Unlocking the Codex harness: how we built the App Server | OpenAI
OpenAI’s coding agent Codex exists across many different surfaces: the web app (opens in a new window) , the CLI (opens in a new window) , the IDE extension (opens in a new window) , and the new Codex macOS app. Under the hood, they’re all powered by the same Codex harness—the agent loop and logic that underlies all Codex experiences. The critical link between them? The Codex App Server (opens in a new window) , a client-friendly, bidirectional JSON-RPC1 API. In this post, we’ll introduce the Codex App Server; we’ll share our learnings so far on the best ways to bring Codex’s capabilities into your product to help your users supercharge their workflows. We’ll cover the App Server’s architecture and protocol and how it integrates with different Codex surfaces, as well as tips on leveraging Codex, whether you want to turn Codex into a code reviewer, an SRE agent, or a coding assistant. Before diving into architecture, it’s helpful to know the App Server’s backstory. Initially, the Ap
OpenAI’s coding agent Codex exists across many different surfaces: the web app (opens in a new window) , the CLI (opens in a new window) , the IDE extension (opens in a new window) , and the new Codex macOS app. Under the hood, they’re all powered by the same Codex harness—the agent loop and logic that underlies all Codex experiences. The critical link between them? The Codex App Server (opens in a new window) , a client-friendly, bidirectional JSON-RPC1 API. In this post, we’ll introduce the Codex App Server; we’ll share our learnings so far on the best ways to bring Codex’s capabilities
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