[Website] Fix plugin-proxy artifact lookup for busy repos

[akirk]

Motivation for the change, related issues

The plugin-proxy was failing with artifact_not_found when trying to fetch GitHub Actions artifacts from repositories with high workflow activity (e.g., Gutenberg).

For example, @getdave ran into this in his call for testing: https://make.wordpress.org/test/2026/01/27/call-for-testing-customizable-navigation-mobile-overlays/

Which uses this URL https://href.li/?https://playground.wordpress.net/?blueprint-url=https://gist.githubusercontent.com/getdave/6feb0e42612912a25cec599320e67766/raw/78004dc70b666b9c82c639c49340159a629788fe/blueprint-gutenberg-experiment.json&gutenberg-branch=trunk

The gutenberg-branch=trunk tries to fetch the build artifact using a URL like this:

https://playground.wordpress.net/plugin-proxy.php?org=WordPress&repo=gutenberg&workflow=Build%20Gutenberg%20Plugin%20Zip&artifact=gutenberg-plugin&branch=trunk

The issue: The proxy used the generic /repos/{org}/{repo}/actions/runs?branch={branch} endpoint which returns only 30 results by default. For repos like Gutenberg where "Props Bot" runs very frequently, it would dominate the first page of results, pushing the "Build Gutenberg Plugin Zip" workflow runs out of view.

Implementation details

Changed the artifact lookup to:

1. First fetch all workflows from /repos/{org}/{repo}/actions/workflows
2. Find the workflow matching the requested name
3. Query that specific workflow's runs via /repos/{org}/{repo}/actions/workflows/{workflow_id}/runs?branch={branch}

This ensures we always find runs for the requested workflow regardless of how frequently other workflows run.

Testing Instructions (or ideally a Blueprint)

Test the plugin proxy endpoint locally:

cd packages/playground/website/public
GITHUB_TOKEN=<your-token> php -S localhost:8080

Then verify the Gutenberg artifact can be fetched:

curl 'http://localhost:8080/plugin-proxy.php?org=WordPress&repo=gutenberg&workflow=Build%20Gutenberg%20Plugin%20Zip&artifact=gutenberg-plugin&branch=trunk&verify_only'

Should return HTTP 200 instead of the previous {"error":"artifact_not_found"}.

[adamziel]

If the API response is sorted by "most recent", this is good to go

[getdave]

I tested this locally according to instructions.

Results

###On trunk (before fix): ❌
HTTP Status: 400 Bad Request
Response: {"error":"artifact_not_found"}
Issue: The generic /actions/runs?branch=trunk endpoint returns only 30 results by default. With Gutenberg's high workflow activity (especially frequent "Props Bot" runs), the "Build Gutenberg Plugin Zip" workflow gets pushed out of the first page of results.

###On fix/plugin-proxy-workflow-lookup (after fix): ✅
HTTP Status: 200 OK
Response: Success (artifact found)
Solution: The fix first fetches all workflows, finds the specific workflow ID for "Build Gutenberg Plugin Zip", then queries only that workflow's runs. This ensures the correct workflow is always found regardless of other workflow activity.

Conclusion

LGTM 🚀

[adamziel]

Merging and deploying to help the users impacted by this. Let's still confirm the API endpoint returns the most recent runs first