Add auto-subscription for real-time message notifications

- ReceiveMessagesTool subscription activates automatically on startup
- No need to call receive_messages manually first
- Messages arrive in real-time like chat
- Notifications appear instantly when messages sent

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/registry/ToolRegistry.ts

@@ -17,6 +17,21 @@ export class ToolRegistry {
 
   async initialize(): Promise<void> {
     this.setupDiscovery();
+    await this.setupMessageSubscription();
+  }
+
+  private async setupMessageSubscription(): Promise<void> {
+    // Auto-activate receive_messages subscription for real-time notifications
+    const receiveMessagesTool = this.builtinHandlers.get('receive_messages');
+    if (receiveMessagesTool) {
+      try {
+        // Trigger initial subscription by calling the tool with empty params
+        await this.executeBuiltinTool(receiveMessagesTool, {});
+        logger.info('Message subscription activated for real-time notifications');
+      } catch (error) {
+        logger.warn({ error }, 'Failed to auto-activate message subscription');
+      }
+    }
   }
 
   private setupDiscovery(): void {