From some posts there are apparently some versions of hardware that sense and display zone current. I have a OSPI without it but wanted to look at how this is implemented in other models. I have burned out several zones due to failed zone valve solenoids (and I have to admit 1 due to my mistake).
OpenSprinkler 3.0 has current sensing; OpenSprinkler Pi does not. The current sensing circuit itself does not prevent damage due to shorting because the sensing resistor can be burned if there is a solenoid shorting. So having a fuse on board (which OSPi has) is a better option for short protection.