SSE (Server-Sent Events)

Real-time app state updates via Server-Sent Events. Reduces server load ~95% vs polling.

Endpoints

Endpoint	Method	Purpose
/sse/state	GET	Stream state updates (requires Bearer token)
/sse/stats	GET	Debug: connected clients, queued events

Usage

Connect to SSE Stream

curl -H "Authorization: Bearer YOUR_API_TOKEN" \
  http://localhost:5000/sse/state

Check Connection Stats

curl -H "Authorization: Bearer YOUR_API_TOKEN" \
  http://localhost:5000/sse/stats

Event Types

• state_update - App state changed (e.g., "Scanning", "Processing")
• unread_notifications_count_update - Number of unread notifications changed (count: int)

Backend Integration

Broadcasts automatically triggered in app_state.py via broadcast_state_update():

from api_server.sse_broadcast import broadcast_state_update

# Called on every state change - no additional code needed
broadcast_state_update(current_state="Scanning", settings_imported=time.time())

Frontend Integration

Auto-enabled via sse_manager.js:

// In browser console:
netAlertXStateManager.getStats().then(stats => {
  console.log("Connected clients:", stats.connected_clients);
});

Fallback Behavior

• If SSE fails after 3 attempts, automatically switches to polling
• Polling starts at 1s, backs off to 30s max
• No user-visible difference in functionality

Files

File	Purpose
server/api_server/sse_endpoint.py	SSE endpoints & event queue
server/api_server/sse_broadcast.py	Broadcast helper functions
front/js/sse_manager.js	Client-side SSE connection manager

Troubleshooting

Issue	Solution
Connection refused	Check backend running, API token correct
No events received	Verify broadcast_state_update() is called on state changes
High memory	Events not processed fast enough, check client logs
Using polling instead of SSE	Normal fallback - check browser console for errors

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