feat(workspace): journal panel toggle, view kept across tabs, sections nest under headings

- the journal opens as a framed panel and closes on a second click,
  returning to the previous note; journal state and the last regular note
  survive tab switches, the fallback note is never a journal day
- pasted and imported markdown nests content under its heading (H2 below
  H1), Enter on a heading creates a child, '- ' / '* ' / '+ ' start a bullet

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/src/features/workspace/WorkspaceView.tsx

@@ -53,7 +53,7 @@ import { PresenceAvatars } from './PresenceAvatars';
 import { TrashView } from './TrashView';
 import { JournalView } from './JournalView';
 import { JournalCalendar } from './JournalCalendar';
-import { isJournalEnabled, todayISO } from '../../lib/journal';
+import { isJournalEnabled, readWorkspaceSession, todayISO, writeWorkspaceSession } from '../../lib/journal';
 import { MergeDialog } from './MergeDialog';
 import { CountBadge } from '../../components/CountBadge';
 import { extractHashtags } from '../../lib/hashtags';
@@ -319,10 +319,15 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
     return list.sort((a, b) => b.count - a.count || a.tag.localeCompare(b.tag));
   }, [docs, serverTagsSummary]);
 
-  const [selectedDocId, setSelectedDocId] = useState<string | null>(initialDocId || null);
+  const [selectedDocId, setSelectedDocId] = useState<string | null>(
+    initialDocId || readWorkspaceSession().docId || null
+  );
   const [targetBlockId, setTargetBlockId] = useState<string | null>(initialBlockId || null);
   const [newlyCreatedDocId, setNewlyCreatedDocId] = useState<string | null>(null);
-  const [subView, setSubView] = useState<WorkspaceSubView>('editor');
+  // Journal open and the last regular note survive switching to other tabs (the view remounts)
+  const [subView, setSubView] = useState<WorkspaceSubView>(() =>
+    !initialDocId && isJournalEnabled() && readWorkspaceSession().journal ? 'journal' : 'editor'
+  );
   const [trash, setTrash] = useState<TrashedDocument[]>([]);
   // Bumped after a restore so the open editor reloads the note without the trash banner
   const [editorNonce, setEditorNonce] = useState(0);
@@ -398,7 +403,9 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
     }
     setShowNewFolderModal(true);
   };
-  const [mobileShowDetail, setMobileShowDetail] = useState<boolean>(Boolean(initialDocId));
+  const [mobileShowDetail, setMobileShowDetail] = useState<boolean>(
+    Boolean(initialDocId) || subView === 'journal'
+  );
   const [isSidebarCollapsed, setIsSidebarCollapsed] = useState<boolean>(() => {
     try {
       return localStorage.getItem('mindsift:workspace_sidebar_collapsed') === 'true';
@@ -473,12 +480,14 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
 
   const loadWorkspaceData = useCallback(async () => {
     try {
-      const [docsRes, foldersRes, sharedFoldersRes, tagsRes] = await Promise.all([
+      const [docsRes, foldersRes, sharedFoldersRes, tagsRes, journalRes] = await Promise.all([
         api.getDocuments(),
         api.getFolders(),
         api.getSharedFolders().catch(() => []),
         api.getWorkspaceTags().catch(() => []),
+        isJournalEnabled() ? api.getJournal().catch(() => [] as JournalDay[]) : Promise.resolve([] as JournalDay[]),
       ]);
+      const journalIds = new Set(journalRes.map((d) => d.docId));
       setDocs(docsRes);
       setFolders(foldersRes);
       setSharedFolders(sharedFoldersRes);
@@ -488,7 +497,9 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
         if (prevId && docsRes.some((d) => d.id === prevId)) {
           return prevId;
         }
-        return docsRes.length > 0 ? docsRes[0].id : null;
+        // Not a journal day: those open in the journal
+        const first = docsRes.find((d) => !(d.isOwner && journalIds.has(d.id)));
+        return first ? first.id : null;
       });
     } catch {
       // ignore
@@ -620,6 +631,16 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
     setMobileShowDetail(true);
   }, [reloadJournal]);
 
+  // A second click closes the journal and shows the regular note again
+  const toggleJournal = useCallback(() => {
+    if (subView === 'journal') {
+      setSubView('editor');
+      setSelectedDocId((prev) => prev ?? treeDocsRef.current[0]?.id ?? null);
+    } else {
+      openJournal();
+    }
+  }, [subView, openJournal]);
+
   const openTrash = useCallback(() => {
     reloadTrash();
     setSubView('trash');
@@ -1004,6 +1025,12 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
     () => (journalDocIds.size ? docs.filter((d) => !(d.isOwner && journalDocIds.has(d.id))) : docs),
     [docs, journalDocIds]
   );
+  const treeDocsRef = useRef(treeDocs);
+  treeDocsRef.current = treeDocs;
+
+  useEffect(() => {
+    writeWorkspaceSession({ journal: subView === 'journal', docId: selectedDocId });
+  }, [subView, selectedDocId]);
 
   const allFolderPaths = useMemo(() => {
     const set = new Set<string>(folders);
@@ -1569,28 +1596,31 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
 
         {/* Scrollable Navigation Tree */}
         <div className="flex-1 overflow-y-auto p-2 space-y-3">
-          {/* Journal on top; while open, its calendar stays below it */}
+          {/* Journal on top; open, it becomes a panel with the calendar (click the heading to close) */}
           {journalEnabled && (
-            <div className="border-b border-border pb-1.5 -mb-1.5">
+            <div
+              className={
+                subView === 'journal'
+                  ? 'rounded-card border-2 border-accent/40 bg-panel-elevated p-2.5'
+                  : 'border-b border-border pb-1.5 -mb-1.5'
+              }
+            >
               <button
                 type="button"
-                onClick={openJournal}
-                className={`w-full flex items-center gap-2 px-2 h-11 sm:h-8 rounded-btn text-xs border transition-colors cursor-pointer ${
+                onClick={toggleJournal}
+                aria-expanded={subView === 'journal'}
+                title={subView === 'journal' ? 'Journal schließen' : 'Journal öffnen'}
+                className={`w-full flex items-center gap-2 text-left cursor-pointer transition-colors ${
                   subView === 'journal'
-                    ? 'bg-panel-elevated text-main font-semibold border-border/80'
-                    : 'border-transparent text-main hover:bg-panel-elevated'
+                    ? 'h-11 sm:h-7 px-0.5 text-sm font-bold text-main'
+                    : 'h-11 sm:h-8 px-2 rounded-btn text-xs text-main border border-transparent hover:bg-panel-elevated'
                 }`}
               >
-                <CalendarDays className="w-3.5 h-3.5 text-accent" />
-                <span className="flex-1 text-left">Journal</span>
-                {subView === 'journal' ? (
-                  <ChevronDown className="w-3.5 h-3.5 text-muted" />
-                ) : (
-                  <ChevronRight className="w-3.5 h-3.5 text-muted" />
-                )}
+                <CalendarDays className={subView === 'journal' ? 'w-4 h-4 text-accent' : 'w-3.5 h-3.5 text-accent'} />
+                <span>Journal</span>
               </button>
               {subView === 'journal' && (
-                <div className="hidden lg:block px-1 pt-2 pb-1">
+                <div className="hidden lg:block pt-2">
                   <JournalCalendar
                     activeDate={journalActive}
                     entryDates={new Set(journalDays.filter((d) => !d.empty).map((d) => d.date))}