docs(02-02): complete state machine and scoring plan

- Created 02-02-SUMMARY.md documenting full game state machine implementation
- STATE.md updated: Phase 2 complete (2/2 plans), decisions 15-17 added
- ROADMAP.md updated: Phase 2 marked Complete (2 plans, 2 summaries)
- REQUIREMENTS.md: CORE-05 and CORE-06 marked complete

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.planning/phases/02-core-gameplay/02-02-SUMMARY.md

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+---
+phase: 02-core-gameplay
+plan: 02
+subsystem: ui
+tags: [canvas, game-loop, state-machine, scoring, pong, vanilla-js]
+
+# Dependency graph
+requires:
+  - phase: 02-core-gameplay/02-01
+    provides: paddle2, AI module, predictive ray-cast, 3 difficulty presets, Input cleanup
+
+provides:
+  - Full game state machine (modeSelect → diffSelect → playing → scored → gameover)
+  - Scoring detection (ball exits left/right edge → score1/score2 increment)
+  - 1-second post-score pause with auto-serve
+  - Match-end condition (first to WIN_SCORE=7 wins)
+  - Mode selection UI (1=Solo vs AI, 2=2-Player)
+  - Difficulty selection UI (1=Easy, 2=Medium, 3=Hard)
+  - Winner overlay with "Press R to play again"
+  - R-key restart (scores reset, back to modeSelect)
+  - Center divider dashed line rendering
+  - Score numbers rendered on canvas (top-left / top-right)
+
+affects: [03-menus-audio, 04-effects-powerups, 05-polish-release]
+
+# Tech tracking
+tech-stack:
+  added: []
+  patterns:
+    - State machine pattern via gameState string field driving render/update branches
+    - GameLoop owns scoring detection; Physics.update() no longer owns out-of-bounds reset
+    - pauseTime field on GameLoop tracks scored-state start for 1s serve delay
+
+key-files:
+  created: []
+  modified:
+    - index.html
+
+key-decisions:
+  - "GameLoop owns scoring/serve, not Physics: removed auto-reset from Physics.update() so GameLoop can increment scores before calling serveBall()"
+  - "modeSelect state renders full-screen prompt and returns early — no physics/paddles rendered until game starts"
+  - "pauseTime stored on GameLoop object (not GameState) — transient timing data that doesn't need to survive restart"
+  - "Ball hidden during 'scored' pause state (gameState !== 'scored' guard on drawCircle) — clean visual signal to players"
+  - "2-Player mode skips diffSelect entirely — straight to playing after pressing 2"
+  - "Winner identity set on GameState.winner as 'player1' | 'ai' | 'player2' — AI win labeled 'AI', not 'Player 2'"
+
+patterns-established:
+  - "State machine pattern: gameState string drives render/update branches in GameLoop.main()"
+  - "GameLoop owns game-level events (scoring, match end, serve); Physics owns physics-level events (collision, deflection)"
+
+requirements-completed: [CORE-05, CORE-06]
+
+# Metrics
+duration: ~5min (continuation after human-verify checkpoint)
+completed: 2026-03-10
+---
+
+# Phase 2 Plan 02: Core Gameplay State Machine Summary
+
+**Full game loop with state machine, mode/difficulty selection UI, scoring detection, 1s re-serve pause, match-end at 7 points, and R-key restart — all in a single index.html**
+
+## Performance
+
+- **Duration:** ~5 min
+- **Started:** 2026-03-10T20:10:00Z
+- **Completed:** 2026-03-10T20:15:00Z
+- **Tasks:** 2 (1 auto + 1 checkpoint)
+- **Files modified:** 1
+
+## Accomplishments
+
+- Game state machine fully wired: modeSelect → diffSelect → playing → scored → gameover → modeSelect
+- Scoring detection moved to GameLoop (after Physics.update()), Physics auto-reset removed — scores now correctly increment
+- Mode/difficulty selection screens rendered on canvas with clear key prompts
+- Winner overlay with player name and restart prompt; R-key cleanly resets all state
+- Phase 1 debug speed text removed; center divider dashed line added
+
+## Task Commits
+
+Each task was committed atomically:
+
+1. **Task 1: State machine — mode/difficulty selection, scoring, match end, and restart** - `77071a5` (feat)
+2. **Task 2: Checkpoint: Verify Phase 2 complete gameplay** - approved by user (no code commit)
+
+## Files Created/Modified
+
+- `index.html` - GameLoop.main() rewritten with full state machine; Input._handleKeyDown extended with mode/difficulty/restart keys; Physics.update() out-of-bounds auto-reset removed; pauseTime field added to GameLoop
+
+## Decisions Made
+
+- GameLoop owns scoring detection and serve calls — Physics.update() no longer has out-of-bounds reset. This separation is critical: if Physics auto-resets, GameLoop never sees the scoring condition.
+- Ball hidden during `scored` pause via guard on drawCircle — cleaner player feedback than showing stationary ball.
+- 2-Player mode bypasses difficulty selection entirely (no AI to configure).
+- pauseTime stored on GameLoop (not GameState) — it's transient per-point timing that doesn't need to survive an R-key restart.
+
+## Deviations from Plan
+
+None - plan executed exactly as written.
+
+## Issues Encountered
+
+None.
+
+## User Setup Required
+
+None - no external service configuration required.
+
+## Next Phase Readiness
+
+- Phase 2 complete: full playable Pong with mode selection, AI opponent, scoring, match end, and restart
+- Phase 3 (menus, audio, pause) can proceed — GameState fields (gameState, mode, difficulty, score1, score2, winner) are stable contracts
+- No blockers
+
+---
+*Phase: 02-core-gameplay*
+*Completed: 2026-03-10*