[bug]: Issue-update emails show broken "None" / raw TipTap comment boxes

Is there an existing issue for this?

• I have searched the existing issues

Current behavior

Issue-update notification emails often render a Comments section that looks broken and unprofessional:

1. Literal None text boxes (from deleted comments)
2. Short status-like text such as UPDATE in plain white boxes that look like form controls
3. Raw TipTap custom elements (mention-component, image-component) that email clients cannot render

Screenshot description: EQA-6 updates email → Comments shows two white boxes labeled UPDATE and None under the actor name, instead of a real comment body.

Root cause

Confirmed on self-hosted CE against production activity/email logs:

1. delete_comment_activity creates an activity with field=comment, verb=deleted, and no new_value/old_value (they stay SQL NULL).
2. notification_task serializes with str(issue_activity.get("new_value")) → the Python string "None".
3. create_payload in email_notification_task treats any truthy string as content, so "None" is appended to comment.new_value.
4. When a comment is created and quickly deleted (or batched in the same email window), the email template iterates:

{% for actor_comment in comment.actor_comments.new_value %}
  <p> {{ actor_comment|safe }} </p>
{% endfor %}

and renders both the real HTML and the literal None.

5. Separately, only mentions were run through process_html_content; regular comments were injected raw, so TipTap nodes never convert for email clients.

Reproduced payload (EQA-6, sent 2026-08-01 13:05 UTC):

{
  "comment": {
    "old_value": ["None"],
    "new_value": [
      "<p ...><strong>UPDATE</strong></p>",
      "None"
    ]
  }
}

Expected behavior

• Deleted comments must not appear as None (or at all) in email bodies
• Comments in email should show readable text (mentions as @name, images as a placeholder)
• Empty create/delete-only batches should not send a content-less “Comments” email

Steps to reproduce

1. Enable email notifications for issue comments
2. Add a short comment on an issue (e.g. UPDATE)
3. Immediately delete that comment (or delete any comment so a deleted activity is logged)
4. Wait for the stacked issue-update email
5. Observe Comments section: boxes with the comment text and/or None

Environment

• Plane CE self-hosted (v1.3.x / current preview)
• apps/api/plane/bgtasks/email_notification_task.py
• apps/api/plane/bgtasks/notification_task.py
• Template: apps/api/templates/emails/notifications/issue-updates.html ({{ actor_comment|safe }})

Related

• #9218 — Stored XSS via the same |safe comment path (security; complementary)
• #8673 — poor TEXT multipart alternative (related quality)

Anything else?

Happy to open a PR with:

• str(None) → "" when building email logs
• skip verb=deleted comment/mention activities in create_payload
• filter empty / "None" values
• process comment HTML for email (mentions + image/embed placeholders)
• unit test reproducing the EQA-6 payload shape

Start with apps/api/plane/bgtasks/notification_task.py and email_notification_task.py, then inspect apps/api/templates/emails/notifications/issue-updates.html and reproduce the EQA-6 payload shape. Add a unit test covering deleted and TipTap comment content. Done means deleted or empty comments do not produce a Comments section, while remaining comments render readable mentions and image placeholders.