[grade=B] - New src/utilities/validate.js: validateBody(schema) middleware + 9 schemas (backupConfigUpdate, backupScheduleCreate, backupRestore, backupRestoreFile, appDeploy, appRestore, appRevert, assetUpload, logoUpload) - Uses Joi's authoritative CIDR validator (rejects malformed IPv6 like ::::/64 that the previous hex/colon regex would have accepted) - appDeploy.config uses .unknown(true) for forward-compat with template-specific fields (sslType, dnsType, plexClaimToken, etc.) — preserves fields the live frontend posts, prevents a behavioural regression - appRestore uses Joi.any().custom() so the empty-body semantics hold under middleware stripUnknown (default) — body with extra keys now rejected - Wired into 8 destructive routes: backups schedule/restore/config, apps deploy/restore/revert, assets upload/logo - Duplicate legacy POST /backups/schedule handler (line 519) marked LEGACY with TODO removal note (Express only matches first registration; this handler is unreachable under normal routing) - Removed redundant manual appId check in /backups/schedule (Joi schema enforces it) - Removed unused 'mime' destructure in /assets/favicon (decodeImageData validates MIME internally) - 41 unit tests covering every exported schema + middleware integration - 1539/1539 Jest tests pass, zero new ESLint warnings