feat(streaming): add global activity watchers, client-side buffering, and improved real-time streaming UX

ts_web/elements/tsview-activity-stream.ts

@@ -23,8 +23,12 @@ export class TsviewActivityStream extends DeesElement {
   @state()
   private accessor autoScroll: boolean = true;
 
+  @state()
+  private accessor now: number = Date.now();
+
   private subscription: plugins.smartrx.rxjs.Subscription | null = null;
   private connectionSubscription: plugins.smartrx.rxjs.Subscription | null = null;
+  private nowInterval: ReturnType<typeof setInterval> | null = null;
 
   public static styles = [
     cssManager.defaultStyles,
@@ -159,6 +163,15 @@ export class TsviewActivityStream extends DeesElement {
         background: rgba(255, 255, 255, 0.05);
       }
 
+      .event-time-col {
+        width: 70px;
+        flex-shrink: 0;
+        text-align: right;
+        font-size: 11px;
+        color: #666;
+        padding-top: 2px;
+      }
+
       .event-icon {
         width: 36px;
         height: 36px;
@@ -192,7 +205,6 @@ export class TsviewActivityStream extends DeesElement {
       .event-header {
         display: flex;
         align-items: center;
-        justify-content: space-between;
         margin-bottom: 4px;
       }
 
@@ -202,11 +214,6 @@ export class TsviewActivityStream extends DeesElement {
         color: #e0e0e0;
       }
 
-      .event-time {
-        font-size: 11px;
-        color: #666;
-      }
-
       .event-details {
         font-size: 12px;
         color: #888;
@@ -285,50 +292,66 @@ export class TsviewActivityStream extends DeesElement {
 
   async connectedCallback() {
     super.connectedCallback();
+    this.nowInterval = setInterval(() => {
+      this.now = Date.now();
+    }, 1000);
     await this.initializeStreaming();
   }
 
   disconnectedCallback() {
     super.disconnectedCallback();
+    if (this.nowInterval) {
+      clearInterval(this.nowInterval);
+      this.nowInterval = null;
+    }
     this.cleanup();
   }
 
   private async initializeStreaming() {
     this.isLoading = true;
 
+    // Subscribe to connection status and trigger re-subscription on reconnect
+    this.connectionSubscription = changeStreamService.connectionStatus$.subscribe(async (status) => {
+      const wasConnected = this.isConnected;
+      this.isConnected = status === 'connected';
+      if (status === 'connected' && !wasConnected) {
+        await this.setupSubscriptions();
+        this.isLoading = false;
+      }
+    });
+
     try {
-      // Connect to WebSocket if not connected
       await changeStreamService.connect();
-
-      // Subscribe to connection status
-      this.connectionSubscription = changeStreamService.connectionStatus$.subscribe((status) => {
-        this.isConnected = status === 'connected';
-      });
-
-      // Subscribe to activity stream
-      await changeStreamService.subscribeToActivity();
-
-      // Load recent events
-      const recentEvents = await changeStreamService.getRecentActivity(100);
-      this.events = recentEvents;
-
-      // Subscribe to new events
-      this.subscription = changeStreamService.getActivityStream().subscribe((event) => {
-        this.events = [...this.events, event].slice(-500); // Keep last 500 events
-
-        // Auto-scroll if enabled
-        if (this.autoScroll) {
-          this.scrollToBottom();
-        }
-      });
-
-      this.isConnected = true;
+      // setupSubscriptions() is triggered by connectionStatus$ subscriber above
     } catch (error) {
       console.error('Failed to initialize activity stream:', error);
       this.isConnected = false;
+      this.isLoading = false;
+    }
+  }
+
+  private async setupSubscriptions() {
+    // Read buffered events (captured while on other tabs by app-level subscription)
+    const buffered = changeStreamService.getBufferedActivity();
+    if (buffered.length > 0) {
+      this.events = buffered;
+    } else {
+      // Buffer empty (fresh start) — fetch from server
+      const recentEvents = await changeStreamService.getRecentActivity(100);
+      if (recentEvents.length > 0) {
+        this.events = recentEvents;
+      }
     }
 
-    this.isLoading = false;
+    // Set up RxJS listener only once for new live events
+    if (!this.subscription) {
+      this.subscription = changeStreamService.getActivityStream().subscribe((event) => {
+        this.events = [...this.events, event].slice(-500);
+        if (this.autoScroll) {
+          this.scrollToTop();
+        }
+      });
+    }
   }
 
   private cleanup() {
@@ -340,14 +363,15 @@ export class TsviewActivityStream extends DeesElement {
       this.connectionSubscription.unsubscribe();
       this.connectionSubscription = null;
     }
-    changeStreamService.unsubscribeFromActivity();
+    // DO NOT call changeStreamService.unsubscribeFromActivity()
+    // The app-level subscription keeps the server sending events for buffering
   }
 
-  private scrollToBottom() {
+  private scrollToTop() {
     requestAnimationFrame(() => {
       const list = this.shadowRoot?.querySelector('.events-list');
       if (list) {
-        list.scrollTop = list.scrollHeight;
+        list.scrollTop = 0;
       }
     });
   }
@@ -361,10 +385,11 @@ export class TsviewActivityStream extends DeesElement {
   }
 
   private get filteredEvents(): IActivityEvent[] {
-    if (this.filterMode === 'all') {
-      return this.events;
+    let events = this.events;
+    if (this.filterMode !== 'all') {
+      events = events.filter((e) => e.source === this.filterMode);
     }
-    return this.events.filter((e) => e.source === this.filterMode);
+    return events.sort((a, b) => new Date(b.timestamp).getTime() - new Date(a.timestamp).getTime());
   }
 
   private formatTime(timestamp: string): string {
@@ -378,11 +403,13 @@ export class TsviewActivityStream extends DeesElement {
 
   private formatRelativeTime(timestamp: string): string {
     const date = new Date(timestamp);
-    const now = new Date();
-    const diff = now.getTime() - date.getTime();
+    const diff = this.now - date.getTime();
 
-    if (diff < 60000) {
-      return 'just now';
+    if (diff < 1000) {
+      return 'now';
+    } else if (diff < 60000) {
+      const secs = Math.floor(diff / 1000);
+      return `${secs}s ago`;
     } else if (diff < 3600000) {
       const mins = Math.floor(diff / 60000);
       return `${mins}m ago`;
@@ -534,6 +561,9 @@ export class TsviewActivityStream extends DeesElement {
               : this.filteredEvents.map(
                   (event) => html`
                     <div class="event-item" @click=${() => this.handleEventClick(event)}>
+                      <div class="event-time-col" title=${this.formatTime(event.timestamp)}>
+                        ${this.formatRelativeTime(event.timestamp)}
+                      </div>
                       <div class="event-icon ${event.source}">
                         ${event.source === 'mongodb' ? this.renderMongoIcon() : this.renderS3Icon()}
                       </div>
@@ -543,9 +573,6 @@ export class TsviewActivityStream extends DeesElement {
                             <span class="event-type ${this.getEventType(event)}">${this.getEventType(event)}</span>
                             ${this.getEventTitle(event)}
                           </div>
-                          <div class="event-time" title=${this.formatTime(event.timestamp)}>
-                            ${this.formatRelativeTime(event.timestamp)}
-                          </div>
                         </div>
                         <div class="event-details">
                           <span class="event-path">${this.getEventDetails(event)}</span>