feat(voice): live dictation with browser pause restart and server audio chunking

frontend/src/lib/voice.ts

@@ -86,19 +86,7 @@ export class VoiceRecorder {
     this.stream = await navigator.mediaDevices.getUserMedia({
       audio: { echoCancellation: true, noiseSuppression: true, autoGainControl: true },
     });
-    const type = recordingType();
-    this.recorder = new MediaRecorder(this.stream, type ? { mimeType: type } : undefined);
-    this.chunks = [];
-    this.recorder.ondataavailable = (e) => {
-      if (e.data.size > 0) this.chunks.push(e.data);
-    };
-    this.recorder.onstop = () => {
-      const blob = this.chunks.length ? new Blob(this.chunks, { type: this.recorder?.mimeType || type || 'audio/webm' }) : null;
-      this.release();
-      this.done?.(blob);
-      this.done = null;
-    };
-    this.recorder.start(1000);
+    this.startSegmentRecorder();
     try {
       const Ctx = (window as any).AudioContext || (window as any).webkitAudioContext;
       this.audioCtx = new Ctx();
@@ -113,6 +101,25 @@ export class VoiceRecorder {
     }
   }
 
+  private startSegmentRecorder(): void {
+    if (!this.stream) return;
+    const type = recordingType();
+    const rec = new MediaRecorder(this.stream, type ? { mimeType: type } : undefined);
+    const chunks: Blob[] = [];
+    rec.ondataavailable = (e) => {
+      if (e.data.size > 0) chunks.push(e.data);
+    };
+    rec.onstop = () => {
+      const blob = chunks.length ? new Blob(chunks, { type: rec.mimeType || type || 'audio/webm' }) : null;
+      this.release();
+      this.done?.(blob);
+      this.done = null;
+    };
+    this.recorder = rec;
+    this.chunks = chunks;
+    rec.start(1000);
+  }
+
   /** Input level 0..1 (roughly loudness), or null when unknown. */
   level(): number | null {
     if (!this.analyser || !this.samples) return null;
@@ -137,6 +144,30 @@ export class VoiceRecorder {
     });
   }
 
+  /**
+   * Stops the current MediaRecorder segment and immediately starts a new one on the same MediaStream.
+   * Resolves with the finished segment's audio Blob while recording continues seamlessly.
+   */
+  cutSegment(): Promise<Blob | null> {
+    if (!this.stream || !this.recorder || this.recorder.state === 'inactive') {
+      return Promise.resolve(null);
+    }
+    const oldRecorder = this.recorder;
+    const oldChunks = this.chunks;
+
+    this.startSegmentRecorder();
+
+    return new Promise((resolve) => {
+      oldRecorder.onstop = () => {
+        const blob = oldChunks.length
+          ? new Blob(oldChunks, { type: oldRecorder.mimeType || 'audio/webm' })
+          : null;
+        resolve(blob);
+      };
+      oldRecorder.stop();
+    });
+  }
+
   cancel(): void {
     this.done = null;
     if (this.recorder && this.recorder.state !== 'inactive') {