tavolo/server/README.md

# tavolo (backend)

The backend for a multiplayer card-game platform, built on the
[kaya](../kaya) framework. It is a monorepo of four distributions
sharing the `tavolo` namespace (see
[`packages/tavolo-platform/README.md`](packages/tavolo-platform/README.md),
[`packages/tavolo-scopone/README.md`](packages/tavolo-scopone/README.md)
and
[`packages/tavolo-briscola/README.md`](packages/tavolo-briscola/README.md)):

- **`tavolo-platform`** (`packages/tavolo-platform/`) — everything
  game-independent: the lobby API, the live-game store, the WebSocket
  endpoint, the deadline scheduler, match persistence and the Elo
  leaderboards, plus the `GameEngine` contract games implement.
- **`tavolo-scopone`** (`packages/tavolo-scopone/`) — scopone
  scientifico, the four-player, fixed-partnership variant of the classic
  Italian card game: pure rules plus the platform adapter.
- **`tavolo-briscola`** (`packages/tavolo-briscola/`) — briscola, the
  Italian trick-taking game, in its classic two-player (`briscola`) and
  four-player partnership (`briscola_a_quattro`) variants: pure rules
  plus the platform adapter.
- **`tavolo-app`** (`packages/tavolo-app/`) — the
  composition root wiring the platform to the games, with the
  environment-driven settings and the SPA shell.

Players authenticate with the configured **OIDC** provider. Live game
state is kept in **Redis** (with real-time play over WebSocket), and
completed matches — every participant and the game-specific result — are
persisted to **Postgres** for history and leaderboard statistics.

## Quick start (Docker Compose)

```sh
# From the repository root (docker-compose.yml lives there):
docker compose up --build
```

The stack starts Postgres, Redis, a mock OIDC provider
(navikt/mock-oauth2-server) with four ready-made players
(`alice`, `bob`, `carol`, `dave`), a one-shot database migration service,
and the app itself on `http://127.0.0.1:8080`. The same container also
serves the Sycamore/WASM frontend (built from `../web/` by the Docker
image), so the UI is available at that address.

Because the browser and the app both talk to the OIDC issuer at
`http://mockoauth:8180/tavolo`, add a host entry once:

```sh
echo "127.0.0.1 mockoauth" | sudo tee -a /etc/hosts
```

Then log in: `GET http://localhost:8080/auth/login` (a provider-agnostic
alias that redirects to the first configured provider), type any username
(e.g. `alice`) in the interactive login, and you are redirected back with a
session cookie. That cookie authenticates both the REST API and the
WebSocket endpoint.

OpenAPI documentation is served at `/api/docs` (`/api/openapi.json`).

## Configuration

All configuration comes from environment variables (see `.env.example`):

| Variable | Default | Description |
|---|---|---|
| `DATABASE_ENGINE` | `postgres` | Database DSN scheme/driver |
| `DATABASE_HOST` | `localhost` | Postgres host |
| `DATABASE_PORT` | unset | Postgres port; omitted from the DSN when empty (driver default, 5432 for Postgres) |
| `DATABASE_NAME` | `tavolo` | Postgres database name |
| `DATABASE_USER` | `tavolo` | Postgres user |
| `DATABASE_PASSWORD` | `password` | Postgres password |
| `DATABASE_OPTIONS` | unset | Extra DSN query parameters, e.g. `ssl=require` |
| `DATABASE_URL` | unset | Full-DSN override; when set, the `DATABASE_*` parts above are ignored (used for sqlite in tests and for managed-DB URLs) |
| `REDIS_URL` | unset | Redis DSN for sessions + live games. Unset falls back to in-memory stores |
| `OIDC_<n>_PROVIDER` | `default` ¹ | Provider name (required when OIDC is configured): used in the login URL `/auth/<provider>/login` and to namespace its session keys. Unique, `[A-Za-z0-9_-]+` |
| `OIDC_<n>_ISSUER` | `http://localhost:8180/tavolo` ¹ | OIDC issuer URL |
| `OIDC_<n>_CLIENT_ID` | `tavolo` ¹ | OIDC client id |
| `OIDC_<n>_CLIENT_SECRET` | unset | OIDC client secret; leave unset for public clients |
| `OIDC_<n>_REDIRECT_URI` | `http://localhost:8080/auth/<provider>/callback` | Login callback URL; must be registered at the provider |
| `OIDC_<n>_POST_LOGIN_REDIRECT` | `/` | Where the browser is sent after login |
| `OIDC_<n>_POST_LOGOUT_REDIRECT` | `/` | Where the browser is sent after logout |
| `GAME_TTL_SECONDS` | `86400` | Sliding TTL of a live game in Redis |
| `HAND_ACK_TIMEOUT_SECONDS` | `30` | Seconds the between-hands scoring summary waits for acknowledgements (wired into the game engines) |
| `TURN_TIMEOUT_SECONDS` | `30` | Seconds a player has to play before the server plays a random legal card for them (wired into the game engines) |
| `DEADLINE_HEARTBEAT_MS` | `30000` | Backstop poll interval of the deadline consumer; enqueued deadlines are announced over pub/sub and wake consumers immediately, so this only bounds recovery from lost notifications or a dead worker |
| `LOGGING_CONFIG` | unset | Path to a YAML logging configuration file (see below). Unset logs DEBUG to the console |
| `CORS_ALLOW_ORIGINS` | unset | Comma-separated origins allowed for cross-origin requests, or `*` for any. CORS is disabled unless this or `CORS_ALLOW_ORIGIN_REGEX` is set |
| `CORS_ALLOW_ORIGIN_REGEX` | unset | Regex (fullmatch) additionally matched against request origins, e.g. `https://tavolo-[a-z0-9-]+\.vercel\.app` |
| `CORS_ALLOW_METHODS` | `GET` | Comma-separated methods allowed for cross-origin requests, or `*` for all |
| `CORS_ALLOW_HEADERS` | unset | Comma-separated request headers allowed in cross-origin requests, or `*` to mirror back the requested ones. The CORS-safelisted headers are always allowed |
| `CORS_ALLOW_CREDENTIALS` | `false` | `1`/`true`/`yes`/`on` allow cookies/credentials on cross-origin requests |
| `CORS_EXPOSE_HEADERS` | unset | Comma-separated response headers exposed to the browser |
| `CORS_MAX_AGE` | `600` | Seconds browsers may cache the preflight response |
| `OTEL_ENABLED` | `false` | `1`/`true`/`yes`/`on` enable OpenTelemetry traces, metrics and logs (the Docker image bundles the `otel` extra; non-image installs need `pip install tavolo-app[otel]`) |
| `OTEL_SERVICE_NAME` | `tavolo` | `service.name` resource attribute of the exported telemetry |
| `OTEL_EXPORTER_OTLP_ENDPOINT` | unset | Base URL of an OTLP/HTTP collector (e.g. `http://localhost:4318`); unset uses the exporter default |
| `OTEL_EXPORTER_OTLP_HEADERS` | unset | Comma-separated `key=value` headers sent to the collector (e.g. authentication) |
| `OTEL_EXCLUDED_PATHS` | `/api/health` | Comma-separated paths excluded from tracing and metrics (exact matches) |
| `OTEL_METRIC_EXPORT_INTERVAL_MILLIS` | `60000` | How often the OTLP metric reader exports |
| `OTEL_METRICS_POLL_INTERVAL_SECONDS` | `15` | How often the session/game count gauges are refreshed |
| `APP_HOST` / `APP_PORT` | `0.0.0.0` / `8080` | Bind address |

¹ When no `OIDC_<n>_*` variable is set at all, a single provider named
`default` pointing at the dev mock IdP is used. Indices must be contiguous
from 0 (`OIDC_0_*`, `OIDC_1_*`, ...).

### Multiple OIDC providers

Providers are configured in indexed blocks; each becomes its own login
route `/auth/<provider>/login` with its own callback URL and session
namespace:

```sh
OIDC_0_PROVIDER=google
OIDC_0_ISSUER=https://accounts.google.com
OIDC_0_CLIENT_ID=...
OIDC_0_CLIENT_SECRET=...
OIDC_0_REDIRECT_URI=https://tavolo.example.com/auth/google/callback

OIDC_1_PROVIDER=github
OIDC_1_ISSUER=https://github.com/login/oauth
OIDC_1_CLIENT_ID=...
OIDC_1_CLIENT_SECRET=...
OIDC_1_REDIRECT_URI=https://tavolo.example.com/auth/github/callback
```

The login page reads `GET /api/auth/providers` and shows one button per
provider. `GET /auth/login` redirects to the first provider (useful for
bookmarks and scripts), and `GET /auth/logout` signs out whichever
provider the session is logged in with.

Sessions hold a single identity: logging in with another provider
replaces the previous one. Each provider's `sub` is a separate account,
so match history and Elo ratings are per provider identity (someone using
two providers has two accounts). Migrating from the pre-0.0.6 unindexed
variables: rename `OIDC_ISSUER`/`OIDC_CLIENT_ID`/... to `OIDC_0_...`, add
`OIDC_0_PROVIDER`, and register the new callback path
(`/auth/<provider>/callback`) at the provider. Sessions survive only when
the provider is named `default`; otherwise users log in once more.

## Logging

The application logs through the Python stdlib `logging` module, one
`getLogger(__name__)` per module: lifecycle and business events at INFO
(game created/joined, websocket connections, match results, auto-plays),
per-move and store detail at DEBUG.

By default everything at DEBUG level goes to the console. Set
`LOGGING_CONFIG` to the path of a YAML file to take over the
configuration; the file follows the
[`logging.config.dictConfig`](https://docs.python.org/3/library/logging.config.html#logging-config-dictschema)
schema. Keep `disable_existing_loggers: false` — Granian configures its own
loggers before importing the app, and disabling them would silence the
server. Example for quieter production logs (WARNING for third parties,
INFO for the application):

```yaml
version: 1
disable_existing_loggers: false
formatters:
  default:
    format: "{asctime} [{levelname}] ({processName:s}/{threadName:s}) - {name} - {message}"
    style: "{"
handlers:
  console:
    class: logging.StreamHandler
    formatter: default
root:
  level: WARNING
  handlers: [console]
loggers:
  tavolo:
    level: INFO
```

## OpenTelemetry

With `OTEL_ENABLED` set, the app exports over OTLP/HTTP (kaya-otel plus
`tavolo.telemetry`):

- **Traces**: HTTP server spans, one span per WebSocket connection, plus
  database spans for the Postgres (asyncpg, through Tortoise) and Redis
  clients. Redis command values are redacted by the instrumentation
  (`GET ? ?`) and asyncpg spans carry the parameterized SQL only — no
  parameter values. Each HTTP/WebSocket span is tagged with the request's
  session and user, so all traces of a session can be found together:
  `session.id` is a truncated SHA-256 of the session id (the cookie is a
  credential, so it is never exported verbatim) and `user.id` is the OIDC
  `sub`, present once logged in.
- **Metrics**: the HTTP server metrics from kaya-otel, plus
  `tavolo.active_users` (sessions in the session store),
  `tavolo.ongoing_games` (live matches not finished yet, maintained by the
  game store), and process/CPython metrics from
  `opentelemetry-instrumentation-system-metrics`: `process.cpu.time`,
  `process.cpu.utilization`, `process.memory.usage`,
  `process.memory.virtual`, `cpython.gc.collections`,
  `cpython.gc.collected_objects` and `cpython.gc.uncollectable_objects`.
- **Logs**: forwarded from the root logger at the configured console level
  (OpenTelemetry's own records are filtered out to avoid export loops).

The session/game gauges are polled every
`OTEL_METRICS_POLL_INTERVAL_SECONDS` (Redis-backed stores report
cluster-wide counts, in-memory stores the process's own). Note that with
multiple workers or replicas each process reports the same global counts:
aggregate with `max`, not `sum`.

## Data model

### Redis (live games)

- `tavolo:game:<uuid>` — the whole session as JSON: the platform-owned
  envelope (`id`, `game_type`, `join_code`, seats, timestamps) plus the
  game-specific `state` blob, which only the registered engine
  interprets. Sliding TTL (`GAME_TTL_SECONDS`).
- `tavolo:code:<JOINCODE>` — the 6-character join code → game id index.
- `tavolo:game:<uuid>:lock` — a short-lived lock serializing every mutation.
- `tavolo:game:<uuid>:events` — a pub/sub channel carrying "state changed"
  signals; every open WebSocket reloads the session and pushes the
  personalized view to its player.
- `tavolo:deadlines` — a sorted set (score = due timestamp) of pending
  timeouts (e.g. the games' turn auto-plays and hand-end auto-continues).
  Every worker runs a consumer that fires due entries under the per-game
  lock by calling the engine's `fire_deadline`, so timeouts do not depend
  on any player being connected and survive the death of any worker
  (delivery is at-least-once; engines revalidate the entry's token
  against the live state before firing).
- `tavolo:deadlines:events` — a pub/sub channel announcing newly enqueued
  deadlines; it wakes every worker's consumer immediately, while the
  heartbeat poll remains as a backstop for lost signals.

### Postgres (statistics, via Tortoise ORM + aerich migrations)

- `match` — one row per finished match: the game played (`game_type`, one
  of the ids from `GET /api/game-types`, indexed so statistics can be
  scoped per game), start/finish timestamps, and the game-specific outcome
  as reported by the engine (`result` JSON — for scopone: both teams'
  final scores, winner, target score, hands played and the per-hand
  audit; for briscola: the final scores, winner, target score, deals
  played and the per-deal audit).
- `match_player` — one row per participant: the OIDC `sub`, display name,
  seat, game-defined team label (nullable), whether they won, the points
  they scored, the Elo change the match produced (`elo_delta`) and
  game-specific extras (`details` JSON). Unique per `(match, user_sub)`.
- `player_rating` — current Elo rating per `(user_sub, game_type)`, with
  the number of rated matches played.

When a match ends, the engine's result is written transactionally to
Postgres (once, guarded by a flag on the session); the finished session
stays in Redis until its TTL expires so clients can still fetch the final
board.

### Elo ratings

Players carry a chess-style Elo rating per game type
(`tavolo.platform.elo`): everyone starts at 1500, a team's rating is the
mean of its members, and the standard formula
`E = 1 / (1 + 10 ** ((R_opp - R_team) / 400))` with `K = 32` decides how
many points the match result moves — the same delta for every member of
a team, zero-sum between the two teams. Ratings update in the same
transaction as the match result. To recompute every rating from the
recorded match history (e.g. to backfill matches recorded before ratings
existed):

```sh
.venv/bin/python -m tavolo.platform.backfill_elo \
  --database-url postgres://tavolo:tavolo@localhost:5432/tavolo
```

## REST API

All endpoints except `/api/health`, `/api/docs`, `/api/openapi.json`,
`/api/game-types`, `/api/leaderboard` and the game snapshot
(`GET /api/games/{id}`) require authentication.

| Method | Path | Description |
|---|---|---|
| `GET` | `/api/game-types` | The games the platform can host (for the creation dropdown), each with its `options_schema` |
| `POST` | `/api/games` | Create a lobby game. Optional body `{"game_type": "scopone_scientifico", "options": {"target_score": 11, "napola": true, "asso_pigliatutto": false}}`; briscola games use `{"game_type": "briscola"}` or `{"game_type": "briscola_a_quattro"}` with an optional `{"target_score": 61}`. Returns the lobby (`{id, join_code, players, seats_open, ...}`) |
| `POST` | `/api/games/join` | Join with `{"code": "ABC123"}`. The last player triggers the start and gets the game view back |
| `GET` | `/api/games/preview?code=ABC123` | Pre-join summary of the lobby behind a code: game name/description, seated players, open seats and the engine-echoed options. `404` when the code is unknown |
| `GET` | `/api/games/{id}` | Game snapshot. Seated players get the personalized view (own hand plus the join code); anyone else gets the read-only spectator view: table, scores, captured counts and scope, no hands and no join code |
| `GET` | `/api/me/games` | Live games the caller is seated in (waiting lobbies, matches in progress or between hands), newest first, for the lobby's "Continue" list. Finished matches are not included |
| `GET` | `/api/me/matches` | Cursor-paginated match history with the engine's `result` and per-player Elo deltas (`?limit=&cursor=&game_type=`) |
| `GET` | `/api/me/ratings` | The caller's Elo rating per game type |
| `GET` | `/api/leaderboard` | Elo rating, aggregated wins / matches / points per player, sorted by Elo (`?game_type=`) |

## WebSocket protocol

Connect to `/ws/games/{game_id}`; the session cookie is optional. Anyone
who knows the game id is accepted: seated players get their personalized
view, everyone else — anonymous users and authenticated non-players — is
a read-only **spectator**. Only an unknown game id is refused before the
handshake completes, with `404`. (Browsers report a refused handshake as
an abnormal close — there is no close code to read.)

Server → client messages are JSON objects with a `type`:

- `{"type": "state", "game": {...}}` — personalized game view. Your own
  hand is included; other players expose only their card counts.
  Spectators get no hand at all, `spectator: true` marks the view and
  `join_code` is omitted for them. `your_turn: true` is present when it
  is your move. `seats_open` reports the free chairs (0 once the match
  started).
- `{"type": "game_over", "scores": {"A": 11, "B": 7}, "winner": "A"}`
- `{"type": "error", "code": "illegal_move", "message": "..."}`

Client → server messages are JSON objects with an `action`. The
platform handles `state` (resend the snapshot) itself; every other action
is dispatched to the session's game engine with the rest of the message
as its payload. Spectators may only send `state`/`sync`: any other
action is answered with an `error` whose `code` is `forbidden`. For
scopone scientifico:

```json
{"action": "play", "card": "07D", "capture": ["02D", "05C"]}
{"action": "play", "card": "07D"}
{"action": "ack"}
{"action": "state"}
```

- `card` is the card you play, rendered as `RRSUIT` (`01A`..`10D`; suits
  `D` denari, `C` coppe, `S` spade, `B` bastoni — e.g. `07D` is the
  settebello).
- `capture` lists the table cards to take. When a capture is legal it is
  mandatory to provide one; when no capture exists it must be omitted.
- `ack` acknowledges the hand-end scoring summary (see below). The next
  hand is dealt once all four players have acknowledged, or automatically
  after `HAND_ACK_TIMEOUT_SECONDS`.
- `state` asks for a fresh snapshot.

For briscola (`briscola`, `briscola_a_quattro`) the game actions are
`play` (with `card` only — every card in hand is legal) and `ack`:

```json
{"action": "play", "card": "04C"}
{"action": "ack"}
```

- `card` uses the same `RRSUIT` convention.
- `ack` acknowledges the deal-end summary; the next deal is dealt once
  every player has acknowledged, or automatically after
  `HAND_ACK_TIMEOUT_SECONDS`.

After every accepted move the new state is broadcast to every connected
client, spectators included.

### Turn timeout

The state carries a `turn_deadline` while a hand is being played. If the
player on turn does not move before it, the server plays a random legal
card for them (picking one of the legal captures at random when a capture
is required), so a disconnected or idle player cannot stall the match. The
timeout is `TURN_TIMEOUT_SECONDS` (default 30); the auto-played move is
broadcast like any other. Deadlines fire from the shared `tavolo:deadlines`
queue (see above), not from timers tied to client connections, so the
match keeps progressing even with every player disconnected.

### Hand-end summary

When a hand finishes but the match continues, the game enters the
`hand_end` phase instead of dealing immediately: the state carries the
scoring breakdown of the hand just played (`last_hand` with an `award`
map naming the team that won each scopone category; `last_deal` with the
deal's points and running totals for briscola), the `acknowledged` seats
and a `hand_end_deadline`. The frontend renders this as a screen every
player must dismiss. A play attempted in this phase is rejected with an
`illegal_move` error.

## Rules implemented

### Scopone scientifico

- 40-card Italian deck, ten cards per player, empty table at hand start.
- A card captures a **single card of equal rank** (mandatory when present)
  or a **combination of table cards whose ranks sum to its own**.
- Emptying the table scores a *scopa* (+1), except on the last play of a
  hand. Remaining table cards go to the last player who captured.
- Hand points: `carte` (most captured cards), `denara` (most diamonds),
  `settebello` (7♦), `primiera` (best 7/6/5/4 per suit, all four suits
  required), plus one point per scopa. Ties award nothing.
- Optional *napola* rule (per-game `napola` creation option, default on):
  the longest run of consecutive denari starting from the ace scores one
  point per card once it reaches three cards (A-2-3 = 3, A-2-3-4 = 4, …).
  A team that captures the whole denari suit (ace to king) wins the match
  instantly, regardless of the score.
- Optional *asso pigliatutto* rule (per-game `asso_pigliatutto` creation
  option, default off): an ace played when no equal rank is on the table
  sweeps every card on the table — or captures itself when the table is
  empty. The capture never scores a scopa, but it counts as the last
  capture, and the mandatory equal-rank capture still applies when another
  ace is on the table.
- The match ends when a team reaches the target score (default 11,
  configurable per game via the `target_score` creation option) with a
  clear lead; a tie at or above the target is broken by another hand.

### Briscola

- 40-card Italian deck, three cards per player. The card turned up after
  the deal fixes the trump (*briscola*) suit for the whole deal and is the
  last card drawn from the stock.
- Trick play: the highest trump wins; when no trump was played, the
  highest card of the led suit wins. The winner takes the trick and leads
  the next one.
- After each trick every player draws back up to three cards, starting
  with the trick winner; the face-up briscola card goes to whoever's turn
  to draw it is.
- Card points: ace 11, three 10, king 4, horse 3, jack 2 — 120 points per
  deal. Trick strength is unrelated to points: ace > three > king > horse
  > jack > 7 > 6 > 5 > 4 > 2.
- Match points accumulate across deals; a 60–60 deal is a *patta*: its
  points are discarded and the deal is replayed. The match ends when a
  team reaches the target score (default 61, configurable per game via
  the `target_score` creation option) with a clear lead; a tie at or
  above the target is broken by another deal.
- `briscola` is the classic two-player game; `briscola_a_quattro` seats
  four players in two fixed partnerships (seats 0/2 vs 1/3, partners
  opposite).

## Development

```sh
python3 -m venv .venv
.venv/bin/pip install -r requirements.txt
.venv/bin/pip install -e ./packages/tavolo-platform -e ./packages/tavolo-scopone -e ./packages/tavolo-briscola -e './packages/tavolo-app[dev]'
# app integration suite:
.venv/bin/python -m unittest discover -s tests -t .
# per-package suites (each package is self-contained):
.venv/bin/python -m unittest discover -s packages/tavolo-platform/tests
.venv/bin/python -m unittest discover -s packages/tavolo-scopone/tests
.venv/bin/python -m unittest discover -s packages/tavolo-briscola/tests
# type checks (see packages/tavolo-app/README.md for the app modules):
.venv/bin/python -m mypy -p tavolo.platform
.venv/bin/python -m mypy -p tavolo.scopone
.venv/bin/python -m mypy -p tavolo.briscola
```

Tests run fully in-process: in-memory sqlite for Postgres, in-memory stores
for Redis, a fake OIDC user patched onto the mixins, and `httpx` /
`httpx-ws` ASGI transports for HTTP and WebSocket coverage. The platform
suite additionally runs against a `DummyEngine` toy game, so the
game-independent machinery is covered without importing scopone.

### Migrations

The Postgres schema is owned by aerich migrations in `migrations/`. The
`db-migrate` compose service runs `aerich upgrade` before the app starts.
To add a migration after changing
`packages/tavolo-platform/src/tavolo/platform/models.py`:

```sh
DATABASE_URL=postgres://tavolo:tavolo@localhost:5432/tavolo .venv/bin/aerich migrate
DATABASE_URL=postgres://tavolo:tavolo@localhost:5432/tavolo .venv/bin/aerich upgrade
```

(`aerich init-db` produces sqlite-flavored DDL when pointed at sqlite;
adjust `UUID`/`TIMESTAMPTZ`/`BOOL`/`JSONB` for Postgres like the existing
baseline.)

## Layout

```
packages/tavolo-platform/     # game-independent platform (own pyproject + tests)
  src/tavolo/platform/
  ├── __init__.py             # public surface (GameEngine, GameSession, Platform, ...)
  ├── engine.py               # the platform<->game contract
  ├── registry.py             # game id -> engine lookup
  ├── mixin.py                # Platform + PlatformMixin (mounts everything on a kaya app)
  ├── errors.py               # shared GameError hierarchy
  ├── models.py               # Match / MatchPlayer / PlayerRating (Postgres)
  ├── elo.py                  # chess-style Elo math (1500 start, K=32)
  ├── stats.py                # MatchResult -> Postgres persistence + Elo update
  ├── backfill_elo.py         # recompute all ratings from the match history
  ├── store.py                # Redis / in-memory live-session store (+ deadline queue)
  ├── deadlines.py            # connection-independent timeout scheduler
  ├── ws.py                   # WebSocket live-play endpoint (generic envelope)
  ├── auth.py                 # auth helpers (HTTP + WebSocket)
  ├── http.py                 # JSON request/response helpers
  ├── pagination.py           # keyset (cursor) pagination
  ├── openapi.py              # shared OpenAPI parameter fragments
  ├── tortoise_mixin.py       # TortoiseORM lifecycle (HTTP + WebSocket)
  └── routes/
      ├── health.py           # GET /api/health
      ├── me.py               # GET /api/me
      ├── games.py            # lobby: game-types / create / join / snapshot
      └── stats.py            # match history + leaderboard + Elo ratings
packages/tavolo-scopone/      # scopone scientifico game (own pyproject + tests)
  src/tavolo/scopone/
  ├── state.py                # ScoponeState / PlayerState / Card, JSON (de)serialization
  ├── engine.py               # pure scopone scientifico rules
  ├── errors.py               # scopone-specific rule violations
  └── plugin.py               # ScoponeEngine: the GameEngine adapter
packages/tavolo-briscola/     # briscola game (own pyproject + tests)
  src/tavolo/briscola/
  ├── state.py                # BriscolaState / PlayerState / Card / Trick, JSON (de)serialization
  ├── engine.py               # pure briscola rules (2- and 4-player)
  ├── errors.py               # briscola-specific rule violations
  └── plugin.py               # BriscolaEngine + BriscolaQuattroEngine adapters
packages/tavolo-app/          # deployable app: composition root (own pyproject)
  src/tavolo/
  ├── app.py                  # session/OIDC/Tortoise/OpenAPI/Platform/DeadlineScheduler mixins
  ├── config.py               # env -> frozen Settings
  ├── telemetry.py            # OTLP metric/log providers, app gauges, count poller
  ├── aerich_config.py        # aerich CLI configuration
  ├── logging_config.py       # logging setup
  └── static.py               # SPA shell hosting
pyproject.toml                # tooling shim: [tool.aerich] + [tool.mypy] for server/ CWD
migrations/                   # aerich migrations for the platform models
tests/                        # app integration suite (platform + games wired together)
```