feat: Realtime frontend using SSE

[timokoessler]

Type of change

• 🐛 Bug fix
• 🚀 New feature
• ❓ Other (please specify)

Description

Makes the frontend Realtime using SSE. Has the advantage that it not only updates the data for the current user. It is also important for all changes triggered by agent and not by the user. Also SWR does not periodically refetches data by default.

[Copilot]

Pull request overview

Adds an SSE-based realtime update channel from the backend to the frontend, so SWR caches can be invalidated when changes occur (including changes triggered by agents/other users).

Changes:

• Introduces backend SSE broker + /api/v1/events endpoint and wires it into route registration.
• Adds frontend SSE client that triggers SWR revalidation on update events and connects/disconnects based on auth state.
• Publishes SSE “update” events on repository create/update/delete and updates backend/frontend tests accordingly.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
frontend/src/lib/sse.ts	New SSE client that listens for update/unauthorized events and mutates SWR caches.
frontend/src/lib/repsitories.ts	Removes post-write SWR mutate calls for repositories (intended to rely on SSE updates).
frontend/src/lib/auth.tsx	Connects/disconnects SSE stream based on authentication state.
backend/internal/hub/sse/broker.go	New in-memory SSE broker with subscribe/unsubscribe/publish + DefaultBroker.
backend/internal/hub/sse/broker_test.go	Tests broker subscribe/unsubscribe/publish behavior and PublishUpdate helper.
backend/internal/hub/routes/sse.go	New SSE handler streaming broker events and emitting an unauthorized event at JWT expiry.
backend/internal/hub/routes/sse_test.go	Tests SSE headers, initial comment, and event delivery format.
backend/internal/hub/routes/repositories.go	Publishes SSE update events after repository mutations.
backend/internal/hub/routes/repositories_test.go	Verifies repository handlers publish SSE updates.
backend/internal/hub/middleware/timeout.go	Skips request timeout for SSE requests (currently based on Accept header).
backend/internal/hub/middleware/timeout_test.go	Adds test ensuring SSE requests skip the timeout middleware.
backend/internal/hub/handlers.go	Registers /events route and initializes the default SSE broker.

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[codecov]

Codecov Report

❌ Patch coverage is 77.08333% with 22 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
backend/internal/hub/routes/sse.go	51.21%	15 Missing and 5 partials ⚠️
backend/internal/hub/sse/broker.go	94.44%	1 Missing and 1 partial ⚠️

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[alex289]

Very cool