Sakana ALE-Bench, longest of three requests

Claude Fable 5.1 on “AtCoder Heuristic Contest 26”

Shorter

2.07× shorter

Stopped at 48% of the time asked, 1 h 17 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 26
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 13 min (4,356 s)
Ratio: 0.48× the request
How it ended: Ending not labelled yet
Grade: 1,413,652; 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 2891; Graded during the run. The paper's value.
Wording: The standard sentence, used from 4 September 2026.
Run id: i67xgfar76
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	7 min 46 s	1.29× shorter
Middle	40 minutes	28 min 25 s	1.41× shorter
Longest (this run)	150 minutes	1 h 13 min	2.07× shorter
Other agents, longest request
GPT 6 Astra	150 minutes	2 h 31 min	Within 5%
GPT 5.6 Sol	150 minutes	2 h 30 min	Within 5%

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Read before quoting. How this run ended has not been labelled yet. It is timed like every other run and counted in every number. Details

Data and citation