## Summary
Adds a new `diff_status_change` event kind to the `/chats/watch` pubsub
stream so the sidebar can update diff status (PR created, files changed,
branch info) without a full page reload.
### Problem
When a chat's diff status changes (e.g. PR created via GitHub, git
branch pushed), the sidebar didn't update because:
1. The backend `publishChatPubsubEvent` didn't include diff status data
2. The frontend watch handler only merged `status`, `title`, and
`updated_at` from events
### Solution
A **notify-only** approach: a new `ChatEventKindDiffStatusChange` event
kind tells the frontend "diff status changed for chat X" — the frontend
then invalidates the relevant React Query cache entries to re-fetch.
### Backend changes
- **`coderd/pubsub/chatevent.go`**: New `ChatEventKindDiffStatusChange =
"diff_status_change"` constant
- **`coderd/chatd/chatd.go`**: New `PublishDiffStatusChange(ctx,
chatID)` method on `Server`
- **`coderd/chats.go`**: New `publishChatDiffStatusEvent` helper.
Published from:
- `refreshWorkspaceChatDiffStatuses` — after each chat's diff status is
refreshed via GitHub API
- `storeChatGitRef` — after persisting git branch/origin info from
workspace agent
### Frontend changes
- **`AgentsPage.tsx`**: Handle `diff_status_change` event by
invalidating `chatDiffStatusKey` and `chatDiffContentsKey` queries
- **`ChatContext.ts`**: Remove redundant diff status invalidation that
fired on every chat status change (the new event kind handles this
properly)
This PR is part of the inbox notifications topic, and rely on previous
PRs merged - it adds :
- Endpoints to :
- WS : watch new inbox notifications
- REST : list inbox notifications
- REST : update the read status of a notification
Also, this PR acts as a follow-up PR from previous work and :
- fix DB query issues
- fix DBMem logic to match DB
Kyle Carberry