# Code Style

> Last Updated: 2026-04-02T18:12:18.000Z

## Language & Version

- Primary language: TypeScript 5.x.
- Compiler settings from `tsconfig.json`: `target: ES2020`, `module: ESNext`, `moduleResolution: bundler`, `strict: true`, `noEmit: true`.
- Secondary language: Java for the Capacitor Android wrapper.

## Naming Conventions

| Kind | Convention | Real examples |
|------|------------|---------------|
| Classes | PascalCase | `BootScene`, `MenuScene`, `GameScene`, `CardTracker` |
| Interfaces | PascalCase | `Card`, `Capture`, `GameState`, `AIDecisionProgress`, `SearchProfile` |
| Type aliases | PascalCase | `Suit`, `PlayerIndex`, `Difficulty` |
| Functions | camelCase | `installFullscreenRequest`, `findCaptures`, `createInitialState`, `chooseMove`, `updateThinkBar` |
| Constants | UPPER_SNAKE or descriptive `const` names | `SUITS`, `PRIMIERA_VALUES`, `SEARCH_PROFILES`, `SCOREBAR_H` |
| Private fields | camelCase with `private` modifier | `state`, `tracker`, `thinkBar`, `selectedGlowTween` |
| Parameters and locals | camelCase | `playerIdx`, `captureChoice`, `remainingRatio`, `partnerHandSize` |

## Structural Conventions

- Phaser scenes extend `Phaser.Scene` and put setup in `create()` and asset loading in `preload()`.
- Core rule modules use exported functions and interfaces rather than classes.
- Stateful scene code uses `private` fields for long-lived UI and interaction state.
- AI configuration is table-driven through `SEARCH_PROFILES` and helper interfaces rather than nested literals inside `chooseMove()`.

## Indentation & Formatting

- TypeScript files use 2-space indentation.
- String literals use single quotes consistently.
- Semicolons are used consistently.
- Early returns are common for guard clauses.
- Multi-line object literals and function calls keep trailing commas when the surrounding style already uses them.
- `const` is the default; `let` is used only where reassignment is needed.

The Android Java wrapper follows the generated template style instead of the TypeScript style. `MainActivity.java` uses tab indentation and standard Android brace placement.

## Import Patterns

Named imports are used for local modules:

```ts
import { Card, GameState, PlayerIndex, Difficulty } from './types';
import { findCaptures, canCapture, teamOf, applyMove } from './engine';
import { CardTracker } from './card-tracker';
```

Framework imports use default or type-only imports where appropriate:

```ts
import Phaser from 'phaser';
import type { CapacitorConfig } from '@capacitor/cli';
```

The project uses only relative import paths. No path aliases are configured.

## Export Patterns

- Public APIs use named exports: `export function`, `export class`, `export interface`, `export type`, `export const`.
- Default exports are reserved for configuration entry points: `vite.config.ts` and `capacitor.config.ts`.
- Internal helpers remain file-local, for example `getSubsets`, `scoreRound`, `shuffleArray`, and `alphaBeta`.

## Typing Patterns

- Union types model constrained domains: `PlayerIndex = 0 | 1 | 2 | 3`, `Difficulty = 'beginner' | 'advanced' | 'master'`.
- Fixed-size tuples represent stable game structures such as four players and two team scores.
- `Record<number, number>` is used for lookup tables like `PRIMIERA_VALUES`.
- Exported functions generally declare explicit return types.
- Async behavior is typed directly in signatures such as `chooseMove(...): Promise<AIMove>`.

## Comments & Documentation

- Section banners are used heavily in larger files:

```ts
// ---------------------------------------------------------------------------
// Turn management
// ---------------------------------------------------------------------------
```

- JSDoc appears on rule-heavy or non-obvious APIs, for example `findCaptures()`, `applyMove()`, and `CardTracker` methods.
- Scene files include `[trueref]` provenance notes near Phaser-specific APIs.
- Inline comments explain rule edge cases, heuristics, and visual-effect intent rather than restating syntax.

## Code Examples

### Guarded DOM capability checks

```ts
const installFullscreenRequest = (host: HTMLElement): void => {
  const canRequestFullscreen =
    typeof document.fullscreenEnabled === 'boolean'
      ? document.fullscreenEnabled
      : typeof host.requestFullscreen === 'function';

  if (!canRequestFullscreen || typeof host.requestFullscreen !== 'function') {
    return;
  }
};
```

### Rule-first capture selection

```ts
export function findCaptures(played: Card, table: Card[]): Card[][] {
  const directMatches = table.filter(c => c.value === played.value);
  if (directMatches.length > 0) {
    return directMatches.map((directMatch): Card[] => [directMatch]);
  }

  const results: Card[][] = [];
  const subsets = getSubsets(table);
  for (const subset of subsets) {
    if (subset.length >= 2) {
      const sum = subset.reduce((acc, c) => acc + c.value, 0);
      if (sum === played.value) {
        results.push(subset);
      }
    }
  }
  return results;
}
```

### Async AI entry point with progress reporting

```ts
export async function chooseMove(
  state: GameState,
  playerIdx: PlayerIndex,
  difficulty: Difficulty = 'advanced',
  tracker?: CardTracker,
  onProgress?: (progress: AIDecisionProgress) => void,
): Promise<AIMove> {
  const startedAt = Date.now();
  const profile = getSearchProfile(state, difficulty);
  reportDecisionProgress(onProgress, difficulty, startedAt, profile.timeBudgetMs, 0, 0);
  // ...
}
```

## Linting & Formatting

No ESLint or Prettier configuration is present.

Formatting is maintained manually, with TypeScript compiler strictness acting as the main automated correctness gate. The only repository-wide verification command currently supplied is `npx tsc --noEmit`.
