feat: enforce activity site capacity

tests/action_system_boundaries_test.gd

@@ -6,6 +6,7 @@ class FakeActiveWorld:
 
 	var resource_candidates: Array[Dictionary] = []
 	var activity_position := Vector3(4.0, 0.0, 7.0)
+	var activity_candidates: Array[Dictionary] = []
 
 	func get_resource_candidates(_action_id: StringName) -> Array[Dictionary]:
 		return resource_candidates
@@ -13,6 +14,9 @@ class FakeActiveWorld:
 	func get_activity_target(_action_id: StringName, _origin: Vector3 = Vector3.ZERO) -> Dictionary:
 		return {"target_id": "", "position": activity_position}
 
+	func get_activity_candidates(_action_id: StringName) -> Array[Dictionary]:
+		return activity_candidates
+
 
 var failures: Array[String] = []
 var travel_requests: Array[Vector3] = []
@@ -135,14 +139,22 @@ func _test_target_resolution_and_travel_are_separate() -> void:
 	)
 
 	manager.release_npc_reservation(npc.id)
+	adapter.activity_candidates = [
+		{"target_id": "study_desk_full", "position": Vector3(1.0, 0.0, 0.0), "capacity": 1},
+		{"target_id": "study_desk_open", "position": Vector3(4.0, 0.0, 7.0), "capacity": 1}
+	]
+	var occupying_npc: SimNPC = manager.npcs[1]
+	occupying_npc.set_task(SimulationIds.ACTION_STUDY)
+	occupying_npc.target_id = &"study_desk_full"
+	occupying_npc.task_state = SimNPC.TASK_STATE_WORKING
 	npc.set_task(SimulationIds.ACTION_STUDY)
 	_check(
 		manager.resolve_npc_target(npc.id, Vector3.ZERO),
 		"Target resolver should resolve an activity through the adapter"
 	)
 	_check(
-		travel_requests.back() == adapter.activity_position,
-		"Activity resolution should publish the adapter's position"
+		npc.target_id == &"study_desk_open" and travel_requests.back() == adapter.activity_position,
+		"Activity resolution should skip a full-capacity site and publish the open site's position"
 	)
 	manager.free()
 	adapter.free()