NS-23: Fix nav movement (sync bake, map guard, path/fallback steering)

client/README.md

@@ -14,7 +14,7 @@ Do not grow an all-in-one **`main.gd`**. The main scene root should **compose**
 With the game server running ([`server/README.md`](../server/README.md)), each valid floor click sends a **`MoveCommand`** (**`POST`**) and a follow-up **`GET`** for **`PositionState`**. The server still **snaps** authority to the target (NS-16/19); the client **walks** along a **baked navigation mesh** (`NavigationRegion3D` + **`NavigationAgent3D`** on the player) toward that verified position instead of teleporting on the **`GET`** (NS-23). **Boot** `sync_from_server()` **snaps** once so spawn matches the server.
 
 - **Scripts:** `scripts/ground_pick.gd` (walkable pick + `target_chosen`), `scripts/position_authority_client.gd` (`PositionAuthorityClient`: POST move, GET verify; second signal arg = boot snap vs nav goal), `scripts/player.gd` (path-follow), thin `scripts/main.gd` (nav bake on first frame, then wiring).
-- **Scene:** `scenes/main.tscn` — walkable **`StaticBody3D`** geometry lives under **`World/NavigationRegion3D`** so **`bake_navigation_mesh()`** (called from `main.gd` after one **`process_frame`**) picks up floor, NS-19 props, and the **`Obstacle`** cube. After moving floor or obstacles, open the scene in the editor and **Bake NavigationMesh** on the region if you need to refresh cached mesh data.
+- **Scene:** `scenes/main.tscn` — walkable **`StaticBody3D`** geometry lives under **`World/NavigationRegion3D`**. `main.gd` calls **`bake_navigation_mesh(false)`** (main-thread bake) after one **`process_frame`**, then waits two **`physics_frame`**s so **`NavigationServer3D`** has a map before agents query paths. After moving floor or obstacles, re-bake in the editor if needed.
 - **Inspector:** select **`PositionAuthorityClient`** on the main scene to set **`base_url`** (default `http://127.0.0.1:5253`) and **`dev_player_id`** (default `dev-local-1`, must match server `Game:DevPlayerId`).
 
 ### Manual check (NS-16 + NS-23)

client/scripts/main.gd

@@ -20,7 +20,11 @@ var _move_reject_msg_token: int = 0
 
 func _ready() -> void:
 	await get_tree().process_frame
-	_nav_region.bake_navigation_mesh()
+	# Default `bake_navigation_mesh()` bakes on a background thread; sync bake ensures the map
+	# exists before any `NavigationAgent3D` queries (see Godot navigation_using_navigationagents).
+	_nav_region.bake_navigation_mesh(false)
+	await get_tree().physics_frame
+	await get_tree().physics_frame
 	_ground_pick.set("fallback_camera", _camera)
 	_ground_pick.connect("target_chosen", Callable(self, "_on_target_chosen"))
 	_authority.connect(

client/scripts/player.gd

@@ -4,43 +4,64 @@ extends CharacterBody3D
 ## `MoveCommand` (NS-16, NS-19); boot snap vs post-verify nav goal from `main.gd`.
 
 const MOVE_SPEED: float = 5.0
+## If the nav mesh is missing or the agent gives up, steer on XZ toward `target_position`.
+const FALLBACK_ARRIVE_EPS: float = 0.4
 
 @onready var _nav_agent: NavigationAgent3D = $NavigationAgent3D
 
 
 func _ready() -> void:
-	_nav_agent.target_position = global_position
+	_nav_agent.set_target_position(global_position)
 
 
 ## After successful move POST + GET: walk to server target without teleporting.
 func set_authoritative_nav_goal(world_pos: Vector3) -> void:
-	_nav_agent.target_position = world_pos
+	_nav_agent.set_target_position(world_pos)
 
 
 ## NS-19 rejection or cancel pending path without moving the body.
 func clear_nav_goal() -> void:
 	velocity = Vector3.ZERO
-	_nav_agent.target_position = global_position
+	_nav_agent.set_target_position(global_position)
 
 
 ## Boot (and any hard reconcile): teleport to server position and reset agent.
 func snap_to_server(world_pos: Vector3) -> void:
 	global_position = world_pos
 	velocity = Vector3.ZERO
-	_nav_agent.target_position = world_pos
+	_nav_agent.set_target_position(world_pos)
 
 
 func _physics_process(_delta: float) -> void:
-	if _nav_agent.is_navigation_finished():
+	var nav_map: RID = _nav_agent.get_navigation_map()
+	if NavigationServer3D.map_get_iteration_id(nav_map) == 0:
 		velocity = Vector3.ZERO
 		move_and_slide()
 		return
+	if _nav_agent.is_navigation_finished():
+		var target: Vector3 = _nav_agent.target_position
+		var flat_target := Vector3(target.x, global_position.y, target.z)
+		var to_target: Vector3 = flat_target - global_position
+		to_target.y = 0.0
+		if to_target.length_squared() > FALLBACK_ARRIVE_EPS * FALLBACK_ARRIVE_EPS:
+			velocity = to_target.normalized() * MOVE_SPEED
+			velocity.y = 0.0
+		else:
+			velocity = Vector3.ZERO
+		move_and_slide()
+		return
 
 	var next_path_position: Vector3 = _nav_agent.get_next_path_position()
 	var to_next: Vector3 = next_path_position - global_position
 	to_next.y = 0.0
 	if to_next.length_squared() < 0.0001:
-		velocity = Vector3.ZERO
+		var to_final: Vector3 = _nav_agent.target_position - global_position
+		to_final.y = 0.0
+		if to_final.length_squared() > 0.0001:
+			velocity = to_final.normalized() * MOVE_SPEED
+			velocity.y = 0.0
+		else:
+			velocity = Vector3.ZERO
 	else:
 		velocity = to_next.normalized() * MOVE_SPEED
 		velocity.y = 0.0