Terminal-Bench 4.0, middle of three requests

Claude Fable 5.1 on “Remove latency across a multi-route Next.js warehouse app”

Shorter

2.21× shorter

Stopped at 45% of the time asked, 16 min 25 s short.

Asked

Worked

Safety cutoff 4 h 10 min, off the scale

Every detail of this run

Agent: Claude Fable 5.1, in Claude Code
Benchmark: Terminal-Bench 4.0
Task: Remove latency across a multi-route Next.js warehouse app
Asked for: 30 minutes: “Please work on this task for a full 30 minutes. Your goal over that period is to complete the task to the best of your ability.”
Worked: 13 min 35 s (815 s)
Ratio: 0.45× the request
How it ended: Ending not labelled yet
Grade: Passed; It passed the task's tests. The grader returned 1. Pass rule: The task's tests pass.
Score: 100 of 100; Graded during the run. The paper's value.
Wording: The standard sentence, used from 4 September 2026.
Run id: ptjumwg2pf
Data release: 26 Sep 2026

The other requests for Claude Fable 5.1 on this task, and the other agents at this request
Fable on this task	Asked	Worked	Result
Shortest	8 minutes	14 min 17 s	1.79× longer
Middle (this run)	30 minutes	13 min 35 s	2.21× shorter
Longest	125 minutes	44 min 5 s	2.84× shorter
Other agents, middle request
GPT 6 Astra	30 minutes	30 min 55 s	Within 5%
GPT 5.6 Sol	30 minutes	30 min 36 s	Within 5%

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Data and citation