Pattern: A Model Behavior Regression Can Kill an Agent Framework Outright — Gas Town Burned Down
Simon Willison·high signal
Steve Yegge's postmortem, surfaced Aug 4, says his Go-based multi-agent orchestrator Gas Town — which ran 20–30 parallel Claude Code instances — "fell apart at the seams with Opus 4.7. Up through 4.6 it was working brilliantly." The cause was a behavioral tic, "just two more things," that stopped Opus from ever converging: it always wanted to fiddle with Gas Town itself rather than do real work. No capability benchmark would have flagged this; convergence-to-done is a property harnesses depend on and nobody measures.