undercooked/README.md

# Undercooked

A cooperative, **in-browser**, Overcooked-style kitchen game: 1–4 players share one
kitchen over WebSockets, cook orders against the clock, and climb a campaign of
levels that get progressively harder. Lobbies are **anonymous** — no accounts, no
email, no password: you create a room, share the 5-character code, play.

> Working title. "Overcooked" is a trademark of Ghost Town Games/Studio MDG; this
> project is an independent homage with its own art, code, and content.

## Status

Phases **01** (runnable service scaffold), **02** (level content, schema and
validation), and **03** (the deterministic simulation kernel: fixed-step tick,
movement and collision, the action button, the hands, the replay goldens) are
**complete**; the next pending phase is `04_kitchen_pipeline_and_scoring`. What
runs today:

- **The service.** The Python toolchain is locked (`uv.lock`), configuration is a
  single typed, validated `Settings` object (`DEBUGPY` support included), and
  `uv run undercooked` starts a FastAPI server that serves the client shell at `/`,
  the browser assets from `app/static/`, and `GET /healthz` — which answers
  `{"status":"ok","version":"0.1.0","rooms":0}` (`rooms` stays `0` until phase 05 owns
  a supervisor) — with the security headers (CSP `default-src 'self'`) on every
  response.
- **The content.** The recipe book and the first two campaign levels live in
  `levels/`; `sim/level.py` parses them into typed models, `sim/validation.py` runs
  PLAN §8's named rules, and `create_app` loads + validates that bundle at startup and
  **refuses to boot** broken content — the named-rule report goes to stderr and
  `undercooked` exits `2` instead of serving a half-working kitchen. `GET /api/levels`,
  `GET /api/levels/{id}` and `GET /api/config` answer from it, and
  `undercooked-levels` gives authors the same gate from the command line
  (`docs/LEVELS.md` is the schema reference).
- **The tick.** `sim/state_build.py` builds a round from level + seats + seed and
  `sim/step.py` advances it in whole `0.05` s substeps (20 Hz, A4) with a splitmix64 RNG
  seeded from the round seed — pure (no clock, no `random`, nothing mutated), replayable
  from a seed plus an input script, and 100 % covered. The clock, the input contract and
  the round's end condition are real. `docs/SIMULATION.md`
  is the contract, `tests/sim/test_rng.py` locks the generator's published vectors.
- **Walking the kitchen.** `sim/movement.py` + `sim/collision.py` are stage 3 of the tick:
  intent is clamped server-side (`move=(50,0)` walks at 3.5 tiles/s, not 175), accelerated
  at 30 tiles/s² and integrated one axis at a time against an axis-aligned sweep, so a cook
  stops flush against a wall instead of inside it, slides along it for free, cannot tunnel a
  1-tile wall even at the coarsest legal `dt`, and cannot clip a diagonal corner. Walls,
  counters, void, off-map and the solid fixtures (`spawn_shelf`, `chop_board`, `stove`,
  `prep`) block; `serve`, `sink` and `trash` do not. Cooks soft-push each other apart
  symmetrically and positionally — a bump never injects velocity — and only a genuine
  terrain deadlock drops an input, the later-received one, exactly like the kernel's
  arbitration. Stun (`0.6` s) pins velocity and position and reports one `stunned` event on
  entry; facing follows the last non-zero intent, so an action press while standing still
  does not spin the cook. Proven by hand-computed geometry in `tests/sim/test_movement.py`,
  by a 2000-substep four-cook random walk from the sim's own RNG that re-checks containment,
  non-overlap and hash equality after *every* substep
  (`tests/sim/test_movement_stress.py`), and by the same walk on the shipped levels through
  the whole `step()` (`tests/sim/test_movement_kernel.py`).
- **The action button.** `sim/interact.py` is the second half of stage 2 of the tick:
  the one `action` flag per frame becomes one press per rising edge, so however long the
  button is held there is one effect — and one named refusal when there is nothing to do
  (`DENIED` with `out_of_reach`, `hands_full`, `station_busy`, `contested_lost`, … in the
  payload, which the client turns into a nudge; a silent no-op is the failure mode PLAN §5
  bans by name). A press resolves a reach zone — the tile in front, then the two
  diagonal-front tiles (a 0.6-tile forgiveness beyond the 1-tile reach), then the tile
  underfoot — and a ladder picks the verb: a full hand sets its item down on the fixture
  (the spawn shelf is the escape hatch), a free hand picks from a ready fixture or shelf
  stock, a stunned cook is refused before the target is even read, and a fixture owns
  what is on it (an onion on a chop board is *to be chopped*, not grabbable). Two cooks
  pressing the same item in the same substep are arbitrated by arrival, `seq`, then seat
  index — the loser is told `contested_lost`, never left wondering. The work verbs (chop,
  cook, plate, serve, wash) are named by the ladder but no-ops until phase 04's pipeline
  spends them (the long-press trash is real — see "The hands" below); `docs/SIMULATION.md`
  §"The action button" is the contract. Proven by
  `tests/sim/test_targeting.py` (hand-computed reach geometry, the press edge through the
  whole `step()`) and `tests/sim/test_verbs.py` (a table that covers every `Verb` and every
  `DeniedReason`, plus the gate's contested arbitration).
- **The hands.** `sim/carry.py` is what the verbs *do*: one carried item per cook (a
  second pick is `hands_full`), no floor drops in v1 (a press at open floor is the named
  `nothing_here`), and a set-down is a *placed object* — `RELEASE` / `PLACE_ON_STATION` /
  `PLATE_DISH` put the item on the fixture and stamp it with a mark, so a teammate's pick
  of a set-down within 20 ticks is a `HANDED_OFF` with both ids (the sanctioned pass) and
  an unmarked pipeline input stays the work press's. The trash is long-press and always
  available: holding the button over the can for 8 substeps destroys the carried item
  (`TRASHED`, the raw `−2` score nudge in the payload for phase 04's clamped scoring,
  `counters["trashed"]` up by one); a short press and a walk-away do nothing. A 100-tick
  fuzz of random simultaneous presses re-checks the conservation law
  (`hands + stations + trashed == initial`) after every tick, and a scripted two-player
  pass-and-contest reaches its committed golden hash. `docs/SIMULATION.md` §"The hand" is
  the contract (phase 09's co-op E2E asserts exactly this tie-break). Proven by
  `tests/sim/test_carry.py` and `tests/sim/test_replay_carry.py`.
- **The rules are tests, not promises.** The no-external-asset rule is
  `tests/unit/test_no_external_assets.py`, "no level or recipe id in Python" is
  `tests/unit/test_content_not_hardcoded.py`, the documentation set is guarded by
  `tests/unit/test_docs_index.py`, and `bash .agents/validate.sh` is the gate the
  phase pipeline runs after every task.

What does not exist yet: the rest of the simulation (the cooking pipeline, order spawning
and scoring in phase 04), rooms and the WebSocket
protocol (05-06 — the lobby buttons answer "Not implemented until phase 05.") and the
playable Canvas renderer (07). Execute phases with the `phased-execution` skill
(`auto-phase.sh`); it always takes the lowest-numbered directory still in
`.agents/phases/todo/`.

## How to play

The intended loop, once the room flow ships: open the site, **Create lobby**, read out
the 5-character code, everyone else **Joins** with it, the host picks a level, the room
readies up, and the kitchen starts. Each cook has one movement control and **one action
button** that picks up, uses and puts down whatever is in reach — one carried item at a
time. Orders appear in the HUD with a shrinking deadline; assemble the dish and serve it
at the window before the timer runs out. Levels escalate: more recipes, fewer stations,
hostile floors. Nothing is saved between rounds and nothing identifies you: the browser
keeps only a random per-tab token and the last code you typed, both in `sessionStorage`.

What actually works today is the shell of that: the page loads, normalises a typed code to
five uppercase alphanumerics (codes themselves are Crockford base32, and only get issued
once phase 05 runs the room supervisor), and answers "Not implemented until phase 05."
Movement keys and touch controls are defined by the phase-07/08 client and documented in
`docs/CLIENT.md` once that phase writes it.

## Quickstart (development)

Requires [`uv`](https://docs.astral.sh/uv/), Python ≥ 3.12, and `podman`/`docker`
for container builds. **There is no database** — all live game state is in memory.

```bash
uv sync --extra dev
uv run undercooked                 # http://127.0.0.1:8000 (shell page + /healthz)
uv run undercooked --host 0.0.0.0 --port 8000   # e.g. to reach it from a phone
uv run undercooked --reload        # dev reload
uv run undercooked --levels-dir levels          # point at another content dir
curl -fsS http://127.0.0.1:8000/api/levels      # the campaign cards the lobby will show
curl -fsS http://127.0.0.1:8000/api/config      # client-safe settings + protocol version
```

`python -m undercooked` is the same command (the container uses it). A flag
always beats the environment, which beats the built-in default. There is no
`/docs` or `/openapi.json`: FastAPI renders those pages from a public CDN, which
this project forbids. The validation the server runs at startup (every level
file loads, and no rule of PLAN §8 is broken) is a command too —
`undercooked-levels`, see **Authoring content** below.

Debug the server with a real debugger attached (dev only - the listener binds
`0.0.0.0`, so never enable it on a public host):

```bash
DEBUGPY=1 uv run undercooked       # opens a debugpy listener on :5678, then serves as usual
```

Authoring content:

```bash
uv run undercooked-levels list                        # the campaign, in campaign order
uv run undercooked-levels show 01_first_kitchen --grid  # resolved level + reachability overlay
uv run undercooked-levels validate                    # the content gate; --json for scripts
uv run undercooked-levels new 03_riverboat            # scaffold a level from the recipe book
uv run undercooked-levels axes                        # escalation-axis table (phase 11's curve)
```

`undercooked-levels` is a thin shell over the loader and the PLAN §8 rules
`create_app` runs at startup, so a green `validate` is a server that boots. It
finds content through the settings (`--dir` > `UNDERCOOKED_LEVELS_DIR` >
`levels`, plus `--recipes` > `UNDERCOOKED_RECIPES_PATH` > `<dir>/recipes.yaml`)
and never from the current directory, so it works from any path. Exit codes:
`0` ok, `1` a level breaks a rule, `2` nothing usable to work with (load
failure, unknown id, refused overwrite, usage error). The schema, every field,
the overlay trick and a "which rule did I just hit" table live in
[docs/LEVELS.md](docs/LEVELS.md); `tests/unit/test_content_not_hardcoded.py`
is what keeps levels and recipes out of the Python.

Run the checks:

```bash
uv run ruff check .
uv run pyright
uv run pytest                              # everything, coverage floor included
uv run pytest -m "not e2e"                 # the quick loop: no browser launches
uv run playwright install chromium         # once, before the first e2e run
uv run pytest -m e2e                       # browser suites only
uv run pytest -m slow tests/sim -q --no-cov  # the gate's slow stage: goldens + perf smoke
bash .agents/validate.sh                   # the pipeline gate: full suite + ruff + pyright
```

The replay goldens behind `tests/sim/test_replay.py` are checked the same way a
level is validated: `uv run python -m undercooked.sim.replay check
<tests/fixtures/replays/<name>.json>` runs the committed input script and
gates it on `tests/goldens/<name>.golden.json` (exit `0` match, `1` divergence
with the first divergent tick and the changed fields, `2` missing script/level/
golden). `record` writes a golden — the manual re-bless, legitimate only after a
deliberate sim-contract change recorded in the phase task; the contract is
[docs/SIMULATION.md](docs/SIMULATION.md) ("Replaying and re-blessing goldens").

`pytest` with no `-m` runs the browser suites too, so chromium has to be
installed for the pipeline gate. Those suites start the app themselves on a free
loopback port (`live_server` in `tests/conftest.py`) — nothing needs to be
running first, and no test ever listens on a routable interface.

`bash .agents/validate.sh` is the gate a phase task must pass before it moves to
`.agents/phases/complete/`. It stops at the first failure, in this order:
`ruff check .`, `pyright`, `undercooked-levels validate` (unconditional: the same
loader and PLAN §8 rules `create_app` runs at startup, so a campaign that cannot
validate cannot commit), the **full** `pytest` suite with the 90 % coverage floor,
the slow sim stage (`pytest -m slow tests/sim`: the replay goldens and the perf
smoke, named on their own so a quick loop that skips them cannot let them slip
through the gate), then repo-hygiene checks (nothing tracked that `.gitignore`
excludes, no log drops or key material committed). Run it from the repo root or
from `.agents/`.

## Container

```bash
podman build -t undercooked -f Containerfile .
podman run --rm -p 8000:8000 undercooked
# or
podman compose up -d
```

## Configuration

All settings come from the environment, parsed once into
`undercooked.config.Settings` — the only module that reads the environment, so
nothing else in the codebase touches `os.environ`. Precedence: `undercooked` CLI
flags, then exported environment variables, then a local `.env` (found from the
current directory upwards; never commit it), then the built-in defaults. A blank value counts as
unset. Invalid values (`UNDERCOOKED_TICK_HZ=99`) raise `ConfigError` at startup
instead of half-configuring the server, and unusable content is refused the same
way — an unreadable `UNDERCOOKED_LEVELS_DIR` or a level that breaks a PLAN §8
rule prints the named-rule report and exits `2` (under `--reload` the reload
child reports and restarts instead; docs/LEVELS.md). `.env.example` and the table below list
every variable with its default; tests keep both in sync with `config.py`.

| Variable | Default | Meaning |
|---|---|---|
| `UNDERCOOKED_HOST` | `127.0.0.1` | Bind address |
| `UNDERCOOKED_PORT` | `8000` | Bind port |
| `UNDERCOOKED_TICK_HZ` | `20` | Server simulation rate (5-60) |
| `UNDERCOOKED_SNAPSHOT_HZ` | `20` | Snapshot broadcast rate to players (<= tick rate) |
| `UNDERCOOKED_MAX_PLAYERS` | `4` | Players per room (1-4) |
| `UNDERCOOKED_MAX_ROOMS` | `200` | Concurrent rooms before new rooms are refused |
| `UNDERCOOKED_LEVELS_DIR` | `levels` | Directory of level YAML files (`~` is expanded) |
| `UNDERCOOKED_RECIPES_PATH` | *(derived)* | Recipe book file; empty = `recipes.yaml` inside `UNDERCOOKED_LEVELS_DIR` (here: `levels/recipes.yaml`) |
| `UNDERCOOKED_STATIC_DIR` | *(derived)* | Directory served at `/static`; empty = `app/static/` beside the source (containers set it) |
| `UNDERCOOKED_LOBBY_IDLE_TIMEOUT_S` | `900` | Close empty/idle lobbies |
| `UNDERCOOKED_GUEST_IDLE_TIMEOUT_S` | `45` | Drop a disconnected player's seat after this |
| `UNDERCOOKED_MAX_MESSAGE_BYTES` | `4096` | Hard cap on inbound WS frame size |
| `UNDERCOOKED_MAX_INPUTS_PER_S` | `40` | Per-connection inbound message rate limit |
| `UNDERCOOKED_SIM_LATENCY_MS` | `0` | Injected server-side downlink latency (netcode tests) |
| `UNDERCOOKED_ALLOWED_ORIGINS` | *(empty)* | Comma-separated `Origin`s accepted on the WebSocket handshake; empty = same-host only |
| `DEBUGPY` | `0` | `1` = open a debugpy listener on `DEBUGPY_PORT` at startup |
| `DEBUGPY_PORT` | `5678` | debugpy listen port |

## Layout

```
src/undercooked/        server: FastAPI app, rooms, WebSocket protocol, simulation
src/undercooked/__main__.py  the `undercooked` command (CLI > env > default)
src/undercooked/config.py  typed env settings (the only `os.environ` reader)
src/undercooked/debug.py   DEBUGPY-gated debugger bootstrap
src/undercooked/sim/       pure simulation kernel: entities (`model`), grid geometry
                           (`grid`), content schema + loader (`recipe`, `level`,
                           `content` — the YAML contract is docs/LEVELS.md), the
                           level validator (`validation` — PLAN §8 named rules;
                           rule table in docs/LEVELS.md), the fixed-step tick (`step`,
                           `state_build`, `rng`, and the subsystem hooks `movement`
                           (+ `collision`, its pure geometry), `interact` (the action
                           button — reach zone, verb ladder, named denials, contested
                           arbitration, the long-press trash), `carry` (the hands — one
                           item per hand, the marked set-down and counter hand-off,
                           the always-available trash), `stations`, `orders`, `hazards`,
                           `round_state` —
                           contract in docs/SIMULATION.md), and the A5 purity guard
                           (`purity`, test-enforced)
src/undercooked/sim/replay.py  the replay harness: the input-script format, the golden
                        hashes, `run_script`/`compare`, and the record/check CLI
                        (docs/SIMULATION.md "Replaying and re-blessing goldens")
src/undercooked/tools/levels.py   the `undercooked-levels` author CLI — validate, list,
                        show [--grid], new, axes; same loader, same rules, no
                        hard-coded content list (docs/LEVELS.md "Authoring workflow")
src/undercooked/server/app.py     app factory, `/healthz`, `/`, `/static`, mounts the content API
src/undercooked/server/routes_content.py  `/api/levels`, `/api/levels/{id}`, `/api/config`,
                        plus the startup gate: broken content refuses startup
src/undercooked/server/headers.py the security-header middleware
.env.example            every configuration variable, with its default
levels/                 data-driven content (YAML): the recipe book (A8) and the
                        first two campaign levels (01_first_kitchen, 02_double_shift)
app/static/             browser client: the ES-module shell today; Canvas 2D renderer
                        and this repo's SVG art arrive with phase 07
tests/                  unit/, integration/, e2e/ (one Playwright suite per story) and
                        sim/ (the pure kernel: grid, entities, purity guard, validation,
                        the seeded RNG and the tick; plus the replay harness — committed
                        goldens in goldens/, scripts in fixtures/replays/ — and the
                        `slow` perf smoke);
                        fixtures/levels/ is the content dir tests see (a recipe book and no
                        levels; `_bad/` holds the deliberately-broken campaign the `_`
                        discovery rule ignores); conftest.py
docs/                   DESIGN.md, LEVELS.md (the level & recipe YAML contract),
                        SIMULATION.md (the tick contract), TESTING.md (how this project
                        is verified), DEPLOYMENT.md; PROTOCOL / CLIENT land with their
                        own phases (the index is PLAN.md §13)
.agents/                PLAN.md, user_stories/, phases/, validate.sh — the phased-execution plan
```

**No external CDNs.** Every byte of JS, CSS, font, and image is served by this app
from `app/static/`. `tests/unit/test_no_external_assets.py` enforces it, and the
e2e suite fails if loading the page ever issues a request off-origin.

## Contributing

Read [AGENTS.md](AGENTS.md) first: it points at `.agents/PLAN.md` (LOCKED decisions)
and the phase protocol. Code changes land by executing phase task files, not by
editing ad hoc.