Agents API

OpenAI put the Codex harness behind an API. The Agents API, in public beta from September 10, 2026, runs cloud agents on the same harness and infrastructure that power Codex while OpenAI manages session orchestration, context compaction, and failure recovery: durable sessions carry work across turns, custom tools and MCP servers plug in, and the agent's compute can sit in an OpenAI-managed sandbox, on the developer's own infrastructure, or with a sandbox partner. There are no fees beyond the tokens and tools an agent consumes. It is the clearest case yet of a frontier lab selling the execution layer, not only the model, and the counterpart to open harnesses such as DeepSeek Harness. Filed from press coverage; OpenAI's own post is blocked to crawlers.