opencode-git-trailers

OpenCode plugin that automatically adds git trailers to commits made through OpenCode.

Problem

Some projects require commits created with AI assistance to include metadata denoting this fact. Git trailers provide a standardized way to add such metadata to commit messages. This plugin ensures that trailers are deterministically added to all commits made through OpenCode.

What It Does

This plugin intercepts git commit commands invoked by OpenCode and automatically appends configured trailers to the commit message. Trailers are added to the end of the commit message following the git trailer format.

Installation

npm install opencode-git-trailers

Usage

Basic Setup

Add the plugin to your OpenCode configuration:

{
  "plugins": ["opencode-git-trailers"]
}

Configuration

Configure trailers using git config with the opencode.git-trailers prefix.

Global Configuration

Configure trailers globally to apply to all repositories:

# Add the model used for the commit
git config --global opencode.git-trailers.model '{{model}}'

# Add yourself as a co-author with the AI
git config --global opencode.git-trailers.co-authored-by 'AI Assistant <ai@opencode.ai>'

# Add a signed-off-by trailer
git config --global opencode.git-trailers.signed-off-by '{{user.name}} <{{user.email}}>'

Per-Repository Configuration

Configure trailers for a specific repository by running commands within the repository directory:

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

# Add the model used for the commit (repository-specific)
git config opencode.git-trailers.model '{{model}}'

# Add a signed-off-by trailer (repository-specific)
git config opencode.git-trailers.signed-off-by '{{user.name}} <{{user.email}}>'

Per-repository configuration overrides global configuration for the same trailer key.

Result

These configuration options result in the following trailers being added to commits:

Model: claude-sonnet-4-5@20250929
Co-authored-by: AI Assistant <ai@opencode.ai>
Signed-off-by: John Doe <john@example.com>

Variable Interpolation

Trailers support variable interpolation to include contextual information such as the model used:

# Configure a trailer with model interpolation
git config opencode.git-trailers.model '{{model}}'

# Use git user information
git config opencode.git-trailers.signed-off-by '{{user.name}} <{{user.email}}>'

Available Variables

• {{model}} - The model identifier used for the commit
• {{provider}} - The provider name (e.g., "anthropic", "openai")
• {{timestamp}} - ISO 8601 timestamp of the commit
• {{session}} - OpenCode session ID
• {{user.name}} - Git user name from git config
• {{user.email}} - Git user email from git config

Example Commit Message

Before this plugin:

Add user authentication

This commit implements JWT-based authentication
for the API endpoints.

After this plugin (with configured trailers):

Add user authentication

This commit implements JWT-based authentication
for the API endpoints.

Model: claude-sonnet-4-5@20250929
Co-authored-by: AI Assistant <ai@opencode.ai>
Signed-off-by: John Doe <john@example.com>

Development

Prerequisites

• Bun 1.x or later

Setup

bun install

Build

bun run build

Test

# Run tests once
bun run test

# Run tests in watch mode
bun run test:watch

# Run tests with coverage
bun run test:coverage

Lint

bun run lint

License

MIT