OpenAI Blog · Feb 4, 2026
Unlocking the Codex harness: how we built the App Server
Reviewed by Errol Vogt, Site support technician & online learning analyst · original summary · editorial policy
Unlocking the Codex harness: how we built the App Server. Learn how to embed the Codex agent using the Codex App Server, a bidirectional JSON-RPC API powering streaming progress, tool use, approvals, and diffs. This update is relevant for small-office operators tracking changes in their tools.
Operator takeaway: For operators: review whether 'Unlocking the Codex harness: how we built the App Server' affects your current setup before relying on it in production.