Adds skill for generating engine diffs for new releases. - #189869

Let's be crisp about the formats you want to accept here. Are they tags?

Also I think for now given how infrequently we expect this skill to be used we should say that the skills should be run only when called out by name.

If you want to leave it with the prompts I would ask that you move the skill to a agent for the engine team "engine-agent"

Let's be crisp about the formats you want to accept here. Are they tags?

That's part of the value I see this skill providing. There is a lot of knowledge that goes into determining a git ref from a semantic version name.

Also I think for now given how infrequently we expect this skill to be used we should say that the skills should be run only when called out by name.

Sounds good, done.

This summary section is both common when you ask Gemini based models to author a skills and also un-needed token bloat. Information here needs to be in the description or deleted.

Done

Non blocking but I would encourage you to author this not as a script but as a dart package that has tests. Especially given the complexity

I want the skill and the script to evolve together. Maybe it will evolve into a script that will have independent value at some point.

If your script is doing the bulk of the work and not the llm running the skill is the script alone valuable enough to check on without the skill?

The llm provides 2 valuable features:

1. Mapping semantic names to git references, example "version 3.47" means 3.47.0-0.1.pre today. It will be something different in the future.
2. Summarizes and characterizes the changes outlined by the script. The script is there just to provide a deterministic base for it to summarize from.

I would expect the llm to be used more in this skill to help with the identification and summarization

It is providing summarizations, I wanted it to generate a paper trail too though so that it's auditable.

The way I used it was to read the summarization, then look through the generated files to get more information. Wether the summary was helpful was hit or miss and I hope we can refine it.

The class CommitInfo (and other public members in this file, such as ReleaseAnalysis, findRepoRoot, runGit, etc.) lacks documentation comments. According to the repository style guide, all public members should have documentation using ///.

The list of candidates contains duplicate entries when cleanVersion starts with '3.' (e.g., 'origin/flutter-3.47-candidate.0' and 'flutter-3.47-candidate.0' are added twice). Using a Set<String> instead of a List<String> is a cleaner and more efficient way to automatically eliminate duplicates.

The categorizeCommit function has several redundancies and potential false positives:

1. Redundancies:

   • title.startsWith('Roll Skia') etc. are redundant because lower.contains('roll skia') is already checked.
   • lower.contains('[android]') is redundant because lower.contains('android') is checked.
   • Same for [ios], [macos], [darwin], [windows], [linux].

2. False Positives:

   • lower.contains('flow') matches "workflow" (very common in CI/tooling), causing CI commits to be miscategorized under "Impeller & Graphics Rendering".
   • lower.contains('format') matches "information" and "transformation", causing general commits to be miscategorized under "Build System, CI & Tooling".

Using RegExp with word boundaries (\b) resolves these false positives elegantly.

String categorizeCommit(String title) {
  final String lower = title.toLowerCase();

  if (lower.contains('roll skia') ||
      lower.contains('roll dart sdk') ||
      lower.contains('roll icu') ||
      lower.contains('roll harfbuzz') ||
      lower.contains('roll angle')) {
    return '🔄 Dependency Rolls';
  }

  if (lower.contains('impeller') ||
      lower.contains('ubersdf') ||
      lower.contains('flutter gpu') ||
      lower.contains('display_list') ||
      lower.contains('displaylist') ||
      lower.contains('vulkan') ||
      lower.contains('metal') ||
      lower.contains('opengl') ||
      lower.contains('shader') ||
      lower.contains('render') ||
      RegExp(r'\bflow\b').hasMatch(lower)) {
    return '🚀 Impeller & Graphics Rendering';
  }

  if (lower.contains('web_ui') ||
      lower.contains('web_sdk') ||
      lower.contains('wasm') ||
      lower.contains('skwasm') ||
      lower.contains('html') ||
      lower.contains('canvaskit') ||
      RegExp(r'\bweb\b').hasMatch(lower)) {
    return '🌐 Web Engine & Wasm';
  }

  if (lower.contains('android') ||
      lower.contains('agp') ||
      lower.contains('gradle') ||
      lower.contains('embedding/engine')) {
    return '📱 Android Embedding';
  }

  if (lower.contains('darwin') ||
      lower.contains('ios') ||
      lower.contains('macos') ||
      lower.contains('xcode') ||
      lower.contains('metalview')) {
    return '🍎 iOS & macOS Embeddings';
  }

  if (lower.contains('windows') ||
      lower.contains('linux') ||
      lower.contains('win32') ||
      lower.contains('embedder')) {
    return '🪟 Windows & Linux Desktop Embeddings';
  }

  if (lower.contains('semantics') ||
      lower.contains('accessibility') ||
      lower.contains('typography') ||
      lower.contains('txt') ||
      lower.contains('font') ||
      lower.contains('text input') ||
      lower.contains('autofill') ||
      RegExp(r'\ba11y\b').hasMatch(lower)) {
    return '🔤 Text, Typography & Accessibility';
  }

  if (lower.contains('build.gn') ||
      lower.contains('tools') ||
      lower.contains('testing') ||
      lower.contains('header_guard') ||
      lower.contains('license') ||
      RegExp(r'\bci\b').hasMatch(lower) ||
      RegExp(r'\bformat\b').hasMatch(lower)) {
    return '🛠️ Build System, CI & Tooling';
  }

  return '⚙️ Core Runtime & Shell';
}