Epoch Brief: AI Work Automation Test, SpireClimb Benchmark, and Gemini 4 Argon's Frontier Push

Epoch AI tested six leading models on 11 realistic Epoch work tasks and found none could reliably meet its quality bar, with Claude Fable 5.1 and GPT-6 Astra roughly tied for the lead. Its new SpireClimb benchmark shows frontier models went from struggling at Slay the Spire to winning over 90% of base-difficulty runs in six months, with GPT-6 Astra at 98%. Gemini 4 Argon scored 166 on the Epoch Capabilities Index, tying Claude Fable 5.1 and trailing Claude Opus 5.5 and GPT-6 Astra at 169.