Voice assistant: hands-free barge-in (WI-174 v2)

[thedancingdeveloper]

Stacked on #680 (base feat/voice-handsfree). Adds opt-in barge-in to hands-free mode: with interrupt_response on, the speaker can talk over a playing reply — the device stops speaking and listens the moment they start.

What

• voiceTurn.ts — speechDetected(): halts the reply and re-opens the mic, gated on interrupt_response and a reply actually playing (a stray onset outside playback is a no-op); the halted reply's own speechFinished is then ignored.
• voiceVad.ts (new) — a pure OnsetDetector (leaky accumulator over frame RMS: a sustained ~500 ms onset fires once; a click or the echo-cancellation residual does not) + frameRms, unit-tested off frame energies. startBargeInDetection is a thin Web Audio shell (echo-cancelled getUserMedia → AnalyserNode, 50 ms frames) that a WASM Silero VAD can replace behind the same seam later — not adopted here to avoid the onnxruntime bundle/model weight.
• Assistant.tsx — runs the echo-cancelled capture only during speaking (a createEffect on voiceState), torn down the moment playback ends, so the second mic is never held longer than the reply it listens over.

Off by default — the WebView's AEC residual is imperfect and a false trigger cuts a reply short; half-duplex is the safe default. Config: vogt.assistant.voice.{interrupt_response,vad_threshold,vad_onset_ms}.

Tests

• Full web unit suite green (931), typecheck clean.
• New: 3 barge-in machine tests + 7 VAD tests; a real-browser Playwright test proves the onset halts the reply (cancel) and re-opens the mic mid-playback.

Notes

• Merge Voice assistant: tap-to-talk + hands-free conversation mode (WI-173, WI-174 v1) #680 first (this is stacked on it); GitHub will retarget this to main once Voice assistant: tap-to-talk + hands-free conversation mode (WI-173, WI-174 v1) #680 lands.
• Docs: ENGINE.md §6 + USER_GUIDE §2.5; design note in docs/local/VOICE_HANDSFREE_DESIGN.md.
• Android AEC (capture off the Capacitor recognizer, communication audio mode) is a native follow-up.

🤖 Generated with Claude Code

https://claude.ai/code/session_01BojRRh8yXBBqwemk6WkqVo