diff --git a/docs/how/architecture-plan.txt b/docs/how/architecture-plan.txt
index 3e3d3dd..de596c1 100644
--- a/docs/how/architecture-plan.txt
+++ b/docs/how/architecture-plan.txt
@@ -332,6 +332,11 @@ things the ecosystem learned the hard way:
   direct command execution is simple but it doesn't compose with timing-based
   combat, NPC AI, or periodic world events. the tick loop is fundamental.
 
+  note: when combat/NPC AI gets added to the game loop, add tick health
+  monitoring — log warnings when tick processing exceeds TICK_INTERVAL. the
+  skeleton loop handles overruns correctly (skips sleep, catches up) but
+  sustained overruns mean the tick rate is too ambitious for the workload.
+
 "we should have designed entities for composition"
   inheritance hierarchies (Item > Weapon > Sword > MagicSword) get brittle.
   composition (entity with damage_component + magic_component) stays flexible.