Use Codex as a development environment, not another chat window
Follow one path from the CLI and agent loop through context, tool execution, AGENTS.md, and model selection.
GUIDE OUTCOME
The goal is to design a Codex workflow with explicit permissions, project rules, and verification rather than relying on the model alone.
- Published articles
- 05
LEARNING TRACK
Understand the agent
Start with how a coding agent differs from chat, then examine context and the agent loop.
- Generative AIWhat Is Codex CLI? How It Differs from Chat-Based AICodex CLI does more than answer coding questions. It can inspect project files, edit code, run commands, and verify the results. This beginner-friendly guide explains how a coding agent differs from conventional chat-based AI.
- AI AgentInside AI Coding Agents: Models, Context, Tools, and the Agent LoopAn AI coding agent does not generate a complete solution in one shot. It combines a model, context management, tools, an execution environment, and safety controls in a repeated cycle of deciding, acting, and observing. This article follows a practical API change to explain that architecture, its failure modes, and how to use coding agents safely and effectively.
- AI AgentInside the Codex Agent Loop: Separating Model Reasoning from Tool ExecutionThis article decomposes the mechanism that lets Codex CLI inspect, edit, test, and revise software into four responsibilities: model, harness, tools, and environment. It follows the tool-call boundary through execution feedback, permissions, MCP, termination, and context management.
LEARNING TRACK
Shape the project workflow
Treat AGENTS.md and model choice as parts of a repeatable engineering process.
- AI AgentWhat Is AGENTS.md? A Beginner’s Guide to Project Rules in Codex CLIA beginner-friendly guide to using `AGENTS.md` so Codex CLI can consistently follow project-specific instructions. Learn how it differs from a README and task prompt, where to place it, what to write, how to create it with `/init`, and how to verify that Codex loaded it.
- AI AgentHow to Use GPT-5.6 in Codex: Choosing Between Sol, Terra, and LunaLearn how to update Codex CLI for GPT-5.6, switch between Sol, Terra, and Luna, and configure reasoning effort independently. This guide also presents a reproducible comparison protocol covering quality, latency, usage, and human rework, followed by practical model-selection guidance for common engineering tasks.