feat: add validated quicksave persistence

simulation/persistence/SaveSlotController.gd

@@ -0,0 +1,21 @@
+extends Node
+
+@export var simulation_manager: Node
+
+var store := SaveSlotStore.new()
+
+func _unhandled_key_input(event: InputEvent) -> void:
+	if not event.pressed or event.echo:
+		return
+	if event.keycode == KEY_F5:
+		if store.save(simulation_manager):
+			print("[SaveSlot] Quicksave written")
+		else:
+			push_error("[SaveSlot] " + store.last_error)
+		get_viewport().set_input_as_handled()
+	elif event.keycode == KEY_F9:
+		if store.load_into(simulation_manager):
+			print("[SaveSlot] Quicksave restored")
+		else:
+			push_error("[SaveSlot] " + store.last_error)
+		get_viewport().set_input_as_handled()

simulation/persistence/SaveSlotController.gd.uid

@@ -0,0 +1 @@
+uid://cwvdljsh148wh

simulation/persistence/SaveSlotStore.gd

@@ -0,0 +1,131 @@
+class_name SaveSlotStore
+extends RefCounted
+
+const DEFAULT_DIRECTORY := "user://saves"
+const DEFAULT_SLOT := "quicksave"
+const MAX_SAVE_BYTES := 16 * 1024 * 1024
+
+var save_directory: String
+var last_error := ""
+
+func _init(directory: String = DEFAULT_DIRECTORY) -> void:
+	save_directory = directory
+
+func save(manager: Node, slot_name: String = DEFAULT_SLOT) -> bool:
+	last_error = ""
+	if manager == null or not manager.has_method("serialize_state"):
+		return _fail("Save source cannot serialize simulation state")
+	if not _is_valid_slot_name(slot_name):
+		return _fail("Invalid save slot name")
+
+	var json_text: String = manager.serialize_state()
+	if json_text.to_utf8_buffer().size() > MAX_SAVE_BYTES:
+		return _fail("Save exceeds the supported size limit")
+	if SimulationStateRecord.from_json(json_text) == null:
+		return _fail("Simulation produced an invalid save record")
+	if not _ensure_directory():
+		return false
+
+	var final_path := get_slot_path(slot_name)
+	var temporary_path := final_path + ".tmp"
+	var backup_path := final_path + ".bak"
+	_remove_if_present(temporary_path)
+
+	var file := FileAccess.open(temporary_path, FileAccess.WRITE)
+	if file == null:
+		return _fail("Could not open temporary save file")
+	file.store_string(json_text)
+	file.flush()
+	file.close()
+	if _read_record(temporary_path) == null:
+		_remove_if_present(temporary_path)
+		return _fail("Temporary save failed validation")
+
+	var had_existing := FileAccess.file_exists(final_path)
+	if had_existing:
+		_remove_if_present(backup_path)
+		if DirAccess.rename_absolute(final_path, backup_path) != OK:
+			_remove_if_present(temporary_path)
+			return _fail("Could not preserve the previous save")
+	if DirAccess.rename_absolute(temporary_path, final_path) != OK:
+		if had_existing:
+			DirAccess.rename_absolute(backup_path, final_path)
+		_remove_if_present(temporary_path)
+		return _fail("Could not install the new save")
+	_remove_if_present(backup_path)
+	return true
+
+func load_into(manager: Node, slot_name: String = DEFAULT_SLOT) -> bool:
+	last_error = ""
+	if manager == null or not manager.has_method("restore_state"):
+		return _fail("Save target cannot restore simulation state")
+	if not _is_valid_slot_name(slot_name):
+		return _fail("Invalid save slot name")
+
+	var final_path := get_slot_path(slot_name)
+	var record := _read_record(final_path)
+	if record == null:
+		record = _read_record(final_path + ".bak")
+	if record == null:
+		return _fail("Save slot is missing, invalid, or unsupported")
+	if not bool(manager.restore_state(record)):
+		return _fail("Simulation refused the validated save record")
+	return true
+
+func has_slot(slot_name: String = DEFAULT_SLOT) -> bool:
+	if not _is_valid_slot_name(slot_name):
+		return false
+	var final_path := get_slot_path(slot_name)
+	return (
+		_read_record(final_path) != null
+		or _read_record(final_path + ".bak") != null
+	)
+
+func delete_slot(slot_name: String = DEFAULT_SLOT) -> bool:
+	if not _is_valid_slot_name(slot_name):
+		return false
+	var final_path := get_slot_path(slot_name)
+	_remove_if_present(final_path)
+	_remove_if_present(final_path + ".tmp")
+	_remove_if_present(final_path + ".bak")
+	return true
+
+func get_slot_path(slot_name: String = DEFAULT_SLOT) -> String:
+	return save_directory.path_join(slot_name + ".json")
+
+func _read_record(path: String) -> SimulationStateRecord:
+	if not FileAccess.file_exists(path):
+		return null
+	var file := FileAccess.open(path, FileAccess.READ)
+	if file == null:
+		return null
+	if file.get_length() > MAX_SAVE_BYTES:
+		file.close()
+		return null
+	var json_text := file.get_as_text()
+	file.close()
+	return SimulationStateRecord.from_json(json_text)
+
+func _ensure_directory() -> bool:
+	var absolute_directory := ProjectSettings.globalize_path(save_directory)
+	var error := DirAccess.make_dir_recursive_absolute(absolute_directory)
+	if error != OK and error != ERR_ALREADY_EXISTS:
+		return _fail("Could not create the save directory")
+	return true
+
+func _is_valid_slot_name(slot_name: String) -> bool:
+	if slot_name.is_empty() or slot_name.length() > 32:
+		return false
+	var allowed := "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_-"
+	for character in slot_name:
+		if not allowed.contains(character):
+			return false
+	return true
+
+func _remove_if_present(path: String) -> void:
+	if FileAccess.file_exists(path):
+		DirAccess.remove_absolute(path)
+
+func _fail(message: String) -> bool:
+	last_error = message
+	return false

simulation/persistence/SaveSlotStore.gd.uid

@@ -0,0 +1 @@
+uid://3w3wsbtr4gpw