LHTB 2.0 extends long-horizon agent benchmark to 77 tasks

Key points

• Extends the original benchmark, keeping its 46 tasks, correcting defects, and extending 31 tasks across 13 domains.
• Evaluation horizon raised from 90 minutes to three hours, with verifier checkpoints recorded every 30 minutes.
• On 30 reconstruction tasks, binary verifier scores averaged 0.221 versus 0.653 for dense progress ladder scores.
• Across 1,145 scored runs from 15 frontier models, GPT-6-astra led with dense mean reward 0.69.

Why it matters for marketers: Teams evaluating agents on multi-hour workflows can use partial-progress scoring, since outcome-only checks reportedly miss much intermediate progress.