read_only
Make a property read only:
extends Node3D
@export_custom(PROPERTY_HINT_NONE, "read_only")
var read_only: int = 0
@export
var not_read_only: int = 0
It is enable_if / disable_if with no condition to evaluate, and takes no arguments – anything written after the key is ignored.
Note
A read-only property is greyed out and refuses input in the inspector. Nothing stops the value from being written from code, and validators still run on it.