2026-06-04 - Announcement board

A new school-wide announcement board: staff post notices that everyone in the school can read, with an unread badge and per-announcement read receipts (avatars of who has read each notice).

Requires two migrations. No behavior changes to existing features.

Data model

Three additions in the public schema (see 20260603120000_announcement.sql and 20260603140000_announcement_read_receipts.sql):

• announcement - id, school_id, author_user_profile_id, title, body, timestamps. FK-cascaded to school and (set-null) user_profile. RLS: anyone in the school reads; members insert; author-or-admin update/delete.
• announcement_read - (announcement_id, user_profile_id) read receipts with read_at. RLS: school members see in-school receipts; a user records only their own.

An interim announcement_read_state (last-read timestamp) shipped first and was replaced by the per-announcement announcement_read table in the same release, so read receipts could show who read each notice. The drop is handled in the second migration.

RBAC

A new announcement resource was added to the code-owned permission catalog (permission.catalog.ts) with the usual create/read/update/delete actions. Default grants: admins everything, teachers full control, members read-only. The catalog syncs to public.permission_catalog on boot, so the resource appears in the role permissions editor automatically.

Backend

New AnnouncementModule (announcement.module.ts) wired into app.module.ts and the versioning registry.

Method	Route	Permission
GET	/announcements	announcement:read
GET	/announcements/unread-count	announcement:read
POST	/announcements/mark-read	announcement:read
GET	/announcements/:id	announcement:read
POST	/announcements	announcement:create
PATCH	/announcements/:id	announcement:update
DELETE	/announcements/:id	announcement:delete

Notable service behavior (announcement.service.ts):

• Author-or-admin edits. announcement:update/delete alone isn't sufficient - the service additionally requires the caller to be the author or a school admin, so a teacher can't modify another staff member's notice.
• Read tracking. markRead bulk-upserts a receipt per in-school announcement; getUnreadCount returns the count of announcements posted by others the user hasn't read. The author is never counted as unread on, or shown as a reader of, their own post.
• Caching. Announcement content (title/body/author) is cached per school (announcements:content:<schoolId>, 30-day TTL) and invalidated only on create/update/delete. Read receipts are fetched live on each list and merged in, so "read by" stays accurate without invalidating the content cache on every read.

Frontend

• New board at /dashboard/announcements (page.tsx) - a card feed with a permission-gated "New Announcement" dialog, author + timestamp, and edit/delete shown only to the author/admin.
• Unread badge. A global signal (lib/announcements.ts) drives a count badge on the sidebar "Announcements" item; it refreshes on navigation and clears when the board is opened (which marks everything read).
• Read receipts. Each card shows a "Read by" row of overlapping avatars (ReaderAvatars.tsx) with a name tooltip on hover and a "+N" overflow. A read is recorded when a user opens the board (board-level "seen", not per-message).

Deploy

Run both announcement migrations, then restart the backend so the permission catalog re-syncs the announcement resource.

Tests

Backend suite green; typecheck clean on both apps. Verified end-to-end against a local stack: create → list → update → delete, and the unread count going 0 → 2 → 0 across two users with reader avatars resolving correctly.