DeepSWE v1.1, longest of three requests

Claude Fable 5.1 on “Add duration-aware sharding to Vitest”

Shorter

2.87× shorter

Stopped at 35% of the time asked, 52 min 10 s short.

Asked

Worked

Safety cutoff 2 h 40 min, off the scale

Every detail of this run

Agent: Claude Fable 5.1, in Claude Code
Benchmark: DeepSWE v1.1
Task: Add duration-aware sharding to Vitest
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: 27 min 50 s (1,670 s)
Ratio: 0.35× the request
How it ended: Ended on its own
Grade: Passed; It passed its hidden tests. The grader returned 1. Pass rule: The hidden 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: zxg7ryfttb
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	5 minutes	16 min 14 s	3.25× longer
Middle	20 minutes	20 min 7 s	Within 5%
Longest (this run)	80 minutes	27 min 50 s	2.87× shorter
Other agents, longest request
GPT 6 Astra	80 minutes	1 h 21 min	Within 5%
GPT 5.6 Sol	80 minutes	1 h 21 min	Within 5%

See it on the chart. Transcripts are not published yet.

Data and citation