cmt is a command-line tool that generates meaningful git commit messages using AI models. It analyzes your staged changes and generates a well-formatted, descriptive commit message following conventional commit standards.
- 🤖 Supports multiple AI providers:
- Google's Gemini (
gemini-3-flash-preview, default - fastest & cheapest) - Anthropic's Claude (
claude-sonnet-4-5-20250929) - OpenAI's GPT (
gpt-5.2)
- Google's Gemini (
- 📝 Follows conventional commit format (
type: subject) - 🧠 Rich context: README, branch name, recent commits, full diff analysis
- 💡 Contextual hints to guide message generation
- ✅ Interactive commit prompt by default
- 📋 Copy to clipboard with
-c/--copy - ⚡ Configurable reasoning depth (none/minimal/low/high)
- 💰 Shows estimated token usage, time, and cost
brew install clifton/tap/cmtcurl -sSL https://raw.githubusercontent.com/clifton/cmt/main/scripts/install.sh | shcargo install cmtgit clone https://github.com/clifton/cmt.git
cd cmt
cargo install --path .Set your API key as an environment variable:
# For Gemini (default provider)
export GEMINI_API_KEY='your-api-key'
# For Claude (optional)
export ANTHROPIC_API_KEY='your-api-key'
# For OpenAI (optional)
export OPENAI_API_KEY='your-api-key'Or create a .env file in your project directory.
# Stage your changes
git add .
# Generate commit message and prompt to commit (default)
cmt
# Just show the message without committing
cmt --no-commit
# Commit without confirmation prompt
cmt -y# Use Gemini (default)
cmt
# Use Claude
cmt --provider claude
# Use OpenAI
cmt --provider openai
# List available models for a provider
cmt --provider openai --list-modelsCLI tool that generates commit messages using AI
Usage: cmt [OPTIONS]
Options:
-m, --message-only
Only output the generated commit message, without formatting
--no-diff-stats
Hide the diff statistics for staged changes
--show-raw-diff
Show the raw git diff that will be sent to the AI model
--context-lines <CONTEXT_LINES>
Number of context lines to show in the git diff [default: 20]
--model <MODEL>
Use a specific AI model (defaults to gemini-3-flash-preview,
claude-sonnet-4-5-20250929, or gpt-5.2 depending on provider)
--list-models
List available models for the selected provider
-t, --temperature <TEMPERATURE>
Adjust the creativity of the generated message (0.0 to 2.0)
--hint <HINT>
Add a hint to guide the AI in generating the commit message
--max-lines-per-file <MAX_LINES_PER_FILE>
Number of maximum lines to show per file in the git diff [default: 2000]
--max-line-width <MAX_LINE_WIDTH>
Maximum line width for diffs [default: 500]
--template <TEMPLATE>
Use a specific template for the commit message
--list-templates
List all available templates
--create-template <CREATE_TEMPLATE>
Create a new template
--template-content <TEMPLATE_CONTENT>
Content for the new template (used with --create-template)
--show-template <SHOW_TEMPLATE>
Show the content of a specific template
--no-recent-commits
Disable including recent commits for context
--recent-commits-count <RECENT_COMMITS_COUNT>
Number of recent commits to include for context [default: 10]
--init-config
Create a new configuration file
--config-path <CONFIG_PATH>
Path to save the configuration file (defaults to .cmt.toml in current directory)
--provider <PROVIDER>
Use a specific provider (gemini, claude, openai) [default: gemini]
-c, --copy
Copy the generated commit message to clipboard
--no-commit
Skip commit prompt (just show the message)
-y, --yes
Skip confirmation when committing
--thinking <THINKING>
Reasoning depth for AI models (none=fastest, minimal, low, high) [default: low]
-h, --help
Print help
-V, --version
Print version
# Default: generate message and prompt to commit
cmt
# Provide context to improve the message
cmt --hint "This fixes the login timeout issue"
# Review message without committing
cmt --no-commit
# Copy message to clipboard
cmt --copy
# Fastest mode (no reasoning)
cmt --thinking none
# Default uses low reasoning for balanced speed/quality
cmt
# Commit immediately without prompting
cmt -y
# Use a different provider with custom temperature
cmt --provider openai -t 0.8
# Pipe message to git directly
git commit -F <(cmt -m)cmtgathers rich context: README excerpt, branch name, recent commits- Analyzes staged changes to suggest commit type
- Sends full context + diff to the AI using rstructor for structured output
- Shows stats (tokens, time, estimated cost)
- You review and confirm (or regenerate with a hint)
Built with rstructor - a Rust library for type-safe structured outputs from LLMs (similar to Python's Instructor).
For detailed implementation documentation including diff assembly, file filtering, prompt construction, and all default parameters, see METHODOLOGY.md.
Example output:
Staged: 3 files +150 -42
src/main.rs +100 -20
src/lib.rs +30 -12
Cargo.toml +20 -10
Commit message:
feat: add user authentication endpoint
- Implement JWT token validation
- Add password hashing with bcrypt
- Create login and logout handlers
~1250 tokens, 1.2s, $0.0008
[y]es to commit, [n]o to cancel, [h]int to regenerate:
type: subject
- Detail about change 1
- Detail about change 2
Scope (type(scope): subject) is only used for monorepos or large codebases with distinct modules.
Types: feat, fix, docs, style, refactor, test, chore, perf, build, ci
# List available templates
cmt --list-templates
# Use a specific template
cmt --template detailed
# Create a custom template
cmt --create-template my-template --template-content "{{type}}: {{subject}}"Templates are stored in ~/.config/cmt/templates/ as .hbs files.
Available variables: {{type}}, {{subject}}, {{details}}, {{scope}}, {{breaking}}, {{issues}}
MIT License - see LICENSE file for details.