Implementation plan

Related note from issue OD-2989: since mentions span projects, expose a cross-project surface under Global Views.

Current behavior

Mentions today are membership flags only (IssueMention / PullRequestMention / CodeCommentMention, unique per entity+user). They drive mentioned me queries, authorize/watch side effects, and "(Mentioned You)" emails, but have no timestamp, source comment, or seen/unread state. The existing "Mentioned me" saved query is therefore not enough for an inbox with deep links.

This issue stays narrower than issue OD-1995 (general notification center).

Proposed design

1. New MentionNotification entity (server-core)

Keep existing mention join tables for query/auth/watch. Add a separate inbox row per mention event:

• Recipient user, actor, date
• Seen flag / seen date
• Target type + ids needed to open the right page with comment anchor (issue / pull request / code comment)
• Indexes suitable for (user, seen, date) listing

Write rows from existing mention handling in IssueNotificationManager (and PR / code-comment managers in the same feature or a follow-up). Prefer one notification per mentioning event even if the join-table mention already exists, so re-mentions stay visible.

2. Topbar dropdown (primary UX)

Mirror the Alerts dropdown in LayoutPage (topbar-right):

• Icon + unread badge
• Opening the dropdown marks listed items as seen
• Row click navigates via UrlService to the entity URL with comment anchor
• Live refresh via the same observer/websocket pattern as alerts

3. Global Views page (cross-project)

Add a Mentions entry under Global Views (main menu), with a cross-project list page in the same family as ~issues / ~pulls:

• Shows the current user's mention notifications across projects
• Deep-links to the mentioning comment
• Complements the dropdown (dropdown = recent/unread; page = fuller history while retained)

4. Cleanup

Daily scheduled task (same idea as chat retention): delete seen notifications older than about 14 days.

5. Nice-to-haves (can be follow-ups)

• Profile setting (near Notify Own Events) to enable/disable mention emails
• First-class PR and code-comment mentions in the same table/UI

Out of scope here

• Full notification center / watch / build bells (issue OD-1995)
• Replacing email with in-app-only delivery

Suggested order

1. Entity + service + write path for issue mentions
2. Topbar dropdown + mark-seen + cleanup
3. Global Views list page + menu entry
4. PR/code-comment coverage + optional email preference

Please review/adjust before implementation.

@robin I didn't realize that this change may require schema modification and event-based actions.

What are your thoughts on how to achieve this? Is there an existing framework for event-based actions within OneDev server?

I am thinking of addressing this as part of OD-2115