fix(ui): reset session view on stop and exit

frontend/src/shell/AppShell.session-mgmt.test.tsx

@@ -1213,6 +1213,38 @@ test("closing and reopening Model activity preserves the complete activity log",
   expect(useSessionStore.getState().activityLog).toEqual(beforeClose);
 });
 
+test.each(["stop", "session_exit"])("%s restores the empty landing with model activity closed", async (exit) => {
+  const close = vi.fn(() => new HttpResponse(null, { status: 204 }));
+  server.use(
+    http.post("/api/sessions/:id/resume", () => resumeResult("s1")),
+    http.post("/api/sessions/:id/close", close),
+  );
+  wrap(adminUser);
+  await userEvent.click(await screen.findByText("Attiva uno"));
+  await userEvent.click(await screen.findByRole("button", { name: "Resume" }));
+  await userEvent.click(screen.getByRole("button", { name: "Show model activity" }));
+  act(() => useSessionStore.getState().setLastUserEntry({ kind: "input", text: "Previous question" }));
+  expect(screen.getByLabelText("Model activity timeline")).toHaveTextContent("Previous question");
+  const source = FakeEventSource.instances.at(-1)!;
+
+  if (exit === "stop") {
+    await userEvent.click(screen.getByRole("button", { name: /stop and save session/i }));
+    await userEvent.click(screen.getAllByRole("button", { name: "Stop & save" })[0]);
+  } else {
+    act(() => source.emit({ type: "system_event", event: "session_exit" }));
+  }
+
+  expect(await screen.findByText(/type your question/i)).toBeInTheDocument();
+  expect(screen.queryByRole("heading", { name: "Model activity" })).not.toBeInTheDocument();
+  expect(screen.getByTestId("app-shell")).toHaveAttribute("data-activity-layout", "closed");
+  expect(screen.queryByRole("complementary", { name: "Session summary" })).not.toBeInTheDocument();
+  expect(screen.getByRole("complementary", { name: "Session navigation" })).toBeVisible();
+  expect(screen.getByRole("textbox", { name: /new question/i })).toHaveValue("");
+  expect(useSessionStore.getState().activityLog).toEqual([]);
+  expect(source.closed).toBe(true);
+  expect(close).toHaveBeenCalledTimes(exit === "stop" ? 1 : 0);
+});
+
 test("a new question after finalization restores the landing and administration navigation", async () => {
   useSessionStore.getState().resetSession();
   let finalized = false;

frontend/src/shell/AppShell.tsx

@@ -694,6 +694,20 @@ export function AppShell({ canLogout }: AppShellProps) {
     authGeneration,
   );
 
+  function resetSessionView() {
+    invalidateResumeIntent();
+    newSessionOperationRef.current = null;
+    resetSession();
+    selectActiveSession(null);
+    // Panel visibility belongs to the shell, outside the session store.
+    // Clear it too so leaving a session restores the initial landing layout.
+    setPanelSession(null);
+    setShowActivity(false);
+    setCreatingSession(false);
+    setAwaitingQuestion(false);
+    setStopConfirm(false);
+  }
+
   // A backend "session_exit" system event (e.g. the replay server emitting it
   // when the reviewer picks "Esci") asks us to leave the live session view and
   // return to the landing state. We deliberately do NOT also POST /close here —
@@ -705,10 +719,7 @@ export function AppShell({ canLogout }: AppShellProps) {
     if (ev === "session_exit") {
       // Never let a streamed event terminate the managed Pi child. Only the
       // explicit “Stop & save” action is allowed to call /close.
-      invalidateResumeIntent();
-      resetSession();
-      selectActiveSession(null);
-      setAwaitingQuestion(false);
+      resetSessionView();
     }
     // The final workflow turn ends with the session already finalized on disk:
     // refetch now instead of waiting for the 10s poll, so the completed state
@@ -725,15 +736,8 @@ export function AppShell({ canLogout }: AppShellProps) {
     }
     if (!canLeaveDatabaseManagement()) return;
     navigate({ surface: "core" }, true);
-    invalidateResumeIntent();
-    newSessionOperationRef.current = null;
-    resetSession();
-    // Restore the landing layout, including the right-hand administration rail.
-    setPanelSession(null);
-    setShowActivity(false);
+    resetSessionView();
     setAwaitingQuestion(true);
-    setCreatingSession(false);
-    selectActiveSession(null);
     // Best effort only: session creation keeps the authoritative readiness gate.
     // Composer focus is deliberately independent of this network request.
     void prewarmRuntime().catch(() => undefined);
@@ -781,9 +785,7 @@ export function AppShell({ canLogout }: AppShellProps) {
     } finally {
       if (!isAuthOperationCurrent(guard, { sessionId: id, disposalEpoch: operationEpochRef.current })
         || activeSessionIdRef.current !== id) return;
-      resetSession();
-      selectActiveSession(null);
-      setAwaitingQuestion(false);
+      resetSessionView();
     }
   }