Unreal Labs open-sourced Unreal Agent, a Go coding-agent harness that runs tool calls asynchronously and matched Codex on Terminal-Bench 4.0 for 39% less

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Unreal Agent (MIT, Go) records each tool call as 'in-progress' in the session log and lets the tool run in the background, so the model never spends tokens waiting on it or polling it. Unreal Labs reports the same 57.9% Terminal-Bench 4.0 pass rate as Codex at $1,428 instead of $2,350, and 65.8% on SWE-Atlas with GPT-6 Astra at $936 against Codex's $1,303. The repo appeared on 2026-09-21 and had 1,413 stars the next day, 193 HN points, and an integration request already filed on stablyai/orca. All benchmark numbers come from the vendor.