add update service

frontend/src/App.tsx

@@ -897,6 +897,7 @@ function Flow() {
   const [executingNodeId, setExecutingNodeId] = useState<string | null>(null);
   const [helpTabs, setHelpTabs] = useState<{ label: string; type?: string; content: string | null }[]>([]);
   const [activeHelpTab, setActiveHelpTab] = useState<string | null>(null);
+  const [updateInfo, setUpdateInfo] = useState<{ latest: string; url: string } | null>(null);
 
   const flowContainerRef = useRef<HTMLDivElement | null>(null);
   const panTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null);
@@ -918,6 +919,19 @@ function Flow() {
   const reactFlow = useReactFlow<TonoNode, TonoEdge>() as ReturnType<typeof useReactFlow<TonoNode, TonoEdge>> & { updateNodeInternals: (id: string) => void };
   const undoRedo = useUndoRedo();
 
+  // ── Update check (native builds only) ──────────────────────────────
+  useEffect(() => {
+    if (!(window as any).pywebview) return;
+    fetch('/check-update')
+      .then((r) => r.ok ? r.json() : null)
+      .then((data) => {
+        if (data?.update_available && data.latest) {
+          setUpdateInfo({ latest: data.latest, url: data.url });
+        }
+      })
+      .catch(() => {});
+  }, []);
+
   const scheduleAutoRun = useCallback(() => {
     if (autoRunTimer.current) clearTimeout(autoRunTimer.current);
     autoRunTimer.current = setTimeout(() => autoRunRef.current?.(), 300);
@@ -3179,6 +3193,15 @@ function Flow() {
           <div className={`status-bar ${status.level}`}>{status.text}</div>
         </div>
 
+        {updateInfo && (
+          <div className="update-banner">
+            tono {updateInfo.latest} is available.
+            {' '}
+            <a href={updateInfo.url} target="_blank" rel="noopener noreferrer">Download</a>
+            <button className="update-banner-dismiss" onClick={() => setUpdateInfo(null)} title="Dismiss">✕</button>
+          </div>
+        )}
+
         {/* React Flow canvas */}
         <div
           ref={flowContainerRef}

frontend/src/styles.css

@@ -212,6 +212,34 @@ html, body, #root {
 .status-bar.info  { color: var(--accent-light); }
 .status-bar.error { color: var(--error-text); background: var(--error-bg); }
 
+.update-banner {
+  background: var(--accent);
+  color: #fff;
+  text-align: center;
+  padding: 4px 12px;
+  font-size: 12px;
+  position: relative;
+}
+.update-banner a {
+  color: #fff;
+  font-weight: 600;
+  text-decoration: underline;
+}
+.update-banner-dismiss {
+  position: absolute;
+  right: 8px;
+  top: 50%;
+  transform: translateY(-50%);
+  background: none;
+  border: none;
+  color: #fff;
+  cursor: pointer;
+  font-size: 13px;
+  padding: 2px 4px;
+  opacity: 0.7;
+}
+.update-banner-dismiss:hover { opacity: 1; }
+
 /* ── React Flow container ──────────────────────────────────────────── */
 .flow-container {
   flex: 1;