threejs-agent-starter: Instructions file for Codex

Agent Rules — Three.js Game Dev Starter Pack

You are helping a developer build or extend a browser game using this starter kit. Read this file fully before writing any code.

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Stack

• Vite + TypeScript + Three.js (vanilla, no framework)
• All game logic lives in src/main.ts
• All styles live in src/style.css
• No additional packages unless explicitly requested

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Architecture Rules

1. Single class pattern — all game logic belongs inside one top-level game class named after the game (e.g. AsteroidsGame, BlockBreakerGame). Do not create loose functions or module-level state outside the class.
2. Config object — all tunable values (speeds, sizes, positions, thresholds) go in GAME_CONFIG. No magic numbers inline.
3. Game phases — use a const-object pattern (not TS enum — erasableSyntaxOnly forbids it): const GamePhase = { MENU: 'MENU', PLAYING: 'PLAYING', GAME_OVER: 'GAME_OVER' } as const. State is always one of these. Every behaviour must respect the current phase.
4. Typed interfaces — define TypeScript interfaces for all non-trivial objects (e.g. Enemy, Projectile, Pickup).
5. Cleanup — any new event listeners, animation frames, or Three.js objects added must be disposed/removed in destroy().
6. No new files — unless explicitly asked, keep all code in src/main.ts and src/style.css.

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Three.js Rules

• Always cap pixel ratio: Math.min(window.devicePixelRatio, 2)
• Always cap delta: delta = Math.min(delta, 0.04) to prevent physics explosions on tab switch
• Use THREE.Box3 for AABB collision detection — update bounds each frame with setFromObject()
• Use THREE.MathUtils.damp() for smooth deceleration, not manual lerp
• Dispose geometries and materials when removing objects from the scene
• Shadow maps are enabled — new meshes that should cast/receive shadows must set those flags explicitly

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Code Style

• const over let wherever possible
• Private class fields with readonly where applicable
• Descriptive variable names — no single-letter variables except loop indices
• Group related logic into clearly named private methods