Experiment: Add Suggest Reply experiment

[Infinite-Null]

Closes: #508

Suggest Reply Experiment

Description

This PR implements the Suggest Reply experiment, which adds an AI-powered "Suggest reply" action to both the Comments admin screen and the Activity dashboard widget.

This feature allows moderators to generate contextual reply suggestions based on the comment's content, the parent post's context, and optional editorial guidelines.

Key Features

• WP Ability Integration: Registers the ai/reply-suggestion WP Ability which handles the context building and communication with the AI client.
• Interactive Modal UI:
  • Allows selecting a reply tone (Friendly, Professional, or Casual).
  • Includes a textarea for optional free-text editorial guidelines (e.g. "always mention our support email").
  • Generates and displays the AI suggestion.
• Quick Actions:
  • Use this reply: Automatically opens the WordPress inline comment reply form, populates it with the generated suggestion, and focuses the textarea.
  • Copy: Includes a transient "Copied!" button to easily grab the text for manual usage.

Testing Instructions

1. Ensure you have an AI provider connected and enabled in Settings → AI and also Suggest Reply experiment is enabled under Admin Experiments in /wp-admin/options-general.php?page=ai-wp-admin .
2. Go to the Comments screen in the WordPress admin.
3. Hover over a comment and click Suggest reply.
4. Test changing the tone and adding custom guidelines, then click Generate.
5. Click Use this reply to verify the inline reply form opens and populates correctly.
6. Click Copy to verify clipboard functionality.
7. Go to the Dashboard and repeat the tests from the Activity (Recent Comments) widget.

Screenshot/Screencast

Usage

WhatsApp.Video.2026-06-16.at.7.30.39.PM.mp4

Screen.Recording.2026-06-16.at.7.16.22.PM.mov

Error Examples

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Co-authored-by: Infinite-Null <ankitkumarshah@git.wordpress.org>
Co-authored-by: dkotter <dkotter@git.wordpress.org>
Co-authored-by: jeffpaul <jeffpaul@git.wordpress.org>

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[Infinite-Null]

Hi @jeffpaul and @dkotter,

I've completed the implementation for this experiment and updated the flow based on the feedback shared in the issue discussion.

The PR is ready for review. Thank you!