Related Posts: Add WordPress Abilities API integration

[dsas]

Fixes #

Proposed changes:

• Register Jetpack Related Posts as a discoverable ability via the WordPress Abilities API (WP 6.9+)
• Expose a jetpack/get-related-posts ability that returns related post data (title, URL, excerpt, date, author, context) for a given post ID
• Uses Jetpack_RelatedPosts::init_raw() to avoid DOM/asset side effects

Other information:

• Have you written new tests for your changes, if applicable?
• Have you checked the E2E test CI results, and verified that your changes do not break them?
• Have you tested your changes on WordPress.com, if applicable (if so, you'll see a generated comment below with a script to run)?

Jetpack product discussion

Does this pull request change what data or activity we track or use?

No.

Testing instructions:

• Ensure WordPress 6.9+ and Jetpack with Related Posts module active
• Verify the ability appears in the REST API: GET /wp-json/wp-abilities/v1/abilities (look for jetpack/get-related-posts)
• Execute the ability from the browser console on the Gutenberg editor screen:

await wp.apiFetch({
  path: wp.url.addQueryArgs('/wp-abilities/v1/abilities/jetpack/get-related-posts/run', {
    input: { post_id: 16 }
  }),
});

• Verify error handling: omit post_id (expect missing_post_id error), use non-existent ID (expect post_not_found error)
• Confirm no errors on WP < 6.9 (abilities registration is guarded by function_exists() checks)

Changelog

• Generate changelog entries for this PR (using AI).

[github-actions]

Are you an Automattician? Please test your changes on all WordPress.com environments to help mitigate accidental explosions.

• To test on WoA, go to the Plugins menu on a WoA dev site. Click on the "Upload" button and follow the upgrade flow to be able to upload, install, and activate the Jetpack Beta plugin. Once the plugin is active, go to Jetpack > Jetpack Beta, select your plugin (Jetpack), and enable the try/abilities-similar-posts branch.
• To test on Simple, run the following command on your sandbox:

bin/jetpack-downloader test jetpack try/abilities-similar-posts

Interested in more tips and information?

• In your local development environment, use the jetpack rsync command to sync your changes to a WoA dev blog.
• Read more about our development workflow here: PCYsg-eg0-p2
• Figure out when your changes will be shipped to customers here: PCYsg-eg5-p2

[github-actions]

Thank you for your PR!

When contributing to Jetpack, we have a few suggestions that can help us test and review your patch:

• ✅ Include a description of your PR changes.
  
• ✅ Add a "[Status]" label (In Progress, Needs Review, ...).
  
• ✅ Add testing instructions.
  
• ✅ Specify whether this PR includes any changes to data or privacy.
  
• ✅ Add changelog entries to affected projects
  

This comment will be updated as you work on your PR and make changes. If you think that some of those checks are not needed for your PR, please explain why you think so. Thanks for cooperation 🤖

---

Follow this PR Review Process:

1. Ensure all required checks appearing at the bottom of this PR are passing.
2. Make sure to test your changes on all platforms that it applies to. You're responsible for the quality of the code you ship.
3. You can use GitHub's Reviewers functionality to request a review.
4. When it's reviewed and merged, you will be pinged in Slack to deploy the changes to WordPress.com simple once the build is done.

If you have questions about anything, reach out in #jetpack-developers for guidance!

---

Jetpack plugin:

The Jetpack plugin has different release cadences depending on the platform:

• WordPress.com Simple releases happen as soon as you deploy your changes after merging this PR (PCYsg-Jjm-p2).
• WoA releases happen weekly.
• Releases to self-hosted sites happen monthly:
  • Scheduled release: March 31, 2026
  • Code freeze: March 31, 2026

If you have any questions about the release process, please ask in the #jetpack-releases channel on Slack.

[jp-launch-control]

Code Coverage Summary

Coverage changed in 2 files.

File	Coverage	Δ%	Δ Uncovered
projects/plugins/jetpack/modules/related-posts.php	12/15 (80.00%)	3.08%	0 💚
projects/plugins/jetpack/modules/related-posts/jetpack-related-posts.php	223/844 (26.42%)	11.85%	-100 💚

1 file is newly checked for coverage.

File	Coverage
projects/plugins/jetpack/modules/related-posts/class-related-posts-abilities.php	78/99 (78.79%) 💚

Full summary · PHP report · JS report