I’m not aware of Rhino having anything built-in to help with this.
I’m also not sure how much detail you are looking for, but the high-level options I’d investigate are:
If you want event driven updates, then I’d look at:
A more manual approach would be to use Python’s os.stat to compare modified times.
One could also just read the file and compare lines, but that could take a while for larger files.
Next you will need to update the mesh’s texture coordinates after reading them from the obj file:
I guess another approach would be to make a new mesh. Rhino has an obj reader:
Then the user could delete the old one or keep it for reference or something.