation.py` |
 | Rooms, lobby lifecycle, session records | `src/undercooked/server/rooms.py`, `room.py` |
 | Wire messages + validation | `src/undercooked/server/protocol.py`, `docs/PROTOCOL.md` |
-| HTTP app (`/`, `/healthz`, `/static`), lifespan | `src/undercooked/server/app.py` |
+| HTTP app (`/`, `/healthz`, `/static`), lifespan, startup content gate | `src/undercooked/server/app.py` |
+| Content HTTP API (`/api/levels`, `/api/levels/{id}`, `/api/config`) + strict response models | `src/undercooked/server/routes_content.py` |
+| Author CLI `undercooked-levels` (`validate`, `list`, `show`, `new`, `axes`); workflow in `docs/LEVELS.md` | `src/undercooked/tools/levels.py` |
 | Security headers (CSP `default-src 'self'`, no-sniff, frame-ancestors) | `src/undercooked/server/headers.py` |
 | CLI entry point (`undercooked`): flags → `--help` → serve | `src/undercooked/__main__.py` |
 | Renderer, HUD, input, interpolation | `app/static/js/`, `app/static/assets/` |
@@ -146,8 +164,12 @@
 
 Tests mirror that: `tests/unit/` (pure, no-I/O logic incl. HTTP-route unit tests),
 `tests/integration/` (in-process app boot, live uvicorn + WebSocket clients), `tests/sim/`
-(headless determinism and replays), `tests/e2e/` (Playwright, named `test_usNN_*.py`,
-marked `e2e`). `tests/` is not a package; shared fixtures live in `tests/conftest.py`.
+(the pure kernel without a server: grid geometry, entity model, the A5 purity guard,
+the level validator — headless determinism and replays join it with the tick in
+phase 03), `tests/e2e/` (Playwright, named `test_usNN_*.py`, marked `e2e`). `tests/` is
+not a package; shared fixtures live in `tests/conftest.py`, and the autouse fixture there
+points `UNDERCOOKED_LEVELS_DIR` at `tests/fixtures/levels/` so no test silently reads the
+shipped `levels/`.
 
 - The browser suites use the **`playwright` sync API directly with fixtures written in
   `tests/e2e/conftest.py`** — `pytest-playwright` is deliberately not a dependency, so