Requirements change after the first clean generate — that is not failure, that is the job. The reaction timer worked for a week and now the request lands: "can I pick the difficulty?" A knob. Design does not start over; it ITERATES: reopen the pin plan, spend three of the free GPIOs on a rotary_encoder, and let the arithmetic tell you what changed before the engine does.
The Studio is built for the loop. Save the working board under a name; change it; Save revision. The design keeps your recent history — up to twenty saves deep — so an experiment that goes wrong is a revision to step back from, not an evening lost. Name designs for what they are, not when you made them: "Reaction Timer" beats board_final_v2_ACTUAL.
And the output artifact: Download Gerbers hands you a zip of eleven files — copper layers, silkscreen, solder mask, solder paste, the board outline, a fabrication layer, and the drill file — the exact package a fabrication house manufactures from. It is a BUILD PRODUCT, like a compiled program: regenerate it from the spec any time, never edit it, and do not store it in version control. The spec is source; the Gerber is output. PS-3 opens that zip file by file.
potentiometer would spend an ADC pin the timer never needed, and analog pins are the scarcest thing on the board.Swap the buzzer for an RGB LED: predict the new counts from 13 components and 27 traces.
When do you Save revision versus Save as a new design?
Why do Gerbers stay out of git while specs go in?
The knob could have been a pot. Give one argument each way, then the deciding constraint here.