diff --git a/src/agents/ollama-stream.test.ts b/src/agents/ollama-stream.test.ts
index 7b085d90f..79dd8d4a9 100644
--- a/src/agents/ollama-stream.test.ts
+++ b/src/agents/ollama-stream.test.ts
@@ -302,9 +302,10 @@ async function withMockNdjsonFetch(
 
 async function createOllamaTestStream(params: {
   baseUrl: string;
-  options?: { maxTokens?: number; signal?: AbortSignal };
+  defaultHeaders?: Record<string, string>;
+  options?: { maxTokens?: number; signal?: AbortSignal; headers?: Record<string, string> };
 }) {
-  const streamFn = createOllamaStreamFn(params.baseUrl);
+  const streamFn = createOllamaStreamFn(params.baseUrl, params.defaultHeaders);
   return streamFn(
     {
       id: "qwen3:32b",
@@ -361,6 +362,41 @@ describe("createOllamaStreamFn", () => {
     );
   });
 
+  it("merges default headers and allows request headers to override them", async () => {
+    await withMockNdjsonFetch(
+      [
+        '{"model":"m","created_at":"t","message":{"role":"assistant","content":"ok"},"done":false}',
+        '{"model":"m","created_at":"t","message":{"role":"assistant","content":""},"done":true,"prompt_eval_count":1,"eval_count":1}',
+      ],
+      async (fetchMock) => {
+        const stream = await createOllamaTestStream({
+          baseUrl: "http://ollama-host:11434",
+          defaultHeaders: {
+            "X-OLLAMA-KEY": "provider-secret",
+            "X-Trace": "default",
+          },
+          options: {
+            headers: {
+              "X-Trace": "request",
+              "X-Request-Only": "1",
+            },
+          },
+        });
+
+        const events = await collectStreamEvents(stream);
+        expect(events.at(-1)?.type).toBe("done");
+
+        const [, requestInit] = fetchMock.mock.calls[0] as unknown as [string, RequestInit];
+        expect(requestInit.headers).toMatchObject({
+          "Content-Type": "application/json",
+          "X-OLLAMA-KEY": "provider-secret",
+          "X-Trace": "request",
+          "X-Request-Only": "1",
+        });
+      },
+    );
+  });
+
   it("accumulates reasoning chunks when content is empty", async () => {
     await withMockNdjsonFetch(
       [