Terminal-Bench 4.0, middle of three requests

Claude Fable 5.1 on “Make a Kafka payments worker recover quickly without losing notifications”

Shorter

3.10× shorter

Stopped at 32% of the time asked, 54 min 12 s short.

Asked

Worked

Safety cutoff 10 h, off the scale

Every detail of this run

Agent: Claude Fable 5.1, in Claude Code
Benchmark: Terminal-Bench 4.0
Task: Make a Kafka payments worker recover quickly without losing notifications
Asked for: 80 minutes: “Please work on this task for a full 80 minutes. Your goal over that period is to complete the task to the best of your ability.”
Worked: 25 min 48 s (1,548 s)
Ratio: 0.32× the request
How it ended: Ended on its own
Grade: Passed; It passed the task's tests. The grader returned 1. Pass rule: The task's 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: cnokcgxirw
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	20 minutes	10 h	30.00× longer
Middle (this run)	80 minutes	25 min 48 s	3.10× shorter
Longest	300 minutes	1 h 6 min	4.57× shorter
Other agents, middle request
GPT 6 Astra	80 minutes	1 h 21 min	Within 5%
GPT 5.6 Sol	80 minutes	1 h 21 min	Within 5%

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