Add loopback STT debug logging

src/audio/realtime-segmenter.ts

@@ -1,5 +1,9 @@
 interface RealtimeSegmenterOptions {
   onSegment: (pcm16: Buffer) => void;
+  onLevel?: (peak: number) => void;
+  onSpeechStart?: (peak: number) => void;
+  onSpeechDiscarded?: (samples: number) => void;
+  onSpeechReady?: (samples: number) => void;
 }
 
 export class RealtimeSegmenter {
@@ -44,6 +48,8 @@ export class RealtimeSegmenter {
       }
     }
 
+    this.options.onLevel?.(peak);
+
     if (!this.speechActive) {
       appendWithCap(this.preRoll, frame, this.preRollSamples);
       if (peak >= this.speechStartThreshold) {
@@ -60,6 +66,7 @@ export class RealtimeSegmenter {
       this.silenceFrames = 0;
       this.speech.splice(0, this.speech.length, ...this.preRoll);
       this.preRoll.splice(0, this.preRoll.length);
+      this.options.onSpeechStart?.(peak);
     }
 
     this.speech.push(...frame);
@@ -81,9 +88,11 @@ export class RealtimeSegmenter {
     this.speechCandidateFrames = 0;
 
     if (speechPcm.length < this.minSpeechSamples * 2) {
+      this.options.onSpeechDiscarded?.(speechPcm.length / 2);
       return;
     }
 
+    this.options.onSpeechReady?.(speechPcm.length / 2);
     this.options.onSegment(speechPcm);
   }
 }