diff --git a/__tests__/unit/hooks/useRequireAuth.test.tsx b/__tests__/unit/hooks/useRequireAuth.test.tsx
new file mode 100644
index 000000000..cee3fa368
--- /dev/null
+++ b/__tests__/unit/hooks/useRequireAuth.test.tsx
@@ -0,0 +1,101 @@
+/**
+ * The hydration ceiling has to reach every gate, including `isAuthenticated`.
+ *
+ * `useRequireAuth` exposes `isLoading` and `hydrated` as EFFECTIVE values: once
+ * a 4s ceiling fires, they resolve so a page stops waiting on an auth store
+ * that is never going to answer. `isAuthenticated` was computed from the RAW
+ * store instead, so it opted itself out of the ceiling.
+ *
+ * On /timeline that produced an infinite spinner. The page renders
+ * `isLoading ? spinner : !isAuthenticated ? spinner : content`; the ceiling
+ * cleared the first gate after 4s and the second stayed shut forever. It never
+ * redirected either — the redirect only fires when there is no user, and there
+ * was one. Measured live before the fix: 122 seconds of skeleton, zero network
+ * requests, zero long tasks. The app was not slow; it was waiting on a gate
+ * that could no longer open.
+ *
+ * The two cases below are the whole contract: a wedged store with a user must
+ * eventually let the page render, and a wedged store WITHOUT one must not.
+ */
+
+import { renderHook, act } from '@testing-library/react';
+import { useRequireAuth } from '@/hooks/useAuthRedirects';
+
+const replace = jest.fn();
+const push = jest.fn();
+jest.mock('next/navigation', () => ({
+  useRouter: () => ({ replace, push }),
+  usePathname: () => '/timeline',
+}));
+
+let storeState: Record<string, unknown> = {};
+jest.mock('@/stores/auth', () => ({
+  useAuthStore: () => storeState,
+}));
+
+function wedged(overrides: Record<string, unknown> = {}) {
+  // What a stuck Supabase session looks like: never hydrated, never resolves.
+  storeState = {
+    user: { id: 'u1' },
+    session: { access_token: 'x' },
+    profile: null,
+    isLoading: true,
+    hydrated: false,
+    ...overrides,
+  };
+}
+
+describe('useRequireAuth hydration ceiling', () => {
+  beforeEach(() => {
+    jest.clearAllMocks();
+    jest.useFakeTimers();
+  });
+  afterEach(() => {
+    jest.useRealTimers();
+  });
+
+  it('lets a signed-in user through once the ceiling fires', () => {
+    wedged();
+    const { result } = renderHook(() => useRequireAuth());
+
+    // Before the ceiling: still waiting, which is correct.
+    expect(result.current.isLoading).toBe(true);
+    expect(result.current.isAuthenticated).toBe(false);
+
+    act(() => {
+      jest.advanceTimersByTime(4100);
+    });
+
+    // After it: the page must be able to render rather than sit on a spinner.
+    expect(result.current.isLoading).toBe(false);
+    expect(result.current.hydrated).toBe(true);
+    expect(result.current.isAuthenticated).toBe(true);
+    expect(result.current.hydrationTimedOut).toBe(true);
+  });
+
+  it('does not claim authentication for someone with no user', () => {
+    wedged({ user: null, session: null });
+    const { result } = renderHook(() => useRequireAuth());
+
+    act(() => {
+      jest.advanceTimersByTime(4100);
+    });
+
+    // The ceiling widens the exit; it must never invent a session.
+    expect(result.current.isAuthenticated).toBe(false);
+  });
+
+  it('reports authentication normally when auth resolves in time', () => {
+    storeState = {
+      user: { id: 'u1' },
+      session: { access_token: 'x' },
+      profile: { id: 'u1' },
+      isLoading: false,
+      hydrated: true,
+    };
+    const { result } = renderHook(() => useRequireAuth());
+
+    expect(result.current.isAuthenticated).toBe(true);
+    expect(result.current.hydrationTimedOut).toBe(false);
+  });
+});
diff --git a/src/hooks/useAuthRedirects.ts b/src/hooks/useAuthRedirects.ts
index b62dbcab4..538b51ffe 100644
--- a/src/hooks/useAuthRedirects.ts
+++ b/src/hooks/useAuthRedirects.ts
@@ -119,7 +119,22 @@ export function useRequireAuth() {
     /** True when the 4s hydration ceiling fired before auth resolved.
      * Pages can branch on this to show "auth seems stuck — sign in" UX. */
     hydrationTimedOut,
-    isAuthenticated: !!user && hydrated && !isLoading,
+    // The EFFECTIVE flags, for the same reason the two above are computed:
+    // this line used to read raw `hydrated` / `isLoading`, so it opted itself
+    // out of the ceiling that every other field honours.
+    //
+    // What that cost, measured on /timeline in production: the page renders
+    // `isLoading ? spinner : !isAuthenticated ? spinner : content`. After 4s
+    // the ceiling cleared the FIRST gate and the second one — reading raw
+    // state — stayed false forever, so the page sat on "Redirecting to
+    // login..." indefinitely. It never redirected either, because the redirect
+    // only fires when there is no `user`, and there was one. Observed live:
+    // 122 seconds of skeleton, zero network requests, zero long tasks — the
+    // app was not slow, it was waiting for a gate that could no longer open.
+    //
+    // `!!user` is unchanged and still does the real work: a timed-out ceiling
+    // can only report authenticated for someone who already has a user object.
+    isAuthenticated: !!user && effectiveHydrated && !effectiveIsLoading,
   };
 }