- Export splitSentences() with title-abbreviation protection (Dr., Mr. etc.)
- Add synthesizeSentenceStream() AsyncGenerator yielding per-sentence audio chunks
- Add synthesizeMultiLang() synthesizing same text in N voices via Promise.all
- Add POST /api/synthesize/stream SSE endpoint with base64 audio per sentence
- Add POST /api/synthesize/multi-lang returning array of voiceId+audio pairs
- Existing POST /api/synthesize unchanged (backward compatible)
- Install ffmpeg-static and @types/ffmpeg-static
- Create voice-pipeline.ts with voicePipelineService factory function
- transcodeToWav16k: pipes audio through ffmpeg at 16kHz mono WAV
- transcribe: whisper-cpp cascade with --language auto, falls back to openai-whisper
- synthesize: piper TTS with sentence chunking and 8s timeout via Promise.race
- formatForVoice: extracts SPOKEN marker or strips markdown as fallback
- Unit tests with mocked child_process (12 tests all passing)
