E2E suites that don't rust

Test suites do not die from bugs — they die from maintenance. Whoever does not maintain them has manual regression again in six months.

Three patterns

• Selector isolation: a data-testid convention instead of CSS-path surgery.
• Flaky quarantine: unstable tests get marked and fixed within one sprint, never ignored.
• Journeys, not assertions: one test covers one user journey, not 40 details.

That keeps the suite green in CI — and regression automated.