# Phase 39: Voice Polish - Context

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

<domain>
## Phase Boundary

Voice responses begin playing before synthesis is complete (sentence-buffered), a single response can be synthesized in multiple languages simultaneously, and new installs can detect STT/TTS hardware capability during onboarding and enable voice in one step.

Requirements: VPIPE-07, VPIPE-08, ONBRD-01, ONBRD-02

</domain>

<decisions>
## Implementation Decisions

### Claude's Discretion
All implementation choices are at Claude's discretion — discuss phase was skipped per user setting.

Key research findings to incorporate:
- Sentence-buffered TTS: split response on sentence boundaries (.!?), synthesize first sentence immediately, start playback while subsequent sentences synthesize
- Multi-language TTS: Piper supports multiple language models; user requests same text as audio in multiple languages (e.g. English + Danish) without a second agent call
- Onboarding hardware detection: extend existing hardware probe to check for Whisper/Piper binary availability and hardware capability
- VoiceStep already exists from v1.5 (Phase 34) — enhance it with hardware probe results rather than creating a new step
- Use existing systeminformation probe pattern from Phase 30
- Sentence splitting: simple regex on .!? followed by whitespace; no NLP library needed

</decisions>

<code_context>
## Existing Code Insights

### Reusable Assets
- `server/src/services/voice-pipeline.ts` — VoicePipelineService (synthesize already does sentence chunking)
- `ui/src/components/ChatVoicePlayer.tsx` — audio playback (needs streaming support)
- `ui/src/components/onboarding/VoiceStep.tsx` — existing voice enable/skip step
- `server/src/routes/voice.ts` — POST /api/synthesize
- Hardware detection from Phase 30 (systeminformation probe)

### Integration Points
- `server/src/routes/voice.ts` — new endpoint for multi-language synthesis
- `ui/src/components/ChatVoicePlayer.tsx` — sentence-buffered playback
- `ui/src/components/onboarding/VoiceStep.tsx` — hardware capability display
- `server/src/services/nexus-settings.ts` — piperBinaryPath, whisperBinaryPath

</code_context>

<specifics>
## Specific Ideas

No specific requirements — discuss phase skipped.

</specifics>

<deferred>
## Deferred Ideas

None — discuss phase skipped.

</deferred>