Sakana ALE-Bench, longest of three requests

Claude Fable 5.1 on “AtCoder Heuristic Contest 9”

Shorter

1.82× shorter

Stopped at 55% of the time asked, 1 h 8 min short.

Asked

Worked

Safety cutoff 5 h, off the scale

Every detail of this run

Agent: Claude Fable 5.1, in Claude Code
Benchmark: Sakana ALE-Bench
Task: AtCoder Heuristic Contest 9
Asked for: 150 minutes: “Please work on this task for a full 150 minutes. Your goal over that period is to complete the task to the best of your ability.”
Worked: 1 h 22 min (4,940 s)
Ratio: 0.55× the request
How it ended: Ended on its own
Grade: 7,780,162,558; Raw score on the private test cases, in each problem's own units; also reports rank against human contest entrants. No official pass rule.
Score: Performance 3482; Graded during the run. The paper's value.
Wording: The standard sentence, used from 4 September 2026.
Run id: n6wqhzxvo4
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	10 minutes	5 min 16 s	1.90× shorter
Middle	40 minutes	26 min 39 s	1.50× shorter
Longest (this run)	150 minutes	1 h 22 min	1.82× shorter
Other agents, longest request
GPT 6 Astra	150 minutes	2 h 31 min	Within 5%
GPT 5.6 Sol	150 minutes	2 h 32 min	Within 5%

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Data and citation