2026-07-30 · CI-CD

Postmortem: hunting a flaky E2E test in CI

The test failed one run in twenty; here is the race, the fix, and the policy that followed.

Introduction

Documents how we isolated timing issues in a Playwright suite and the retry rules we decided to stop using.

What usually goes wrong

Teams that skip this step tend to share three failure modes:

  • Optimizing a number nobody agreed to move.
  • Copying a setup from a project with different constraints.
  • Deferring the decision until it is expensive to reverse.

How to approach it

  1. State the problem in one sentence, in the words your users would use.
  2. Pick a signal you can measure weekly, not just at launch.
  3. Timebox a small trial; a two-day spike beats a two-week debate.

Wrap-up

If CI-CD taught us anything, it is that boring consistency beats clever one-offs. Bring the lessons back to your team before they fossilize into folklore.