Codex CLI

Codex CLI

Run OpenAI Codex CLI locally for second-opinion audits, code review, and non-interactive task execution.

Prerequisites

Codex CLI must be installed and authenticated:

1. Install: npm install -g @openai/codex
2. Auth: codex login
3. Verify: codex --version

Core Execution Pattern

Use codex exec for delegated prompts (non-interactive):

codex exec "Your prompt here"

When the user says "codex prompt", treat it as:

codex exec "<user prompt>"

Model Guidance

Use the default configured model unless the user asks otherwise.

Latest tested working model in this environment:

codex exec -m gpt-5.3-codex "Your prompt"

Compatibility note:

• gpt-5-codex may fail if config uses model_reasoning_effort = "xhigh".
• If you must use gpt-5-codex, set reasoning effort explicitly:

codex exec -m gpt-5-codex -c model_reasoning_effort="high" "Your prompt"

Commands

Non-Interactive Execution

# Basic task
codex exec "Audit this logic for edge cases"

# Explicit model
codex exec -m gpt-5.3-codex "Review this implementation strategy"

# Full-auto mode (sandboxed, lower friction)
codex exec --full-auto "Implement the requested refactor"

# Read-only sandbox (analysis only)
codex exec -s read-only "Find bugs in this code path"

# Workspace-write sandbox
codex exec -s workspace-write "Apply the fix and update tests"

# Custom working directory
codex exec -C /path/to/project "Evaluate this repository"

# Save final output to file
codex exec -o output.txt "Summarize key risks"

# JSONL event stream
codex exec --json "Produce structured findings"

# Pipe context from stdin
cat context.txt | codex exec -

Code Review

Use codex review for repository diffs:

# Review uncommitted changes
codex review --uncommitted

# Review against a base branch
codex review --base main

# Review a specific commit
codex review --commit abc123

# Custom review instructions
codex review "Focus on security issues"

# Combined
codex review --base main "Check for performance regressions"

Important Flag Placement

--search and -a/--ask-for-approval are top-level flags. Put them before exec or review.

Correct:

codex --search -a on-request exec "Your prompt"
codex --search -a on-request review --uncommitted

Avoid:

codex exec --search "Your prompt"
codex exec -a on-request "Your prompt"

Useful Flags

Best Practices

• Prefer codex exec for delegated prompts instead of interactive codex
• Start with -s read-only for audits and second opinions
• Use --full-auto only when you expect autonomous edits
• Keep prompts explicit about expected output format
• Add -o when another tool or agent must consume the result
• Run codex review --uncommitted before committing as a quick extra pass