scg

scg is a Swift-based command line tool that inspects your current Git repository, summarizes the staged and unstaged changes, and generates a commit message proposal with Apple's on-device generative model. The goal is to keep human-in-the-loop Git commits fast, consistent, and privacy-preserving by relying on system-provided AI capabilities instead of cloud services.

CommitGen.mov

Features

• Detects dirty Git worktrees and extracts concise change context
• Crafts commit message drafts with Apple's onboard generative APIs
• Provides an interactive acceptance/edit flow before writing the commit
• Persists CLI defaults with an interactive config command
• Respects local-only privacy requirements (no network calls)

Project Status

The CLI currently supports end-to-end commit generation, including Git inspection, AI-assisted drafting, interactive editing, optional auto-staging/committing, and persistent configuration defaults. Advanced batching for huge diffs is available and continues to evolve based on real-world feedback.

Prerequisites

• macOS Tahoe (26) or later with the Apple Intelligence feature set enabled
• Xcode 26 (or newer) with the command line tools installed (xcode-select --install)
• Swift 6 toolchain (ships with Xcode 26)
• Git 2.40+ available on PATH
• Full Disk Access enabled for the Terminal (or your preferred shell) so the FoundationModels framework can initialize properly

Installation

Option 1: Homebrew (Recommended)

brew tap Iron-Ham/swift-commit-gen
brew install scg

Or install directly without tapping:

brew install Iron-Ham/swift-commit-gen/scg

Option 2: Install Script

1. Clone the repository:

   git clone https://github.com/Iron-Ham/swift-commit-gen.git
   cd swift-commit-gen

2. Run the bundled install script (installs into ~/.local/bin by default):

   Scripts/install.sh

   Pass a custom destination as the first argument to install elsewhere, e.g. Scripts/install.sh /usr/local/bin.

Option 3: Manual Build

If you prefer manual installation, build and copy the binary yourself:

git clone https://github.com/Iron-Ham/swift-commit-gen.git
cd swift-commit-gen
swift build -c release
install -d "$HOME/.local/bin"
install .build/release/scg "$HOME/.local/bin/"

Add export PATH="$HOME/.local/bin:$PATH" to your shell profile if needed.

First-Run Notes

• The first invocation may prompt for Apple Intelligence access; approve the request in System Settings → Privacy & Security → Apple Intelligence.
• If scg reports that the model is unavailable, ensure Apple Intelligence is enabled and the device satisfies the on-device requirements.

Usage

From the root of a Git repository with pending changes:

swift run scg generate

Or, after installation:

scg generate

Command

You can invoke the tool either with the explicit generate subcommand or omit it because generate is the default subcommand.

Primary (shorter) form:

scg [OPTIONS]

Equivalent explicit form:

scg generate [OPTIONS]

Generation Flow

1. Inspect repository (staged changes only)
2. Summarize diff and plan prompt batches if large
3. Request draft commit message from on-device model
4. Interactive review loop (accept / edit / regenerate)
5. Optional auto-commit

Flags & Options

Flag	Short	Description	Default	Notes
--format <text|json>		Output format for the draft	text	JSON skips the interactive review loop.
--commit / --no-commit		Apply the accepted draft with git commit	On	--no-commit leaves the draft uncommitted.
--stage		Stage all pending changes (including untracked) before drafting	Off	Equivalent to git add --all before generation.
--no-stage		Disable staging, even if configured as a default	-	Wins over stored auto-stage preferences.
--verbose	-v	Emit detailed prompt diagnostics and debug lines	Off	Shows [DEBUG] messages. Overrides --quiet.
--no-verbose		Force verbose output off, even if configured as default	-	Useful for scripts overriding stored settings.
--quiet	-q	Suppress routine info lines	Off	Hides [INFO] but keeps [NOTICE], warnings, errors. Ignored if --verbose is present.
--no-quiet		Ensure quiet mode is disabled, even if configured	-	Helpful when scripts need full output.
--single-file		Analyze each file independently and then combine per-file drafts	Off	Sends a larger diff slice per file, useful when you need high-fidelity summaries.
--function-context		Include entire functions containing changes in the diff	On	Provides better semantic context for the AI model.
--no-function-context		Disable function context in diffs	-	May reduce diff size for very large changesets.
--detect-renames		Detect renamed and copied files in diffs	On	Shows moves as renames rather than delete + add.
--no-detect-renames		Disable rename/copy detection	-	Use raw add/delete representation.
--context-lines <n>		Number of context lines around changes	3	Higher values give more surrounding code context.

Verbosity Levels

The logger uses distinct levels to balance clarity and noise:

• [ERROR]: Fatal issues preventing progress
• [WARNING]: Non-fatal problems or user action advisories
• [NOTICE]: Essential workflow milestones (always shown, even with --quiet)
• [INFO]: Routine progress details (hidden with --quiet)
• [DEBUG]: High-volume diagnostics (only with --verbose)

Precedence: --verbose > --quiet. Supplying both yields verbose output.

Examples

Generate and interactively accept a draft (default):

scg

Auto-commit the already staged changes:

scg --commit

Stage everything first, then show verbose diagnostics:

scg --stage --verbose

Minimal essential output (quiet mode) but still commit:

scg --quiet --commit

Produce machine-readable JSON (no interactive loop):

scg --format json

Request high-fidelity per-file drafts before they are combined:

scg --single-file

Generate with more context lines and disabled function context (for very large diffs):

scg --context-lines 5 --no-function-context

Configuration Defaults

Use the config subcommand to inspect or update stored defaults. Running it with no flags opens an interactive, colorized editor that walks through each preference:

scg config

Available options:

Flag	Description
--show	Print the current configuration without making changes.
--auto-stage-if-clean <true|false>	Persist whether generate should stage all files when nothing is staged.
--clear-auto-stage	Remove the stored auto-stage preference.
--verbose <true|false>	Set the default verbose logging preference.
--clear-verbose	Remove the stored verbose preference.
--quiet <true|false>	Set the default quiet logging preference.
--clear-quiet	Remove the stored quiet preference.
--mode <automatic|per-file>	Set the default generation mode.
--clear-mode	Remove the stored generation mode preference.
--function-context <true|false>	Set whether to include entire functions in diffs.
--clear-function-context	Remove the stored function-context preference.
--detect-renames <true|false>	Set whether to detect renamed/copied files in diffs.
--clear-detect-renames	Remove the stored detect-renames preference.
--context-lines <n>	Set the default number of context lines around changes.
--clear-context-lines	Remove the stored context-lines preference.

When no options are provided, the command detects whether the terminal is interactive and presents guided prompts with recommended defaults highlighted. Stored settings live in ~/Library/Application Support/scg/config.json.

Help

For a full list of commands:

scg help # or scg -h

For help with a specific command, such as generate:

scg help generate # or scg generate -h