ThreadKeeper is an Autodesk® Fusion 360™ add-in that restores custom thread definitions every time they are removed (i.e. when Fusion 360 is updated).
Thread definitions to restore are put in the Threads directory of ThreadKeeper.
Every time Fusion 360 starts, ThreadKeeper checks if thread definition files are missing. In that case, the files are restored.
This add-in is free, but if you like it, you can buy me a coffee (Ko-fi link).