diff --git a/src/lib/collaboration/realtime.ts b/src/lib/collaboration/realtime.ts
index 0396e54..e5b0cb8 100644
--- a/src/lib/collaboration/realtime.ts
+++ b/src/lib/collaboration/realtime.ts
@@ -44,6 +44,7 @@ const RECONNECT_BASE_DELAY_MS = 1000
 const RECONNECT_MAX_DELAY_MS = 30_000
 const INACTIVITY_TIMEOUT_MS = 5 * 60_000 // 5 minutes of inactivity before pausing
 const CONNECTION_TIMEOUT_MS = 15_000 // 15s timeout for initial connection
+const STALE_THRESHOLD_MS = 60_000 // 60s of inactivity = force fresh reconnect on return
 
 export class RealtimeConnection {
   private channel: RealtimeChannel | null = null
@@ -58,6 +59,7 @@ export class RealtimeConnection {
   private callbacks: RealtimeCallbacks
   private isDestroyed = false
   private isPaused = false
+  private lastActivityTime = Date.now()
   private supabase = createClient()
 
   constructor(projectId: string, userId: string, displayName: string, callbacks: RealtimeCallbacks) {
@@ -70,6 +72,7 @@ export class RealtimeConnection {
   async connect(): Promise<void> {
     if (this.isDestroyed) return
     this.isPaused = false
+    this.lastActivityTime = Date.now()
     this.callbacks.onConnectionStateChange('connecting')
     this.resetInactivityTimer()
     this.clearConnectionTimer()
@@ -244,15 +247,43 @@ export class RealtimeConnection {
   /**
    * Notify that user activity has occurred, resetting the inactivity timer.
    * If the connection was paused due to inactivity, it will resume.
+   * If the connection was idle for a significant period, force a fresh reconnect
+   * to ensure the WebSocket isn't stale.
    */
   notifyActivity(): void {
     if (this.isDestroyed) return
+    const now = Date.now()
+    const idleDuration = now - this.lastActivityTime
+    this.lastActivityTime = now
     this.resetInactivityTimer()
+
     if (this.isPaused) {
       this.resume()
+    } else if (idleDuration > STALE_THRESHOLD_MS && this.channel) {
+      // Connection may appear alive but WebSocket could be stale after idle.
+      // Force a fresh reconnect to ensure broadcasts actually work.
+      this.forceReconnect()
     }
   }
 
+  /**
+   * Force a fresh reconnect by tearing down the current channel and reconnecting.
+   */
+  private async forceReconnect(): Promise<void> {
+    if (this.isDestroyed || this.isPaused) return
+    this.stopHeartbeat()
+    this.clearReconnectTimer()
+    this.clearConnectionTimer()
+
+    if (this.channel) {
+      this.supabase.removeChannel(this.channel)
+      this.channel = null
+    }
+
+    this.reconnectAttempts = 0
+    await this.connect()
+  }
+
   getIsPaused(): boolean {
     return this.isPaused
   }