WIP checkpoint: Implement chunk streaming system in GDScript

scenes/main.tscn

@@ -0,0 +1,6 @@
+[gd_scene load_steps=2 format=3 uid="uid://main_scene"]
+
+[ext_resource type="Script" path="res://scripts/chunk_stream_manager.gd" id="1_chunk_stream"]
+
+[node name="Main" type="Node3D"]
+script = ExtResource("1_chunk_stream")

scripts/chunk_stream_manager.gd

@@ -77,18 +77,32 @@ var _server_rpc: Object = null
 ## Internal: track which chunks are currently being loaded (to avoid duplicates).
 var _loading_in_progress: Dictionary = {}
 
+## Internal: time accumulator for throttled streaming updates.
+var _update_accumulator: float = 0.0
+
+## Internal: interval between streaming updates (seconds).
+const UPDATE_INTERVAL: float = 0.1
+
 
 func _ready() -> void:
-	_process_thread = Thread.create(_streaming_loop, Thread.PRIORITY_LOW)
+	# Streaming is driven from _process (main thread) so we can safely
+	# manipulate the scene tree. No background thread is used.
+	set_process(true)
 
 
-func _streaming_loop() -> void:
-	while is_inside_tree():
+func _process(delta: float) -> void:
+	if not is_active or player == null:
+		return
+
+	_update_accumulator += delta
+	if _update_accumulator < UPDATE_INTERVAL:
+		return
+	_update_accumulator = 0.0
+
 	_update_streaming()
 	_process_load_queue()
 	_process_unload_queue()
 	streaming_updated.emit()
-		await get_tree().create_timer(0.1).timeout  # Check every 100ms
 
 
 func _update_streaming() -> void:
@@ -132,7 +146,7 @@ func _compute_target_chunks() -> Dictionary:
 	var half := streaming_radius
 	for dx in range(-half, half + 1):
 		for dy in range(-half, half + 1):
-			for dz in range(-Chunk.CHUNK_SIZE_Z, Chunk.CHUNK_SIZE_Z + 1):
+			for dz in range(-half, half + 1):
 				var coord := Vector3i(
 					_player_chunk_coord.x + dx,
 					_player_chunk_coord.y + dy,