- POST /api/me/avatar/url stores the https link (users.avatar_link) instead
of downloading it; GET /api/me/avatar and /api/users/:id/avatar answer 302
to it (no referrer). Link rules: https, no userinfo, <= 2048 chars, no
localhost or private/reserved IP literal. Upload and link replace each other.
- Settings -> Account first loads the link as an embedded image and refuses
one this browser cannot show: a picture behind a login (Mattermost's
/api/v4/users/<id>/image) gets no cookie cross-site and 401s.
- Files sidebar: each workspace under its owner's home, chevrons remembered
per browser (agenthub.files.homesOpen); ownerless ones stay flat.
