Watten

A Watten card-game trainer (Tyrolean / 33-card variant) written in Rust with a WebAssembly frontend. The bots use a memoized legal-completion search to pick their cards and to estimate per-card win rates for the human player.

Crate features

• 33-card Watten deck (four suits × Seven..Ace plus the Weli)
• Card, Suit, Rank, GameResult, Player, GameState
• card_strength enforcing Rechte > Striker rank > trump > lead > rest
• Seeing-player must-follow-trump rule (GameState::allowed_indices)
• GameState::play_round / play_round_logged (non-interactive)
• start_round_interactive + human_play + advance_bots (interactive)
• raise_round(team) / concede_round(team) for "raising" and "geh"
• Two move evaluators selectable via set_evaluator:
  • Evaluator::Search (default): memoized enumeration of all legal trick completions from the current state. Sub-second per round.
  • Evaluator::Database: legacy 120⁴ brute-force, kept as a benchmark fallback. cargo full exercises it.

Running

Quick start (play locally)

You need:

• Rust (stable) + the wasm32-unknown-unknown target (rustup target add wasm32-unknown-unknown)
• wasm-pack (cargo install wasm-pack)
• Node.js 18+

Then, from the repository root:

make dev

Open http://localhost:5173 in your browser. The Vite dev server hot-reloads both the React frontend and the Rust → WASM bundle.

Equivalent without make:

npm start

Tests

cargo test           # fast Rust unit + integration tests
cargo full           # also runs the heavy database population tests

Frontend unit / integration tests (Vitest + Testing Library, builds wasm first):

cd frontend
npm install
npm test             # Vitest
npm run test:watch   # Vitest in watch mode

End-to-end browser tests (Playwright on Chromium, Firefox and WebKit):

cd frontend
npx playwright install   # first time only
npm run test:e2e

Code coverage

From the repository root:

npm run coverage         # Rust (cargo-llvm-cov) + JS (Vitest v8)
npm run coverage:rust    # Rust only — HTML in coverage-rust/html
npm run coverage:js      # JS only   — HTML in frontend/coverage

cargo llvm-cov requires the llvm-tools-preview rustup component and the cargo-llvm-cov cargo subcommand:

rustup component add llvm-tools-preview
cargo install cargo-llvm-cov

Deployment

Pushes to main trigger .github/workflows/gh-pages.yml, which builds the Vite bundle with VITE_BASE set to the repo path and deploys it to GitHub Pages. Enable Pages in repository settings → Pages → Source: GitHub Actions once, and subsequent pushes deploy automatically. The deployed URL is reported in each workflow run.

CLI

cargo run

Plays a game in the terminal. Set verbose = true on GameState to see narration (already enabled by the CLI binary).

WebAssembly frontend

You will need wasm-pack and Node.js. From the repository root:

npm start

This installs JS dependencies, runs wasm-pack build --target web, and starts Vite. Open http://localhost:5173. The UI shows your hand with a per-card win-rate estimate (wins / total over all legal completions); opponent hand sizes; the current trick; the running scores; and Raise (+1) and Concede round buttons.

To build a production bundle and preview it:

cd frontend
npm run build
npm run serve

To run the Playwright UI tests (Firefox only):

cd frontend
npm run test:ui

Rules summary

• Trump (Schlag) is the suit of the top card of the dealer's pile (the first card dealt to the dealer).
• Striker rank (Weisen) is the rank of the top card of the forehand's pile (the first card dealt to the player after the dealer).
• Card strength: Rechte (the trump-suit + striker-rank card) > Weli > any Striker > any trump > lead suit > rest. First-played wins ties between equal-strength cards (card_strength in src/game.rs).
• Seeing players (dealer + forehand) must play a trump or striker when trump is led if they have one (enforced by GameState::allowed_indices).

Status / known limitations

• The Critical cards (Maxi/Belli/Spitz) of Bavarian Watten are not modelled — this is the Tyrolean/generic 33-card variant.
• Winning score defaults to 15 (game::WINNING_POINTS). Not yet runtime- configurable from the UI.