Rewrite writeErr(w, err) to wrap *apierror.Error via apierror.From,
preserving the existing {"error": {"code", "message"}} wire envelope.
Add writeErrWithLog helper for 500-class errors that need an operator
log line. Migrate all 13 admin_*.go handler files (~76 call sites) to
the new signature; T3 will sweep the remaining api package.
The old 4-arg writeErr is removed, so non-admin call sites in
internal/api will not compile until T3 lands. This is by design — T2
and T3 are paired.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
New admin handler returns the library-wide cover-art coverage rollup
{total, with_art, pending, settled, pending_no_mbid} for the admin
dashboard gauge. Always 200; zeros on empty library. Same RequireAdmin
middleware as /api/admin/scan/status. Lives under a new /library/
admin sub-namespace, parallel to /scan/ (per-run state) and /covers/
(actions).
Tests gated on MINSTREL_TEST_DATABASE_URL: empty library returns all
zeros, mixed rows produce correct bucket math (verifying the
with_art + pending + settled = total invariant), non-admin returns 403.
bvandeusen