A card window toolbar control shows and hides the trailing sidebar — View ▸ Show Sidebar joins Edit Body, Raw Source and Add Attachment

The card window's trailing attributes sidebar has always been unconditional
since m6; this adds View ▸ Show Sidebar (a checkmark toggle, ShowComments'
shape) and a matching toolbar item on the customizable card toolbar
(NSToolbar/WindowToolbarController), a fourth default beside Edit Body,
Raw Source and Add Attachment. sidebar.right for the trailing pane; one
shared animated write path (AppPreferences.setShowCardSidebar) both faces
call, structural-voice reflow with a trailing slide-and-fade transition
(Motion.cardSidebarTransition), Reduce Motion respected throughout.

CardWindowMetrics.minimumSize gains a sidebar: Bool = true parameter so a
hidden sidebar shrinks the window's floor, composing with the existing
commentsColumn parameter. The toolbar item's read/write are injectable
closures (defaulted to the real UserDefaults-backed pair) so its plumbing
is testable without touching the developer's own preferences domain.
WindowToolbarController's observation tracking only sees @Observable
reads, so a small HostedWindowController.revalidateToolbar() plus an
onChange nudge keeps the toolbar button's on-state in step with the
View-menu row's write.

Scope held narrowly to visibility, per the card: no sidebar section
reordering, no action-moving.

Claude-Session: https://claude.ai/code/session_014PtZdPwqZuqEDLc6wZMtEy

Kanban/App/FutureCommands.swift

@@ -107,6 +107,13 @@ struct FindSteppingCommands: View {
 /// The comments pane's two rows join them (11-command-nexus.md lists Show Comments and Comments
 /// Beside Body between Edit Body and Raw Source): both are live, both are app-wide persisted bits,
 /// and both are scoped to the card window (`ShowCommentsCommand`, `CommentsBesideBodyCommand`).
+///
+/// **Show Sidebar joined at the end** (05-card-window.md ▸ Composition, the toolbar-toggle card):
+/// the trailing attributes sidebar's own visibility bit, `ShowCommentsCommand`'s shape exactly and
+/// mirroring the toolbar's own item (`CardToolbar`) the way View ▸ Show Trash mirrors its toolbar
+/// twin. Appended rather than interleaved with the comments pair, to leave the block 11 already
+/// documents (Edit Body · Show Comments · Comments Beside Body · Raw Source) in the order it names —
+/// this row is additive, not a resequencing.
 struct CardViewCommands: View {
     var body: some View {
         EditBodyCommand()
@@ -114,5 +121,6 @@ struct CardViewCommands: View {
         CommentsBesideBodyCommand()
         RawSourceCommand()
         FutureCommand(title: "History")
+        ShowSidebarCommand()
     }
 }