Cache Action
============

A Gitea Action that caches build files as `tar.xz` archives on the runner filesystem. Simple, fast, no external dependencies.

## Branches

| Branch | Purpose |
|--------|---------|
| `restore` | Restores cache archive if it exists |
| `save` | Saves cache archive (use after build) |

## Inputs

| Input | Description | Required | Default |
|-------|-------------|----------|---------|
| `path` | Single directory to cache | No | `~/.cache/` |
| `key-prefix` | Prefix for the cache key | Yes | — |
| `key-file` | File to hash (SHA-256) for the cache key | Yes | — |

## Outputs

| Output | Description |
|--------|-------------|
| `cache-hit` | `true` if exact key match found, `false` otherwise (restore only) |

## How It Works

1. Hashes `key-file` with SHA-256, combines with `key-prefix` as `<prefix>-<hash>`
2. Stores archives at `~/.cache/.cache-store/<key>.tar.xz`
3. `restore` branch extracts the archive, `save` branch creates one

## Usage

This action must be used **twice** in your workflow:

1. **Before build** — use `@restore` to restore cache if it exists
2. **After build** — use `@save` to save the cache archive

## Rust Example

```yaml
name: Rust Build
on: push

defaults:
  run:
    shell: bash

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      # 1. Restore cache before build
      - uses: Actions/Cache@restore
        id: cache
        with:
          key-prefix: 'cargo-registry'
          key-file: 'Cargo.lock'
          path: '~/.cargo/registry'

      - name: Build
        run: cargo build --release

      # 2. Save cache after build
      - uses: Actions/Cache@save
        with:
          key-prefix: 'cargo-registry'
          key-file: 'Cargo.lock'
          path: '~/.cargo/registry'
```

## Skip Steps on Cache Hit

```yaml
name: Build with Conditional Steps
on: push

defaults:
  run:
    shell: bash

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      # 1. Restore cache
      - uses: Actions/Cache@restore
        id: cache
        with:
          key-prefix: 'rust'
          key-file: 'Cargo.lock'
          path: '~/.cargo/registry'

      - name: Fetch dependencies
        if: steps.cache.outputs.cache-hit != 'true'
        run: cargo fetch

      - name: Build
        run: cargo build --release

      # 2. Save cache
      - uses: Actions/Cache@save
        with:
          key-prefix: 'rust'
          key-file: 'Cargo.lock'
          path: '~/.cargo/registry'
```