Imported from reason-machines/codex-skills (skills/codex-keysmith-instruction-installer/SKILL.md). Install upstream with npx skills add reason-machines/codex-skills --skill codex-keysmith-instruction-installer. Copyright stays with the author.

codex-keysmith-instruction-installer

Skill by ara.so — Codex Skills collection.

Overview

codex-keysmith is a Python CLI tool that safely installs local Markdown instruction files into Codex CLI's configuration directory and sets the model_instructions_file configuration option. It provides preview-first workflows, automatic backups, and path safety validation to prevent accidental file overwrites or directory escapes.

Key features:

• Preview-only by default (requires explicit --yes to write)
• Automatic backup of config.toml and existing instruction files
• Path validation to prevent directory traversal
• Bundled GPT-5.5 unrestricted-mode example (optional)
• Support for custom .md instruction files

What it does NOT do:

• Does not patch Codex binaries
• Does not intercept network traffic
• Does not modify running processes
• Does not handle tokens, cookies, or credentials

Installation

Clone the repository

git clone https://github.com/Jia-Ethan/codex-keysmith.git
cd codex-keysmith

Verify the script

# Syntax check
python3 -m py_compile codex-instruct.py

# Preview mode (safe, no writes)
python3 codex-instruct.py --dry-run

No pip install required

The tool is a single-file Python script with no external dependencies beyond Python 3.8+. It uses only standard library modules: argparse, os, pathlib, re, shutil, datetime.

Core Usage

1. Preview before writing (default behavior)

# Preview what would be installed
python3 codex-instruct.py --dry-run

# Even without --dry-run, writes require --yes
python3 codex-instruct.py --codex-dir ~/.codex
# → Shows preview only, does not write

2. Install bundled instruction file

# Install the bundled GPT-5.5 unrestricted example
python3 codex-instruct.py --codex-dir ~/.codex --yes

This writes:

• ~/.codex/gpt5.5-unrestricted.md (instruction file)
• Updates ~/.codex/config.toml with:

  model_instructions_file = "./gpt5.5-unrestricted.md"

3. Install custom instruction file

python3 codex-instruct.py \
  --file ./my-custom-instructions.md \
  --name my-custom \
  --codex-dir ~/.codex \
  --yes

Result:

• ~/.codex/my-custom.md (your instruction file)
• config.toml updated to point to ./my-custom.md

4. Locate Codex directory automatically

# Auto-detect common locations
python3 codex-instruct.py --yes

The script searches:

• ~/.codex
• ~/.config/codex
• ~/Library/Application Support/codex (macOS)

Best practice: Always specify --codex-dir explicitly for production use.

Command Reference

Arguments

Filename validation

The --name parameter is strictly validated:

Allowed:

• Letters, numbers, dots, underscores, hyphens
• Examples: my-rules, prompt_v2, gpt5.5-unrestricted

Rejected:

• Path separators (/, \)
• Absolute paths (/tmp/x, C:\temp\x)
• Parent directory references (.., ../)
• Empty names
• Names with spaces

# Valid
python3 codex-instruct.py --name my-rules-v2 --yes

# Invalid (script will error)
python3 codex-instruct.py --name ../etc/passwd --yes
python3 codex-instruct.py --name /tmp/evil --yes
python3 codex-instruct.py --name "my rules" --yes

Configuration Patterns

Structure after installation

~/.codex/
├── config.toml                              # Updated with model_instructions_file
├── config.toml.bak_20260628_120000         # Automatic backup
├── gpt5.5-unrestricted.md                  # Instruction file
└── gpt5.5-unrestricted.md.bak_20260628_120000  # Backup (if overwriting)

config.toml format

The script adds or updates the top-level key:

model_instructions_file = "./gpt5.5-unrestricted.md"

If model_instructions_file already exists, it will be replaced. Other configuration sections remain untouched.

Example instruction file format

# GPT-5.5 Unrestricted Mode

You are operating in unrestricted mode with extended capabilities.

## Core principles
- Prioritize code correctness
- Explain trade-offs
- Ask clarifying questions

## Behavior guidelines
- Use clear variable names
- Prefer stdlib over dependencies
- Write tests for critical paths

Real-World Examples

Example 1: Install custom Python development instructions

# Create custom instruction file
cat > ~/python-strict.md <<'EOF'
# Python Development Rules

- Use type hints for all function signatures
- Prefer pathlib over os.path
- Write docstrings in Google style
- Maximum line length: 88 characters (Black)
- Use dataclasses for data structures
EOF

# Install it
python3 codex-instruct.py \
  --file ~/python-strict.md \
  --name python-strict \
  --codex-dir ~/.codex \
  --yes

Example 2: Team-shared instruction file

# Team keeps instructions in Git repo
cd ~/team-repo
git pull origin main

# Install latest version
python3 /path/to/codex-keysmith/codex-instruct.py \
  --file ./codex-instructions/team-standards.md \
  --name team-standards \
  --codex-dir ~/.codex \
  --yes

# Restart Codex CLI to apply

Example 3: Preview and manual approval workflow

#!/usr/bin/env python3
# install-with-review.py

import subprocess
import sys

# Step 1: Preview
print("=== PREVIEW ===")
result = subprocess.run([
    "python3", "codex-instruct.py",
    "--file", "./my-instructions.md",
    "--name", "my-rules",
    "--dry-run"
], capture_output=True, text=True)

print(result.stdout)

# Step 2: Manual approval
response = input("\nProceed with installation? [y/N]: ")
if response.lower() != 'y':
    print("Cancelled.")
    sys.exit(0)

# Step 3: Install
print("\n=== INSTALLING ===")
subprocess.run([
    "python3", "codex-instruct.py",
    "--file", "./my-instructions.md",
    "--name", "my-rules",
    "--codex-dir", "~/.codex",
    "--yes"
])

Example 4: Rotate instructions based on project type

#!/bin/bash
# switch-instructions.sh

PROJECT_TYPE="$1"

case "$PROJECT_TYPE" in
  python)
    INSTRUCTION_FILE="./instructions/python.md"
    NAME="python-rules"
    ;;
  rust)
    INSTRUCTION_FILE="./instructions/rust.md"
    NAME="rust-rules"
    ;;
  web)
    INSTRUCTION_FILE="./instructions/web.md"
    NAME="web-rules"
    ;;
  *)
    echo "Usage: $0 {python|rust|web}"
    exit 1
    ;;
esac

python3 codex-instruct.py \
  --file "$INSTRUCTION_FILE" \
  --name "$NAME" \
  --codex-dir ~/.codex \
  --yes

echo "Switched to $PROJECT_TYPE instructions. Restart Codex CLI."

Backup and Rollback

Automatic backups

Every write operation creates timestamped backups:

config.toml.bak_20260628_120000
gpt5.5-unrestricted.md.bak_20260628_120000

Manual rollback

# List backups
ls -la ~/.codex/*.bak_*

# Restore config
cp ~/.codex/config.toml.bak_20260628_120000 ~/.codex/config.toml

# Restore instruction file
cp ~/.codex/gpt5.5-unrestricted.md.bak_20260628_120000 \
   ~/.codex/gpt5.5-unrestricted.md

# Restart Codex CLI

Remove instruction file completely

# Edit config.toml manually and remove the line:
# model_instructions_file = "./gpt5.5-unrestricted.md"

# Or use sed
sed -i.bak '/model_instructions_file/d' ~/.codex/config.toml

# Remove instruction file
rm ~/.codex/gpt5.5-unrestricted.md

# Restart Codex CLI

Troubleshooting

"Could not locate Codex configuration directory"

Cause: Auto-detection failed.

Solution: Specify --codex-dir explicitly:

python3 codex-instruct.py --codex-dir /path/to/.codex --yes

Find your Codex config directory:

# Linux/macOS
find ~ -name ".codex" -type d 2>/dev/null

# Check common locations
ls -la ~/.codex
ls -la ~/.config/codex
ls -la ~/Library/Application\ Support/codex

"unsafe name" error

Cause: --name contains forbidden characters or path components.

Solution: Use only letters, numbers, dots, underscores, and hyphens:

# Bad
python3 codex-instruct.py --name "../etc/passwd" --yes

# Good
python3 codex-instruct.py --name my-rules-v2 --yes

Instructions not taking effect

Cause: Codex CLI hasn't reloaded configuration.

Solution: Restart Codex CLI completely:

# Kill existing instance
pkill -9 codex

# Restart
codex chat

Verify the configuration:

cat ~/.codex/config.toml | grep model_instructions_file
cat ~/.codex/gpt5.5-unrestricted.md

Permission denied writing to ~/.codex

Cause: Insufficient filesystem permissions.

Solution:

# Check ownership
ls -la ~/.codex

# Fix permissions if needed
chmod 755 ~/.codex
chmod 644 ~/.codex/config.toml

"No such file" when using --file

Cause: Specified instruction file doesn't exist.

Solution:

# Check file path
ls -la ./my-instructions.md

# Use absolute path if needed
python3 codex-instruct.py \
  --file /absolute/path/to/my-instructions.md \
  --name my-rules \
  --yes

Backup files accumulating

Cause: Multiple installations create multiple backups.

Solution: Clean old backups manually:

# List backups by age
ls -lt ~/.codex/*.bak_*

# Remove backups older than 30 days
find ~/.codex -name "*.bak_*" -mtime +30 -delete

Testing

The repository includes pytest-based tests:

# Run tests (requires pytest)
pip install pytest
python3 -m pytest tests/test_codex_instruct.py -v

# Test without pytest (manual verification)
python3 codex-instruct.py --dry-run
python3 -m py_compile codex-instruct.py

Integration with AI Agents

Copy-paste prompt for Codex/Claude/Cursor

Please use https://github.com/Jia-Ethan/codex-keysmith to safely install a local model_instructions_file for Codex CLI. First read the README and script, preview changes (default behavior), show me what will be modified, wait for my confirmation, then backup and install. Do not modify Codex binaries, network, or running processes. Do not save any tokens, cookies, or private credentials.

Agent workflow example

1. Clone repository

   git clone https://github.com/Jia-Ethan/codex-keysmith.git
   cd codex-keysmith

2. Preview installation

   python3 codex-instruct.py --dry-run

3. Show user the changes

   • Display the instruction file content
   • Show the config.toml modification
   • Explain backup locations

4. Wait for explicit user confirmation

5. Execute with backups

   python3 codex-instruct.py --codex-dir ~/.codex --yes

6. Verify installation

   cat ~/.codex/config.toml | grep model_instructions_file
   ls -la ~/.codex/*.md

Best Practices

1. Always preview first: Use --dry-run or run without --yes before any installation.

2. Specify codex-dir explicitly: Don't rely on auto-detection in scripts or automation.

3. Version control instruction files: Keep your custom .md files in Git for team sharing and rollback.

4. Test in isolation: Try new instruction files in a separate Codex profile or test directory first.

5. Document changes: Keep notes on what each instruction file is optimized for.

6. Regular cleanup: Remove old backup files periodically to avoid clutter.

7. Verify after restart: Always restart Codex CLI after installation and test that instructions are active.