Originally published on hexisteme notes.
On 2026-07-13 I was orchestrating two AI subagents in parallel from a main Claude Code session, on a side project — a food-discovery iOS app. Worker A (Sonnet) had the easy job: restyle 7 SwiftUI files to match an updated look. Worker B (Opus) had the harder one: build a FastAPI+Postgres cache relay from scratch. Routine delegation, nothing exotic. I already had a standing rule for this kind of work — verify the output surface yourself instead of trusting the agent's account of it — built up from running cross-vendor CLI workers, where it's intuitive that a different vendor's model might not report honestly.
This is the write-up of the day that rule saved me, and the day I found out it wasn't strict enough.
Worker A says done
Worker A reported back first: "7 files changed," with a clean per-file summary of what got restyled. It read fine. Nothing about it looked like a hallucination on a skim.
