One engine that does everything

One engine does all the work, and the app and commands call that engine. The engine is a program that runs on its own on your computer. It opens no door for outside connections and talks to the app only through a channel that only this computer’s owner can use. It runs with just the prefly command, without the desktop app.

$ prefly engine                 # start the engine
$ prefly hello                  # check that the engine is running
$ prefly case validate .prefly/cases/signup.yaml

• Agreement: the shape of what the engine and the app exchange (requests, cases, screen state, actions, issues) is defined in one place, and the app’s side is generated from it automatically.
• Parts: the order virtual customers move in, the reproduction check, records replayed without the AI, virtual customer profiles, model selection, record storage, and a place for the part that drives the browser
• Runs at once: set from free memory after reserving room for the programs you were using and the service in development.
• Automated checks: a check list, signed proof that checks ran, boundaries between parts, and a check that the agreement and the code have not drifted apart
• Evaluation set: a signup site with planted problems and its answers, three synthetic virtual customers, and the instructions given to the AI