diff --git a/docs/ARCHITECTURE.md b/docs/ARCHITECTURE.md
index 20af1a90..de071a43 100644
--- a/docs/ARCHITECTURE.md
+++ b/docs/ARCHITECTURE.md
@@ -63,7 +63,7 @@ Members of the cross-cutting layer have no entity of their own, no user-facing C
 | `audit` | Append-only event store (`audit_log`) for all domain mutations. Feeds the activity feed and Family Pulse dashboard. | Consumed by 5+ domains; no user-facing CRUD of its own |
 | `config` | Infrastructure bean definitions: `MinioConfig`, `AsyncConfig`, `WebConfig` | Framework infra; no business logic |
 | `dashboard` | Stats aggregation for the admin dashboard and Family Pulse widget | Aggregates from 3+ domains; no owned entities |
-| `exception` | `DomainException`, `ErrorCode` enum, `GlobalExceptionHandler` | Framework infra; consumed by every controller and service. Adding a new `ErrorCode` requires matching updates in `frontend/src/lib/shared/errors.ts` and all three `messages/*.json` locale files. |
+| `exception` | `DomainException`, `ErrorCode` enum, `GlobalExceptionHandler` | Framework infra; consumed by every controller and service. Adding a new `ErrorCode` requires matching updates in `frontend/src/lib/shared/errors.ts` and all three `messages/*.json` locale files. Current security-related codes: `CSRF_TOKEN_MISSING` (403 on mutating request without valid `X-XSRF-TOKEN` header), `TOO_MANY_LOGIN_ATTEMPTS` (429 when login rate limit exceeded). |
 | `filestorage` | `FileService` — MinIO/S3 upload, download, presigned-URL generation | Generic service; consumed by `document` and `ocr` |
 | `importing` | `MassImportService` — async ODS/Excel batch import | Orchestrates across `person`, `tag`, `document` |
 | `security` | `SecurityConfig`, `Permission` enum, `@RequirePermission` annotation, `PermissionAspect` (AOP) | Framework infra; enforced globally across all controllers |
@@ -117,7 +117,7 @@ Controllers never call repositories directly. Services never reach into another
 ### Permission system
 Permissions are enforced via `@RequirePermission(Permission.X)` on controller methods, checked at runtime by `PermissionAspect` (Spring AOP). The `Permission` enum defines the available capabilities (`READ_ALL`, `WRITE_ALL`, `ADMIN`, `ADMIN_USER`, `ADMIN_TAG`, `ADMIN_PERMISSION`, `ANNOTATE_ALL`, `BLOG_WRITE`). This is not Spring Security's `@PreAuthorize` — do not mix the two mechanisms.
 
-Sessions use a Base64-encoded Basic Auth token stored in an `httpOnly`, `SameSite=strict` cookie (`auth_token`, maxAge=86400 s). CSRF protection is disabled because this cookie configuration structurally prevents cross-origin credential theft. See [docs/security-guide.md](security-guide.md) for the full security reference.
+Sessions use a Spring Session JDBC-backed cookie (`fa_session`, `httpOnly`, `SameSite=strict`, maxAge=86400 s). CSRF protection uses the double-submit cookie pattern: Spring Security sets an `XSRF-TOKEN` cookie (readable by JS); SvelteKit's `handleFetch` injects the value as `X-XSRF-TOKEN` on every mutating request; a missing or mismatched token returns `403 CSRF_TOKEN_MISSING`. See [ADR-022](adr/022-csrf-session-revocation-rate-limiting.md) and [docs/security-guide.md](security-guide.md) for the full security reference.
 
 ---