feat(chats): add managed projectless chat sessions

Create projectless chat sessions under a managed, date-scoped Chats directory and clean abandoned or deleted session folders.

Add Chats to sidebar state, startup cache, shared context, and Electron Mini Chat while keeping VS Code project-only. Resolve managed chat directories to one server-side memory owner and document the runtime contracts.

packages/ui/src/components/layout/Header.tsx

@@ -22,6 +22,8 @@ import { useSessionUIStore } from '@/sync/session-ui-store';
 import { useSessionWorktreeStore } from '@/sync/session-worktree-store';
 import { formatSessionWorktreeBadge } from '@/sync/session-worktree-contract';
 import { buildSessionMessageRecordsSnapshot, useDirectoryStore, useGlobalSessionStatus, useSessionMessagesResolved } from '@/sync/sync-context';
+import { useDirectoryStore as useAppDirectoryStore } from '@/stores/useDirectoryStore';
+import { isChatDirectoryForHome } from '@/lib/chatDirectories';
 import { useSync } from '@/sync/use-sync';
 import { useProjectsStore } from '@/stores/useProjectsStore';
 import { useQuotaAutoRefresh, useQuotaStore } from '@/stores/useQuotaStore';
@@ -1052,6 +1054,10 @@ export const Header: React.FC<HeaderProps> = ({
     }
     return normalize(state.newSessionDraft.bootstrapPendingDirectory ?? state.newSessionDraft.directoryOverride ?? '');
   });
+  const draftTarget = useSessionUIStore((state) => state.newSessionDraft.target);
+  const draftProjectId = useSessionUIStore((state) => state.newSessionDraft.selectedProjectId);
+  const selectedSessionDirectory = useSessionUIStore((state) => state.currentSessionDirectory);
+  const homeDirectory = useAppDirectoryStore((state) => state.homeDirectory);
 
   const openDirectory = React.useMemo(() => {
     return worktreeDirectory || sessionDirectory || draftDirectory;
@@ -1080,10 +1086,13 @@ export const Header: React.FC<HeaderProps> = ({
 
   const gitBranchForDirectory = useGitBranchLabel(openDirectory || null);
   const currentBranchLabel = gitBranchForDirectory || currentSessionWorktreeBranch || catalogWorktreeBranch;
+  const isChatContext = isNewSessionDraftOpen
+    ? draftTarget === 'chat'
+    : isChatDirectoryForHome(sessionDirectory || selectedSessionDirectory, homeDirectory);
 
   // Whether the title carries a second line under it. Hoisted because the
   // session menu's vertical alignment depends on the same answer.
-  const showHeaderMetaRow = !workStatusPanelVisible
+  const showHeaderMetaRow = !isChatContext && !workStatusPanelVisible
     && Boolean(activeProjectLabel || currentBranchLabel || (!isNewSessionDraftOpen && worktreeBadgeKind));
 
 
@@ -1423,14 +1432,14 @@ export const Header: React.FC<HeaderProps> = ({
 
   const handleOpenDraftMiniChat = React.useCallback(() => {
     void invokeDesktop('desktop_open_draft_mini_chat_window', {
-      directory: normalize(openDirectory || activeProject?.path || ''),
-      projectId: activeProject?.id ?? null,
+      directory: isChatContext ? '' : draftDirectory,
+      projectId: isChatContext ? null : draftProjectId,
       apiBaseUrl: getRuntimeApiBaseUrl(),
       clientToken: getRuntimeBearerTokenSync(),
     }).catch((error) => {
       console.warn('[header] failed to open draft mini chat window', error);
     });
-  }, [activeProject?.id, activeProject?.path, openDirectory]);
+  }, [draftDirectory, draftProjectId, isChatContext]);
 
   const handleOpenCurrentMiniChat = React.useCallback(() => {
     if (isNewSessionDraftOpen) {
@@ -1443,13 +1452,13 @@ export const Header: React.FC<HeaderProps> = ({
     }
     void invokeDesktop('desktop_open_session_mini_chat_window', {
       sessionId: currentSessionId,
-      directory: normalize(openDirectory || activeProject?.path || ''),
+      directory: sessionDirectory || normalize(selectedSessionDirectory || '') || worktreeDirectory,
       apiBaseUrl: getRuntimeApiBaseUrl(),
       clientToken: getRuntimeBearerTokenSync(),
     }).catch((error) => {
       console.warn('[header] failed to open session mini chat window', error);
     });
-  }, [activeProject?.path, currentSessionId, handleOpenDraftMiniChat, isNewSessionDraftOpen, openDirectory]);
+  }, [currentSessionId, handleOpenDraftMiniChat, isNewSessionDraftOpen, selectedSessionDirectory, sessionDirectory, worktreeDirectory]);
 
   const handleOpenContextPanel = React.useCallback(() => {
     const directory = normalize(openDirectory || '');