fix(chats): use a dedicated empty message

Show a localized Chats-specific empty state instead of reusing the project workspace session message.

packages/ui/src/components/session/SessionSidebar.tsx

@@ -1790,10 +1790,11 @@ const SessionSidebarComponent: React.FC<SessionSidebarProps> = ({
       folderScopeKey: chatsRoot,
       folderScopes,
       draftTarget: 'chat',
+      emptyMessage: t('sessions.sidebar.activity.chatsEmpty'),
       sessions: items.map((item) => item.node),
     };
     return renderGroupSessions(group, 'managed-chats', null, true);
-  }, [homeDirectory, renderGroupSessions, renderSessionNode]);
+  }, [homeDirectory, renderGroupSessions, renderSessionNode, t]);
 
   const topContent = React.useMemo(
     () => (!isVSCode && !hasSessionSearchQuery && hasActivitySectionItems) ? (

packages/ui/src/components/session/sidebar/DOCUMENTATION.md

@@ -16,6 +16,7 @@
 - Root session menus can quickly create a worktree from the session directory's current branch and move the full session subtree there while idle.
 - Managed Chats never offer the worktree-move action in either the sidebar row menu or the active-session header menu because their directories are not project repositories.
 - Managed Chats use the shared Chats root as their folder scope. Their activity section renders the normal folder tree, and sessions created from a Chats folder are assigned back to that root-scoped folder after their date/session directory materializes. Per-session folder scopes created by older builds remain visible for compatibility.
+- An empty Chats section says that there are no chats yet; it never reuses the project/workspace empty message.
 - The New session keyboard command inherits the active materialized session directory. Explicit sidebar entry points, including the top New session row and the Chats `+`, open a fresh managed Chat draft instead.
 - The new-worktree keyboard command is a silent no-op while a managed Chat draft is open. It must not retarget that draft to the active project or show a Git/worktree error because Chats never participate in worktrees.
 - Directory loading is demand-driven: the sidebar publishes one complete priority plan for all known project/worktree directories, while the sync layer owns bounded execution.

packages/ui/src/components/session/sidebar/SessionGroupSection.tsx

@@ -1056,7 +1056,7 @@ function SessionGroupSectionBase(props: Props): React.ReactNode {
               )
               : bootstrapFailureNotice
                 ? bootstrapFailureNotice
-            : t('sessions.sidebar.group.empty.noSessionsInWorkspace')}
+            : group.emptyMessage ?? t('sessions.sidebar.group.empty.noSessionsInWorkspace')}
         </div>
       ) : null}
       {totalSessions > 0 && bootstrapFailureNotice ? (

packages/ui/src/components/session/sidebar/types.ts

@@ -30,6 +30,7 @@ export type SessionGroup = {
    */
   folderScopes?: SessionGroupFolderScope[];
   draftTarget?: 'chat' | 'project';
+  emptyMessage?: string;
   sessions: SessionNode[];
 };