git-permachine

permachine

Automatically merge machine-specific configuration files with base configurations in git repositories. Like Husky for git hooks, but for config file management.

Problem

When working across multiple machines, you often need:

• Shared configuration - Settings that work across all machines
• Machine-specific overrides - Local paths, API keys, ports, etc.
• Automatic merging - No manual copy-paste or merge steps
• Git-friendly - Base and machine configs in version control, output gitignored

Solution

permachine automatically:

• Detects your machine name
• Finds machine-specific config files (e.g., config.homezone.json)
• Merges them with base configs (e.g., config.base.json)
• Outputs the final config (e.g., config.json) - gitignored
• Runs automatically on git operations via hooks

Quick Start

# In your repository
cd /path/to/your/repo

# Initialize (one-time setup)
npx permachine init

# That's it! Your configs will now auto-merge on git operations

Installation

Development (Local)

cd D:/projects/git-permachine
bun install
bun link

# In your target repo
cd /path/to/your/repo
bun link git-permachine

Production

npm install -g git-permachine
# or
bun add -g git-permachine

Usage

File Naming Convention

Given machine name homezone (auto-detected):

Purpose	Filename	In Git?
Base config (shared)	config.base.json	✅ Yes
Machine-specific	config.homezone.json	✅ Yes
Final output (merged)	config.json	❌ No (gitignored)

Same pattern works for .env files:

Purpose	Filename	In Git?
Base config	.env.base	✅ Yes
Machine-specific	.env.homezone	✅ Yes
Final output	.env	❌ No (gitignored)

Commands

init - Initialize in repository

permachine init [options]

Options:
  --legacy            Use .git/hooks wrapping instead of core.hooksPath
  --auto              Auto-detect best installation method

What it does:

• Detects machine name (e.g., homezone)
• Installs git hooks (post-checkout, post-merge, post-commit)
• Scans for existing *.{machine}.* files
• Performs initial merge
• Updates .gitignore with output files

Example output:

✓ Machine detected: homezone
✓ Git hooks installed via core.hooksPath
✓ Updated .gitignore with 2 file(s)
✓ Merged 2 file(s)

Git hooks will auto-merge on:
  - checkout (switching branches)
  - merge (git pull/merge)
  - commit

merge - Manually trigger merge

permachine merge [--silent]

Useful for:

• Testing merge logic
• Running manually without git hooks
• CI/CD pipelines

info - Show current setup

permachine info

Example output:

Machine name: homezone
Repository: /path/to/repo
Hooks method: core.hooksPath
Hooks path: .permachine/hooks
Tracked patterns: 2
  - config.base.json + config.homezone.json → config.json
  - .env.base + .env.homezone → .env

uninstall - Remove git hooks

permachine uninstall

Removes git hooks and restores original hooks (if using legacy mode).

How It Works

1. Machine Detection

Automatically detects machine name across platforms:

• Windows: COMPUTERNAME environment variable
• Linux/Mac: hostname()
• Normalized to lowercase for consistency

2. File Discovery

Scans repository for files matching *.{machine}.* pattern:

• config.homezone.json ✅
• .env.homezone ✅
• settings.homezone.json ✅
• Ignores node_modules/, .git/, dist/

3. Merging Strategy

JSON Files

• Deep merge: Machine config recursively overrides base
• Arrays: Replaced entirely (not merged by index)
• Output: 2-space indentation, ends with newline

Example:

// config.base.json
{
  "server": { "host": "localhost", "port": 3000 },
  "logging": { "level": "info" }
}

// config.homezone.json
{
  "server": { "port": 8080 },
  "database": { "password": "secret" }
}

// config.json (merged output)
{
  "server": { "host": "localhost", "port": 8080 },
  "logging": { "level": "info" },
  "database": { "password": "secret" }
}

ENV Files

• Simple key-value merge: Machine values override base
• Preserves comments: From base file
• Quoted values: Auto-quotes values with spaces or special chars

Example:

# .env.base
DATABASE_HOST=localhost
DATABASE_PORT=5432
API_KEY=default

# .env.homezone
DATABASE_PORT=3306
API_KEY=secret_key_123

# .env (merged output)
DATABASE_HOST=localhost
DATABASE_PORT=3306
API_KEY=secret_key_123

4. Git Hooks

Two installation methods:

Preferred: core.hooksPath

git config core.hooksPath .permachine/hooks

• Clean, modern approach
• No modification of .git/hooks
• Easy to uninstall

Legacy: .git/hooks wrapping

• Backs up existing hooks to .git/hooks/*.pre-mcs
• Wraps existing hooks (calls them after merge)
• Compatible with other git hook tools

5. Automation

Hooks run on:

• post-checkout: After switching branches
• post-merge: After git pull or git merge
• post-commit: After committing

Merge happens silently in background (only logs errors).

Examples

Example 1: OpenCode Configuration

cd C:\Users\josch\.config\opencode

# Initialize
permachine init

# Machine detected: homezone

# Reorganize existing config
mv config.json config.homezone.json

# Create base config with shared settings
cat > config.base.json << EOF
{
  "theme": "nightowl-transparent",
  "autoupdate": true
}
EOF

# Add machine-specific settings to config.homezone.json
# ...edit file...

# Merge
permachine merge

# Output: config.json (gitignored)
# Future git operations auto-merge!

Example 2: Multi-Environment Project

# Different machines, different settings
# Machine: "workstation"
config.workstation.json → Development settings, localhost
.env.workstation → Local database credentials

# Machine: "server"
config.server.json → Production settings, real domains
.env.server → Production database credentials

# Shared base
config.base.json → Common app settings
.env.base → Default environment variables

# Each machine gets its own merged config automatically!

Example 3: Multiple Config Files

# Project structure
project/
├── config.base.json
├── config.homezone.json
├── settings/
│   ├── app.base.json
│   ├── app.homezone.json
│   ├── database.base.json
│   └── database.homezone.json
└── .env.base
    .env.homezone

# All files auto-merge on git operations:
# - config.json
# - settings/app.json
# - settings/database.json
# - .env

Supported File Types

• ✅ JSON (.json)
• ✅ ENV (.env, .env.*)
• 🔜 YAML (future)
• 🔜 TOML (future)

Error Handling

Base missing, machine exists

→ Uses machine file only

Machine missing, base exists

→ Uses base file only (rare, scanner looks for machine files)

Both missing

→ Skips silently

Parse error

→ Logs error with file path, skips merge

Write error

→ Logs error, doesn't crash

Development

Setup

git clone <repo>
cd permachine
bun install

Run Tests

# All tests
bun test

# Watch mode
bun test --watch

# Specific test file
bun test tests/unit/json-adapter.test.ts

Build

bun run build

Run Locally

bun run dev init
bun run dev merge
bun run dev info

Troubleshooting

Hooks not running

Check hook installation:

permachine info

Verify git config:

git config --get core.hooksPath
# Should output: .permachine/hooks

Check hook files exist:

ls .permachine/hooks/

Merge not happening

Run manually to see errors:

permachine merge

Check machine name:

permachine info
# Verify "Machine name" matches your file pattern

Conflicts with other git hook tools

Use legacy mode:

permachine uninstall
permachine init --legacy

Contributing

Contributions welcome! Please:

• Fork the repository
• Create a feature branch
• Add tests for new functionality
• Ensure all tests pass (bun test)
• Submit a pull request

License

MIT © JosXa

Roadmap

• JSON support
• ENV support
• Git hooks (hooksPath & legacy)
• CLI interface
• Comprehensive tests
• YAML support
• TOML support
• Custom merge strategies
• Config file for patterns
• Watch mode for development
• Dry-run mode
• npm package publication

Credits

Inspired by:

• Husky - Git hooks made easy
• The need for machine-specific configurations across development environments