refreshStartupPathCacheDirectory(dir_path)
By default, Houdini caches search paths during startup to accelerate the startup process by reducing filesystem activity, however it makes Houdini’s view of the filesystem effectively static during this time. If the filesystem is modified during startup, you should pass the directory to this method after you have finished your modifications so that the changes will
>>> hou.refreshStartupPathCacheDirectory('/the/path/to/a/directory')