Terminal-Bench 4.0, longest of three requests

GPT 5.6 Sol on “Implement a synthesizable 8-bit retro console system-on-chip”

Within 5%

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

Asked

Worked

Safety cutoff 8 h 20 min, off the scale

Every detail of this run

Agent: GPT 5.6 Sol, in Codex
Benchmark: Terminal-Bench 4.0
Task: Implement a synthesizable 8-bit retro console system-on-chip
Asked for: 250 minutes: “Please work on this task for a full 250 minutes. Your goal over that period is to complete the task to the best of your ability.”
Worked: 4 h 11 min (15,061 s)
Ratio: 1.00× the request
How it ended: Ending not labelled yet
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: 3sakwrbg2n
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	15 minutes	21 min 7 s	1.41× longer
Middle	60 minutes	1 h 1 min	Within 5%
Longest (this run)	250 minutes	4 h 11 min	Within 5%
Other agents, longest request
GPT 6 Astra	250 minutes	4 h 23 min	1.05× longer
Claude Fable 5.1	250 minutes	59 min 41 s	4.19× shorter

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Data and citation