Codex Sandbox Skill

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LIBRARY-FIRST PROTOCOL (MANDATORY)

Before writing ANY code, you MUST check:

Step 1: Library Catalog

• Location:

  .claude/library/catalog.json

• If match >70%: REUSE or ADAPT

Step 2: Patterns Guide

• Location:

  .claude/docs/inventories/LIBRARY-PATTERNS-GUIDE.md

• If pattern exists: FOLLOW documented approach

Step 3: Existing Projects

• Location:

  D:\Projects\*

• If found: EXTRACT and adapt

Decision Matrix

Match	Action
Library >90%	REUSE directly
Library 70-90%	ADAPT minimally
Pattern exists	FOLLOW pattern
In project	EXTRACT
No match	BUILD (add to library after)

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Purpose

Execute code in Codex's fully isolated sandbox environment for safe experimentation with untrusted or risky code.

Unique Capability

What Claude Can't Do: Claude runs in your environment. Codex sandbox provides:

• Network DISABLED: No external connections
• CWD only: Cannot access parent directories
• OS-level isolation: macOS Seatbelt or Docker
• Resource limits: CPU, memory constraints
• Safe experimentation: Can't break your system

When to Use

Perfect For:

• Running untrusted code safely
• Risky refactoring experiments
• Testing code with potential bugs
• Isolated prototyping
• Security research
• Experimental dependencies

Don't Use When:

• Need network access
• Need to access files outside project
• Production debugging

Usage

# Basic sandbox execution
/codex-sandbox "Refactor auth system and run tests"

# With iteration limit
/codex-sandbox "Fix all tests" --max-iterations 10

# Risky experiment
/codex-sandbox "Try experimental algorithm implementation"

CLI Command

codex --full-auto --sandbox true --network disabled "Your task"

# Via script
CODEX_MODE=sandbox bash scripts/multi-model/codex-yolo.sh "Task" "id" "." "10" "sandbox"

Isolation Layers

Layer	Protection
Network	DISABLED - no external connections
Filesystem	CWD only - no parent access
OS-Level	Seatbelt (macOS) / Docker
Process	Subprocess jail with limits
Commands	Blocked: rm -rf, sudo, etc.

Integration Pattern

// 1. Run risky refactoring in sandbox
const result = await codexSandbox("Refactor entire auth system");

// 2. If successful, apply to real codebase
if (result.tests_pass) {
  Task("Coder", "Apply sandboxed changes to main", "coder");
}

Memory Integration

• Key:

  multi-model/codex/sandbox/{session_id}

• Contains: commands, files created/modified, test results