fix: dedupe vscode notifications across panels

Prevents duplicate native notifications when a session is open in both sidebar and editor
Uses an extension-host claim step so only one VS Code webview displays each notification
Keeps notification behavior unchanged for single-panel sessions

packages/vscode/src/bridge-system-runtime.ts

@@ -22,6 +22,26 @@ type SystemRuntimeDeps = {
   clientReloadDelayMs: number;
 };
 
+const NOTIFICATION_CLAIM_TTL_MS = 10_000;
+const notificationClaims = new Map<string, number>();
+
+const claimNotification = (key: string): boolean => {
+  const now = Date.now();
+  for (const [claimKey, claimedAt] of notificationClaims) {
+    if (now - claimedAt > NOTIFICATION_CLAIM_TTL_MS) {
+      notificationClaims.delete(claimKey);
+    }
+  }
+
+  const existing = notificationClaims.get(key);
+  if (existing && now - existing <= NOTIFICATION_CLAIM_TTL_MS) {
+    return false;
+  }
+
+  notificationClaims.set(key, now);
+  return true;
+};
+
 
 const getOpenChamberConfigDir = (): string => {
   if (process.platform === 'win32') {
@@ -225,6 +245,13 @@ export async function handleSystemBridgeMessage(
       return { id, type, success: true, data: getSessionActivitySnapshot() };
     }
 
+    case 'api:notifications:claim': {
+      const key = typeof (payload as { key?: unknown } | undefined)?.key === 'string'
+        ? (payload as { key: string }).key.trim()
+        : '';
+      return { id, type, success: true, data: { claimed: key ? claimNotification(key) : false } };
+    }
+
     case 'api:zen:models': {
       const models = await fetchFreeZenModels();
       return { id, type, success: true, data: { models } };

packages/vscode/webview/main.tsx

@@ -1279,12 +1279,32 @@ onCommand('showSettings', () => {
   window.dispatchEvent(new CustomEvent('openchamber:navigate', { detail: { view: 'settings' } }));
 });
 
-const showOpenChamberNotification = (payload: { title?: unknown; body?: unknown; sessionId?: unknown; requireHidden?: unknown } | undefined) => {
+const getNotificationClaimKey = (payload: { title?: unknown; body?: unknown; sessionId?: unknown; tag?: unknown } | undefined): string => {
+  const tag = typeof payload?.tag === 'string' ? payload.tag.trim() : '';
+  if (tag) return tag;
+  return [payload?.sessionId, payload?.title, payload?.body]
+    .filter((value): value is string => typeof value === 'string' && value.trim().length > 0)
+    .map((value) => value.trim())
+    .join('|');
+};
+
+const claimOpenChamberNotification = async (payload: { title?: unknown; body?: unknown; sessionId?: unknown; tag?: unknown } | undefined): Promise<boolean> => {
+  const key = getNotificationClaimKey(payload);
+  if (!key) return true;
+  try {
+    const result = await sendBridgeMessage<{ claimed?: boolean }>('api:notifications:claim', { key });
+    return result?.claimed === true;
+  } catch {
+    return true;
+  }
+};
+
+const showOpenChamberNotification = (payload: { title?: unknown; body?: unknown; sessionId?: unknown; tag?: unknown; requireHidden?: unknown } | undefined) => {
   if (typeof Notification === 'undefined') {
     return false;
   }
 
-  const show = () => {
+  const show = async () => {
     const isVSCodeWindowFocused = window.__OPENCHAMBER_VSCODE_WINDOW_FOCUSED__ ?? document.hasFocus();
     if (payload?.requireHidden === true && isVSCodeWindowFocused) {
       return false;
@@ -1300,6 +1320,9 @@ const showOpenChamberNotification = (payload: { title?: unknown; body?: unknown;
     const sessionId = typeof payload?.sessionId === 'string' && payload.sessionId.trim().length > 0
       ? payload.sessionId.trim()
       : '';
+    if (!await claimOpenChamberNotification({ ...payload, title, body, sessionId })) {
+      return false;
+    }
 
     const notification = new Notification(title, { body });
     notification.onclick = () => {
@@ -1316,13 +1339,14 @@ const showOpenChamberNotification = (payload: { title?: unknown; body?: unknown;
   if (Notification.permission === 'default') {
     void Notification.requestPermission().then((permission) => {
       if (permission === 'granted') {
-        show();
+        void show();
       }
     });
     return true;
   }
 
-  return show();
+  void show();
+  return true;
 };
 
 onCommand('showNotification', (payload) => {