A script to update user emails was approved, deployed, and broke login in production.
The root cause was clear within an hour. What nobody could answer was: why was the original email logic built that way? The engineer who made that call had moved on. The constraints they were protecting against existed nowhere except in their memory.
This is decision archaeology — the work of reconstructing why something was built, after the people who knew are gone. Not a documentation failure. A reasoning capture failure.
This post covers: what decision archaeology is, why ADRs don't fully solve it, what a decision-focused KBA looks like in practice, and a companion Colab notebook that demos the concept end-to-end.
👉Full post: https://sriharshacr.github.io/blogs/decision-archaeology-kba/
