josh-sync/README.md

# josh-sync

Bidirectional monorepo ↔ subrepo sync via [josh-proxy](https://josh-project.github.io/josh/). Supports multiple sync targets from a single config.

## Quick Start

### 1. Add config

Create `.josh-sync.yml` in your monorepo root:

```yaml
josh:
  proxy_url: "https://josh.example.com"
  monorepo_path: "org/monorepo"

targets:
  - name: "billing"
    subfolder: "services/billing"
    subrepo_url: "git@gitea.example.com:ext/billing.git"
    subrepo_auth: "ssh"
    branches:
      main: main
    exclude:                          # files excluded from subrepo (optional)
      - ".monorepo/"

bot:
  name: "josh-sync-bot"
  email: "josh-sync-bot@example.com"
  trailer: "Josh-Sync-Origin"
```

### 2. Add CI workflows

Copy from [examples/](examples/) and customize paths/branches:

```yaml
# .gitea/workflows/josh-sync-forward.yml
- uses: https://your-gitea.example.com/org/josh-sync@v1
  with:
    direction: forward
  env:
    SYNC_BOT_USER: ${{ secrets.SYNC_BOT_USER }}
    SYNC_BOT_TOKEN: ${{ secrets.SYNC_BOT_TOKEN }}
    SUBREPO_SSH_KEY: ${{ secrets.SUBREPO_SSH_KEY }}
```

### 3. Local dev (Nix)

Add josh-sync as a flake input, then:

```nix
{ inputs, ... }: {
  imports = [ inputs.josh-sync.devenvModules.default ];
}
```

Run `josh-sync preflight` to validate your setup.

## Documentation

- **[Setup Guide](docs/guide.md)** — Step-by-step: prerequisites, importing existing subrepos, CI workflows, file exclusion, and troubleshooting
- **[Configuration Reference](docs/config-reference.md)** — Full `.josh-sync.yml` field documentation
- **[Architecture Decision Records](docs/adr/)** — Design rationale and trade-offs
- **[Changelog](CHANGELOG.md)** — Version history

## CLI

```
josh-sync sync [--forward|--reverse] [--target NAME[,NAME]] [--branch BRANCH]
josh-sync preflight
josh-sync import <target>
josh-sync reset <target>
josh-sync onboard <target> [--restart]
josh-sync migrate-pr <target> [PR#...] [--all]
josh-sync status
josh-sync state show <target> [branch]
josh-sync state reset <target> [branch]
```

## How It Works

- **Forward sync** (mono → subrepo): pushes directly if clean, creates conflict PR if not. Uses `--force-with-lease` for safety.
- **Reverse sync** (subrepo → mono): always creates a PR, never pushes directly.
- **File exclusion**: `exclude` patterns are embedded inline in the josh-proxy URL. Excluded files exist only in the monorepo.
- **Filter reconciliation**: Changing the exclude list auto-creates a merge commit that connects old and new histories — no force-push needed.
- **Loop prevention**: `Josh-Sync-Origin:` git trailer filters out bot commits.
- **State tracking**: orphan branch `josh-sync-state` stores JSON per target/branch.

## Dependencies

`bash >=4`, `git`, `curl`, `jq`, `yq` ([mikefarah/yq](https://github.com/mikefarah/yq) v4+), `openssh`, `rsync`

> The Nix flake bundles all dependencies automatically.

## License

MIT