Just a few suggestions for additions, although they might be for a setup a little larger than a window ledge.
Control over reservoir water level, automatic top up and redundant overflow indicators (we don't want a flood)
If using a hydroponic system then control over nutrients, pH and water temperature become important. That will require:
- One bottle plus stepper motor controlled pump (found in old inkjet printers) for acid buffer solution
- One bottle plus stepper motor controlled pump for base buffer solution
- Two bottles plus stepper motor controlled pumps for two part nutrient solution.
- one TDS probe to measure nutrient concentration
- one pH probe to measure current pH
- one aquarium heater for reservoir water temperature control
Control over lights is a good idea. I addition to their timing they need to be kept as close as possible to the plants without burning them as they grow. Some method of automatically raising the lights would be necessary.
If you wanted to go crazy you could add monitoring and control for the humidity (misting), temperature (fans/venting) and CO2 levels as well.
Finally if you upgrade to the newer foneras with usb you could add a web cam although they have some problems with grow lights.