- admin_safe_set_is_admin: short-circuit when target.is_admin == value,
before writing audit. PATCH {is_admin: true} on someone already admin
previously wrote a misleading "promote_user" row even though the UPDATE
was a no-op.
- list_chapters (/admin/mangas/:id/chapters): explicit exists() check on
manga_id, returns 404 instead of 200 [] for a typo'd / deleted manga.
- ChapterSyncState priority: the Failed branch now requires page_count = 0,
so a chapter with pages on disk AND a historical dead job (from a
re-download attempt that crashed) stays Synced. The old order
contradicted Synced's documented "downloaded at some point" contract.
Doc comments updated alongside the SQL.
Three new regression tests pin the behaviour.
Adds /api/v1/admin/users list / DELETE / PATCH guarded by RequireAdmin,
plus the audit-log substrate every future destructive admin endpoint
will reuse.
Safety properties:
- Cannot self-delete or self-demote (409 conflict, message calls out
"yourself" so the UI can render an explanation).
- Cannot remove the last admin via either DELETE or demote. The check
takes pg_advisory_xact_lock(ADMIN_INVARIANT_LOCK_KEY) and re-counts
admins inside the same tx, closing the parallel-demote race that a
bare "if count > 1" check would let through. The HTTP-serial path to
this guard is structurally unreachable (the actor would have to be
the lone admin demoting themselves, which the self-guard fires on
first); the parallel race test exercises it via repo calls.
Audit log (admin_audit table) records the action inside the same tx
as the action itself, so a rolled-back action never leaves an orphan
audit row. actor_user_id is ON DELETE SET NULL so the log outlives a
later-deleted admin. target_id is not a FK because future audit kinds
will target non-user rows.
