Playwright

Most of the time, proving a flow works means walking it once, now. That needs no install and no files — drive the app with the browser control you already have and report what you saw.

Save a test only for a flow worth running again. In a two-week sprint that's a very short list.

Walk it first

Default behaviour, every time: start the app, click through the flow as a person would, report what happened at each step, and say plainly whether it worked.

This covers almost everything: a new form, a sign-up, a page that should show the thing that was just created. No spec file, no runner, no browsers downloaded. If the builder asks for "a test" and this answers their actual question, do this and tell them what you did instead.

When to save a test

Write a saved spec only when a flow is worth re-running for the rest of the sprint:

• The core action. The one thing their product does. If this breaks, they have nothing to demo.
• The money path, if one exists — checkout, upgrade, anything that charges.
• Anything that already broke once. Same rule as keep-it-working: it broke, so it can break again.