Real bugs, real fixes, real production receipts — as simulations you operate instead of prose you skim. Flip the gates, run the races, see exactly what changed. Every sim below shipped as a PR.
Adding a client used to email them instantly — twice, sometimes. Four gates and an atomic queue claim later, play both bugs and both fixes.
A daily cron suspended entire businesses because THEIR customers paid an invoice 5 days late — one missing SQL filter in a multi-tenant table. Run the cron yourself.
Payroll computed PAYE three different ways: an invented flat ladder, last year's SARS tables mislabelled as this year's, and the real thing. Drag a salary and watch the same employee owe three different amounts.
Paste a GitHub pull-request URL. An agent reads the diff, works out the behaviour change, and builds a playable sim on this site. Operator key required for now — this spends real model tokens.