feat: add navigation_failed signal with time-based stuck detection and simulation pipeline

NpcVisual:
- Add navigation_failed(sim_id) signal distinct from arrived_at_target
  so the simulation layer can distinguish genuine arrival from failure
- Replace integer stuck_counter with delta-based stuck_time and
  exported stuck_timeout (1.5s) for frame-rate-independent detection
- Add path_request_id / path_pending mechanism to reject stale
  async path results when a new target is set or NPC dies
- On empty path or stuck movement, emit navigation_failed instead
  of arriving; only emit arrived_at_target when truly close to target
- Reduce arrival_distance back to 0.6 now that navigation_failure
  is properly signalled (no longer needed as a workaround)
- clamp arrival_distance reference in apply_dead_visual_state

SimNPC:
- Remove retry_count (replaced by navigation_failed signal pathway)
- Move last_task assignment from set_task() to task completion in
  SimulationManager so it reflects the task that actually finished

SimulationManager:
- Add notify_npc_navigation_failed(): release reservation, record
  last_task, send NPC to wander for 2s, emit task_changed signal
- Add notify_npc_target_unavailable() as public alias of above
- Guard extraction with node.reserved_by == npc.id to prevent
  stale/illegitimate extraction when reservation is lost
- Guard fallback zone task completion (apply_npc_task) so it only
  fires for non-resource tasks (gather_food/wood with no target
  silently skip instead of applying zone values)
- Remove retry_count safety net (fully replaced by signal pipeline)

WorldViewManager:
- Connect navigation_failed signal in spawn_npc_visual()
- Skip target assignment for empty/idle/dead task states
- When no resource node available for gather_food/wood, call
  notify_npc_target_unavailable() so NPC wanders instead of idling
- Add _on_npc_visual_navigation_failed handler delegating to
  SimulationManager.notify_npc_navigation_failed()
- Remove retry_count references

player/npc/NpcVisual.gd

@@ -1,12 +1,14 @@
 extends CharacterBody3D
 
 signal arrived_at_target(sim_id: int)
+signal navigation_failed(sim_id: int)
 
 const DEBUG_LOGS := true
 
 @export var move_speed := 3.0
 @export var rotation_speed := 8.0
 @export var waypoint_reached_distance := 0.35
+@export var stuck_timeout := 1.5
 
 @onready var nav_agent: NavigationAgent3D = $NavigationAgent3D
 
@@ -18,8 +20,10 @@ var profession: String = ""
 var current_path: PackedVector3Array = []
 var path_index := 0
 var current_target := Vector3.INF
-var arrival_distance := 1.5
-var stuck_counter := 0
+var arrival_distance := 0.6
+var stuck_time := 0.0
+var path_request_id := 0
+var path_pending := false
 
 var is_dead_visual := false
 var dead_material := StandardMaterial3D.new()
@@ -38,8 +42,12 @@ func setup_from_sim(npc: SimNPC) -> void:
 	name = "NPC_%s_%s" % [sim_id, npc_name]
 
 func set_target_position(pos: Vector3) -> void:
+	path_request_id += 1
+	var request_id := path_request_id
 	current_target = pos
 	has_reported_arrival = false
+	stuck_time = 0.0
+	path_pending = false
 
 	if global_position.distance_to(pos) <= arrival_distance:
 		current_path = PackedVector3Array()
@@ -48,9 +56,13 @@ func set_target_position(pos: Vector3) -> void:
 		return
 
 	nav_agent.target_position = pos
+	path_pending = true
 
 	await get_tree().physics_frame
 
+	if request_id != path_request_id or is_dead_visual:
+		return
+
 	current_path = NavigationServer3D.map_get_path(
 		get_world_3d().navigation_map,
 		global_position,
@@ -58,11 +70,12 @@ func set_target_position(pos: Vector3) -> void:
 		true
 	)
 
+	path_pending = false
 	path_index = 0
 
 	if current_path.is_empty():
-		debug_log("Path is empty, stuck counter will handle fallback.")
-		nav_agent.target_position = global_position
+		debug_log("Path is empty")
+		_report_navigation_failure_once()
 	else:
 		debug_log("New target: %s Path points: %s" % [pos, current_path.size()])
 
@@ -77,6 +90,11 @@ func _physics_process(delta: float) -> void:
 		move_and_slide()
 		return
 
+	if path_pending:
+		velocity = Vector3.ZERO
+		move_and_slide()
+		return
+
 	if global_position.distance_to(current_target) <= arrival_distance:
 		_report_arrival_once()
 		velocity = Vector3.ZERO
@@ -86,10 +104,7 @@ func _physics_process(delta: float) -> void:
 	if current_path.is_empty() or path_index >= current_path.size():
 		velocity = Vector3.ZERO
 		move_and_slide()
-		stuck_counter += 1
-		if stuck_counter > 90:
-			debug_log("Stuck with no valid path, reporting arrival")
-			_report_arrival_once()
+		_report_navigation_failure_once()
 		return
 
 	var next_pos := current_path[path_index]
@@ -109,14 +124,15 @@ func _physics_process(delta: float) -> void:
 
 	move_and_slide()
 
-	if global_position.distance_squared_to(prev_pos) < 0.001:
-		stuck_counter += 1
-		if stuck_counter > 90:
-			debug_log("Stuck while navigating, reporting arrival")
-			_report_arrival_once()
+	var minimum_progress := move_speed * delta * 0.1
+	if global_position.distance_squared_to(prev_pos) < minimum_progress * minimum_progress:
+		stuck_time += delta
+		if stuck_time >= stuck_timeout:
+			debug_log("Movement remained blocked")
+			_report_navigation_failure_once()
 			return
 	else:
-		stuck_counter = 0
+		stuck_time = 0.0
 
 	var target_angle := atan2(direction.x, direction.z)
 	rotation.y = lerp_angle(rotation.y, target_angle, rotation_speed * delta)
@@ -132,12 +148,28 @@ func _report_arrival_once() -> void:
 	debug_log("Arrived at target")
 	arrived_at_target.emit(sim_id)
 
+func _report_navigation_failure_once() -> void:
+	if has_reported_arrival:
+		return
+
+	has_reported_arrival = true
+	current_path = PackedVector3Array()
+	path_index = 0
+	current_target = Vector3.INF
+	path_pending = false
+	velocity = Vector3.ZERO
+
+	debug_log("Navigation failed")
+	navigation_failed.emit(sim_id)
+
 func apply_dead_visual_state() -> void:
 	is_dead_visual = true
+	path_request_id += 1
 	velocity = Vector3.ZERO
 	current_path = PackedVector3Array()
 	path_index = 0
 	current_target = Vector3.INF
+	path_pending = false
 	has_reported_arrival = true
 
 	scale = Vector3(0.8, 0.25, 1.2)

simulation/SimNPC.gd

@@ -28,7 +28,6 @@ var task_duration := 0.0
 var task_progress := 0.0
 var task_complete := true
 var target_id: StringName = &""
-var retry_count := 0
 var last_task := ""
 
 func _init(
@@ -247,7 +246,6 @@ func calculate_task_score(
 	return score
 
 func set_task(task: String, duration: float) -> void:
-	last_task = current_task
 	current_task = task
 	task_duration = duration
 	task_progress = 0.0

simulation/SimulationManager.gd

@@ -87,21 +87,25 @@ func simulate_tick() -> void:
 
 			if npc.target_id != &"":
 				var node := ResourceNode.get_by_id(npc.target_id)
-				if node != null:
+				if node != null and node.reserved_by == npc.id:
 					var extracted := node.extract()
 					if extracted > 0:
 						village.apply_resource_delta(node.resource_id, extracted)
 						if DEBUG_LOGS:
 							print("[SimulationManager] ", npc.npc_name, " extracted ", extracted, " ", node.resource_id, " from ", node.node_id)
+				elif DEBUG_LOGS:
+					print("[SimulationManager] ", npc.npc_name, " could not complete ", completed_task, ": target reservation was invalid")
 				release_npc_reservation(npc.id)
-			else:
+			elif completed_task not in ["gather_food", "gather_wood"]:
 				village.apply_npc_task(npc)
+			elif DEBUG_LOGS:
+				print("[SimulationManager] ", npc.npc_name, " could not complete ", completed_task, ": no resource target")
 
 			village_was_changed = true
-			npc.retry_count = 0
 
 			npc.task_complete = true
 			npc.task_state = SimNPC.TASK_STATE_IDLE
+			npc.last_task = completed_task
 			npc.current_task = "idle"
 
 			if needs_immediate_food_after_gather and village.food > 0:
@@ -111,15 +115,6 @@ func simulate_tick() -> void:
 				if DEBUG_LOGS:
 					print("[SimulationManager] ", npc.npc_name, " gathered food while starving and is going to eat immediately.")
 
-		if npc.task_state == SimNPC.TASK_STATE_TRAVELING and npc.target_id == &"":
-			npc.retry_count += 1
-			if npc.retry_count >= 5:
-				if DEBUG_LOGS:
-					print("[SimulationManager] ", npc.npc_name, " stuck traveling without target for ", npc.retry_count, " attempts, replanning")
-				npc.task_state = SimNPC.TASK_STATE_IDLE
-				npc.current_task = ""
-				npc.retry_count = 0
-
 		if DEBUG_LOGS:
 			print(
 				npc.npc_name,
@@ -184,10 +179,7 @@ func notify_npc_arrived(npc_id: int) -> void:
 					if node == null or not node.can_extract():
 						if DEBUG_LOGS:
 							print("[SimulationManager] ", npc.npc_name, " arrived but target ", npc.target_id, " is unavailable, replanning")
-						release_npc_reservation(npc.id)
-						npc.task_state = SimNPC.TASK_STATE_IDLE
-						npc.current_task = ""
-						npc.retry_count += 1
+						notify_npc_navigation_failed(npc.id)
 						return
 
 				npc.start_working()
@@ -196,6 +188,26 @@ func notify_npc_arrived(npc_id: int) -> void:
 					print("[SimulationManager] ", npc.npc_name, " arrived and started working on: ", npc.current_task)
 			return
 
+func notify_npc_navigation_failed(npc_id: int) -> void:
+	for npc in npcs:
+		if npc.id != npc_id:
+			continue
+		if npc.is_dead or npc.task_state != SimNPC.TASK_STATE_TRAVELING:
+			return
+
+		var failed_task := npc.current_task
+		release_npc_reservation(npc.id)
+		npc.last_task = failed_task
+		npc.set_task("wander", 2.0)
+		npc_task_changed.emit(npc, failed_task, npc.current_task)
+
+		if DEBUG_LOGS:
+			print("[SimulationManager] ", npc.npc_name, " could not navigate for ", failed_task, " and is trying a wander target")
+		return
+
+func notify_npc_target_unavailable(npc_id: int) -> void:
+	notify_npc_navigation_failed(npc_id)
+
 func eat_food(amount: float) -> void:
 	village.food -= amount
 	village_changed.emit(village)

world/world_view_manager.gd

@@ -71,6 +71,11 @@ func spawn_npc_visual(npc: SimNPC) -> void:
 	else:
 		push_error("WorldViewManager: NPCVisual has no arrived_at_target signal")
 
+	if visual.has_signal("navigation_failed"):
+		visual.navigation_failed.connect(_on_npc_visual_navigation_failed)
+	else:
+		push_error("WorldViewManager: NPCVisual has no navigation_failed signal")
+
 	active_npc_visuals[npc.id] = visual
 	debug_log("Spawned visual for %s at %s" % [npc.npc_name, npc.position])
 
@@ -83,18 +88,23 @@ func update_npc_targets() -> void:
 			continue
 
 		var visual = active_npc_visuals[npc.id]
+		var task = npc.current_task
+		if task in ["", "idle", "dead"]:
+			continue
+
 		var resource_pos = _try_get_resource_target(npc, npc.current_task)
 		if resource_pos != null:
 			visual.set_target_position(resource_pos)
 			continue
 
-		var task = npc.current_task
 		if task == "wander":
 			var offset = Vector3(randf_range(-6.0, 6.0), 0.0, randf_range(-6.0, 6.0))
 			visual.set_target_position(visual.global_position + offset)
 			continue
 
 		if task in ["gather_food", "gather_wood"]:
+			if simulation_manager.has_method("notify_npc_target_unavailable"):
+				simulation_manager.notify_npc_target_unavailable(npc.id)
 			continue
 
 		var target = get_target_for_task(task)
@@ -137,7 +147,7 @@ func _try_get_resource_target(npc: SimNPC, task: String) -> Variant:
 
 	var node := ResourceNode.find_available(action_id, npc.id, visual.global_position)
 	if node == null:
-		debug_log("No available resource node for %s, using zone fallback" % task)
+		debug_log("No available resource node for %s" % task)
 		return null
 
 	if not node.reserve(npc.id):
@@ -145,7 +155,6 @@ func _try_get_resource_target(npc: SimNPC, task: String) -> Variant:
 		return null
 
 	npc.target_id = node.node_id
-	npc.retry_count = 0
 	debug_log("%s reserved %s for %s" % [npc.npc_name, node.node_id, task])
 	return node.interaction_point.global_position
 
@@ -155,6 +164,9 @@ func _on_npc_task_changed(npc: SimNPC, old_task: String, new_task: String) -> vo
 	
 	if not active_npc_visuals.has(npc.id):
 		return
+
+	if new_task in ["", "idle", "dead"]:
+		return
 	
 	var visual = active_npc_visuals[npc.id]
 	var resource_pos = _try_get_resource_target(npc, new_task)
@@ -168,6 +180,10 @@ func _on_npc_task_changed(npc: SimNPC, old_task: String, new_task: String) -> vo
 		return
 	
 	if new_task in ["gather_food", "gather_wood"]:
+		if simulation_manager.has_method("notify_npc_target_unavailable"):
+			simulation_manager.notify_npc_target_unavailable(npc.id)
+		else:
+			push_error("WorldViewManager: SimulationManager cannot handle unavailable targets")
 		return
 	
 	var target := get_target_for_task(new_task)
@@ -186,8 +202,19 @@ func _on_npc_visual_arrived(sim_id: int) -> void:
 		simulation_manager.notify_npc_arrived(sim_id)
 	else:
 		push_error("WorldViewManager: SimulationManager has no notify_npc_arrived method")
-		
-		
+
+func _on_npc_visual_navigation_failed(sim_id: int) -> void:
+	debug_log("NPC visual navigation failed. sim_id=%s" % sim_id)
+
+	if simulation_manager == null:
+		push_error("WorldViewManager: simulation_manager missing during navigation failure")
+		return
+
+	if simulation_manager.has_method("notify_npc_navigation_failed"):
+		simulation_manager.notify_npc_navigation_failed(sim_id)
+	else:
+		push_error("WorldViewManager: SimulationManager has no notify_npc_navigation_failed method")
+
 func _on_npc_died(npc: SimNPC) -> void:
 	if not active_npc_visuals.has(npc.id):
 		return