C# Companion PR Review

The orchestrator mechanically generates the companionPr section in raw-results.json with file lists, diffs, and categories (added/changed). Your job is to:

1. Add a summary to each file item (same as upstream/interop summaries)
2. Review the diffs for correctness (see checklist below)
3. Add relatedFiles cross-links to interop files where applicable

What to Ignore

• All *Api.generated.cs files — already filtered out by check_companion.py
• Whitespace-only changes — not worth reviewing
• Comment-only changes — unless they document a behavioral change

What to Review

1. New or Changed C# Wrappers

Files in binding/SkiaSharp/ (excluding generated). Check:

• Null handling — factory methods return null on failure, constructors throw
• Parameter validation — ArgumentNullException before P/Invoke calls
• Disposal patterns — SKObject.GetObject() for owned objects, owns: false for borrowed
• Same-instance returns — methods like Subset(), ToRasterImage() may return this
  csharpCopy

  // ✅ Required pattern for same-instance returns
  var result = source.Subset(bounds);
  if (result != source)
      source.Dispose();
  

2. ABI Compatibility

SkiaSharp maintains stable ABI. Flag any:

• Modified existing method signatures (parameters, return types)
• Removed public APIs (use [Obsolete] instead)
• Default parameters in public APIs (use overloads instead)

3. New API Overloads

New overloads are safe and expected. Verify:

• They delegate to existing methods (not duplicate logic)
• Parameter names follow existing conventions (camelCase)
• SK prefix on new types/enums

4. Platform-Specific Changes

Skia updates often change platform behavior. Check:

• Font manager changes (platform-specific singletons)
• GPU context factory changes (namespace moves, new parameters)
• Build configuration changes (*.targets, *.props)

5. Test Coverage

Check tests/Tests/ for:

• New tests covering new APIs
• Updated tests reflecting changed behavior
• No skipped tests (except hardware-dependent: GPU, display)

Output Format

Add a companionPr section to the JSON report using the same sourceFile structure as upstream/interop integrity sections:

{
  "companionPr": {
    "prNumber": 3560,
    "status": "REVIEW_REQUIRED",
    "summary": "Brief overview of C# changes...",
    "recommendations": ["Action item 1", "..."],
    "added": [
      {
        "path": "binding/SkiaSharp/SKFoo.cs",
        "summary": "New wrapper for sk_foo_bar API — creates SKFoo with factory method",
        "diff": "--- a/dev/null\n+++ b/binding/SkiaSharp/SKFoo.cs\n...",
        "relatedFiles": [
          { "path": "src/c/sk_foo.cpp", "relationship": "C API implementation" }
        ]
      }
    ],
    "changed": [
      {
        "path": "binding/SkiaSharp/SKSurface.cs",
        "summary": "New DrawSurface overload with SKSamplingOptions parameter",
        "diff": "...",
        "oldDiff": "...",
        "newDiff": "...",
        "patchDiff": "..."
      }
    ],
    "unchanged": 4
  }
}

Categories:

• added — new C# files (new wrappers, new test files)
• changed — modified C# files (updated wrappers, new overloads, signature changes)
• unchanged — count of reviewed files with no changes requiring attention (skipped generated files)

Use relatedFiles to cross-link companion PR files to their interop counterparts (e.g., a C# wrapper → its C API implementation in the interop section).