diff --git a/vigilar/constants.py b/vigilar/constants.py
index b877126..5869a7b 100644
--- a/vigilar/constants.py
+++ b/vigilar/constants.py
@@ -210,6 +210,8 @@ class Topics:
     SYSTEM_ALERT = "vigilar/system/alert"
     SYSTEM_SHUTDOWN = "vigilar/system/shutdown"
     SYSTEM_RULES_UPDATED = "vigilar/system/rules_updated"
+    # Web-to-FSM arm/disarm request (FSM verifies the PIN and transitions)
+    SYSTEM_ARM_REQUEST = "vigilar/system/arm_request"
 
     # Classified events forwarded to the web SSE bridge (see events.processor
     # and web.sse_bridge).