diff --git a/frontend/src/App.test.tsx b/frontend/src/App.test.tsx
index b9b03201..7ac276a7 100644
--- a/frontend/src/App.test.tsx
+++ b/frontend/src/App.test.tsx
@@ -3,13 +3,50 @@ import { http, HttpResponse } from "msw";
 import { server } from "./test/msw";
 import { App } from "./App";
 
-test("App renders the shell with create affordance after authentication", async () => {
+function registerAuthenticatedShell(mode: "local" | "upstream") {
   server.use(
-    http.get("/api/settings", () => HttpResponse.json({ workspace: "psd", provider: "zai", model: "glm-5.2", thinking: "medium" })),
+    http.get("/api/auth/config", () => HttpResponse.json({
+      mode,
+      localLogin: mode === "local",
+      oidcLogin: false,
+    })),
+    http.get("/api/me", () => HttpResponse.json({
+      issuer: mode === "local" ? "local" : "portal",
+      subject: "portal-user",
+      displayName: "Portal user",
+      roles: ["user"],
+      permissions: ["session.use"],
+      isAdmin: false,
+      csrfToken: mode === "local" ? "c".repeat(43) : null,
+      session: null,
+    })),
+    http.get("/api/settings", () => HttpResponse.json({
+      workspace: "psd", provider: "zai", model: "glm-5.2", thinking: "medium",
+    })),
     http.get("/api/workspaces", () => HttpResponse.json([])),
     http.get("/api/models", () => HttpResponse.json({ models: [] })),
     http.get("/api/sessions", () => HttpResponse.json([])),
+    http.get("/api/workspace-registry/status", () => HttpResponse.json({
+      branch: "main", ahead: 0, behind: 0, degraded: false,
+    })),
   );
+}
+
+test("local authentication renders the standalone logout control", async () => {
+  registerAuthenticatedShell("local");
+
   render(<App />);
-  expect(await screen.findByRole("button", { name: /new/i })).toBeInTheDocument();
+
+  expect(await screen.findByRole("button", { name: "New session" })).toBeInTheDocument();
+  expect(screen.getByText("Portal user")).toBeInTheDocument();
+  expect(screen.getByRole("button", { name: "Log out" })).toBeInTheDocument();
+});
+
+test("trusted upstream authentication keeps identity but omits ThothII logout", async () => {
+  registerAuthenticatedShell("upstream");
+
+  render(<App />);
+
+  expect(await screen.findByText("Portal user")).toBeInTheDocument();
+  expect(screen.queryByRole("button", { name: "Log out" })).not.toBeInTheDocument();
 });
diff --git a/frontend/src/auth/AuthGate.tsx b/frontend/src/auth/AuthGate.tsx
index 19e25d86..a8469c17 100644
--- a/frontend/src/auth/AuthGate.tsx
+++ b/frontend/src/auth/AuthGate.tsx
@@ -17,14 +17,20 @@ import { Button } from "../components/ui/button";
 
 type GateStatus = "loading" | "login" | "authenticated" | "forbidden" | "unavailable";
 
-function AuthenticatedContent({ onExpired }: { onExpired: () => void }) {
+function AuthenticatedContent({
+  canLogout,
+  onExpired,
+}: {
+  canLogout: boolean;
+  onExpired: () => void;
+}) {
   const user = useAuthUser();
   const authGeneration = useAuthGeneration();
   useEffect(() => {
     if (!user) onExpired();
   }, [onExpired, user]);
   return user
-    ? <AppShell key={`${user.issuer}:${user.subject}:${authGeneration}`} />
+    ? <AppShell key={`${user.issuer}:${user.subject}:${authGeneration}`} canLogout={canLogout} />
     : null;
 }
 
@@ -77,7 +83,12 @@ export function AuthGate() {
   }
 
   if (status === "authenticated") {
-    return <AuthenticatedContent onExpired={() => setStatus("login")} />;
+    return (
+      <AuthenticatedContent
+        canLogout={config?.mode === "local"}
+        onExpired={() => setStatus("login")}
+      />
+    );
   }
 
   if (status === "unavailable") {
diff --git a/frontend/src/shell/AppShell.auth.test.tsx b/frontend/src/shell/AppShell.auth.test.tsx
index 3a13d381..16d5a8df 100644
--- a/frontend/src/shell/AppShell.auth.test.tsx
+++ b/frontend/src/shell/AppShell.auth.test.tsx
@@ -13,18 +13,20 @@ function renderShell(user: {
   isAdmin: boolean;
   roles: readonly ("user" | "admin")[];
   permissions: readonly string[];
-}) {
+}, canLogout = true) {
   const client = new QueryClient({ defaultOptions: { queries: { retry: false } } });
   setAuthState({
     issuer: "local", ...user, csrfToken: null, session: null,
   });
-  return render(<QueryClientProvider client={client}><AppShell /></QueryClientProvider>);
+  return render(<QueryClientProvider client={client}><AppShell canLogout={canLogout} /></QueryClientProvider>);
 }
 
 function KeyedAuthenticatedShell() {
   const user = useAuthUser();
   const generation = useAuthGeneration();
-  return user ? <AppShell key={`${user.issuer}:${user.subject}:${generation}`} /> : null;
+  return user
+    ? <AppShell key={`${user.issuer}:${user.subject}:${generation}`} canLogout />
+    : null;
 }
 
 beforeEach(() => {
@@ -63,6 +65,25 @@ describe("authenticated shell permissions", () => {
     expect(screen.getByRole("button", { name: "All sessions" })).toBeInTheDocument();
   });
 
+  test("hides logout outside local authentication while preserving the identity", async () => {
+    let logoutCalls = 0;
+    server.use(http.post("/api/auth/logout", () => {
+      logoutCalls += 1;
+      return new HttpResponse(null, { status: 204 });
+    }));
+
+    renderShell({
+      subject: "portal-user",
+      isAdmin: false,
+      roles: ["user"],
+      permissions: ["session.use"],
+    }, false);
+
+    expect(await screen.findByText("portal-user")).toBeInTheDocument();
+    expect(screen.queryByRole("button", { name: "Log out" })).not.toBeInTheDocument();
+    expect(logoutCalls).toBe(0);
+  });
+
   test("logout revokes the cookie session and clears in-memory auth", async () => {
     const user = {
       issuer: "local" as const,
@@ -112,7 +133,7 @@ describe("authenticated shell permissions", () => {
 
   const client = new QueryClient({ defaultOptions: { queries: { retry: false } } });
   setAuthState(userA);
-  render(<QueryClientProvider client={client}><AppShell /></QueryClientProvider>);
+  render(<QueryClientProvider client={client}><AppShell canLogout /></QueryClientProvider>);
   await userEvent.click(screen.getByRole("button", { name: "Log out" }));
   await started;
 
diff --git a/frontend/src/shell/AppShell.new-session.test.tsx b/frontend/src/shell/AppShell.new-session.test.tsx
index e570ffd4..99ed7071 100644
--- a/frontend/src/shell/AppShell.new-session.test.tsx
+++ b/frontend/src/shell/AppShell.new-session.test.tsx
@@ -11,7 +11,7 @@ import { workspacePreferences } from "../workspaces/preferences";
 
 function renderShell() {
   const client = new QueryClient({ defaultOptions: { queries: { retry: false } } });
-  return render(<QueryClientProvider client={client}><AppShell /></QueryClientProvider>);
+  return render(<QueryClientProvider client={client}><AppShell canLogout={false} /></QueryClientProvider>);
 }
 
 beforeEach(() => {
diff --git a/frontend/src/shell/AppShell.session-mgmt.test.tsx b/frontend/src/shell/AppShell.session-mgmt.test.tsx
index 3b2b3550..13af31d8 100644
--- a/frontend/src/shell/AppShell.session-mgmt.test.tsx
+++ b/frontend/src/shell/AppShell.session-mgmt.test.tsx
@@ -22,7 +22,7 @@ const adminUser: AuthenticatedUser = {
 function wrap(user: AuthenticatedUser = regularUser) {
   if (user !== regularUser) setAuthState(user);
   const client = new QueryClient({ defaultOptions: { queries: { retry: false } } });
-  return render(<QueryClientProvider client={client}><AppShell /></QueryClientProvider>);
+  return render(<QueryClientProvider client={client}><AppShell canLogout={false} /></QueryClientProvider>);
 }
 
 const LIST = [
diff --git a/frontend/src/shell/AppShell.session-target.test.tsx b/frontend/src/shell/AppShell.session-target.test.tsx
index e4cba8f3..6a7ff664 100644
--- a/frontend/src/shell/AppShell.session-target.test.tsx
+++ b/frontend/src/shell/AppShell.session-target.test.tsx
@@ -11,7 +11,7 @@ import { useSessionStore } from "../store/sessionStore";
 
 function renderShell() {
   const client = new QueryClient({ defaultOptions: { queries: { retry: false } } });
-  return render(<QueryClientProvider client={client}><AppShell /></QueryClientProvider>);
+  return render(<QueryClientProvider client={client}><AppShell canLogout={false} /></QueryClientProvider>);
 }
 
 function deferred() {
diff --git a/frontend/src/shell/AppShell.tsx b/frontend/src/shell/AppShell.tsx
index 7041678e..d7097cd8 100644
--- a/frontend/src/shell/AppShell.tsx
+++ b/frontend/src/shell/AppShell.tsx
@@ -36,7 +36,11 @@ import { useEffect, useMemo, useRef, useState } from "react";
 import type { CSSProperties } from "react";
 import { captureAuthOperation, isAuthOperationCurrent, StaleAuthOperationError, type AuthOperationGuard } from "../auth/authOperation";
 
-export function AppShell() {
+interface AppShellProps {
+  canLogout: boolean;
+}
+
+export function AppShell({ canLogout }: AppShellProps) {
   const authenticatedUser = useAuthUser();
   const [panelSession, setPanelSession] = useState<SessionSummary | null>(null);
   const {
@@ -717,7 +721,11 @@ export function AppShell() {
               <span className="min-w-0 truncate text-xs text-muted-foreground" title={authenticatedUser.displayName ?? authenticatedUser.subject}>
                 {authenticatedUser.displayName ?? authenticatedUser.subject}
               </span>
-              <Button variant="ghost" size="xs" onClick={() => { void signOut().catch(() => undefined); }}>Log out</Button>
+              {canLogout && (
+                <Button variant="ghost" size="xs" onClick={() => { void signOut().catch(() => undefined); }}>
+                  Log out
+                </Button>
+              )}
             </div>
           )}
         </div>