↓Skip to main content
  1. Posts/

From Bug to Blog Post: A Complete Example

·285 words·2 mins
Writing Writing Debugging Workflow
Table of Contents

Many good engineering posts start from a real bug.

Instead of writing abstract advice, I prefer documenting one concrete incident from start to finish. This approach gives readers context, tradeoffs, and a fix they can apply.

1) Context #

The issue: a page occasionally rendered stale data after a deploy. It happened only in a specific sequence: user logs in, opens one tab, then refreshes another tab after a backend release.

The first mistake was assuming this was a backend consistency issue. Logs showed the API returning correct data, which shifted the investigation to client-side caching behavior.

2) Investigation #

I collected three traces:

  1. Network timeline in browser devtools
  2. Server response headers
  3. Client cache key generation

The useful signal was this: two requests with different user states were sharing the same cache key. That key ignored a field that changed after login.

3) Root Cause #

The cache key builder did not include sessionVersion, so data fetched before login could still satisfy requests after login.

The bug was subtle because it only appeared when timing and tab order aligned.

4) Fix #

I made three changes:

  1. Included sessionVersion in cache key derivation
  2. Added a cache invalidation call on auth state transitions
  3. Wrote an integration test for the login + multi-tab scenario

5) Postmortem Notes #

What mattered most was improving detection, not only fixing behavior.

I added structured logs for cache key composition and a dashboard panel for stale-response incidents. Future regressions should now be obvious in minutes, not days.

6) Reusable Writing Template #

If you want to convert your own bug into a post, use this order:

  1. Symptom and user impact
  2. Evidence collected
  3. Root cause
  4. Patch details
  5. Safeguards and tests

This keeps the post practical and avoids storytelling fluff.