Playwright specs that exercise the whole product the way a user does: frontend, backend, and Postgres together, no mocks. The suite locks in the flows that must never silently break: registration and login (including the anti-enumeration behavior on failures), session persistence across reloads, logout teardown, habit CRUD, routine check-ins with their XP and streak effects, goal completion asymmetry, the gamification feedback, the full onboarding tutorial, and the study notebook: the UI path from a new topic to a finished node, plus ownership, paying once, the SSRF refusal, review XP and the AI screens with only the model routes stubbed, plus the study cycle's credit walk, laps and ownership on the wire and a cycle built and used through the UI.
Against an isolated stack: the backend boots with the e2e profile on the dedicated beyou_e2e database, and a safety check refuses to start against anything that does not look like a test database. Fixtures provide authenticated pages with the tutorial bypassed or intact, and seeding helpers build categories and full onboarding states through the real API.
The suite is also a merge gate: the frontend repository's CI boots this stack and runs these specs on every pull request, with a sibling-branch resolver so a frontend change that needs new specs can point at a matching branch here before anything merges.
The security topic documents the auth behaviors these specs pin, and the Beyou Dev Env project covers the isolated e2e overlay they run on.