T22: Collaboration

- presence: avatars ringed in each peer's color with where they are, press to
  follow; a breathing live dot; follow mode frames the view and stops on Escape
- remote cursors and selections painted over a field from its own layout
- comment threads with replies, reactions and resolve; a marker that opens a
  thread in a bubble; a sidebar of open and resolved threads
- annotations washed in their authors' colors, notes on hover
- suggestion mode: edits become suggestions word by word; track changes shows
  them struck and underlined, to accept or reject
- sharing: invite by email with checked chips, roles, the access list and who
  the link lets in, in one dialog
- primitives::hold_focus gives a mode its own focus, shared with ZenMode
- AvatarGroup's tuck and count shared; Avatar::ring_color; TagInput::check;
  TextInput::bounds_for_range; Popover::size
- icons: smile-plus, user-plus, message-square-diff
- gallery: the Collaboration page with scripted states

tasks/ch21-30.md

@@ -55,24 +55,24 @@
 
 ## T22 Collaboration — `src/collab`
 
-- [ ] PresenceAvatars
-- [ ] RemoteCursor
-- [ ] RemoteSelection
-- [ ] CommentThread
-- [ ] CommentBubble / CommentMarker
-- [ ] CommentSidebar
-- [ ] Reply / ReactionPicker
-- [ ] Reactions
-- [ ] Annotation / Highlight
-- [ ] SuggestionMode
-- [ ] TrackChanges
-- [ ] ShareDialog
-- [ ] PermissionSelect
-- [ ] InviteInput
-- [ ] AccessList
-- [ ] ActivityLog → `data_display::ActivityFeed`
-- [ ] FollowMode
-- [ ] LiveIndicator
+- [x] PresenceAvatars
+- [x] RemoteCursor → over a `forms::TextInput`, placed where its offset sits as the field paints
+- [x] RemoteSelection → over a `forms::TextInput`, from `TextInput::bounds_for_range`
+- [x] CommentThread
+- [x] CommentBubble / CommentMarker → `collab::CommentMarker`, its thread in an `overlays::Popover`
+- [x] CommentSidebar
+- [x] Reply / ReactionPicker
+- [x] Reactions
+- [x] Annotation / Highlight → `collab::AnnotatedText`; a plain mark is `typography::Highlight`
+- [x] SuggestionMode → edits become suggestions through `collab::suggested`
+- [x] TrackChanges
+- [x] ShareDialog → with `collab::LinkAccess` for who the link lets in
+- [x] PermissionSelect
+- [x] InviteInput → a `forms::TagInput` that checks each address
+- [x] AccessList
+- [x] ActivityLog → `data_display::ActivityFeed`
+- [x] FollowMode
+- [x] LiveIndicator
 
 ## T23a AI Chat · Messages — `src/chat`