diff --git a/ui/src/App.advanced-tools-routing.test.tsx b/ui/src/App.advanced-tools-routing.test.tsx
new file mode 100644
index 00000000000..69df1267449
--- /dev/null
+++ b/ui/src/App.advanced-tools-routing.test.tsx
@@ -0,0 +1,129 @@
+// @vitest-environment jsdom
+
+import type { ReactNode } from "react";
+import { flushSync } from "react-dom";
+import { createRoot } from "react-dom/client";
+import { MemoryRouter } from "react-router-dom";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { App } from "./App";
+
+// jsdom rejects a custom-property marker emitted by Sandpack's transitive
+// styles. The advanced-tools route does not exercise Sandpack, so keep that
+// eager import from obscuring the routing assertion.
+vi.hoisted(() => {
+  const sheetProto = window.CSSStyleSheet.prototype as unknown as {
+    insertRule: (rule: string, index?: number) => number;
+    __pap17809Patched?: boolean;
+  };
+  if (!sheetProto.__pap17809Patched) {
+    const original = sheetProto.insertRule;
+    sheetProto.insertRule = function patched(this: CSSStyleSheet, rule: string, index?: number) {
+      try {
+        return original.call(this, rule, index);
+      } catch {
+        try {
+          return original.call(this, ".pap17809-noop{}", index);
+        } catch {
+          return this.cssRules?.length ?? 0;
+        }
+      }
+    };
+    sheetProto.__pap17809Patched = true;
+  }
+});
+
+vi.mock("./components/Layout", async () => {
+  const { Outlet } = await import("react-router-dom");
+  return { Layout: () => <Outlet /> };
+});
+
+vi.mock("./components/CloudAccessGate", async () => {
+  const { Outlet } = await import("react-router-dom");
+  return { CloudAccessGate: () => <Outlet /> };
+});
+
+vi.mock("./components/AppsExperimentalGate", async () => {
+  const { Outlet } = await import("react-router-dom");
+  return { AppsExperimentalGate: () => <Outlet /> };
+});
+
+// Treat both EE host features as enabled. If a static gated route shadows the
+// dynamic route, this test still enters it and observes the missing :tab param.
+vi.mock("./components/HostFeatureGate", async () => {
+  const { Outlet } = await import("react-router-dom");
+  return { HostFeatureGate: () => <Outlet /> };
+});
+
+vi.mock("./components/OnboardingWizardVariant", () => ({
+  OnboardingWizardVariant: () => null,
+}));
+
+// Keep the real App route tree and real router params. The sentinel mirrors the
+// tab choice that ToolsAccess makes: an absent param falls back to run-your-own.
+vi.mock("./pages/tools/AdvancedToolsRoute", async () => {
+  const { useParams } = await import("react-router-dom");
+  return {
+    AdvancedToolsRoute: () => {
+      const { tab } = useParams<{ tab?: string }>();
+      if (tab === "profiles") return <div>PROFILES_TAB_MOUNTED</div>;
+      if (tab === "gateways") return <div>GATEWAYS_TAB_MOUNTED</div>;
+      return <div>RUN_YOUR_OWN_TAB_MOUNTED</div>;
+    },
+  };
+});
+
+const PAP_COMPANY = {
+  id: "company-1",
+  name: "Paperclip",
+  issuePrefix: "PAP",
+  status: "active",
+};
+
+vi.mock("./context/CompanyContext", () => ({
+  useCompany: () => ({
+    companies: [PAP_COMPANY],
+    selectedCompanyId: PAP_COMPANY.id,
+    selectedCompany: PAP_COMPANY,
+    loading: false,
+  }),
+  CompanyProvider: ({ children }: { children: ReactNode }) => <>{children}</>,
+}));
+
+function renderAppAt(container: HTMLElement, path: string) {
+  const root = createRoot(container);
+  flushSync(() => {
+    root.render(
+      <MemoryRouter initialEntries={[path]}>
+        <App />
+      </MemoryRouter>,
+    );
+  });
+  return root;
+}
+
+describe("App advanced tools routing", () => {
+  let container: HTMLDivElement;
+
+  beforeEach(() => {
+    container = document.createElement("div");
+    document.body.appendChild(container);
+  });
+
+  afterEach(() => {
+    container.remove();
+    document.body.innerHTML = "";
+    vi.clearAllMocks();
+  });
+
+  it.each([
+    ["profiles", "PROFILES_TAB_MOUNTED"],
+    ["gateways", "GATEWAYS_TAB_MOUNTED"],
+  ])("preserves the %s tab param through the real prefixed route tree", async (tab, expected) => {
+    const root = renderAppAt(container, `/PAP/apps/advanced/${tab}`);
+
+    await vi.waitFor(() => expect(container.textContent).toContain(expected));
+    expect(container.textContent).not.toContain("RUN_YOUR_OWN_TAB_MOUNTED");
+
+    flushSync(() => root.unmount());
+  });
+});
diff --git a/ui/src/App.tsx b/ui/src/App.tsx
index b357d91fde1..ca625c489f2 100644
--- a/ui/src/App.tsx
+++ b/ui/src/App.tsx
@@ -148,11 +148,9 @@ function boardRoutes() {
           <Route path="apps/gateways" element={<GatewaysList />} />
           <Route path="apps/gateways/:gatewayId" element={<Navigate to="overview" replace />} />
           <Route path="apps/gateways/:gatewayId/:tab" element={<GatewayDetail />} />
-          <Route path="apps/advanced/gateways" element={<AdvancedToolsRoute />} />
         </Route>
         <Route path="apps/advanced" element={<AdvancedToolsRoute />} />
         <Route element={<HostFeatureGate feature="apps.access_profiles" />}>
-          <Route path="apps/advanced/profiles" element={<AdvancedToolsRoute />} />
           <Route path="apps/advanced/profiles/new" element={<ProfileWizardRoute mode="new" />} />
           <Route path="apps/advanced/profiles/:profileId/edit" element={<ProfileWizardRoute mode="edit" />} />
           <Route path="apps/advanced/profiles/:profileId" element={<ProfileDetailRoute />} />