Add Server-Sent Events for real-time table notifications

[Copilot]

Implements real-time table updates via SSE. When mutations occur, subscribed clients receive events and auto-refresh affected tables.

Backend

SSE Infrastructure (apps/api/src/sse/)

• SSEManager: Connection registry with resource-based subscriptions
• Route at /api/events: Streams events with 30s heartbeat
• Authentication: JWT via query param (EventSource header limitation)
• Helper: emitTableUpdate(resource) called post-mutation

Integration Points

async handler(options) {
  const result = await prisma.veranstaltung.create({ ... })
  emitTableUpdate('veranstaltung')  // Broadcasts to subscribed clients
  return result
}

Currently integrated: veranstaltung create/update, anmeldung create/update

Frontend

SSE Composable (apps/frontend/src/composables/useSSE.ts)

• Singleton service with exponential backoff (max 5 attempts, 30s cap)
• Auto-subscribe on mount, cleanup on unmount
• 10s connection timeout

Usage Pattern

const dataTableRef = ref<{ query: ReturnType<Query<T>> }>()

useSSE('veranstaltung', () => {
  dataTableRef.value?.query.refetch()
})

Integrated: VeranstaltungList, AnmeldungenTable

Architecture Notes

• One persistent HTTP connection per client
• Events only sent to subscribed resources (no broadcast to all)
• No guaranteed delivery (missed events during disconnect acceptable)
• Extends to new resources via 2-line mutation integration + composable call

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• checkpoint.prisma.io
  • Triggering command: /opt/hostedtoolcache/node/24.13.0/x64/bin/node /opt/hostedtoolcache/node/24.13.0/x64/bin/node /home/REDACTED/work/brahmsee.digital/brahmsee.digital/node_modules/.pnpm/prisma@5.22.0/node_modules/prisma/build/child {"product":"prisma","version":"5.22.0","cli_install_type":"local","information":"","local_timestamp":"2026-02-10T21:42:10Z","project_hash":"b6c57c18","cli_path":"/home/REDACTED/work/brahmsee.digital/brahmsee.digital/apps/api/node_modules/prisma/build/index. (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[Feature] Server Sent Events (SSE) für Tabellen</issue_title>
<issue_description>### Kurzbeschreibung

Wenn neue Daten verfügbar sind, soll der Nutzer eine Benachrichtigung bekommen.

Beschreibung

TODO: AUSFORMULIEREN @supermomme </issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes [Feature] Server Sent Events (SSE) für Tabellen #377

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[axelrindle]

Suggested change

	dataTableRef.value?.query.refetch()
	query.refetch()