diff --git a/frontend/tests/unit/components/workspace/gateway-offline-banner.dom.test.tsx b/frontend/tests/unit/components/workspace/gateway-offline-banner.dom.test.tsx
new file mode 100644
index 000000000..b4c573c5f
--- /dev/null
+++ b/frontend/tests/unit/components/workspace/gateway-offline-banner.dom.test.tsx
@@ -0,0 +1,131 @@
+import { afterEach, describe, expect, it, rs } from "@rstest/core";
+import {
+  cleanup,
+  fireEvent,
+  render,
+  screen,
+  waitFor,
+} from "@testing-library/react";
+
+import { GatewayOfflineBanner } from "@/components/workspace/gateway-offline-banner";
+import { AuthProvider } from "@/core/auth/AuthProvider";
+
+// AuthProvider pulls useRouter/usePathname from next/navigation. Hand it a
+// no-op router so logout()'s `router.push("/")` stays inert under happy-dom
+// instead of trying to drive a real Next.js router.
+rs.mock("next/navigation", () => ({
+  useRouter: () => ({ push: rs.fn(), replace: rs.fn(), refresh: rs.fn() }),
+  usePathname: () => "/workspace",
+}));
+
+// Force the SPA (non-static) branch of AuthProvider.logout — that is the
+// branch that actually performs the POST that issue #3001 is about. The
+// static branch would short-circuit into a `router.push("/")` and never
+// touch the network, masking the very regression we need to lock down.
+rs.mock("@/core/static-mode", () => ({
+  isStaticWebsiteOnly: () => false,
+}));
+
+// Keep the banner's i18n lookup hermetic — real translations are not
+// relevant here, we just need a stable accessible name for the button.
+rs.mock("@/core/i18n/hooks", () => ({
+  useI18n: () => ({
+    locale: "en-US",
+    t: {
+      workspace: {
+        logout: "Log out",
+        gatewayUnavailable: "Gateway unavailable.",
+        gatewayUnavailableRetrying: "Retrying…",
+      },
+    },
+    changeLocale: rs.fn(),
+  }),
+}));
+
+afterEach(() => {
+  rs.restoreAllMocks();
+  cleanup();
+});
+
+/**
+ * Install a fetch double that keeps the gateway "unavailable" for the
+ * banner's `/auth/me` probe (so the banner stays mounted and the recovery
+ * button stays actionable) while recording every call so the logout
+ * request can be inspected. Returns the captured calls for assertions.
+ */
+function installFetch(): Array<{ url: string; method: string }> {
+  const calls: Array<{ url: string; method: string }> = [];
+  rs.spyOn(globalThis, "fetch").mockImplementation(
+    (input: RequestInfo | URL, init?: RequestInit) => {
+      // `input` may be a Request object whose default stringification would
+      // yield "[object Request]" — normalise to the URL string either way.
+      const url =
+        typeof input === "string"
+          ? input
+          : input instanceof URL
+            ? input.toString()
+            : input.url;
+      const method = (init?.method ?? "GET").toUpperCase();
+      calls.push({ url, method });
+      if (url.includes("/auth/logout")) {
+        return Promise.resolve(
+          new Response(JSON.stringify({ message: "Successfully logged out" }), {
+            status: 200,
+            headers: { "Content-Type": "application/json" },
+          }),
+        );
+      }
+      // `/auth/me` probe — return a transient failure so `classifyProbe`
+      // yields "transient" and the banner keeps showing the logout button.
+      return Promise.resolve(
+        new Response("service unavailable", { status: 503 }),
+      );
+    },
+  );
+  return calls;
+}
+
+function renderBanner() {
+  return render(
+    <AuthProvider initialUser={null}>
+      <GatewayOfflineBanner gatewayUnavailable />
+    </AuthProvider>,
+  );
+}
+
+describe("GatewayOfflineBanner logout recovery (#3001)", () => {
+  it("renders a <button> (not a GET-style link) as the logout affordance", async () => {
+    installFetch();
+    renderBanner();
+
+    // The recovery control must be a <button>, not an <a>/<Link> whose
+    // browser navigation would turn into a GET against the POST-only
+    // /auth/logout endpoint — the exact 405 reported in #3001.
+    const logout = await screen.findByRole("button", { name: /log out/i });
+    expect(logout.tagName).toBe("BUTTON");
+    expect(logout.hasAttribute("href")).toBe(false);
+  });
+
+  it("issues a POST (never a GET) to /api/v1/auth/logout when clicked", async () => {
+    const calls = installFetch();
+    renderBanner();
+
+    fireEvent.click(await screen.findByRole("button", { name: /log out/i }));
+
+    const logoutCall = await waitFor(() => {
+      const logoutCalls = calls.filter((c) => c.url.includes("/auth/logout"));
+      expect(logoutCalls).toHaveLength(1);
+      const call = logoutCalls[0];
+      if (!call) {
+        throw new Error("expected exactly one /auth/logout call");
+      }
+      return call;
+    });
+
+    expect(logoutCall.url).toBe("/api/v1/auth/logout");
+    expect(logoutCall.method).toBe("POST");
+    // Lock down the regression documented in #3001: a GET against this
+    // POST-only endpoint returns 405 and fails to clear the session.
+    expect(logoutCall.method).not.toBe("GET");
+  });
+});