DiffDash

A command-line tool to generate Git commit messages using AI.

Demonstration

Features

• Generate Git commit messages in natural English
• Add a footer to the generated commit messages
• Add a prefix or suffix to the summary line
• Select from a choice of LLM models
• Compare messages generated from all configured models
• Disable or auto-approve various stages
• Option to output just the commit message for use in scripts
• Configuration using standard API provider environment variables
• Uses the Vercel AI SDK (version 5)
• Uses structured JSON with compatible models
• Substantially written using AI coding (Claude Code, Roo Code, and Amp)

Installation from npmjs.com

npm install -g @johnowennixon/diffdash

LLM Models

Currently, for this application, the best LLM model is gpt-4.1-mini from OpenAI. It is set as the default model. I can only presume they have done a ton of training on diffs.

I am now testing the GPT-5 models and gpt-5-mini-minimal (GPT-5 Mini with reasoning disabled) is behaving much the same. It will probably become the default model soon.

API Keys

DiffDash requires at least one API key for an LLM provider. These must be provided as environment variables.

# For OpenAI (strongly recommended)
export OPENAI_API_KEY=your-api-key

# For Anthropic
export ANTHROPIC_API_KEY=your-api-key

# For DeepSeek
export DEEPSEEK_API_KEY=your-api-key

# For Google Gemini
export GEMINI_API_KEY=your-api-key

# For OpenRouter (all other models)
export OPENROUTER_API_KEY=your-api-key

Usage

# Basic usage (uses defaults)
diffdash

# Automatically stage all changes, but still prompt for commit and push
diffdash --auto-add

# Automatically stage and commit changes, but still prompt for push
diffdash --auto-add --auto-commit

# Fully automated workflow (stage, commit, and push without prompts)
diffdash --auto-add --auto-commit --auto-push

# Generate message for already staged changes only (won't stage any new changes)
diffdash --disable-add

# Skip displaying the status of staged files before commit
diffdash --disable-status

# Don't display the generated commit message
diffdash --disable-preview

# Generate message but don't commit (exit after displaying the message)
diffdash --disable-commit

# Generate message and commit, but don't push or prompt to push
diffdash --disable-push

# Skip git hooks when pushing
diffdash --no-verify

# Add a prefix to the commit message summary line
diffdash --add-prefix "[FIX]"

# Add a suffix to the commit message summary line
diffdash --add-suffix "(closes #123)"

# Display commit messages generated by all models
diffdash --llm-compare

# Specify the LLM model by name
diffdash --llm-model claude-3.5-haiku

# Just output the commit message for use in scripts
diffdash --just-output

# Debug prompts
diffdash --debug-llm-prompts

Command Line Arguments

All command-line arguments are optional.

Argument	Description
--help	show a help message and exit
--version	show program version information and exit
--auto-add	automatically stage all changes without confirmation
--auto-commit	automatically commit changes without confirmation
--auto-push	automatically push changes after commit without confirmation
--disable-add	disable adding unstaged changes - exit if no changes staged
--disable-status	disable listing the staged files before generating a message
--disable-preview	disable previewing the generated message
--disable-commit	disable committing changes - exit after generating the message
--disable-push	disable pushing changes - exit after making the commit
--push-no-verify	bypass git hooks when pushing to Git
--push-force	apply force when pushing to Git
--add-prefix PREFIX	add a prefix to the commit message summary line
--add-suffix SUFFIX	add a suffix to the commit message summary line
--llm-list	display a list of available Large Language Models and exit
--llm-compare	compare the generated messages from all models - but do not commit
--llm-model MODEL	choose the LLM model by name (the default is normally best)
--llm-excludes MODELS	models to exclude from comparison (comma separated)
--just-output	just output the commit message for use in scripts
--silent	suppress all normal output - errors and aborts still display
--debug-llm-prompts	show prompts sent to the LLM
--debug-llm-inputs	show inputs object sent to the LLM
--debug-llm-outputs	show outputs object received from the LLM

Files containing secrets

Files containing secrets should not be in Git. But if they are, you can add an entry to a .gitattributes file with value -diff to prevent them being viewable by a Git diff. This will prevent DiffDash from sending any contents to the LLM. For example:

# This is file .gitattributes

.env  -diff

Development

To install on your laptop:

# Clone the repository
git clone https://github.com/johnowennixon/diffdash.git
cd diffdash

# Install dependencies
pnpm install

# Build the project
pnpm run build

# Make binaries executable
npm link

To rebuild after editing:

# Lint the code
pnpm run lint

# Fix formatting issues (if required)
pnpm run fix

# Build the project
pnpm run build

License

0BSD