Unrolling the Codex agent loop

Practical AI: Tools, Models & Frameworksapi

What changed

A technical deep dive into the Codex agent loop, explaining how Codex CLI orchestrates models, tools, prompts, and performance using the Responses API.

Why it matters

A concrete addition to Practical AI: Tools, Models & Frameworks: it changes what's available to builders today rather than being general commentary.

How it compares

Related prior coverage to compare against:

  • Introducing Codex
  • Introducing GPT-5.3-Codex
  • Speeding up agentic workflows with WebSockets in the Responses API

Sources