Add workflow to comment on PRs when released (PRs only, not issues)

[maxisbey]

Summary

Create a workflow that comments on PRs when they are included in a release, notifying contributors that their changes are now available.

Context

We previously added apexskier/github-release-commenter in #1750, but removed it in #1758 because:

• It comments on both PRs and linked issues (via "Fixes #XXX")
• This required issues: write permission
• Commenting on issues felt unnecessary - the PR author is the one who wants notification

Requirements

• Comment on PRs included in a release with the release tag/link
• Do not comment on linked issues
• Should handle the comparison between current and previous release tags

Options

1. Roll our own workflow using GitHub's GraphQL API to find PRs between releases
2. Fork apexskier/github-release-commenter and add a skip-issues option
3. Find an alternative action that only comments on PRs

_{AI Disclaimer}

[jlowin]

This is an amazing idea

[yugannkt]

Hy @maxisbey,

I like to work on this!!

[maxisbey]

Hy @maxisbey,

I like to work on this!!

@yugannkt Oh great! Would be keen to hear how you're thinking of solving this?

[yugannkt]

Hy @maxisbey,
I like to work on this!!

@yugannkt Oh great! Would be keen to hear how you're thinking of solving this?
Hi @maxisbey!

I'm going with workflow using GitHub's REST API.

Approach

1. Trigger on release.published event
2. Find the previous release tag using git tag --sort=-version:refname
3. Use GitHub's compareCommits API to get all commits between releases
4. Extract PR numbers from commit messages using regex
5. Validate each number is actually a merged PR (not an issue) by calling github.rest.pulls.get()
6. Comment only on confirmed PRs

Why This Works Best

Issues will fail the pulls.get() API call and be automatically skipped
needs pull-requests: write, not issues: write

Implementation

The workflow explicitly:

• Checks pr.merged_at exists before adding to the list
• Catches errors when a number isn't a valid PR
• Only comments on items that pass both validations