diff --git a/src/browser/profiles-service.test.ts b/src/browser/profiles-service.test.ts
index ef599fad82a..3bc05d99194 100644
--- a/src/browser/profiles-service.test.ts
+++ b/src/browser/profiles-service.test.ts
@@ -61,6 +61,31 @@ describe("BrowserProfilesService", () => {
     expect(writeConfigFile).toHaveBeenCalled();
   });
 
+  it("falls back to derived CDP range when resolved CDP range is missing", async () => {
+    const base = resolveBrowserConfig({});
+    const baseWithoutRange = { ...base } as {
+      [key: string]: unknown;
+      cdpPortRangeStart?: unknown;
+      cdpPortRangeEnd?: unknown;
+    };
+    delete baseWithoutRange.cdpPortRangeStart;
+    delete baseWithoutRange.cdpPortRangeEnd;
+    const resolved = {
+      ...baseWithoutRange,
+      controlPort: 30000,
+    } as BrowserServerState["resolved"];
+    const { ctx, state } = createCtx(resolved);
+
+    vi.mocked(loadConfig).mockReturnValue({ browser: { profiles: {} } });
+
+    const service = createBrowserProfilesService(ctx);
+    const result = await service.createProfile({ name: "work" });
+
+    expect(result.cdpPort).toBe(30009);
+    expect(state.resolved.profiles.work?.cdpPort).toBe(30009);
+    expect(writeConfigFile).toHaveBeenCalled();
+  });
+
   it("accepts per-profile cdpUrl for remote Chrome", async () => {
     const resolved = resolveBrowserConfig({});
     const { ctx } = createCtx(resolved);