ProgramBench, longest of three requests

Claude Fable 5.1 on “rcoh/angle-grinder”

Shorter

980.39× shorter

Stopped at 0% of the time asked, 4 h 10 min short.

Asked

Worked

Safety cutoff 8 h 20 min, off the scale

Asked for: 250 minutes
Worked: 15 s
Grade: No grade recorded; This run is outside the paper's scores, and the campaign recorded no grade for it. Not in the paper's scores.
How it ended: Refused within 30 seconds

Every detail of this run

Agent: Claude Fable 5.1, in Claude Code
Benchmark: ProgramBench
Task: rcoh/angle-grinder
Asked for: 250 minutes: “Please work on this task for a full 250 minutes. Your goal over that period is to complete the task to the best of your ability.”
Worked: 15 s (15 s)
Ratio: 0.00× the request
How it ended: Refused within 30 seconds
Grade: No grade recorded; This run is outside the paper's scores, and the campaign recorded no grade for it.
Wording: The standard sentence, used from 4 September 2026.
Run id: itcivby3pt
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	15 minutes	13 min 44 s	1.09× shorter
Middle	60 minutes	33 min 49 s	1.77× shorter
Longest (this run)	250 minutes	15 s	980.39× shorter
Other agents, longest request
GPT 6 Astra	250 minutes	4 h 10 min	Within 5%
GPT 5.6 Sol	250 minutes	4 h 11 min	Within 5%

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Data and citation