Add changelog preview workflow for pull requests

[Copilot]

Changes

Summary:
Adds a GitHub Action workflow that generates and posts changelog previews on PRs using semantic-release dry-run. The workflow uses a wildcard branch pattern to support GitHub's PR merge refs and includes all necessary setup steps.

Issues

Related issues:

• Related to changelog preview feature request

Dependencies

Depends on:

N/A

Testing

How to test:

1. Open a PR with conventional commit messages (e.g., feat:, fix:)
2. Observe workflow run and comment posted with changelog preview
3. Push additional commits and verify comment is updated (not duplicated)
4. Test PR with non-conventional commits to see "no release" message

Test coverage:

• Manual testing completed
• Automated tests added/updated

Code Quality

Code review checklist:

• Code follows existing patterns and conventions
• Functions are small and focused
• Types are properly defined
• Error handling is appropriate
• Documentation is updated if needed

Breaking Changes

Are there any breaking changes?

• No breaking changes
• Yes, breaking changes (describe below)

Migration notes:
N/A

Additional Context

Workflow behavior:

The workflow (changelog-preview.yaml):

• Triggers on PR open/update/reopen events
• Sets up Node.js environment and installs dependencies
• Runs semantic-release with dry_run: true using a wildcard branch pattern to support any branch including GitHub's PR merge refs (refs/pull/*/merge)
• Uses marocchino/sticky-pull-request-comment@v2 for idempotent comment updates
• Shows version + release notes when commits trigger a release
• Shows guidance message when commits don't follow conventional format
• Includes error handling with informative failure messages

Key implementation details:

• Wildcard branch pattern {name: '*', prerelease: true} allows semantic-release to run on any branch
• Full git history is fetched (fetch-depth: 0) for proper semantic analysis
• Dependencies are installed via npm ci to ensure release configuration is available

Example output:

When PR contains feat: or fix: commits:

## 📝 Changelog Preview

This PR will trigger a release with version **`2.11.0`**

### Release Notes
[Generated release notes from semantic-release]

When no release will be triggered:

## 📝 Changelog Preview

ℹ️ This PR will **not** trigger a new release.

To trigger a release, ensure your commits follow the Conventional Commits format...

When workflow fails:

## 📝 Changelog Preview

⚠️ Failed to generate changelog preview. Please check the workflow logs for details.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Changelog preview</issue_title>
<issue_description>## Motivation

Would be nice to have a preview of what the changelog will look like in every PR

Proposed Solution

Create a new GitHub Action that runs on every PR whenever a new commit is pushed to it. This action should then:

• Run a semantic-release dry-run (don't publish a release, just generate a changelog for preview
• Add a comment under the PR that includes the changelog that the current PR will generate
• If there is already such comment, update it instead of adding a new one
• If possible make sure only changes for this PR will be included (feature to base branch, not to master branch), but this is optional</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Changelog preview #80

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

[github-actions]

📝 Changelog Preview

ℹ️ This PR will not trigger a new release.

To trigger a release, ensure your commits follow the Conventional Commits format with types that trigger releases (e.g., feat:, fix:, refactor:, etc.).

[Copilot]

Pull request overview

This PR adds a GitHub Actions workflow to generate and post changelog previews on pull requests using semantic-release in dry-run mode. The workflow automatically comments on PRs with either the expected changelog/version, a message indicating no release will be triggered, or an error message if the preview generation fails.

Key changes:

• New GitHub Actions workflow (changelog-preview.yaml) that triggers on PR events and uses semantic-release to generate changelog previews
• Modified release.config.cjs to support dry-run mode by conditionally disabling npm publishing based on a DRY_RUN environment variable

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 7 comments.

File	Description
.github/workflows/changelog-preview.yaml	New workflow that generates changelog previews on PRs using semantic-release dry-run mode and posts results as PR comments
release.config.cjs	Added DRY_RUN environment variable handling to conditionally disable npm publishing during dry-run executions

---

I've identified several critical and moderate issues with the implementation that need to be addressed:

1. Missing git history setup: The workflow needs fetch-depth: 0 to fetch full git history for semantic-release to properly analyze commits
2. Missing Node.js setup and dependencies: The workflow lacks steps to setup Node.js, enable corepack, and install dependencies (which are required for semantic-release plugins)
3. Branch configuration issue: The branches array configuration may not correctly identify commits to include in the changelog
4. Missing version in preview: The changelog preview message doesn't display the version number that will be released
5. String boolean handling: The dryRun environment variable check in release.config.cjs doesn't properly handle string-to-boolean conversion
6. Inaccurate documentation: Comments in the workflow describe behavior that doesn't match the actual implementation

These issues should be resolved to ensure the workflow functions correctly and provides accurate changelog previews.

[Copilot]

The branches configuration uses github.head_ref which only contains the branch name (e.g., 'feature-branch'), but semantic-release needs to analyze commits reachable from this ref. Since the workflow checks out the PR head and semantic-release analyzes from the base branch, this configuration may not correctly identify which commits to include in the changelog. Consider using a wildcard pattern like {name: '*', prerelease: true} to allow semantic-release to work with any branch, or ensure the base branch is properly configured for comparison.

Suggested change

	'master',
	'${{ github.head_ref }}'
	"master",
	{ "name": "*", "prerelease": true }