Playwright/Cypress tests flaky due to timing and race conditions

E2E tests pass sometimes and fail other times. Elements not found, clicks not registering, assertions failing intermittently.

Never use fixed waits. Use built-in waiting: (1) Playwright: locator.click() auto-waits. Use expect(locator).toBeVisible() which retries. Use page.waitForResponse() for API calls. (2) Cypress: cy.get() auto-retries. Use cy.intercept() for network. (3) Wait for final state, not timer. (4) Wait for loading indicators to disappear. (5) Isolate tests: each test sets up its own data.

E2E tests run against real browsers where rendering and network are non-deterministic. Fixed waits either waste time or are too short. Retry-based assertions adapt to actual conditions.