diff --git a/src/utils/axios-client.ts b/src/utils/axios-client.ts
index 5a542ad..3c9e9d1 100644
--- a/src/utils/axios-client.ts
+++ b/src/utils/axios-client.ts
@@ -177,10 +177,10 @@ export function createAxiosClient({
   client.interceptors.request.use((config) => {
     if (typeof window !== "undefined") {
       config.headers.set("X-Origin-URL", window.location.href);
-      // On unauthenticated clients, attach a stable anonymous visitor id so the
-      // backend can support anonymous agent access (conversation grouping +
-      // ownership). Authenticated clients are identified by their token instead.
-      if (!token) {
+      // On unauthenticated requests, attach a stable anonymous visitor id so the
+      // backend can support anonymous agent access (conversation grouping + ownership).
+      // Authenticated requests are identified by their Authorization header instead.
+      if (!config.headers.get("Authorization")) {
         config.headers.set("X-Base44-Anonymous-Id", getAnalyticsSessionId());
       }
     }
diff --git a/tests/unit/anonymous-visitor-header.test.ts b/tests/unit/anonymous-visitor-header.test.ts
index b362608..689767f 100644
--- a/tests/unit/anonymous-visitor-header.test.ts
+++ b/tests/unit/anonymous-visitor-header.test.ts
@@ -31,8 +31,18 @@ afterEach(() => {
   vi.unstubAllGlobals();
 });
 
-async function captureRequestHeaders(token?: string) {
+async function captureRequestHeaders(
+  token?: string,
+  { tokenSetAfterConstruction }: { tokenSetAfterConstruction?: string } = {}
+) {
   const client = createAxiosClient({ baseURL: "https://api", token });
+  // Mirrors the common browser path: auth.setToken() applies the Authorization
+  // header on the client's defaults after the client has already been built.
+  if (tokenSetAfterConstruction) {
+    client.defaults.headers.common[
+      "Authorization"
+    ] = `Bearer ${tokenSetAfterConstruction}`;
+  }
   let captured: any;
   client.defaults.adapter = async (config) => {
     captured = config;
@@ -63,4 +73,12 @@ describe("anonymous visitor header", () => {
     expect(headers.get("X-Base44-Anonymous-Id")).toBeFalsy();
     expect(headers.get("Authorization")).toBe("Bearer a-real-token");
   });
+
+  test("token set after construction (browser setToken path) omits the anonymous header", async () => {
+    const headers = await captureRequestHeaders(undefined, {
+      tokenSetAfterConstruction: "a-real-token",
+    });
+    expect(headers.get("Authorization")).toBe("Bearer a-real-token");
+    expect(headers.get("X-Base44-Anonymous-Id")).toBeFalsy();
+  });
 });