hospital-manager-tycoon
Cyclic roster for a team of nurse anaesthetists. A 1 to 12 week cycle, one line per person, every rule the head nurse gave, and everyone at exactly their due hours.
The thing
A head nurse I know had to produce a yearly roster for 20 people: 18 nurse anaesthetists, 2 nurses, full-timers and 80 % contracts. Weekend blocks, nights followed by two rest days, 44 h max over any 7 days, 12 h between two shifts, two rest days a week, and a 37.5 h average over the cycle. By hand it takes a month and is wrong somewhere.
The solver is CP-SAT (OR-Tools), in three phases: weekends, then exact hours, then the rest. The front draws the best roster found while it computes, with a stop button. PDF export, versions, a 15-day forecast repaired with the fewest changes.
Three days of work, 4 to 6 November 2026. The rules came in by voice message, photos of rosters and e-mails, in three batches that contradicted each other a little.
The confession
The code is written by Claude Code, driven by me. I could not rewrite the three-phase model. What I can do is tell when it is wrong: a checker independent of the solver re-runs every rule on every solution, and an audit writes, for each rule, the tightest case as a calculation you can redo by hand. Tests with apte↗, 100 % coverage on the pure modules, ty in strict mode.
What the solver settled
The team was going to vote between "one night then two rest days" and "two nights then two rest days", because the first option supposedly made the hours impossible. Computed: both work, with zero gap to due hours for all 20 people. The vote became a matter of preference.
A canon (each line is the one above shifted by a week) comes out in one second. It is only fair between full-timers and 80 % contracts if weekend nights are doubled, 36 h of doubling a week.
Status
Management made its own 9-week canon by hand, without looking at the PDFs. The app was never used. Private repo, because the docs hold the rules and quotes of a real team.