Gas Town Burned Down Because Opus 4.7 Wouldn't Stop Talking

Steve Yegge's Go-based orchestrator Gas Town ran 20 to 30 parallel Claude Code instances until Opus 4.7 broke it, per a postmortem Simon Willison surfaced on August 4.

Through version 4.6, Yegge says, it worked "brilliantly." Then Opus 4.7 stopped converging. It always found two more improvements to make, and because Gas Town was self-hosting, that meant fiddling with Gas Town itself instead of finishing the job. Yegge built the tool to be reusable. He only ever used it to build itself.

That's not a capability problem. Opus 5 shipped July 24 and landed near the top of the SWE benchmarks, second on Senior SWE-bench per Snorkel AI. It's a stopping problem, and nothing on a leaderboard measures it. SWE-bench checks whether a patch passes, not whether the agent knew when to quit.

The complaints followed the July 24 launch. An r/ClaudeAI thread titled "Opus 5 is just annoying to work with. Back to Opus 4.8 for me" pulled 338 upvotes. Dan Shipper called it "very hard to love," citing an agent that argues with instructions and stops before the work is done, per Implicator.ai. Scope expansion, overconfident certainty, delegation that drives up cost.

One counter-thread matters here: a smaller r/ClaudeAI post (64 upvotes) found switching to Ultracode mode fixed the same complaint, hours of work with no limits hit, though the poster's first unfamiliar run spawned roughly 40 simultaneous agents. Some of this is mode selection, not model quality.

Pin the version, test the stop

I build multi-agent systems for a living, and the failure I'm afraid of isn't a wrong answer. It's an agent that never returns. My fix: pin the model version in the harness config, not "latest," and build five tasks with a hard stop condition to run on every model bump. Convergence-to-done is the benchmark nobody's built, and until someone does, every multi-agent harness is betting its budget that the next bump won't need it.