A link preview's link and image come from attributes on the message body,
which the composer fills in from the unfurl the server performed. A body
written by hand can put anything in those attributes, and the preview
partial rendered them as they were.
Keep the link and the image only when they parse as absolute http or https
URLs, so nothing in a message body can aim either one at another scheme or
at a path on this Campfire, and render the title and the description as
text.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0186eyzivcTn6wqjEE4Wnxdt
Rosa Gutierrez
Kevin McConnell