Improve deployment safety and chat reliability

frontend/js/api.js

@@ -52,15 +52,27 @@ async function api(path, options = {}) {
     return response;
 }
 
-async function apiJSON(path, options = {}) {
-    const response = await api(path, options);
-    if (!response || !response.ok) {
-        const error = await response?.json().catch(() => ({ detail: 'Request failed' }));
-        throw new Error(error.detail || 'Request failed');
+async function ensureOk(response) {
+    // api() returns undefined after a 401 — the redirect is already under way
+    if (!response) throw new Error('Session expired');
+
+    if (!response.ok) {
+        const error = await response.json().catch(() => null);
+        throw new Error(error?.detail || 'Request failed');
     }
+    return response;
+}
+
+async function apiJSON(path, options = {}) {
+    const response = await ensureOk(await api(path, options));
     return response.json();
 }
 
+/* Same, for endpoints that answer 204 No Content (the deletes). */
+async function apiVoid(path, options = {}) {
+    await ensureOk(await api(path, options));
+}
+
 function requireAuth() {
     if (!getToken()) {
         window.location.href = '/';
@@ -81,6 +93,8 @@ function requireAdmin() {
 function logout() {
     clearToken();
     clearUser();
+    // Drop the saved conversation as well — shared devices are the norm here
+    try { sessionStorage.clear(); } catch (e) { /* storage may be blocked */ }
     window.location.href = '/';
 }