fix: remove dead .status assignment and add 503 error test

src/agents/ollama-stream.test.ts

@@ -499,6 +499,31 @@ describe("createOllamaStreamFn", () => {
     );
   });
 
+  it("surfaces non-2xx HTTP response as status-prefixed error", async () => {
+    const originalFetch = globalThis.fetch;
+    const fetchMock = vi.fn(async () => {
+      return new Response("Service Unavailable", {
+        status: 503,
+        statusText: "Service Unavailable",
+      });
+    });
+    globalThis.fetch = fetchMock as unknown as typeof fetch;
+    try {
+      const stream = await createOllamaTestStream({ baseUrl: "http://ollama-host:11434" });
+      const events = await collectStreamEvents(stream);
+
+      const errorEvent = events.find((e) => e.type === "error") as
+        | { type: "error"; error: { errorMessage?: string } }
+        | undefined;
+      expect(errorEvent).toBeDefined();
+      // The error message must start with the HTTP status code so that
+      // extractLeadingHttpStatus can parse it for failover/retry logic.
+      expect(errorEvent!.error.errorMessage).toMatch(/^503\b/);
+    } finally {
+      globalThis.fetch = originalFetch;
+    }
+  });
+
   it("drops thinking chunks when no final content is emitted", async () => {
     await expectDoneEventContent(
       [

src/agents/ollama-stream.ts

@@ -488,9 +488,7 @@ export function createOllamaStreamFn(
 
         if (!response.ok) {
           const errorText = await response.text().catch(() => "unknown error");
-          const err = new Error(`${response.status} ${errorText}`);
-          (err as Error & { status: number }).status = response.status;
-          throw err;
+          throw new Error(`${response.status} ${errorText}`);
         }
 
         if (!response.body) {