I Read OpenAI Codex's Source and Built My Workflow Around It

I cloned the Codex repo and started reading. Not the README. Not the blog post. The actual Rust source under codex-rs/core/. After dissecting the architecture in my previous post, I wanted to answer a different question: how do you actually build a workflow around this thing? The answer turned out to be more interesting than I expected. Codex CLI is not just a coding assistant you run in the terminal. It is a platform with five distinct extension points, each designed to integrate into different parts of the development lifecycle. I spent a week wiring them together. This is what the setup looks like, how it works, and where it breaks. The Configuration Stack: AGENTS.md Meets config.toml Every AI coding tool needs a way to tell the agent what to do and what not to do. Codex CLI splits this into two files with very different purposes. AGENTS.md is the behavioral layer. It tells the agent how to write code, which patterns to follow, and what to avoid. The file loads hierarchically. The g