fix(tts): carry OpenAI talk response format

extensions/openai/speech-provider.test.ts

@@ -77,6 +77,32 @@ describe("buildOpenAISpeechProvider", () => {
     });
   });
 
+  it("preserves talk responseFormat overrides", () => {
+    const provider = buildOpenAISpeechProvider();
+
+    expect(
+      provider.resolveTalkConfig?.({
+        cfg: {} as never,
+        timeoutMs: 30_000,
+        baseTtsConfig: {
+          providers: {
+            openai: {
+              apiKey: "sk-base",
+              responseFormat: "mp3",
+            },
+          },
+        },
+        talkProviderConfig: {
+          apiKey: "sk-talk",
+          responseFormat: " WAV ",
+        },
+      }),
+    ).toMatchObject({
+      apiKey: "sk-talk",
+      responseFormat: "wav",
+    });
+  });
+
   it("uses wav for Groq-compatible OpenAI TTS endpoints", async () => {
     const provider = buildOpenAISpeechProvider();
     const fetchMock = vi.fn(async (_url: string, init?: RequestInit) => {

extensions/openai/speech-provider.ts

@@ -184,6 +184,7 @@ export function buildOpenAISpeechProvider(): SpeechProviderPlugin {
     parseDirectiveToken,
     resolveTalkConfig: ({ baseTtsConfig, talkProviderConfig }) => {
       const base = normalizeOpenAIProviderConfig(baseTtsConfig);
+      const responseFormat = normalizeOpenAISpeechResponseFormat(talkProviderConfig.responseFormat);
       return {
         ...base,
         ...(talkProviderConfig.apiKey === undefined
@@ -209,6 +210,7 @@ export function buildOpenAISpeechProvider(): SpeechProviderPlugin {
         ...(trimToUndefined(talkProviderConfig.instructions) == null
           ? {}
           : { instructions: trimToUndefined(talkProviderConfig.instructions) }),
+        ...(responseFormat == null ? {} : { responseFormat }),
       };
     },
     resolveTalkOverrides: ({ params }) => ({