Architect finds Claude Opus 5.5 can draft permit-quality house plans

Architect Stephen Gallagher tested 13 AI models on drawing a full construction set for a simple house from his rough sketches plus a reference set he drew years ago. Only Claude Opus 5.5 (released 22 September) produced a set he judged good enough to get a building permit, after his written comments and two rounds of redlines; it wrote more than 15,000 lines of Python to produce vector drawings, took twelve hours and cost a few hundred dollars in compute. He notes it still missed a second means of egress that Massachusetts code requires, and that this was one simple building with uneven amounts of human feedback per model, so it is one expert's test, not a benchmark. On Hacker News (11 top-level comments when we read it) two practitioners, an engineer who has Opus 5.5 drive AutoCAD and a former concrete detailer, reported good results of their own, while others asked for proper benchmarks, stressed that an experienced reviewer is still essential, or worried about inspections; no consensus. Sorted take: what worked here is a senior person redlining an AI junior, a pattern that applies well beyond architecture.