move vad config to json

README.md

@@ -132,6 +132,41 @@ the TTS in the pipeline. `response.text.final` fires when the turn ends,
 carrying the full concatenated assistant text and an `interrupted` flag
 (true when an `input.text` or barge-in cut the turn short).
 
+### Turn detection
+
+User-turn segmentation (VAD thresholds + how long to wait after silence
+before declaring the turn done) is configurable per environment:
+
+```json
+"turn": {
+  "vad": {
+    "confidence": 0.7,
+    "start_secs": 0.2,
+    "stop_secs": 0.6,
+    "min_volume": 0.6
+  },
+  "user_speech_timeout_sec": 1.0
+}
+```
+
+- `vad.*` maps directly to `pipecat.audio.vad.vad_analyzer.VADParams` and
+  controls the Silero VAD. `stop_secs` is the duration of silence required
+  before VAD reports the user stopped speaking; raise it if VAD is
+  cutting users off mid-clause, lower it for snappier turn-taking.
+- `user_speech_timeout_sec` is the additional grace window (used by
+  `SpeechTimeoutUserTurnStopStrategy`) during which the user may resume
+  speaking before the aggregator finalizes the turn. The timer is
+  re-armed every time the user resumes, so brief mid-sentence pauses do
+  not split one utterance into multiple LLM turns.
+
+The total "user pause before turn ends" budget is approximately
+`vad.stop_secs + user_speech_timeout_sec`. The repo defaults are tuned
+slightly more conservatively than upstream pipecat to avoid streaming
+ASRs (xfyun in particular) producing many short fragments per logical
+utterance. Setting this stop strategy explicitly also replaces pipecat's
+default Smart Turn v3 analyzer, so the engine no longer loads the
+`smart-turn-v3.*-cpu.onnx` model at startup.
+
 ### Xfyun ASR
 
 The STT provider can be switched to iFlytek/Xfyun's streaming voice dictation