test: preserve caller User-Agent headers

.gitignore

@@ -32,3 +32,5 @@ report.[0-9]_.[0-9]_.[0-9]_.[0-9]_.json
 
 # Finder (MacOS) folder config
 .DS_Store
+
+.codegraph

tests/lib/api.test.ts

@@ -30,6 +30,7 @@ describe("authenticated API transport", () => {
         expect(new Headers(init?.headers).get("content-type")).toBe(
           "application/json",
         );
+        expect(new Headers(init?.headers).has("user-agent")).toBe(false);
         expect(init?.body).toBe('{"name":"demo"}');
         return Response.json({ id: "workspace-1" });
       },
@@ -64,6 +65,19 @@ describe("authenticated API transport", () => {
     ).resolves.toBeUndefined();
   });
 
+  test("preserves a caller-provided User-Agent without adding one by default", async () => {
+    const sent: Array<string | null> = [];
+    globalThis.fetch = mock(async (_input, init) => {
+      sent.push(new Headers(init?.headers).get("user-agent"));
+      return new Response(null, { status: 204 });
+    }) as unknown as typeof fetch;
+
+    const options = { authenticated: false, baseUrl: "https://api.test" };
+    await apiRequest("/plain", {}, options);
+    await apiRequest("/custom", { headers: { "user-agent": "my-app" } }, options);
+    expect(sent).toEqual([null, "my-app"]);
+  });
+
   test("treats an empty successful JSON response as no content", async () => {
     globalThis.fetch = mock(
       async () => new Response("", { status: 200 }),