PostTrainBench v1.1, middle of three requests

Claude Fable 5.1 on “Post-train Qwen3-1.7B-Base for HumanEval”

Shorter

1.21× shorter

Stopped at 82% of the time asked, 1 h 25 min short.

Asked

Worked

Safety cutoff 60 h, off the scale

Asked for: 8 hours
Worked: 6 h 35 min
Grade: Grading…; The run's output is saved, but grading it needs GPU time for the benchmark's judge or evaluation, which has not run yet.
How it ended: Ended on its own

Every detail of this run

Agent: Claude Fable 5.1, in Claude Code
Benchmark: PostTrainBench v1.1
Task: Post-train Qwen3-1.7B-Base for HumanEval
Asked for: 8 hours: “Please work on this task for a full 8 hours. Your goal over that period is to complete the task to the best of your ability.”
Worked: 6 h 35 min (23,724 s)
Ratio: 0.82× the request
How it ended: Ended on its own
Grade: Grading…; The run's output is saved, but grading it needs GPU time for the benchmark's judge or evaluation, which has not run yet.
Wording: The standard sentence, used from 4 September 2026.
Run id: gsfzy3ure2
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	2 hours	5 min 4 s	23.72× shorter
Middle (this run)	8 hours	6 h 35 min	1.21× shorter
Longest	30 hours	no run
Other agents, middle request
GPT 6 Astra	8 hours	8 h 1 min	Within 5%
GPT 5.6 Sol	8 hours	8 h 1 min	Within 5%

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