Built by two people who had the problem.

Between us we spent years running operations where the whole week fell over if the roster was wrong. Someone under 18 rostered past curfew. A closer back on at open with eight hours between. A section left uncovered on the busiest night because a swap never made it off a group chat.

The tools we tried treated a roster as a grid to be filled in. It is not. It is a set of rules — who is qualified, who is available, who is legally allowed to work that shift — and a grid that does not know the rules just moves the thinking back onto you at 9pm on a Sunday.

So Rosie is built the other way round. You tell it the rules once; it builds the week and shows its working, shift by shift. You still make the calls. You just stop doing the arithmetic.