## curltastic

A multiplayer 2D curling game for mobile browser. Any number of clients can join a room, pick Red or Yellow freely, and throw when it is that team's turn (solo pass-and-play or remote opponents).

- **Backend** — Rust, Axum, WebSocket, Rapier2D physics (server-authoritative, 120 Hz).
- **Frontend** — TypeScript, Vite, Canvas2D, portrait-first touch UI.

### Run locally

1. Install Rust via [rustup](https://rustup.rs/) (if not already installed).
2. Start the backend:
   ```bash
   cd backend
   cargo run --release
   # listens on 0.0.0.0:3000
   ```
3. Start the frontend dev server:
   ```bash
   cd frontend
   npm install
   npm run dev
   # opens on 0.0.0.0:5173 by default
   ```
4. Open one or more browser tabs to the same room URL, e.g.:
   ```
   http://localhost:5173/?room=DEMO1
   ```
   Use the team dropdown in the top-right to switch between Red and Yellow — this enables local pass-and-play on one device. Use the *Copy share link* button to invite an opponent on another device.

### Mobile devices

The frontend binds to `0.0.0.0` via `--host`. Find your machine's LAN IP and open `http://<ip>:5173/?room=CODE` on the phone. Both devices must be on the same Wi-Fi and able to reach the backend on port `3000`. The default view is zoomed in on the house; drag the sheet vertically to scroll up to the hog line.

### Controls

- When it is your team's turn, drag on the sheet to place the broom (aim point) — aim is not limited to the house.
- When it is not your turn, drag to pan the ice (default framing shows the house with sidelines; pan up toward the hog line).
- Use the team dropdown to choose which team's stone you are throwing; switch any time (including mid-end for solo play).
- Use the left/right curl buttons and the weight/friction controls; friction is a local scalar.
- Tap **THROW**. Anyone identifying as the turn team may throw.
- The server runs physics for every stone and streams multi-stone paths; the client animates them on one clock so collisions move together.

### Architecture

- WebSocket JSON protocol with tagged messages.
- Server simulates each throw at 120 Hz and sends a subset of `(x, y, t)` path points at 40 Hz.
- All game state, scoring, end management, and hammer rules live on the server.
- Disconnects are tolerated: the room and turn remain in memory.

### E2E tests

With the backend and frontend dev server running:

```bash
cd e2e
npm install -g ws   # or npm install ws locally in the project
node e2e_test.cjs              # room lifecycle, throw, trajectory
node e2e_score.cjs             # alternate turns / stones in play
node e2e_persistence.cjs       # multi-throw stone persistence
node e2e_multi_client.cjs      # 3 clients share state (no room-full)
node e2e_end_score.cjs         # full end → end_scored + next end
node collision_trajectory_qa.cjs  # multi-stone trajectory on collision
```

### Limitations / known simplifications

- No accounts, persistence, anti-cheat, replay log, or turn timer.
- Curl is fixed as a function of release speed (more curl at lower speed); sweeping is not implemented.
- Stones that pass the back line or leave the sheet are removed from play.