changelog-from-tags

name	changelog-from-tags
description	Update a Dart/Flutter package's CHANGELOG.md by computing changes between the previous released git tag and the current branch/HEAD. Use this whenever the user asks to “find changes since last release tag”, “generate/update release notes”, “update CHANGELOG.md”, or “what changed between versions” for a package folder in a git repo (especially Flutter/Dart packages).

changelog-from-tags

Goal

Given a package directory inside a git repo, find the previous released version tag, compute what changed since that tag (preferably scoped to the package directory), then update the package's CHANGELOG.md latest entry with accurate release notes.

Assumptions

• The package is a folder in a git repo and has:
  • pubspec.yaml
  • CHANGELOG.md
• Tags in the repo follow SemVer-ish names (e.g. 2.1.7, 2.1.7+1, 2.1.7-dev.1).

Workflow

1) Identify the target package and its current version

1. Read <package>/pubspec.yaml.
2. Record version: as currentVersion.

2) Identify the “previous released version tag”

1. List tags sorted by version descending.
   • Example:

     git -C <package> tag --list --sort=-v:refname
     

2. Prefer the latest stable tag (no -dev, -alpha, -beta, -rc), unless the user explicitly requests a pre-release comparison.
3. Confirm what tag points at HEAD (if any). If HEAD is already tagged, your diff range should usually still be previousTag..HEAD (unless user asked for tagA..tagB).

3) Collect changes since previous tag (package-scoped)

1. Gather commit list affecting only the package directory:

   git -C <package> log <previousTag>..HEAD --oneline --decorate -- .
   

2. Gather a stat summary:

   git -C <package> diff --stat <previousTag>..HEAD -- .
   

3. If needed, inspect diffs of relevant files (e.g. pubspec.yaml, platform code folders, README).

Optional helper (no extra dependencies):

If you want a single command to print the scoped commits and diffstat, run:

.agents\skills\changelog-from-tags\scripts\collect_changes.cmd <path-to-package>

4) Update CHANGELOG.md

1. Read <package>/CHANGELOG.md and identify the topmost version header.
2. Decide the target section to update:
   • If the topmost section matches currentVersion, update that section.
   • Otherwise, add a new top section ## <currentVersion> (or ## Unreleased if the repo uses that convention) and place notes there.
3. Write release notes based on actual changes between tags:
   • Prefer user-facing impact.
   • Keep bullets concise.
   • Include PR/issue links when present in commit messages or known references.
   • Avoid guessing. If the diff only changes dependency constraints/lockfiles, say so.

5) Sanity checks

• Ensure CHANGELOG.md remains valid Markdown.
• Show git diff -- <package>/CHANGELOG.md for review.

Output expectations

When done, report:

• Previous tag used (e.g. 2.1.7)
• Diff range (e.g. 2.1.7..HEAD)
• A short bullet list of what was added to the changelog
• The updated file path

Edge cases & guidance

• Monorepo tags: If tags are global but package changes are scoped, always scope logs/diffs to the package directory (-- .) to avoid unrelated changes.
• No tags: If no tags exist, treat all history as changes and create an initial changelog entry.
• Mismatch between tag and pubspec version: If pubspec.yaml version is not newer than the latest stable tag, ask the user whether to update the existing top section or create a new one.