A support agent went wrong, and the team could not reconstruct the prompt weeks later

larabyeol · reddit · 2026-07-24

A team lost the ability to reconstruct why a support agent gave a wrong answer weeks later.

They had the customer screenshot, timestamp, and output log.
They did not have the exact prompt version that produced it.
The system prompt had been edited in config files by two people, buried inside unrelated commits.
A model version bump happened around the same time, making attribution even harder.

The takeaway: production agent systems need prompt versioning, model pinning, and change tracking that makes incident forensics possible.

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