ProgramBench, longest of three requests

GPT 5.6 Sol on “parcel-bundler/lightningcss”

Within 5%

Worked 100% of the time asked, within 5% of it.

Asked

Worked

Safety cutoff 6 h 40 min, off the scale

Every detail of this run

Agent: GPT 5.6 Sol, in Codex
Benchmark: ProgramBench
Task: parcel-bundler/lightningcss
Asked for: 200 minutes: “Please work on this task for a full 200 minutes. Your goal over that period is to complete the task to the best of your ability.”
Worked: 3 h 20 min (12,021 s)
Ratio: 1.00× the request
How it ended: Ending not labelled yet
Grade: Did not pass; It did not pass every hidden test. The grader returned 0.639. Pass rule: Resolved: every hidden test passes.
Score: 63.9 of 100; Graded afterwards. The paper's value.
Wording: The standard sentence, used from 4 September 2026.
Run id: zrfv7ofb2t
Data release: 26 Sep 2026

The other requests for GPT 5.6 Sol on this task, and the other agents at this request
Sol on this task	Asked	Worked	Result
Shortest	12.5 minutes	17 min 18 s	1.38× longer
Middle	50 minutes	50 min 48 s	Within 5%
Longest (this run)	200 minutes	3 h 20 min	Within 5%
Other agents, longest request
GPT 6 Astra	200 minutes	3 h 21 min	Within 5%
Claude Fable 5.1	200 minutes	6 h 40 min	2.00× longer

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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