AI Implementation feature(891): Admin Area General Settings and Categories 1.09 (#31)

docs/api/admin.md

@@ -2,8 +2,8 @@
 type: api
 title: Admin Endpoints
 description: Admin-only endpoints for user management, required general settings, categories, and supporting uploads.
-tags: [api, admin, users, general, categories]
-timestamp: 2026-07-22T14:24:08Z
+tags: [api, admin, users, general, categories, default-challenge-ip, ip-hostname, validation]
+timestamp: 2026-07-22T15:46:18Z
 ---
 
 # Endpoints
@@ -53,7 +53,12 @@ removes the row.
   `superRefine` additionally requires `eventEndUtc > eventStartUtc` and
   reports `eventEndUtc must be strictly after eventStartUtc` on the end
   field when both values parse but are out of order.
-* `defaultChallengeIp` 1–255 chars
+* `defaultChallengeIp` is trimmed server-side; empty/whitespace-only values
+  are rejected (`defaultChallengeIp is required and cannot contain only
+  whitespace`), and the trimmed value must be a complete IPv4 address or a
+  valid hostname, otherwise `400 VALIDATION_FAILED` with a per-field
+  `defaultChallengeIp` issue (`defaultChallengeIp must be a valid IPv4
+  address or hostname`). Maximum length is 255 characters.
 * `registrationsEnabled` boolean
 
 On success the handler persists every field via `SettingsService`,