Mattermost Team Edition v11.7.2, self-hosted via Docker, PostgreSQL 15
Description:
When a post contains a permalink to another post, the preview is generated correctly at creation time. However, if the referenced post is later edited, the preview shown in the linking post does not update to reflect the changes — it stays frozen at the original content.
This worked correctly in v10. After upgrading to v11 the previews no longer self-update.
Steps to reproduce:
- Create Post A with some text
- Create Post B containing a permalink to Post A
- Verify the preview of Post A appears correctly in Post B
- Edit Post A to change its content
- Observe that Post B still shows the old preview of Post A
Expected behavior:
The preview in Post B updates to reflect the current content of Post A, as it did in v10.
Actual behavior:
The preview remains stale until the page is manually reloaded, and even after reload it still shows the old content.
Additional context:
Based on investigation, this appears to be related to the security-driven cleanup of embed data from WebSocket payloads (PR #27763, MM-59078). The post_edited WebSocket event no longer carries updated embed content, so clients have no way to refresh the preview without a full re-fetch. The fix for the forward direction (embed data arriving via WebSocket on post creation) was addressed, but the refresh-on-edit case appears to be an unaddressed regression.
IA Helped me describe the problem in a clearer way.