OpenAI Turns Codex’s Agent Harness Into a Developer API
Long-running agents usually fail at the plumbing: context windows, retries, sandboxes, and handoffs. OpenAI’s Agents API now manages those layers through the Codex harness, including durable sessions, context compaction, subagent delegation, MCP connections, and environments that can run code and edit files. That shifts the work from building agent infrastructure to deciding what the agent should actually do.