Real-Time Updates (Mercure SSE)

PSAPLink uses Mercure Server-Sent Events for live dashboard updates. No polling required.

How It Works

1. On login, the frontend subscribes to a Mercure topic derived from the user's ID
2. Cloud publishes SSE events to that topic when relevant state changes
3. The frontend updates the UI immediately

Published Events

Event	When
Incident created	New incident dispatched to a company
Notification sent	Delivery attempt made
ACK received	User acknowledged via any channel
Reply received	Company user sent a reply
PSAP ACK	PSAP TCO acknowledged a reply
Escalation triggered	Timeout with no ACK

Payload Encryption

SSE payloads for sensitive topics are encrypted before publishing to Mercure.

• Keys rotate every 30 minutes, derived deterministically from the master encryption key
• Wire format: enc:<base64(nonce[24] || ciphertext)>
• Frontend uses libsodium-wrappers to decrypt; keys fetched via GET /api/v1/realtime/subscribe-key
• Keys auto-refresh 60 seconds before expiry via the useSseKey hook

Configuration

MERCURE_JWT_SECRET=your-shared-secret
MERCURE_URL=http://mercure/.well-known/mercure   # internal
MERCURE_PUBLIC_URL=https://psaplink.com/.well-known/mercure