Description

As asynchronous collaboration evolves following on from the work in WordPress 6.9 (see #66377), it’s important that users can be notified when activity occurs in Note threads they care about. Currently, there’s no built-in mechanism for users to receive updates when:

• They are @mentioned in a Note
• Someone replies in a thread they’ve participated in
• They follow or are otherwise subscribed to Notifications on a specific post or Note thread

Without a notification system, users have to manually revisit posts to check for new Notes, which disrupts collaboration and limits real-world usability.

Potential Solution

Introduce a Notifications API and initial implementation for email-based notifications, inspired by the commenting experience in tools like Google Docs.

Goals

• When a user is mentioned (@username), they receive an email notification linking directly to the Note.
• When a user replies in a Note thread, previous participants are notified of the new reply.
• When a user follows or subscribes to a post or Note thread, they receive notifications for future replies or resolution events.
• Include the ability to unsubscribe or manage notification preferences (post-level or site-level).

Extensibility

Expose hooks and filters to allow developers to integrate notifications to other channels (e.g., Slack, WordPress mobile app, custom webhooks).

Example hook ideas:

do_action( 'block_comment_notification_sent', $comment_id, $recipients, $channel );
apply_filters( 'block_comment_notification_channels', $channels );

Use Cases to Consider

1. Editor Mentions Reviewer

• An editor requests input by typing @alex in a Note.
• Alex receives an email with a link that jumps directly to the Note in context, ideally including context from other replies in that Note thread, even more optimally including context of what's being referenced in the editor from the Note.

2. Team Collaboration on Drafts

• Multiple contributors are reviewing a post draft.
• Each person who adds or replies in a thread automatically follows it and gets notified of new replies.

3. Author Follows Feedback Thread

• A post author chooses to “Follow thread” for feedback from an editor.
• They get notifications when the thread is responded to, resolved, and reopened.

4. Cross-Channel Integrations

• A site uses a Slack integration to route new Notes or mentions to a team channel.
• Notifications are still handled via email by default, but Slack messages come through using the same hooks.

5. Mobile Notification Support

• A user with the WordPress mobile app installed can receive native push notifications for mentions or replies via an integration layer using the same notification events. A related concept would be a WordPress PWA app providing browser-based notifications for Note updates.

Open Questions

1. Should following/subscription be implicit (e.g., automatically follow threads you respond in) or explicit (user clicks “Follow”)?
2. How should Notifications be grouped or throttled for high-activity threads (batch vs real-time)?
3. Should Notification templates live in Gutenberg or in core?
4. How might this align or integrate with existing WordPress notification systems (or other external components like a separate email delivery service)?

Next Steps

• Start with email notifications via wp_mail() to validate UX and flow.
• Define a Notification registry or event model for events like block_comment_added, block_comment_resolved, block_comment_reopened, etc.
• Add a user-facing UI for managing Notification preferences in the Notes sidebar, editor settings, and/or WP Admin settings (e.g. User profile?).
• Document available actions and filters for third-party integrations.