Adds GET /api/v1/admin/system returning disk (scoped to storage_dir
via statvfs), memory, CPU, and a server-side alerts array that fires
at >90% disk or memory.
Disk uses nix::sys::statvfs directly rather than sysinfo's Disks API
to avoid mountpoint-matching gymnastics for the storage_dir. A new
`Storage::local_root() -> Option<&Path>` trait method exposes the
root; the default returns None so a future S3Storage gets `disk:
null` in the response instead of fabricated numbers.
CPU is sampled inline (refresh → 250ms sleep → refresh → read) so the
endpoint adds 250ms of latency per call. No background-cache yet —
admin traffic is low-volume and the moving parts aren't worth it
until polling shows up.
Alerts are evaluated server-side so the frontend can render them
without re-implementing the thresholds.
Adds GET /api/v1/admin/mangas and /admin/mangas/:id/chapters guarded by
RequireAdmin. Sync state is computed at query time from the existing
crawler signals (manga_sources / chapter_sources / crawler_jobs) — no
new state column is persisted, so the crawler stays the single writer
of these signals.
Per-manga priority: InProgress (in-flight sync_manga or
sync_chapter_list job) > Dropped (all source rows soft-dropped) >
Synced (default; covers user-uploaded mangas with zero source rows).
Per-chapter priority: Downloading (in-flight sync_chapter_content) >
Dropped (all source rows soft-dropped) > Failed (most-recent terminal
job is dead) > NotDownloaded (page_count = 0) > Synced. The Failed
check sits ABOVE NotDownloaded so the more informative "we tried and
it died" state wins over "we never got around to it" — see the
priority comment in repo/admin_view.rs.
Migration 0020 adds a partial index on
crawler_jobs((payload->>'source_manga_key')) for the one job kind
(sync_manga) whose payload doesn't carry manga_id directly — without it
the in-flight detection for a manga falls back to a seqscan over the
job table.
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.
