Backend of #197 Bundle A (auth posture). Owner decisions: single API key;
Api:RequireKeyForReads defaults true (whole /api surface gated; /iptv streaming
+ guide unaffected — outside the filter's /api scope).
- #280 S1: writes are fail-closed. New IApiKeyProvider resolves the key once
(Api:WriteKey config, else persisted /config/api.key, else a generated 256-bit
key written 0600). The empty-key open branch is gone; there is no open mode.
- #282 S3/S5: reads under /api require the key when Api:RequireKeyForReads (default
true) or the endpoint carries the new [RequiresApiKey]. Applied [RequiresApiKey]
to Troubleshoot/Logs/Settings/Maintenance so the sensitive tier stays gated even
if reads are opened. OPTIONS preflight is exempt.
- #281 S2: delete SortController (dead Blazor SortableJS residue; SPA uses PUT
/api/collections/{id}/custom-order) and AccountController (dead OIDC logout) —
both non-/api persistent surfaces that bypassed the key.
- #284 S6: replace CORS AllowAll with an opt-in exact-origin allowlist
(Api:CorsAllowedOrigins; permits X-Api-Key/If-Match, exposes ETag). Default is
no cross-origin (SPA is same-origin).
- #285 S7/S10: gc GET->POST (spec regenerated); ForwardedHeaders trust configurable
via ForwardedHeaders:KnownProxies/KnownNetworks (warns when unrestricted);
ScannerController gains [LocalhostOnly] (scanner always calls back over localhost).
Filter unit tests rewritten for fail-closed + read-gating + tier + OPTIONS;
ApiControllerSecurityTests assert the sensitive tier + scanner-loopback reflectively.
search/all-items paging deferred (SPA add-all coupling) — exposure closed by read-gating.
Refs #197#280#281#282#284#285
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>