AIOpus 5.5 reportedly leads BuildingBench, with GPT-6 Astra 2.5 points behind
EnactraAI reports a sizable cost gap: GPT-6 Astra (ultra) costs $7.05 per building versus about $45.47 for Opus 5.5 (max), with scores of 84.3 and 86.8, respectively.
TLDR
EnactraAI reports a new BuildingBench high of 86.8 for Opus 5.5 (max), compared with Opus 5’s 74.5. GPT-6 Astra (ultra) scores 84.3, followed by Fable 5.1 (max) at 81.4. EnactraAI puts Astra’s cost per building at 84% below Opus 5.5’s, for a 2.5-point score gap.
The update shows a different trade-off for GPT-6 Sol: 69.8 at about $1.92 per building on ultra, and 69.6 at about $1.89 on max. Both score below GPT-5.6 Sol’s 73.9, but EnactraAI says they cost roughly 75% less than its $7.54 per building.