Denny,
Just a thought, but I wonder if you could use the patch program to add your mods to ospi.py and .js files.
https://en.wikipedia.org/wiki/Patch_%28Unix%29
Samer has used it to insert some bug fixes into ospi.py. I think that by using the -u switch you could add your changes to an updated program file and it might even be a way to distribute custom additions to the program.
I am looking into adding the rain sensor logic.
Also, regarding your suggestion for having the rain sensor control individual zones, that could be done by adding something like a “Sense Rain” column to the stations page next to the “Activate Master” check boxes. That looks doable.
Dan