fix(audio): align AudioContext to 48kHz up front for Opus streams

Opus resolved its 48kHz context lazily on the first chunk, close()ing and rebuilding the live graph mid-decode. Move the recreate into initializeStreaming so it runs before any bytes flow; the lazy call early-returns. WAV path unchanged.

DeepDrftPublic/Interop/audio/AudioPlayer.ts

@@ -16,7 +16,7 @@ import { WavFormatDecoder } from './WavFormatDecoder.js';
 import { Mp3FormatDecoder } from './Mp3FormatDecoder.js';
 import { FlacFormatDecoder } from './FlacFormatDecoder.js';
 import { OpusStreamDecoder } from './OpusStreamDecoder.js';
-import { OpusSeekData, parseSidecar, resolveOpusByteOffset, OpusSeekResolution } from './OpusSidecar.js';
+import { OpusSeekData, parseSidecar, resolveOpusByteOffset, OpusSeekResolution, OPUS_SAMPLE_RATE } from './OpusSidecar.js';
 
 export interface AudioResult {
     success: boolean;
@@ -118,7 +118,7 @@ export class AudioPlayer {
 
     // ==================== Streaming ====================
 
-    initializeStreaming(totalStreamLength: number, contentType: string): AudioResult {
+    async initializeStreaming(totalStreamLength: number, contentType: string): Promise<AudioResult> {
         try {
             // Full cleanup before starting new stream
             this.stopProgressTracking();
@@ -137,6 +137,19 @@ export class AudioPlayer {
             // selects Opus when the sidecar parsed, so the null branch is defensive.
             if (this.isOpusContentType(contentType) && this.pendingOpusSidecar) {
                 this.activeOpusSidecar = this.pendingOpusSidecar;
+
+                // Align the AudioContext to 48 kHz NOW, before any Opus bytes flow — the format is
+                // already resolved (C# resolves Opus + injects the sidecar before this call), so the
+                // target rate is known up front. Done here, the decoder's own lazy
+                // recreateWithSampleRate(48000) in ensureConfigured hits its sampleRate-equal early
+                // return and is a no-op; the live graph is never close()'d and rebuilt mid-decode (the
+                // teardown that double-decoded the stream and OOM'd the tab with HW accel off). The
+                // recreate seam itself stays — it is the WAV path's mechanism for non-44.1 sources and
+                // remains the defensive backstop here.
+                if (this.contextManager.sampleRate !== OPUS_SAMPLE_RATE) {
+                    await this.contextManager.recreateWithSampleRate(OPUS_SAMPLE_RATE);
+                }
+
                 // Pass the shared back-pressure signal (21.2b): the Opus decoder stops demuxing/
                 // decoding new packets while the scheduler is full, so the WebCodecs decode queue
                 // and decodedQueue do not balloon behind a throttled socket (OQ7). Same signal the
@@ -148,7 +161,9 @@ export class AudioPlayer {
                 return { success: true };
             }
 
-            // Non-Opus (or Opus-without-sidecar): the existing StreamDecoder path, unchanged.
+            // Non-Opus (or Opus-without-sidecar): the existing StreamDecoder path, unchanged. The
+            // context sample rate is untouched here, so the WAV/lossless path is byte-for-byte
+            // unaffected by the Opus up-front alignment above.
             const formatDecoder = this.createFormatDecoder(contentType);
             this.streamDecoder.initialize(totalStreamLength, formatDecoder);
             return { success: true };

DeepDrftPublic/Interop/audio/OpusStreamDecoder.ts

@@ -123,7 +123,11 @@ export class OpusStreamDecoder implements IStreamingDecoder {
         // Copy the OpusHead into a standalone buffer — the sidecar subarray is a view we keep.
         this.opusHeadDescription = opusHead.slice();
 
-        // Opus decodes at 48 kHz; align the context so no resample is needed.
+        // Opus decodes at 48 kHz; align the context so no resample is needed. AudioPlayer.initializeStreaming
+        // already aligned it to 48 kHz up front (the format is resolved before any bytes flow), so in the
+        // common path this is an early-return no-op — the live graph is NOT close()'d and rebuilt mid-decode.
+        // Kept as the defensive backstop for any path that reaches a configured decoder on a non-48 kHz
+        // context (the same recreate seam the WAV path uses for non-44.1 sources).
         if (this.contextManager.sampleRate !== OPUS_SAMPLE_RATE) {
             await this.contextManager.recreateWithSampleRate(OPUS_SAMPLE_RATE);
         }

DeepDrftPublic/Interop/audio/index.ts

@@ -32,7 +32,7 @@ const DeepDrftAudio = {
         }
     },
 
-    initializeStreaming: (playerId: string, totalStreamLength: number, contentType: string): AudioResult => {
+    initializeStreaming: async (playerId: string, totalStreamLength: number, contentType: string): Promise<AudioResult> => {
         const player = audioPlayers.get(playerId);
         if (!player) return { success: false, error: 'Player not found' };
         return player.initializeStreaming(totalStreamLength, contentType);