gijs_pong/.planning/STATE.md

gsd_state_version, milestone, milestone_name, status, stopped_at, last_updated, progress

gsd_state_version	milestone	milestone_name	status	stopped_at	last_updated	progress
1.0	v1.0	milestone	unknown	Completed 02-01-PLAN.md	2026-03-10T20:07:22.163Z	total_phases completed_phases total_plans completed_plans 5 1 4 3

STATE: Super Pong Next Gen

Project Reference

• Core Value: Pong reimagined with juice and depth — spectacular visuals, rich mechanics, complete game experience
• Current Focus: Phase 1 — executing plans
• Key Constraint: Coarse granularity (5 phases max), HTML5 Canvas + vanilla JS, static deployment

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Current Position

Attribute	Value
Phase	02-core-gameplay
Plan	Plan 1/2 — COMPLETE
Status	Phase 02 in progress — paddle2, AI module, predictive ray-cast, 3 difficulty levels done
Progress	75% (3/4 plans complete; Phase 1 complete, Phase 2 plan 1 complete)

[████████░░] 75% — Phase 2: 1/2 plans complete

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Performance Metrics

Metric	Target	Status
Phase Coverage	100% (37/37 requirements mapped)	✓ Complete
Success Criteria	2-5 per phase	✓ Complete
Dependency Chain	Linear (P1 → P2 → P3 → P4 → P5)	✓ Validated
01-01 Duration	—	1 min (2 tasks, 1 file)

| 01-02 Duration | — | 1 min (2 tasks, 1 file) |

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| Phase 02-core-gameplay P01 | 2min | 2 tasks | 1 files |

Accumulated Context

Key Decisions Made

1. Coarse Granularity Compression: Research suggested 10 phases; compressed to 5 by merging:

   • Game loop + input + physics = Phase 1
   • Second paddle + AI = Phase 2
   • Menus + audio + pause = Phase 3
   • Visual effects + power-ups + arenas = Phase 4
   • Performance + testing = Phase 5

2. Phase 5 (Release) Has No Requirements: All 37 v1 requirements covered by phases 1-4. Phase 5 is purely validation (cross-browser, performance, pitfall mitigation).

3. Success Criteria Grounded in Research Pitfalls: Each phase's criteria address critical pitfalls from research:

   • Phase 1: DPI scaling, game loop timing
   • Phase 2: Ball tunneling, input lag, AI balance
   • Phase 3: Audio autoplay policy
   • Phase 4: Power-up balance
   • Phase 5: Performance, memory leaks, cross-browser

4. deltaTime Cap at 50ms: Game loop caps deltaTime to prevent physics explosion when tab loses focus and resumes — without this a single large delta would fling the ball off screen.

5. Logical vs Bitmap Coordinate Separation: canvas.width/height = logical * devicePixelRatio; ctx.scale(dpr, dpr) makes all game draw calls use logical pixels — correct HiDPI approach for sharp rendering on Retina displays.

6. Module-Object Pattern Established: GameLoop, Renderer, Input, Physics, GameState are plain JS objects with init() methods in a single script tag. No classes, no modules, no build step — runs directly from filesystem.

7. e.code over e.key for Input: Using e.code === 'KeyW' makes W/S detection layout-independent (works on AZERTY and other non-QWERTY keyboards).

8. Zone angles [-60, -30, 5, 30, 60] degrees: Center zone uses 5 deg not 0 to prevent infinite horizontal ball loops; top/bottom edges at 60 degrees for dramatic deflection.

9. GameConfig centralizes tunable constants: initialBallSpeed (220px/s), speedIncrement (18px/s), paddleSpeed (400px/s) — all adjustable without touching Physics logic.

10. vx/vy recomputed from speed+angle each paddle hit: Prevents compound rounding drift from repeated scaling; speed and direction always cleanly separated.

11. AI uses predictive ray-cast with wall bounce simulation: _predictBallY steps forward in time (up to 500 steps) simulating wall bounces — far more accurate than linear Y interpolation.

12. AI difficulty presets as config objects: { speed, reactionDelay, errorMargin } in GameConfig — all three dimensions of difficulty tunable without touching AI logic.

13. AI waits when ball moves toward player (vx < 0): Resets reaction timer and returns early — AI only acts when ball is heading toward its paddle, avoiding premature repositioning.

14. Physics.onResize() calls init() for full reposition: Ensures paddle2 (and paddle1) are properly repositioned on window resize rather than just updating width/height dimensions.

Coverage Validation

Total v1 Requirements: 37

• CORE (8): All mapped to Phase 1-2
• AI (4): All mapped to Phase 2
• SCRN (4): All mapped to Phase 3
• VFX (5): All mapped to Phase 1 (DPI) and Phase 4 (particles/glow/trails/shake)
• PWR (7): All mapped to Phase 4
• ARENA (4): All mapped to Phase 4
• AUD (5): All mapped to Phase 3

Unmapped Requirements: 0 ✓ Coverage: 100% ✓

Research Alignment

• Phase 1 addresses Research Pitfalls: #1 (Game Loop Timing), #2 (Canvas DPI Scaling)
• Phase 2 addresses Research Pitfalls: #3 (Ball Tunneling), #4 (Input Lag), #5 (AI Difficulty Balance)
• Phase 3 addresses Research Pitfall: #6 (WebAudio Autoplay Policy)
• Phase 4 addresses Research Pitfalls: #7 (Power-Up Balance)
• Phase 5 addresses Research Pitfall: #8 (Memory Leaks)

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Session Continuity

What Just Happened

Phase 02 Plan 01 executed: paddle2 added to GameState (mirrors paddle1 structure), Input extended with ArrowUp/ArrowDown + named handler refs + cleanup(), AI module added with predictive ray-cast interception (wall-bounce simulation) and 3 difficulty presets (AI_EASY/MEDIUM/HARD). Physics._checkPaddle2Collision() added with 5-zone deflection sending ball LEFT. Physics.update() extended with paddle2 movement branch. Requirements CORE-08, AI-01, AI-02, AI-03, AI-04 satisfied.

What Comes Next

1. Execute Phase 2 Plan 02 — mode selection UI, scoring system, win/game-over states, ball tunneling safeguards
2. Continue through phases 3-5 after Phase 2 complete

Known Blockers

None.

Decisions Pending

None.

Last Session

Stopped at: Completed 02-01-PLAN.md

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State initialized: 2026-03-10