# arc ![license] ![activity]

[license]: https://badge.hanna.lol/license/BlueOak-1.0.0
[activity]: https://badge.hanna.lol/activity/hanna/arc

A delta-based version control system written in Rust.

Unlike Git's snapshot-based model, Arc stores incremental deltas using
ZSTD-compressed bincode files. Changes are automatically tracked
without manual staging, and commits are immutable once created.

Arc uses a **bookmark** system instead of branches, and bridges to Git
remotes for push, pull, clone, and sync operations via `libgit2`.

## Features

- Incremental delta storage (ZSTD + bincode)
- Automatic change tracking (no staging step)
- Bookmarks and immutable tags
- Named stashes
- Three-way merge and graft (cherrypick/rebase)
- Git bridge for remote operations (push, pull, clone, migrate, sync)
- Optional SSH commit signing
- Per-repo and global YAML configuration with aliases
- `.arcignore` / `.ignore` support

## Building

Arc builds exclusively through Nix:

```sh
nix build
```

The flake uses `nixpkgs-unstable`, `flake-parts`, `fenix`, and `crane`.

A dev shell is available for iterative work:

```sh
nix develop
```

## Usage

```
arc init [path]                        Initialize a new repository
arc commit <message>                   Commit current changes
arc status                             Show changes since last commit
arc diff [start..end]                  Show a diff of changes
arc log [start..end]                   Show commit history
arc show <mark|tag|commit>             Show details of a ref or commit
arc history <file> [start..end]        Show per-line modification history

arc switch <mark|tag>                  Switch worktree to a bookmark or tag
arc merge <mark|tag>                   Merge a bookmark or tag into the worktree
arc revert <commit|start..end>         Revert a commit or range
arc reset [file...]                    Reset worktree to the last commit
arc graft <target> --onto <dest>       Cherrypick commits onto a bookmark

arc mark add|rm|list|rename            Manage bookmarks
arc tag add|rm|list                    Manage tags
arc stash create|use|push|pop|rm|list  Manage named stashes

arc push [-r remote]                   Push to a git remote
arc pull [-r remote]                   Pull from a git remote
arc clone [-b branch] <url> [path]     Clone a git remote as an arc repo
arc migrate                            Convert a git repo to an arc repo
arc sync [-p]                          Sync bookmarks and tags with remote

arc remote add|rm|list                 Manage remotes
arc config set|get|show|unset [-g]     Manage configuration
```

## Testing

```sh
nix develop -c cargo test
nix develop -c cargo clippy
nix develop -c cargo fmt --check
```

## License

[Blue Oak Model License 1.0.0](LICENSE.md)