implement-game-loop

1. Overview

Orchestrates entry point, subsystem bootstrapping, and primary execution loop in required dependency order.

2. Quick Reference

Bootstrap order (dependency-critical):

1. EventBus + Allocators
2. ECS World → register all systems from src/systems/
3. Behavior Tree Engine (tick at spec frequency, default 10Hz)
4. Input Handler
5. State Machine
6. Entity factories → create initial entities
7. Screen Manager (if screens defined)
8. Game loop: world.update(dt) only; delegate rendering to Renderer

3. When to Use

• Scenarios: Initializing main entry point; setting up bootstrap after core design specs finalized.
• Triggers: implement game loop, bootstrap engine, application entry point, system wiring.

3. Core Pattern

1. Platform & Language Detection — Scan project config for target platform and language.
2. Entry Point & Bootstrap — Generate main entry file and bootstrap module wiring EventBus, ECS World, Input Handler, State Machine, Behavior Tree Engine in dependency order.
3. ECS Systems Registration (MANDATORY) — After creating ECS World, scan src/systems/ for all generated systems. Register EACH with correct component mapping and priority per ecs_spec.md Section 4 (Phase A → B → C). Every system must be registered.
4. Behavior Tree Engine (MANDATORY) — Init during bootstrap (after EventBus + ECS World). Tick in game loop at frequency from behavior_tree_spec.md Section 5 (default 10Hz). Connect via assignTree(entityId, rootNode()) using factories from implement-behavior-tree. Interrupt on high-priority events per behavior_tree_spec.md Section 4.
5. Entity Factory (MANDATORY) — Use factories from implement-ecs-systems to create initial entities. Instantiate via factory functions only: createTestEntities() calls createPlayer(world) etc., creates correct entity count, assigns BT via assignTree().
6. Game Loop — Follow game_loop.md: call world.update(dt) exclusively (delegate entity updates to ECS), btEngine.update(currentTime), process input, delegate rendering to Renderer only. Web: Phaser 3 → init Phaser + GameScene; Three.js → init renderer/scene/camera + animation loop.
7. Lifecycle — Wire event bus subscribers, register FSM transitions, implement graceful shutdown.

4. Interaction Protocol

• [Dependency Order]: If incorrect wiring order: "Bootstrap initializes [System X] before dependency [Y]. Crash risk. Reorder?"
• [Missing Subsystem]: "[SubSystem] not initialized or wired. Add bootstrap step?"
• Constraint: Prioritize correct dependency ordering.

5. Red Flags

• Dependency Order Compliance: Initialize subsystems only after all prerequisites are ready.
• Complete Subsystem Initialization: Wire every component from system_roster.md to prevent null reference crashes.
• Graceful Shutdown: Implement clean shutdown handlers per subsystem to prevent data corruption and resource leaks.

6. Final Integrity Audit

• All subsystems from system_roster.md have init steps.
• Dependency order: EventBus/Allocators BEFORE ECS/AI.
• Matches game_loop.md cycle logic.
• Clean shutdown handler per subsystem.
• All ECS systems from src/systems/ registered — none skipped.
• BT engine ticked at correct frequency (10Hz).
• Entity factories used — no manual component instantiation.
• Game loop delegates to world.update(dt) — no manual per-entity logic.
• Rendering delegated to Renderer — no manual render calls.

7. Execution Command

/implement-game-loop