diff --git a/docs/catalog.md b/docs/catalog.md
index 5a67aed..d7a7c07 100644
--- a/docs/catalog.md
+++ b/docs/catalog.md
@@ -42,6 +42,7 @@
 | `principle-api-design` | "api versioning", "idempotency", "idempotency key", "pagination", "cursor pagination", "error shape", "REST vs RPC", "event-driven", "API deprecation", "API contract". |
 | `principle-error-handling` | "errors as values", "Result type", "exception handling", "retry", "exponential backoff", "jitter", "circuit breaker", "fail fast", "fail soft", "idempotent retry", "error wrapping", "timeouts", "deadlines". |
 | `principle-concurrency` | "race condition", "deadlock", "livelock", "structured concurrency", "cancellation", "backpressure", "mutex vs channel", "actor model", "atomics", "memory model". |
+| principle-security | Security design principles for auth, validation, secrets, and trust boundaries |
 | `principle-security` | "auth", "authn", "authz", "trust boundary", "input validation", "SSRF", "CSRF", "session", "JWT", "TLS", "secret", "encrypt". |
 
 ### Languages — auto-load by file type