The Winchester Mystery House is an apt analogy for what happens when coding agents make it trivially cheap to add features: software accumulates endlessly without coherent design, and decision-making becomes harder as complexity grows.

Claire Giordano's analogy — a house with 140 rooms built endlessly by a widow haunted by ghosts — captures how cheap agent-generated features lead to bloated, incoherent software where conceptual integrity breaks down. ✦ AI generated

Simon Willison · Simon Willison's Weblog · 2026-08-19 · original ↗

It's got 140 rooms, because the woman who built it was the widow of the guy who invented the Winchester rifle, and her psychic told her she'd be haunted by the ghosts of everyone killed with that rifle unless she kept building the house forever. So for 40 years she kept adding new rooms. That's exactly the problem with coding agents and software: it's very easy to keep adding new rooms, because the cost of adding those rooms is so much cheaper. What you end up with is something where the conceptual integrity falls apart — and then it's harder to make decisions about it.

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