I use OS for watering indoors (similar to a greenhouse) were watering duration is used to more mimic rain cycle (rainy season/dry season) rather than counteract rain as you do outdoors. It would be nice to be able to schedule a daily % cycle duration for the year to recreate this cycle. How this would be done I am not sure. Maybe pull percentage data from a calendar or spreadsheet that the user creates but I don’t have any idea if that would be feasible.
Also, I’ve read in multiple post were people were looking to have certain days not watering because of water restrictions. If you set the watering percentage to 0% for those days it would stop watering. This maybe another application.
If you want watering percentage to be adjusted on a day to day basis, I don’t think it’s feasible to implement this in the firmware because it would require storing a full calendar and it would complicate the UI design. However, the easiest solution is to use an external script and OpenSprinkler HTTP API to send the daily percentage value to OS that way. The API document is here: https://openthings.freshdesk.com/support/solutions/articles/5000716363
to send watering percentage / level, you can use the /co (change options command) and the parameter is wl (water level), like this: http://your_os_ip/co?pw=md5_hash_of_your_password&wl=value_you_want
Most scripting languages support sending HTTP command. Similarly a lot of custom features can be implemented by using an external script and leveraging the HTTP API, instead of requiring these features to be implemented in the firmware.