DeepSWE v1.1, middle of three requests

Claude Fable 5.1 on “Add duration-aware sharding to Vitest”

Within 5%

Worked 101% of the time asked, within 5% of it.

Asked

Worked

Safety cutoff 2 h 40 min, off the scale

Every detail of this run

Agent: Claude Fable 5.1, in Claude Code
Benchmark: DeepSWE v1.1
Task: Add duration-aware sharding to Vitest
Asked for: 20 minutes: “Please work on this task for a full 20 minutes. Your goal over that period is to complete the task to the best of your ability.”
Worked: 20 min 7 s (1,207 s)
Ratio: 1.01× the request
How it ended: Ending not labelled yet
Grade: Passed; It passed its hidden tests. The grader returned 1. Pass rule: The hidden 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: xyghek3gcd
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	5 minutes	16 min 14 s	3.25× longer
Middle (this run)	20 minutes	20 min 7 s	Within 5%
Longest	80 minutes	27 min 50 s	2.87× shorter
Other agents, middle request
GPT 6 Astra	20 minutes	20 min 38 s	Within 5%
GPT 5.6 Sol	20 minutes	20 min 40 s	Within 5%

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