Codex Knowledge Base
Contract-Driven API Development with Codex CLI: Using Specmatic MCP for Spec-First Full-Stack Builds
Most agentic coding workflows suffer from the same failure mode: the agent generates code that compiles, passes its own tests.
Codex CLI Hooks Graduate to Stable: MCP Observation, Inline Config, and Auto-Review in v0.124
With the release of Codex CLI v0.124.0 on 23 April 2026, hooks have officially graduated from experimental to stable.
Codex CLI Custom Model Providers: The Complete Configuration Guide
Codex CLI ships with three built-in providers, but the real power lies in its extensible provider framework. Point Codex at any Responses API endpoint with a custom config.toml block.
Agent Identity Key Rotation and Security Operations for Codex CLI
The v0.123 release of Codex CLI introduced AuthMode::AgentIdentity, giving each agent its own Ed25519 key pair and replacing forwarded bearer tokens with.
Prompt Injection Defence for Codex CLI: Attack Vectors, Real CVEs, and Practical Hardening
Prompt injection remains OWASP's number-one vulnerability for LLM applications in 2026, appearing in an estimated 73% of production AI deployments.
Mutation Testing with Codex CLI: Why Your AI-Generated Tests Are Lying and How to Fix Them
AI coding agents are excellent at generating tests that hit every line of your code. They are also excellent at generating tests that assert almost nothing.
Context Fragment Injection: Modular DeveloperInstructions via Plugins
Until today, Codex CLI assembled its system prompt as a single monolithic DeveloperInstructions blob — one giant string stuffed into the developer-role.
Codex CLI for Ruby on Rails Teams: AGENTS.md, Bundler Sandboxing, and RSpec Workflows
Ruby on Rails remains one of the most productive full-stack frameworks in production, powering applications from Shopify to GitHub.
Codex CLI Remote Connections: Running Agents on Remote Hosts with SSH, WebSocket, and Secure Tunnels
Your code lives on a beefy cloud devbox. Your credentials sit in a vault accessible only from a private subnet. Your CI runners spin up ephemeral containers.
Prompt Caching in Codex CLI: How the Agent Loop Stays Linear and How to Maximise Cache Hits
Every Codex CLI session resends the full conversation history on each turn. Without mitigation, this is quadratic in cost and latency. The engineering.