Add localhost->127.0.0.1 fallback for transcription fetch

src/tools/builtin/audio-transcribe.ts

@@ -45,22 +45,42 @@ function isTransientNetworkError(error: unknown): boolean {
     || message.includes('ehostunreach');
 }
 
+function buildEndpointCandidates(endpoint: string): string[] {
+  try {
+    const parsed = new URL(endpoint);
+    if (parsed.hostname !== 'localhost') {
+      return [endpoint];
+    }
+    const ipv4Endpoint = new URL(endpoint);
+    ipv4Endpoint.hostname = '127.0.0.1';
+    return [endpoint, ipv4Endpoint.toString()];
+  } catch {
+    return [endpoint];
+  }
+}
+
 async function fetchWithRetry(endpoint: string, init: RequestInit): Promise<Response> {
+  const endpointCandidates = buildEndpointCandidates(endpoint);
+  let lastErrorMessage = 'Unknown network error';
+  let lastEndpoint = endpoint;
   for (let attempt = 1; attempt <= TRANSCRIPTION_FETCH_MAX_ATTEMPTS; attempt += 1) {
+    const endpointForAttempt = endpointCandidates[(attempt - 1) % endpointCandidates.length];
     const controller = new AbortController();
     const timeout = setTimeout(() => controller.abort(), TRANSCRIPTION_FETCH_TIMEOUT_MS);
     try {
-      return await fetch(endpoint, { ...init, signal: controller.signal });
+      return await fetch(endpointForAttempt, { ...init, signal: controller.signal });
     } catch (error) {
       const timedOut = error instanceof Error && error.name === 'AbortError';
       const normalizedMessage = timedOut
         ? `request timed out after ${TRANSCRIPTION_FETCH_TIMEOUT_MS}ms`
         : (error instanceof Error ? error.message : String(error));
+      lastErrorMessage = normalizedMessage;
+      lastEndpoint = endpointForAttempt;
       const retriable = timedOut || isTransientNetworkError(error);
       const exhausted = attempt >= TRANSCRIPTION_FETCH_MAX_ATTEMPTS;
       if (!retriable || exhausted) {
         throw new Error(
-          `Transcription request to ${endpoint} failed after ${attempt} attempt(s): ${normalizedMessage}`,
+          `Transcription service connectivity failure at ${lastEndpoint} after ${attempt} attempt(s): ${normalizedMessage}. This indicates endpoint/network availability, not missing audio bytes.`,
         );
       }
       await sleep(TRANSCRIPTION_FETCH_BASE_DELAY_MS * (2 ** (attempt - 1)));
@@ -69,7 +89,9 @@ async function fetchWithRetry(endpoint: string, init: RequestInit): Promise<Resp
     }
   }
 
-  throw new Error(`Transcription request to ${endpoint} failed after retries`);
+  throw new Error(
+    `Transcription service connectivity failure at ${lastEndpoint} after retries: ${lastErrorMessage}. This indicates endpoint/network availability, not missing audio bytes.`,
+  );
 }
 
 function validateUrl(url: string): { valid: boolean; error?: string } {