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Codex Internals: Deep Dive Series

A step-by-step architectural analysis of the Codex AI coding agent.

Quick Navigation

  1. Getting Started — Project structure and basic data flow.
  2. UI Events and Terminal Interaction — Handling input and streaming feedback.
  3. Operation Processing — The Op protocol and internal dispatching.
  4. Tasks and Turns: The Daemon Model — From user input to Task/Turn abstractions.
  5. LLM Boundary and Stream Processing — Dual-track (Data/Control) stream architecture.
  6. Codex Tools and Toolcalls — Tool routing, execution, and loop continuation.
  7. API Subset and Architectural Trade-offs — Design philosophy and state management.

This series is intended for engineers who want to understand the building blocks of modern AI coding agents.