# rules_apple Workspace Separation

This document explains why `rules_apple` is built in a separate Bazel workspace (`sparkle_workspace/`) and what conditions need to be met before it can be reintegrated into the main workspace.

## Background

The main workspace cannot include `rules_apple` due to transitive dependency conflicts with `rules_swift`. Multiple dependencies require different major versions of `rules_swift`:

| Dependency | rules_swift Version | Compatibility Level |
|------------|---------------------|---------------------|
| grpc | 3.x | 3 |
| flatbuffers | 2.x | 2 |
| rules_apple | 2.x | 2 |

Bzlmod's `single_version_override` can force a single version, but compatibility levels 2 and 3 are incompatible. Forcing `rules_swift` 3.x (required for grpc) breaks `rules_apple` and `flatbuffers`.

## Current Solution

The `SparklePlugin` (the only component requiring `rules_apple`) is built in an isolated workspace:

```
sparkle_workspace/
├── MODULE.bazel      # Minimal deps: apple_support, rules_apple, sparkle
├── BUILD.bazel       # Builds SparklePlugin.bundle
├── SparklePlugin.m   # Objective-C source
├── Info.plist        # Bundle metadata
└── external/
    └── BUILD.sparkle # Build file for Sparkle framework
```

### How It Works

1. **Build script**: `scripts/build_sparkle_plugin.sh` builds the plugin from the separate workspace
2. **Output**: The built `SparklePlugin.bundle` is placed in `Assets/Plugins/macOS/`
3. **CI integration**: `mac_build.yml` calls `inject_sparkle.sh` to embed Sparkle into the Mac app

The main workspace uses `single_version_override` for `rules_swift` 3.x to satisfy grpc, and includes a comment noting that `rules_apple` is intentionally excluded.

## What SparklePlugin Does

SparklePlugin is a native macOS library that:
- Initializes the [Sparkle](https://sparkle-project.org/) auto-update framework
- Exposes C functions for Unity to call via P/Invoke:
  - `SparklePlugin_Initialize`
  - `SparklePlugin_CheckForUpdates`
  - `SparklePlugin_CheckForUpdatesInBackground`
  - `SparklePlugin_IsCheckingForUpdates`
  - `SparklePlugin_GetAutomaticallyChecksForUpdates`
  - `SparklePlugin_SetAutomaticallyChecksForUpdates`
  - `SparklePlugin_IsRunningFromReadOnlyVolume`
  - `SparklePlugin_ShowDMGWarning`

## Conditions for Reintegration

To move `rules_apple` back into the main workspace, **all** of the following must be true:

### 1. rules_swift Version Alignment

Check if grpc, flatbuffers, and rules_apple all support the same `rules_swift` major version:

```bash
# Check what rules_swift version each dependency requires
bazel mod graph 2>&1 | grep -A2 "rules_swift"
```

Or check BCR directly:
- https://registry.bazel.build/modules/grpc
- https://registry.bazel.build/modules/flatbuffers
- https://registry.bazel.build/modules/rules_apple

**Test**: After updating versions, verify you can add this to MODULE.bazel without errors:
```python
bazel_dep(name = "rules_apple", version = "X.Y.Z")
```

### 2. Build Test

If the dependency can be added, test that both the main build and SparklePlugin work:

```bash
# Main workspace builds
bazel build //src/main/scala/net/eagle0/eagle:eagle_server
bazel build //src/main/cpp/net/eagle0/shardok:shardok-server
bazel build //ci:eagle_server_image

# SparklePlugin builds (would move to main workspace)
bazel build //sparkle:SparklePlugin  # After moving files
```

### 3. Files to Move

When reintegrating, move these from `sparkle_workspace/` to the main workspace:

| Source | Destination |
|--------|-------------|
| `sparkle_workspace/SparklePlugin.m` | `src/main/objc/net/eagle0/sparkle/SparklePlugin.m` |
| `sparkle_workspace/Info.plist` | `src/main/objc/net/eagle0/sparkle/Info.plist` |
| `sparkle_workspace/BUILD.bazel` | `src/main/objc/net/eagle0/sparkle/BUILD.bazel` |
| `sparkle_workspace/external/BUILD.sparkle` | (inline into MODULE.bazel http_archive) |

### 4. MODULE.bazel Changes

Add to the main MODULE.bazel:

```python
bazel_dep(name = "rules_apple", version = "X.Y.Z", repo_name = "build_bazel_rules_apple")

# Sparkle framework
http_archive(
    name = "sparkle",
    build_file_content = """...""",  # Contents from external/BUILD.sparkle
    sha256 = "...",
    url = "https://github.com/sparkle-project/Sparkle/releases/download/...",
)
```

Remove the `single_version_override` for `rules_swift` if no longer needed.

### 5. Update Build Scripts

- Update `scripts/build_sparkle_plugin.sh` to build from main workspace
- Update `scripts/build_plugins.sh` if it references the separate workspace
- Verify `mac_build.yml` still works

### 6. Cleanup

After successful integration:
```bash
rm -rf sparkle_workspace/
```

Update comments in MODULE.bazel that reference the separate workspace.

## Version History

| Date | Event |
|------|-------|
| 2026-02-04 | Separated sparkle_workspace (PR #5882) to enable Bazel 8 upgrade |
| 2026-02-05 | Upgraded to Bazel 8.5.1 (PR #5883) |

## Monitoring

Periodically check if the upstream dependencies have aligned:

1. **grpc releases**: https://github.com/grpc/grpc/releases
2. **flatbuffers releases**: https://github.com/google/flatbuffers/releases
3. **rules_apple releases**: https://github.com/bazelbuild/rules_apple/releases
4. **BCR updates**: https://registry.bazel.build/

When a new version of any of these is released, check if the `rules_swift` requirements have converged.
