Paste a writing sample — an essay, a README, work emails, anything you actually wrote. The math and its assumptions are shown with the result; see the disclaimer for exactly what this can and can't tell you. (Connecting real data sources — repos, email — is coming; that needs proper sign-in consent, not shortcuts.)
The ladder: pass each level (70%) to unlock the next. Three misses locks a level behind the study guide — studying earns your attempts back. Supporters skip the study gate.