A four-model Claude ensemble scored 78% on Terminal-Bench 2.1, at double the cost of first place

The run placed seventh with a bill of $1,178, roughly twice what the top entry spent. The division of labor: Fable 5 plans and delegates, Haiku 4.5 scouts, Opus 5 edits code, Sonnet 5 verifies the work.

Three security tasks went unsolved because the executor refused to run them: zero out of 14 delegated attempts. In a control run without delegation, Opus 5 solved the same tasks six times out of six. Credit those three and the ensemble lands at 80.5% and third place.

Verification did most of the heavy lifting. Tasks that went through the verifier passed 91% of the time, versus 43% without the check. Opus 5 in the executor role accounted for 58% of total spend, or $689.

First place on the board still belongs to Claude Code with Fable 5 at 83.8%.