docs(04-01): complete audio system plan

- Add 04-01-SUMMARY.md with execution results
- Update STATE.md with position, decisions, metrics
- Update ROADMAP.md with plan progress
- Mark AUDI-01 through AUDI-05 complete in REQUIREMENTS.md

.planning/REQUIREMENTS.md

@@ -99,11 +99,11 @@ Requirements for initial release (MVP). Each maps to roadmap phases.
 
 ### Audio
 
-- [ ] **AUDI-01**: Richtiger Tastendruck: Kurzer heller Ton (800Hz, 0.1s, Web Audio API)
+- [x] **AUDI-01**: Richtiger Tastendruck: Kurzer heller Ton (800Hz, 0.1s, Web Audio API)
-- [ ] **AUDI-02**: Belohnung: Aufsteigende Tonfolge (0.8s)
+- [x] **AUDI-02**: Belohnung: Aufsteigende Tonfolge (0.8s)
-- [ ] **AUDI-03**: Neues Waldelement: Glitzer-Sound (weisses Rauschen gefiltert, 0.5s)
+- [x] **AUDI-03**: Neues Waldelement: Glitzer-Sound (weisses Rauschen gefiltert, 0.5s)
-- [ ] **AUDI-04**: Mute-Button immer sichtbar, Zustand persistiert
+- [x] **AUDI-04**: Mute-Button immer sichtbar, Zustand persistiert
-- [ ] **AUDI-05**: Optionale Sprachausgabe via Web Speech API (Deutsch, Rate 0.9, Pitch 1.1)
+- [x] **AUDI-05**: Optionale Sprachausgabe via Web Speech API (Deutsch, Rate 0.9, Pitch 1.1)
 
 ### Polish
 
@@ -204,11 +204,11 @@ Which phases cover which requirements. Updated during roadmap creation.
 | PRNT-02 | Phase 3 | Complete |
 | PRNT-03 | Phase 3 | Complete |
 | PRNT-04 | Phase 3 | Complete |
-| AUDI-01 | Phase 4 | Pending |
+| AUDI-01 | Phase 4 | Complete |
-| AUDI-02 | Phase 4 | Pending |
+| AUDI-02 | Phase 4 | Complete |
-| AUDI-03 | Phase 4 | Pending |
+| AUDI-03 | Phase 4 | Complete |
-| AUDI-04 | Phase 4 | Pending |
+| AUDI-04 | Phase 4 | Complete |
-| AUDI-05 | Phase 4 | Pending |
+| AUDI-05 | Phase 4 | Complete |
 | PLSH-01 | Phase 4 | Complete |
 | PLSH-02 | Phase 4 | Complete |
 | PLSH-03 | Phase 4 | Complete |

.planning/ROADMAP.md

@@ -92,7 +92,7 @@ Plans:
 **Plans:** 4 plans
 
 Plans:
-- [ ] 04-01-PLAN.md — Audio system (Web Audio API sounds, Web Speech API speech, mute button)
+- [x] 04-01-PLAN.md — Audio system (Web Audio API sounds, Web Speech API speech, mute button)
 - [x] 04-02-PLAN.md — Animation polish (leaf-fall, stardust, companion float), responsive, error handler
 - [x] 04-03-PLAN.md — Export/Import/Reset in parent area
 - [ ] 04-04-PLAN.md — Wire audio into all screens, end-to-end human verification

.planning/STATE.md

@@ -3,14 +3,14 @@ gsd_state_version: 1.0
 milestone: v1.0
 milestone_name: milestone
 status: executing
-stopped_at: Completed 04-03-PLAN.md
+stopped_at: Completed 04-01-PLAN.md
-last_updated: "2026-03-29T16:17:42.908Z"
+last_updated: "2026-03-29T16:19:56.987Z"
 last_activity: 2026-03-29
 progress:
   total_phases: 4
   completed_phases: 3
   total_plans: 19
-  completed_plans: 17
+  completed_plans: 18
   percent: 0
 ---
 
@@ -26,7 +26,7 @@ See: .planning/PROJECT.md (updated 2026-03-29)
 ## Current Position
 
 Phase: 04 (polish-audio) — EXECUTING
-Plan: 3 of 4
+Plan: 4 of 4
 Status: Ready to execute
 Last activity: 2026-03-29
 
@@ -69,6 +69,7 @@ Progress: [░░░░░░░░░░] 0%
 | Phase 03 P04 | 3min | 2 tasks | 4 files |
 | Phase 04 P02 | 2min | 2 tasks | 3 files |
 | Phase 04 P03 | 2min | 2 tasks | 3 files |
+| Phase 04 P01 | 4min | 2 tasks | 9 files |
 
 ## Accumulated Context
 
@@ -106,6 +107,8 @@ Recent decisions affecting current work:
 - [Phase 04]: Stardust particles use box-shadow on pseudo-elements for 6 total sparkle points
 - [Phase 04]: Error overlay uses tree emoji and German child-friendly message
 - [Phase 04]: Export excludes Blobs (only progress+settings) for JSON portability
+- [Phase 04]: speechEnabled defaults to false (opt-in), audioEnabled defaults to true (opt-out)
+- [Phase 04]: AudioContext lazy init on first user interaction for autoplay policy compliance
 
 ### Pending Todos
 
@@ -117,6 +120,6 @@ None yet.
 
 ## Session Continuity
 
-Last session: 2026-03-29T16:17:42.902Z
+Last session: 2026-03-29T16:19:56.980Z
-Stopped at: Completed 04-03-PLAN.md
+Stopped at: Completed 04-01-PLAN.md
 Resume file: None

.planning/phases/04-polish-audio/04-01-SUMMARY.md

@@ -0,0 +1,126 @@
+---
+phase: 04-polish-audio
+plan: 01
+subsystem: audio
+tags: [web-audio-api, web-speech-api, audiocontext, speech-synthesis, mute-button]
+
+# Dependency graph
+requires:
+  - phase: 03-gameplay-loop
+    provides: Settings store with audioEnabled, IndexedDB persistence
+provides:
+  - Web Audio API sound effects module (playCorrectSound, playRewardSound, playForestElementSound)
+  - Web Speech API text-to-speech module (speakText)
+  - Mute button UI with persisted toggle state
+  - AudioContext lazy initialization on first user interaction
+affects: [04-02, 04-03, 04-04]
+
+# Tech tracking
+tech-stack:
+  added: [Web Audio API, Web Speech API]
+  patterns: [lazy AudioContext initialization, settings-gated audio playback]
+
+key-files:
+  created:
+    - src/audio/sounds.ts
+    - src/audio/speech.ts
+  modified:
+    - src/types.ts
+    - index.html
+    - src/styles/main.css
+    - src/main.ts
+    - src/api/gemini.ts
+    - src/storage/db.test.ts
+    - src/ui/parent.ts
+
+key-decisions:
+  - "speechEnabled defaults to false (opt-in feature, not opt-out)"
+  - "AudioContext created lazily on first click/keydown for autoplay policy compliance"
+  - "All sound functions use try/catch with silent fallback (never throw)"
+
+patterns-established:
+  - "Audio gating: every sound/speech function checks Settings before playing"
+  - "Lazy AudioContext: initAudioOnInteraction() called from user event handlers"
+
+requirements-completed: [AUDI-01, AUDI-02, AUDI-03, AUDI-04, AUDI-05]
+
+# Metrics
+duration: 4min
+completed: 2026-03-29
+---
+
+# Phase 04 Plan 01: Audio System Summary
+
+**Web Audio API procedural sounds (correct/reward/forest) and Web Speech API German TTS with mute button and Settings persistence**
+
+## Performance
+
+- **Duration:** 4 min
+- **Started:** 2026-03-29T16:14:40Z
+- **Completed:** 2026-03-29T16:18:48Z
+- **Tasks:** 2
+- **Files modified:** 9
+
+## Accomplishments
+- Three procedural Web Audio API sounds: correct keystroke beep (800Hz), ascending reward melody (C5-E5-G5-C6), filtered white noise for forest elements
+- German text-to-speech via Web Speech API with async voice loading and settings gate
+- Mute button with fixed-position circular UI, toggle persistence in IndexedDB, and visual state feedback
+
+## Task Commits
+
+Each task was committed atomically:
+
+1. **Task 1: Audio module + Speech module + Settings extension** - `c19b7fe` (feat)
+2. **Task 2: Mute button in HTML + CSS + wiring in main.ts** - `52596c5` (feat)
+
+## Files Created/Modified
+- `src/audio/sounds.ts` - Web Audio API sound effects with AudioContext lazy init
+- `src/audio/speech.ts` - Web Speech API speakText with German voice detection
+- `src/types.ts` - Added speechEnabled to Settings interface
+- `index.html` - Added mute-btn element outside all screen sections
+- `src/styles/main.css` - Mute button fixed-position styles
+- `src/main.ts` - Wired mute button toggle and AudioContext init on first interaction
+- `src/api/gemini.ts` - Added speechEnabled default to getDefaultSettings
+- `src/storage/db.test.ts` - Added speechEnabled to test Settings fixture
+- `src/ui/parent.ts` - Added speechEnabled defaults in inline Settings initializers
+
+## Decisions Made
+- speechEnabled defaults to false (opt-in) while audioEnabled defaults to true (opt-out) -- speech is more intrusive than sound effects
+- AudioContext is created lazily on first user interaction (click or keydown) to comply with browser autoplay policies
+- All audio functions wrap in try/catch and never throw to callers -- silent degradation preferred
+
+## Deviations from Plan
+
+### Auto-fixed Issues
+
+**1. [Rule 2 - Missing Critical] Added speechEnabled defaults to all Settings initializers**
+- **Found during:** Task 1 (Settings extension)
+- **Issue:** Plan only mentioned adding speechEnabled to the types.ts interface, but several files create default Settings objects inline (gemini.ts, parent.ts, db.test.ts) that would fail type checking
+- **Fix:** Added speechEnabled: false to all inline Settings object literals across the codebase
+- **Files modified:** src/api/gemini.ts, src/storage/db.test.ts, src/ui/parent.ts
+- **Verification:** npx tsc --noEmit passes
+- **Committed in:** c19b7fe (Task 1 commit)
+
+---
+
+**Total deviations:** 1 auto-fixed (1 missing critical)
+**Impact on plan:** Essential for type safety. No scope creep.
+
+## Issues Encountered
+None
+
+## User Setup Required
+None - no external service configuration required.
+
+## Next Phase Readiness
+- Audio system ready to be wired into lesson/reward/forest screens (Plan 04-02+)
+- Mute button functional and persisting state across reloads
+- speakText ready for companion dialogue integration
+
+## Self-Check: PASSED
+
+All created files exist, all commit hashes verified.
+
+---
+*Phase: 04-polish-audio*
+*Completed: 2026-03-29*