# Phase 37: Web Chat Voice UI - Context

**Gathered:** 2026-04-04
**Status:** Ready for planning
**Mode:** Auto-generated (discuss skipped via workflow.skip_discuss)

<domain>
## Phase Boundary

Users can speak to any agent in web chat — recording auto-stops on silence, a live waveform confirms the mic is active, responses play back automatically (toggleable), and voice mode is a first-class setting.

Requirements: WCHAT-01, WCHAT-02, WCHAT-03, WCHAT-04, WCHAT-05, WCHAT-06

</domain>

<decisions>
## Implementation Decisions

### Claude's Discretion
All implementation choices are at Claude's discretion — discuss phase was skipped per user setting. Use ROADMAP phase goal, success criteria, and codebase conventions to guide decisions.

Key research findings to incorporate:
- `@ricky0123/vad-react ^0.0.36` for browser-side silence detection (VAD) — delivers Float32Array at 16kHz on speech end
- COOP/COEP headers required on Express server for SharedArrayBuffer (`Cross-Origin-Opener-Policy: same-origin`, `Cross-Origin-Embedder-Policy: require-corp`)
- Waveform via Web Audio API AnalyserNode (Canvas or SVG, 30-50 data points)
- Native `<audio>` element + URL.createObjectURL() for playback — no extra library needed
- Three-state voice mode: "text" | "voice_input" | "full_voice" (already in nexus-settings schema from Phase 36)
- VoiceMicButton replaces/enhances existing VoiceRecordButton from v1.5
- Voice badge + expandable markdown section in ChatMessage for voice interactions
- AudioContext must be unlocked on user's "start voice mode" gesture to avoid autoplay policy blocks
- Existing hooks: usePiperTts (client-side TTS), VoiceRecordButton (MediaRecorder), TtsButton
- POST /api/transcribe and POST /api/synthesize endpoints available from Phase 36

</decisions>

<code_context>
## Existing Code Insights

### Reusable Assets
- `ui/src/components/VoiceRecordButton.tsx` — existing MediaRecorder-based recording button
- `ui/src/components/TtsButton.tsx` — existing TTS playback button
- `ui/src/hooks/usePiperTts.ts` — client-side Piper WASM TTS hook
- `server/src/routes/voice.ts` — POST /api/transcribe, POST /api/synthesize (Phase 36)
- `server/src/services/nexus-settings.ts` — voiceMode setting already in schema

### Established Patterns
- React hooks in ui/src/hooks/
- Components in ui/src/components/
- Settings via nexus-settings service + React hooks

### Integration Points
- `ui/src/components/ChatInput.tsx` — mic button integration point
- `ui/src/components/ChatMessage.tsx` — voice badge + audio player
- Express static middleware — COOP/COEP headers
- `server/src/app.ts` — header middleware

</code_context>

<specifics>
## Specific Ideas

No specific requirements — discuss phase skipped. Refer to ROADMAP phase description and success criteria.

</specifics>

<deferred>
## Deferred Ideas

None — discuss phase skipped.

</deferred>
