fix(speech): fail when the audio stream ends without a terminator

ERRORS.md

@@ -118,6 +118,7 @@ This document lists all error scenarios and the messages users will see.
 | `--text-file` unreadable | `Cannot read file: ${e.message}` |
 | `--out` path no write permission | `Permission denied: cannot write to "${outPath}".` |
 | Disk full | `Disk full — cannot write audio file.` |
+| `--stream` connection drops before the final audio chunk | `Stream disconnected before audio completed.` |
 
 ### `mmx speech transcribe`
 

src/utils/audio-stream.ts

@@ -37,6 +37,13 @@ function missingAudioError(): CLIError {
   );
 }
 
+function truncatedStreamError(): CLIError {
+  return new CLIError(
+    'Stream disconnected before audio completed.',
+    ExitCode.NETWORK,
+  );
+}
+
 export async function* decodeAudioStream(
   response: Response,
 ): AsyncGenerator<Uint8Array<ArrayBuffer>> {
@@ -61,8 +68,13 @@ export async function* decodeAudioStream(
   }
 
   let receivedAudio = false;
+  let streamCompleted = false;
   for await (const event of parseSSE(response)) {
-    if (!event.data || event.data === '[DONE]') break;
+    if (!event.data) break;
+    if (event.data === '[DONE]') {
+      streamCompleted = true;
+      break;
+    }
 
     let parsed: AudioPayload;
     try {
@@ -82,10 +94,14 @@ export async function* decodeAudioStream(
       yield decodeHexAudio(hex);
     }
 
-    if (parsed.data?.status === 2) break;
+    if (parsed.data?.status === 2) {
+      streamCompleted = true;
+      break;
+    }
   }
 
   if (!receivedAudio) throw missingAudioError();
+  if (!streamCompleted) throw truncatedStreamError();
 }
 
 export async function pipeAudioStream(response: Response): Promise<void> {

test/utils/audio-stream.test.ts

@@ -53,4 +53,18 @@ describe('decodeAudioStream', () => {
       'API stream ended without audio data',
     );
   });
+
+  it('rejects a stream that closes after audio chunks but without a terminator', async () => {
+    // A dropped connection: chunks arrive, then the body ends with no
+    // `status: 2` chunk and no `data: [DONE]` terminator.
+    const response = new Response(
+      'data: {"data":{"audio":"414243","status":1}}\n\n'
+      + 'data: {"data":{"audio":"444546","status":1}}\n\n',
+      { headers: { 'Content-Type': 'text/event-stream' } },
+    );
+
+    await expect(collectAudio(response)).rejects.toThrow(
+      'Stream disconnected before audio completed.',
+    );
+  });
 });