Mark server-live sidecar passes as live mode and cover the stream heartbeat with a test

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/server-live.test.ts

@@ -111,7 +111,7 @@ function sessionData(overrides: Partial<LiveSessionData> = {}): LiveSessionData
 }
 
 describe("createLiveWebSocket", () => {
-  test("a committed segment writes the exact PCM bytes and passes model/language/task through", async () => {
+  test("a committed segment writes the exact PCM bytes and passes model/language/task/mode through", async () => {
     const tempDir = await makeTempDir();
     const sidecar = fakeSidecar();
     const handler = createLiveWebSocket({ sidecar });
@@ -123,7 +123,8 @@ describe("createLiveWebSocket", () => {
 
     await waitFor(() => sidecar.requests.length > 0);
     expect(sidecar.requests[0]).toEqual(
-      expect.objectContaining({ model: "base", language: "da", task: "translate" }),
+      // Live passes are short: sequential decoding, no batching/VAD (D-WS5a).
+      expect.objectContaining({ model: "base", language: "da", task: "translate", mode: "live" }),
     );
     // The bytes written to the temp file are exactly the committed segment's
     // samples — not, e.g., a whole shared buffer (see the byteOffset/byteLength fix).