Codex CLI¶

OpenAI's code-focused CLI tool optimized for code generation and programming tasks.

Overview¶

Codex CLI is OpenAI's command-line tool focused on code generation and programming assistance. It excels at:

Rapid code generation
Writing tests and boilerplate
Code transformations
Quick programming tasks

Installation¶

Install Codex CLI from OpenAI:

# Verify installation
which codex
codex --version

Basic Usage¶

# Use Codex with clinvk
clinvk --backend codex "implement a REST API handler"
clinvk -b codex "generate unit tests for user.go"

Models¶

Model	Description
`o3`	Latest and most capable model
`o3-mini`	Faster, lighter model

Specify a model:

clinvk -b codex -m o3-mini "quick code generation"

Configuration¶

Configure Codex in ~/.clinvk/config.yaml:

backends:
  codex:
    # Default model
    model: o3

    # Enable/disable this backend
    enabled: true

    # Extra CLI flags
    extra_flags: []

Environment Variable¶

export CLINVK_CODEX_MODEL=o3-mini

Session Management¶

Codex resumes sessions via the codex exec resume subcommand (handled automatically by clinvk):

# Resume with clinvk
clinvk resume --last --backend codex
clinvk resume <session-id>

Unified Options¶

These options work with Codex:

Option	Description
`model`	Model to use
`max_tokens`	Maximum response tokens
`max_turns`	Maximum agentic turns

Extra Flags¶

Pass additional flags to Codex:

backends:
  codex:
    extra_flags:
      - "--quiet"

Common flags:

Flag	Description
`--quiet`	Reduce output verbosity

Best Practices¶

Use for Code Generation

Codex is optimized for generating code quickly. It's great for boilerplate and repetitive tasks.

Combine with Other Backends

Use Codex to generate code, then Claude to review it - leverage the chain command.

Batch Similar Tasks

Run multiple code generation tasks in parallel for efficiency.

Use Cases¶

Generate Boilerplate¶

clinvk -b codex "create a CRUD API for the User model"

Write Tests¶

clinvk -b codex "generate comprehensive unit tests for the auth module"

Code Transformation¶

clinvk -b codex "convert this callback-based code to async/await"

Quick Implementations¶

clinvk -b codex "implement a binary search function"

Comparison with Claude¶

Aspect	Codex	Claude
Speed	Faster	More thorough
Best for	Code generation	Complex reasoning
Context	Good	Excellent
Safety focus	Standard	High

Workflow Example¶

Use Codex and Claude together:

{
  "steps": [
    {
      "name": "generate",
      "backend": "codex",
      "prompt": "implement user authentication"
    },
    {
      "name": "review",
      "backend": "claude",
      "prompt": "review this code for security: {{previous}}"
    }
  ]
}

Troubleshooting¶

Backend Not Available¶

# Check if Codex is installed
which codex

# Check clinvk detection
clinvk config show | grep codex

Model Errors¶

If a model isn't available:

# List available models
codex models list

# Update config to use available model
clinvk config set backends.codex.model o3