OpenAI Opens the Codex Harness as the Agents API
Image: openai.com
OpenAI introduced the Agents API in public beta on 10 September 2026. The announcement frames it as the harness OpenAI built for Codex and ChatGPT for Work, made available to developers directly.
OpenAI's stated reasoning is that a useful long-running agent needs two things it is awkward to assemble yourself: a harness that manages context, uses tools efficiently and coordinates subagents; and infrastructure that keeps the agent running reliably for days, with an environment where it can work with files, run code and save intermediate results.
The page names OpenAI-hosted sandboxes as one environment option, with a choice of environment left to the developer, and describes support for long sessions, parallel work through subagents, and an evolving Codex harness. It also refers to an open-source foundation.
Pricing is not stated on the announcement.
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