[arcangelini]

Proposed changes

Embeds don't work in the Reader's comment editor, and the Embed block is hard to find. Two changes:

• A host can sign in its embed previews. The editor previews an embed by fetching labels.embedUrl without credentials, and turns any 4xx into a link. That suits a site's own public preview route, but the Reader's route answers signed-in readers only, so every lookup got a 401. mountEditor now takes an optional fetchEmbed( url ) returning a Response, and the embed block uses it in place of its own request. Left out, nothing changes. The Reader passes one that goes through its signed-in API client (Comments: Sign in the comment editor's embed previews so embeds work in the Reader wp-calypso#116348).
• /youtube finds the Embed block. Core's embed block shows up for provider searches through its variations, but this editor registers its own core/embed with no variations or keywords, so only /embed matched. It now has keywords for common providers in core's oEmbed list, plus "video" and "audio".

Related product discussion/links

• READ-775

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

No.

Testing instructions

• On a site running this branch with Jetpack Comments on, open a post's comment form and start the block editor.
• Type /youtube. The Embed block is offered. /video, /vimeo and /spotify offer it too.
• Insert it and paste a YouTube URL. The preview shows, through the site's own route as before.
• For the Reader side, see Comments: Sign in the comment editor's embed previews so embeds work in the Reader wp-calypso#116348.

Created with Claude Opus 5.5 in Claude Code.

[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 or WordPress.com Site Helper), and enable the update/comments-embed-keywords branch.
• To test on Simple, run the following command on your sandbox:

bin/jetpack-downloader test jetpack update/comments-embed-keywords

bin/jetpack-downloader test jetpack-mu-wpcom-plugin update/comments-embed-keywords

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]

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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.
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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: December 8, 2026
  • Code freeze: December 7, 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

This PR did not change code coverage!

That could be good or bad, depending on the situation. Everything covered before, and still is? Great! Nothing was covered before? Not so great. 🤷

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