The archive
Comic cover for issue 012: Works On My Machine
Issue #012
Developer Diaries 5 min read· 14 Feb 2026

Works On My Machine

The four most expensive words in software. What environment drift really costs — and the surprisingly boring fix.

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The strip
Panel 1 · The bug report
Cannot reproduce locally.
Panel 2 · Three days later
It's a Node minor version. Of course it is.
Panel 3 · The fix
One pinned version file. Six hours of work. Never again.

Environment drift never announces itself. It shows up as a bug that only one person can reproduce, a test that fails only in CI, or a deploy that works everywhere except production.

This one cost three engineer-days across two weeks before someone diffed the Node minor versions between a laptop and the CI runner. The behaviour difference was in a date parsing edge case at month boundaries.

Boring infrastructure is the cheapest thing you'll ever buy — and it never feels urgent until it's too late.

The fix was unglamorous: pin runtimes, lock dependencies, make the container the only supported way to run the app locally, and make it fast enough that people actually use it.

If your laptop and CI disagree, one of them is lying to you daily.

Boring infrastructure is the cheapest thing you will ever buy. It just never feels urgent until the week it's already cost you three days.

CTO takeaway

The lesson, minus the scar tissue.

  • Pin every runtime version explicitly and check the file into the repo.
  • Local dev must run the same image as CI, and it must be fast enough to prefer.
  • Track 'cannot reproduce' bugs as an environment metric, not a developer failing.
Comments

War Stories.

Survived something similar? Add it to the record — the best lessons in this archive came from other people's outages.

  • Priya · CTO, logistics startup

    We had the exact same Friday. Except ours was a DNS TTL of 86400 and we spent the weekend explaining caching to the board.

  • Marcus · Founder

    Read this on a Monday morning and immediately cancelled a rewrite. Three seams, not a clean slate. Thank you.

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