You sit down Friday with one messy GitHub issue. You want a usable plan before Monday morning. You paste the text into a chat agent.
The reply looks polished, complete, and very sure. It adds Kafka, Redis, and a new auth service. The issue never named those systems.
You do not have a brownfield budget this weekend. You also do not want fake architecture. You need a gate that blocks invented specs.
The failure you are fixing
Agents fill gaps with confident guesses. That habit wrecks small side projects. You ship a plan that your repo cannot support.
