Implement release-critical contract, security, accessibility, browser, and fault suites

[alexeygrigorev]

Parent epic: #11

Normative spec: 10 — Release-critical scenarios

Scope

Assemble automated suites for full legacy URL/SEO, content sync safety, Course/Cohort migration/isolation/scoring/peer/certificate/API compatibility, event/registration/email concurrency/faults, Studio/API role/capability/idempotency/concurrency, security/privacy, WCAG automation, infrastructure policy/deploy/backup/rollback, and cross-provider fault degradation. Schedule slower full crawl/accessibility/dependency/restore/deployed smoke jobs and publish actionable artifacts.

Non-goals

No verbal waiver for failed gates, blanket “flaky/pre-existing” dismissal, or tests that mutate shared environments/send uncontrolled email.

Acceptance criteria

• Every release-critical bullet in spec 10 maps to a named automated or explicit manual test and owning issue.
• URL/SEO/content/course/event/email/admin/security/privacy/operations negative/fault scenarios run with deterministic evidence.
• Browser suite covers critical desktop/mobile paths, captures and programmatically/human-inspects screenshots, and records counts.
• Manual keyboard/screen-reader/zoom/contrast/reduced-motion/provider/DNS criteria are tracked with human, owner, and evidence.
• Scheduled slow suites and CI fail loudly with full failure enumeration/artifacts; regression attribution process is documented.
• No release-critical failure is accepted without explicit owner/risk/expiry exception.

Test scenarios

1. Deliberately break one invariant in each category and prove correct CI gate/report failure.
2. Run parallel core browser and scheduled full suite; verify artifacts/screenshots/counts/redaction.
3. Simulate external failures, restore/rollback, and privacy tombstone replay.

Playwright

Execute all spec critical paths at desktop/mobile: main/articles/podcast/people/docs/FAQ/Podwiki/course registration/account/enrollment/homework/project/peer/score/certificate/event register-cancel and Studio domain operations, including denial/error/stale/bulk/export/token states.

Dependencies

Depends on #63–#65 and #75 plus the corresponding domain/infra implementation. Blocks #73/#74.