frontend/src/features/workspace/WorkspaceView.tsx

@@ -46,8 +46,9 @@ import {
   Edit3,
   Share,
   Share2,
+  Hash,
 } from 'lucide-react';
-import { BlockType, Document, DocumentBlock, DocLockInfo, DocShare, User } from '../../lib/types';
+import { BlockType, Document, DocumentBlock, DocLockInfo, DocShare, TagDetails, TagSummary, User } from '../../lib/types';
 import { api, getToken, triggerHaptic } from '../../lib/api';
 
 interface WorkspaceViewProps {
@@ -91,8 +92,12 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
   initialDocId,
   onStatsChange,
 }) => {
-  // Top Workspace Tab Mode: 'editor' vs 'todos' (Global To-Do Rollup Dashboard)
+  // Top Workspace Tab Mode: 'editor' vs 'todos' vs 'tag'
-  const [workspaceMode, setWorkspaceMode] = useState<'editor' | 'todos'>('editor');
+  const [workspaceMode, setWorkspaceMode] = useState<'editor' | 'todos' | 'tag'>('editor');
+  const [selectedTag, setSelectedTag] = useState<string | null>(null);
+  const [tagDetails, setTagDetails] = useState<TagDetails | null>(null);
+  const [workspaceTags, setWorkspaceTags] = useState<TagSummary[]>([]);
+  const [isLoadingTag, setIsLoadingTag] = useState(false);
 
   const [docs, setDocs] = useState<Document[]>([]);
   const [selectedDoc, setSelectedDoc] = useState<Document | null>(null);
@@ -281,6 +286,10 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
           : prev
       );
       onStatsChange();
+      api.getWorkspaceTags().then(setWorkspaceTags).catch(() => {});
+      if (selectedTag) {
+        api.getTagDetails(selectedTag).then(setTagDetails).catch(() => {});
+      }
     } catch (e: any) {
       if (e.message && e.message.includes('423')) {
         api.getDocLock(docToSave.id).then((res) => {
@@ -343,12 +352,14 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
 
   const loadDocs = async (selectId?: string | null) => {
     try {
-      const [list, serverFolders] = await Promise.all([
+      const [list, serverFolders, tags] = await Promise.all([
         api.getDocuments(),
         api.getFolders(),
+        api.getWorkspaceTags().catch(() => []),
       ]);
       setDocs(list);
       setCustomFolders(serverFolders);
+      setWorkspaceTags(tags);
       if (selectId) {
         const found = list.find((d) => d.id === selectId);
         if (found) {
@@ -367,6 +378,21 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
     }
   };
 
+  const openTagPage = async (tag: string) => {
+    const clean = tag.replace(/^#/, '').toLowerCase();
+    setSelectedTag(clean);
+    setWorkspaceMode('tag');
+    setIsLoadingTag(true);
+    try {
+      const details = await api.getTagDetails(clean);
+      setTagDetails(details);
+    } catch (err) {
+      console.error('Failed to load tag details', err);
+    } finally {
+      setIsLoadingTag(false);
+    }
+  };
+
   useEffect(() => {
     loadDocs(initialDocId);
   }, [initialDocId]);
@@ -1397,9 +1423,9 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
     URL.revokeObjectURL(url);
   };
 
-  // Helper to render text with clickable Wiki-Links
+  // Helper to render text with clickable Wiki-Links and Hashtags
-  const renderTextWithWikiLinks = (text: string) => {
+  const renderFormattedText = (text: string) => {
-    const parts = text.split(/(\[\[.*?\]\])/g);
+    const parts = text.split(/(\[\[.*?\]\]|#[a-zA-Z0-9äöüÄÖÜß_-]+)/g);
     return parts.map((part, i) => {
       if (part.startsWith('[[') && part.endsWith(']]')) {
         const linkTitle = part.slice(2, -2).trim();
@@ -1412,6 +1438,7 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
               if (target) {
                 setSelectedDoc(target);
                 setZoomedBlockId(null);
+                setWorkspaceMode('editor');
               }
             }}
             className={`inline-flex items-center gap-1 px-1.5 py-0.2 mx-0.5 border text-xs font-medium cursor-pointer rounded-btn transition-colors ${
@@ -1427,6 +1454,23 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
           </span>
         );
       }
+      if (part.startsWith('#') && part.length > 1) {
+        const tagWord = part.slice(1);
+        return (
+          <span
+            key={i}
+            onClick={(e) => {
+              e.stopPropagation();
+              openTagPage(tagWord);
+            }}
+            className="inline-flex items-center gap-0.5 px-1.5 py-0.2 mx-0.5 bg-blue-500/10 border border-blue-500/30 text-blue-500 dark:text-blue-400 hover:bg-blue-500/20 text-xs font-medium cursor-pointer rounded-btn transition-colors"
+            title={`Öffne Hashtag-Seite: #${tagWord}`}
+          >
+            <Hash className="w-2.5 h-2.5 opacity-80" />
+            <span>{tagWord}</span>
+          </span>
+        );
+      }
       return <span key={i}>{part}</span>;
     });
   };
@@ -1496,6 +1540,29 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
       setSelectedDoc(updatedDoc);
     }
 
+    // Also update tagDetails if currently viewing tag page
+    setTagDetails((prev) => {
+      if (!prev) return prev;
+      return {
+        ...prev,
+        documents: prev.documents.map((dg) => {
+          if (dg.docId !== docId) return dg;
+          return {
+            ...dg,
+            matchedBlocks: dg.matchedBlocks.map((mb) => ({
+              rootBlock:
+                mb.rootBlock.id === blockId
+                  ? { ...mb.rootBlock, checked: !mb.rootBlock.checked }
+                  : mb.rootBlock,
+              children: mb.children.map((c) =>
+                c.id === blockId ? { ...c, checked: !c.checked } : c
+              ),
+            })),
+          };
+        }),
+      };
+    });
+
     // Persist immediately to backend & disk
     await api.updateDocument(docId, {
       blocks: updatedBlocks,
@@ -1823,6 +1890,26 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
               {allWorkspaceTodos.filter((t) => !t.block.checked).length}
             </span>
           </button>
+
+          {selectedTag && (
+            <button
+              type="button"
+              onClick={() => setWorkspaceMode('tag')}
+              className={`h-8 px-3 text-xs font-medium border rounded-btn flex items-center gap-1.5 transition-colors ${
+                workspaceMode === 'tag'
+                  ? 'bg-panel border-accent text-main'
+                  : 'bg-canvas border-border text-muted hover:text-main'
+              }`}
+            >
+              <Hash className="w-3.5 h-3.5 text-accent" />
+              <span>#{selectedTag}</span>
+              {tagDetails && (
+                <span className="badge-neutral font-mono text-[10px]">
+                  {tagDetails.totalMatches}
+                </span>
+              )}
+            </button>
+          )}
         </div>
 
         <div className="flex items-center gap-2 text-xs text-muted">
@@ -2047,6 +2134,37 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
 
                 {rootTree.map(renderFolder)}
                 {rootDocs.map((doc) => renderDocItem(doc, 0))}
+
+                {/* Workspace Hashtags Section */}
+                {workspaceTags.length > 0 && !searchQuery && (
+                  <div className="mt-3 pt-2.5 border-t border-border">
+                    <div className="px-2.5 py-1 text-[10px] font-bold text-muted uppercase tracking-wider flex items-center justify-between">
+                      <div className="flex items-center gap-1.5 text-accent">
+                        <Hash className="w-3 h-3" />
+                        <span>Themen & Hashtags ({workspaceTags.length})</span>
+                      </div>
+                    </div>
+                    <div className="flex flex-wrap gap-1 px-1.5 py-1">
+                      {workspaceTags.map((wt) => (
+                        <button
+                          key={wt.tag}
+                          type="button"
+                          onClick={() => openTagPage(wt.tag)}
+                          className={`px-2 py-0.5 rounded-pill text-[11px] font-medium border flex items-center gap-1 transition-colors ${
+                            selectedTag === wt.tag
+                              ? 'bg-accent/20 border-accent text-accent font-semibold'
+                              : 'bg-canvas border-border text-muted hover:border-accent/40 hover:text-main'
+                          }`}
+                          title={`#${wt.tag} (${wt.count} Abschnitte)`}
+                        >
+                          <span>#{wt.tag}</span>
+                          <span className="text-[9px] opacity-60">({wt.count})</span>
+                        </button>
+                      ))}
+                    </div>
+                  </div>
+                )}
+
                 {filteredDocs.length === 0 && searchQuery && (
                   <div className="p-4 text-center text-xs text-faint">
                     Keine Dateien gefunden für &quot;{searchQuery}&quot;
@@ -2430,6 +2548,11 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
                                   </button>
                                 )}
                               </div>
+                              {(block.content.includes('[[') || block.content.includes('#')) && (
+                                <div className="text-xs text-muted flex flex-wrap items-center gap-1 pt-0.5 pl-6">
+                                  {renderFormattedText(block.content)}
+                                </div>
+                              )}
 
                               {/* Progress bar for child todos if any exist */}
                               {(() => {
@@ -2631,9 +2754,9 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
                                   isReadOnly ? 'cursor-default' : ''
                                 }`}
                               />
-                              {block.content.includes('[[') && (
+                              {(block.content.includes('[[') || block.content.includes('#')) && (
-                                <div className="text-xs text-muted">
+                                <div className="text-xs text-muted flex flex-wrap items-center gap-1 pt-0.5">
-                                  {renderTextWithWikiLinks(block.content)}
+                                  {renderFormattedText(block.content)}
                                 </div>
                               )}
                             </div>
@@ -2898,6 +3021,217 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
         </div>
       )}
 
+      {/* ===================================================================== */}
+      {/* VIEW MODE 3: HASHTAG / THEMEN-SEITE (LOGSEQ STYLE)                   */}
+      {/* ===================================================================== */}
+      {workspaceMode === 'tag' && (
+        <div className="space-y-4">
+          {/* Tag Page Header */}
+          <div className="p-4 panel-surface space-y-2 border border-border rounded-card">
+            <div className="flex flex-wrap items-center justify-between gap-3">
+              <div className="flex items-center gap-2">
+                <button
+                  type="button"
+                  onClick={() => setWorkspaceMode('editor')}
+                  className="btn-action h-8 px-2.5 text-xs flex items-center gap-1.5"
+                  title="Zurück zum Editor"
+                >
+                  <ArrowLeft className="w-3.5 h-3.5 text-accent" />
+                  <span>Notizen</span>
+                </button>
+                <div className="h-4 w-px bg-border" />
+                <div className="flex items-center gap-2">
+                  <div className="w-8 h-8 rounded-lg bg-blue-500/10 border border-blue-500/30 flex items-center justify-center text-blue-500 dark:text-blue-400 font-bold">
+                    <Hash className="w-4 h-4" />
+                  </div>
+                  <div>
+                    <h2 className="text-base font-bold text-main leading-tight flex items-center gap-1.5">
+                      <span>#{selectedTag}</span>
+                    </h2>
+                    <p className="text-[11px] text-muted">
+                      {isLoadingTag
+                        ? 'Wird geladen…'
+                        : `${tagDetails?.totalMatches || 0} ${
+                            tagDetails?.totalMatches === 1 ? 'Abschnitt' : 'Abschnitte'
+                          } in ${tagDetails?.documents.length || 0} ${
+                            tagDetails?.documents.length === 1 ? 'Notiz' : 'Notizen'
+                          }`}
+                    </p>
+                  </div>
+                </div>
+              </div>
+
+              {/* Other tags pills for fast hopping */}
+              <div className="flex items-center gap-1 flex-wrap">
+                {workspaceTags
+                  .filter((t) => t.tag !== selectedTag)
+                  .slice(0, 6)
+                  .map((t) => (
+                    <button
+                      key={t.tag}
+                      type="button"
+                      onClick={() => openTagPage(t.tag)}
+                      className="px-2 py-0.5 rounded-pill text-[11px] badge-neutral hover:border-accent/40 hover:text-main transition-colors"
+                    >
+                      #{t.tag} ({t.count})
+                    </button>
+                  ))}
+              </div>
+            </div>
+          </div>
+
+          {/* Matched Documents List */}
+          {isLoadingTag ? (
+            <div className="p-12 text-center text-muted text-xs panel-surface">
+              <Sparkles className="w-6 h-6 animate-spin mx-auto mb-2 text-accent" />
+              Hashtag-Verknüpfungen werden geladen…
+            </div>
+          ) : !tagDetails || tagDetails.documents.length === 0 ? (
+            <div className="p-12 text-center text-muted text-xs panel-surface space-y-2">
+              <Hash className="w-8 h-8 mx-auto text-faint" />
+              <p className="font-medium text-main">Keine Bullet Points mit #{selectedTag} gefunden</p>
+              <p className="text-xs text-faint">
+                Füge einfach in irgendeiner Notiz <code className="text-accent">#{selectedTag}</code> in einen Bullet Point ein.
+              </p>
+            </div>
+          ) : (
+            <div className="space-y-4">
+              {tagDetails.documents.map((docGroup) => (
+                <div
+                  key={docGroup.docId}
+                  className="panel-surface p-4 space-y-3 border border-border rounded-card hover:border-border/80 transition-colors"
+                >
+                  {/* Document Header */}
+                  <div className="flex flex-wrap items-center justify-between gap-2 pb-2 border-b border-border">
+                    <div className="flex items-center gap-2 min-w-0">
+                      <span className="text-base flex-shrink-0">{docGroup.icon || '📄'}</span>
+                      <span className="font-semibold text-xs text-main truncate">{docGroup.title || 'Unbenannt'}</span>
+                      {docGroup.folderPath && (
+                        <span className="badge-neutral text-[10px] flex items-center gap-1 font-mono">
+                          <Folder className="w-2.5 h-2.5" />
+                          <span>{docGroup.folderPath}</span>
+                        </span>
+                      )}
+                      <span className="text-[10px] text-faint">
+                        • {docGroup.matchedBlocks.length}{' '}
+                        {docGroup.matchedBlocks.length === 1 ? 'Treffer' : 'Treffer'}
+                      </span>
+                    </div>
+
+                    <button
+                      type="button"
+                      onClick={() => {
+                        const found = docs.find((d) => d.id === docGroup.docId);
+                        if (found) {
+                          setSelectedDoc(found);
+                          setZoomedBlockId(null);
+                          setWorkspaceMode('editor');
+                        }
+                      }}
+                      className="px-2.5 py-1 text-xs font-medium text-accent hover:text-main bg-accent/10 hover:bg-accent/20 rounded-btn flex items-center gap-1 transition-colors"
+                    >
+                      <span>Notiz öffnen</span>
+                      <ExternalLink className="w-3 h-3" />
+                    </button>
+                  </div>
+
+                  {/* Matched Bullet Points and their children */}
+                  <div className="space-y-3 pl-1">
+                    {docGroup.matchedBlocks.map((mb, idx) => (
+                      <div
+                        key={mb.rootBlock.id || idx}
+                        className="space-y-1.5 bg-canvas/40 p-3 rounded-card border border-border/50"
+                      >
+                        {/* Root Bullet Point */}
+                        <div className="flex items-start gap-2 group">
+                          {mb.rootBlock.type === 'todo' ? (
+                            <input
+                              type="checkbox"
+                              checked={!!mb.rootBlock.checked}
+                              onChange={() => handleToggleRollupTodo(docGroup.docId, mb.rootBlock.id)}
+                              className="w-4 h-4 mt-0.5 checkbox-square cursor-pointer flex-shrink-0"
+                            />
+                          ) : (
+                            <div className="w-3.5 h-3.5 mt-1 rounded-full bg-accent/20 border border-accent flex items-center justify-center flex-shrink-0">
+                              <div className="w-1.5 h-1.5 rounded-full bg-accent" />
+                            </div>
+                          )}
+
+                          <div
+                            onClick={() => {
+                              const found = docs.find((d) => d.id === docGroup.docId);
+                              if (found) {
+                                setSelectedDoc(found);
+                                setZoomedBlockId(mb.rootBlock.id);
+                                setWorkspaceMode('editor');
+                              }
+                            }}
+                            className={`flex-1 text-xs leading-relaxed cursor-pointer hover:text-accent transition-colors ${
+                              mb.rootBlock.checked ? 'line-through text-faint' : 'text-main'
+                            }`}
+                            title="Klick: Zu diesem Bullet Point in der Notiz zoomen"
+                          >
+                            {renderFormattedText(mb.rootBlock.content || '(Leerer Bullet Point)')}
+                          </div>
+                        </div>
+
+                        {/* Children / Sub-bullets */}
+                        {mb.children.length > 0 && (
+                          <div className="space-y-1 mt-1 pl-4 border-l-2 border-border/60 ml-2">
+                            {mb.children.map((child) => {
+                              const indentLevel = Math.max(
+                                0,
+                                (child.level || 0) - (mb.rootBlock.level || 0) - 1
+                              );
+                              return (
+                                <div
+                                  key={child.id}
+                                  style={{ paddingLeft: `${indentLevel * 14}px` }}
+                                  className="flex items-start gap-2 py-0.5 text-xs text-muted"
+                                >
+                                  {child.type === 'todo' ? (
+                                    <input
+                                      type="checkbox"
+                                      checked={!!child.checked}
+                                      onChange={() =>
+                                        handleToggleRollupTodo(docGroup.docId, child.id)
+                                      }
+                                      className="w-3.5 h-3.5 mt-0.5 checkbox-square cursor-pointer flex-shrink-0"
+                                    />
+                                  ) : (
+                                    <span className="w-1.5 h-1.5 mt-1.5 rounded-full bg-muted/60 flex-shrink-0" />
+                                  )}
+                                  <div
+                                    onClick={() => {
+                                      const found = docs.find((d) => d.id === docGroup.docId);
+                                      if (found) {
+                                        setSelectedDoc(found);
+                                        setZoomedBlockId(child.id);
+                                        setWorkspaceMode('editor');
+                                      }
+                                    }}
+                                    className={`flex-1 text-xs leading-relaxed cursor-pointer hover:text-accent transition-colors ${
+                                      child.checked ? 'line-through text-faint' : 'text-muted'
+                                    }`}
+                                    title="Klick: In Notiz fokussieren"
+                                  >
+                                    {renderFormattedText(child.content || '')}
+                                  </div>
+                                </div>
+                              );
+                            })}
+                          </div>
+                        )}
+                      </div>
+                    ))}
+                  </div>
+                </div>
+              ))}
+            </div>
+          )}
+        </div>
+      )}
+
       {/* ===================================================================== */}
       {/* DOCUMENT SHARING MODAL                                               */}
       {/* ===================================================================== */}

frontend/src/lib/api.ts

@@ -17,6 +17,8 @@ import {
   TaskList,
   Thought,
   SubTask,
+  TagDetails,
+  TagSummary,
   User,
   UserInvite,
   WSMessage,
@@ -388,6 +390,27 @@ export const api = {
     );
   },
 
+  // --- WORKSPACE TAGS ---
+  async getWorkspaceTags(): Promise<TagSummary[]> {
+    const res = await request<TagSummary[]>('/api/v1/workspace/tags');
+    return ensureArray(res);
+  },
+
+  async getTagDetails(tag: string): Promise<TagDetails> {
+    const clean = encodeURIComponent(tag.replace(/^#/, ''));
+    const res = await request<TagDetails>(`/api/v1/workspace/tags/${clean}`);
+    return {
+      ...res,
+      documents: ensureArray(res.documents).map((doc) => ({
+        ...doc,
+        matchedBlocks: ensureArray(doc.matchedBlocks).map((mb) => ({
+          rootBlock: mb.rootBlock,
+          children: ensureArray(mb.children),
+        })),
+      })),
+    };
+  },
+
   // --- WORKSPACE DOCUMENTS ---
   async getDocuments(): Promise<Document[]> {
     const res = await request<Document[]>('/api/v1/documents');

frontend/src/lib/types.ts

@@ -170,6 +170,34 @@ export interface Document {
   sharedWith?: DocShare[];
 }
 
+export interface TagSummary {
+  tag: string;
+  count: number;
+}
+
+export interface MatchedTagBlock {
+  rootBlock: DocumentBlock;
+  children: DocumentBlock[];
+}
+
+export interface TagDocumentGroup {
+  docId: string;
+  title: string;
+  icon: string;
+  folderPath: string;
+  updatedAt: string;
+  isOwner: boolean;
+  permission: 'owner' | 'write' | 'read';
+  ownerName?: string;
+  matchedBlocks: MatchedTagBlock[];
+}
+
+export interface TagDetails {
+  tag: string;
+  documents: TagDocumentGroup[];
+  totalMatches: number;
+}
+
 export interface SpaceMember {
   spaceId: string;
   userId: string;

internal/api/server.go

@@ -100,6 +100,10 @@ func (s *Server) Router() http.Handler {
 		r.Post("/api/v1/folders", s.handleCreateFolder)
 		r.Delete("/api/v1/folders", s.handleDeleteFolder)
 
+		// Workspace Tags & Pages
+		r.Get("/api/v1/workspace/tags", s.handleGetWorkspaceTags)
+		r.Get("/api/v1/workspace/tags/{tag}", s.handleGetTagDetails)
+
 		r.Get("/api/v1/documents", s.handleGetDocuments)
 		r.Post("/api/v1/documents", s.handleCreateDocument)
 		r.Get("/api/v1/documents/{id}", s.handleGetDocument)
@@ -871,6 +875,29 @@ func (s *Server) handleDeleteFolder(w http.ResponseWriter, r *http.Request) {
 	})
 }
 
+// --- WORKSPACE TAGS & PAGES ---
+
+func (s *Server) handleGetWorkspaceTags(w http.ResponseWriter, r *http.Request) {
+	userID := auth.GetUserID(r.Context())
+	tags, err := s.store.GetWorkspaceTags(userID)
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+	writeJSON(w, http.StatusOK, tags)
+}
+
+func (s *Server) handleGetTagDetails(w http.ResponseWriter, r *http.Request) {
+	userID := auth.GetUserID(r.Context())
+	tag := chi.URLParam(r, "tag")
+	details, err := s.store.GetTagDetails(userID, tag)
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+	writeJSON(w, http.StatusOK, details)
+}
+
 // --- DOCUMENT SHARING & COLLABORATION ---
 
 func (s *Server) handleGetDocShares(w http.ResponseWriter, r *http.Request) {

internal/api/server_test.go

@@ -619,3 +619,95 @@ func TestSpaceMembersDirectInvitationAPI(t *testing.T) {
 		t.Fatalf("expected 200 OK for remove member, got %d: %s", rec.Code, rec.Body.String())
 	}
 }
+
+func TestWorkspaceTagsAPI(t *testing.T) {
+	srv, store, _ := setupTestServer(t)
+	router := srv.Router()
+
+	user, _ := store.CreateUser("api_tag_user@example.com", "hash", "API Tag User", "member")
+	token, _ := auth.GenerateToken(srv.cfg.JWTSecret, user.ID, user.Email, user.DisplayName)
+
+	// Create document with hashtags
+	blocks := []domain.DocumentBlock{
+		{ID: "b1", Type: "bullet", Content: "Planung #Sprint12", Level: 0},
+		{ID: "b2", Type: "bullet", Content: "Subtask 1", Level: 1},
+	}
+	_, err := store.CreateDocument(user.ID, "", "Sprint Plan", "🚀", "", blocks, nil, false)
+	if err != nil {
+		t.Fatalf("CreateDocument failed: %v", err)
+	}
+
+	// 1. GET /api/v1/workspace/tags
+	req := httptest.NewRequest(http.MethodGet, "/api/v1/workspace/tags", nil)
+	req.Header.Set("Authorization", "Bearer "+token)
+	rec := httptest.NewRecorder()
+	router.ServeHTTP(rec, req)
+	if rec.Code != http.StatusOK {
+		t.Fatalf("expected 200 OK, got %d: %s", rec.Code, rec.Body.String())
+	}
+	var tagList []domain.TagSummary
+	_ = json.Unmarshal(rec.Body.Bytes(), &tagList)
+	if len(tagList) != 1 || tagList[0].Tag != "sprint12" {
+		t.Fatalf("expected tag 'sprint12', got %+v", tagList)
+	}
+
+	// 2. GET /api/v1/workspace/tags/Sprint12
+	req = httptest.NewRequest(http.MethodGet, "/api/v1/workspace/tags/Sprint12", nil)
+	req.Header.Set("Authorization", "Bearer "+token)
+	rec = httptest.NewRecorder()
+	router.ServeHTTP(rec, req)
+	if rec.Code != http.StatusOK {
+		t.Fatalf("expected 200 OK, got %d: %s", rec.Code, rec.Body.String())
+	}
+	var details domain.TagDetails
+	_ = json.Unmarshal(rec.Body.Bytes(), &details)
+	if details.Tag != "sprint12" || details.TotalMatches != 1 || len(details.Documents) != 1 {
+		t.Fatalf("unexpected tag details: %+v", details)
+	}
+	matched := details.Documents[0].MatchedBlocks[0]
+	if matched.RootBlock.ID != "b1" || len(matched.Children) != 1 || matched.Children[0].ID != "b2" {
+		t.Fatalf("unexpected matched blocks or children: %+v", matched)
+	}
+
+	// 3. Folder endpoints test
+	// Create folder
+	createFolderBody := []byte(`{"path":"TestOrdner"}`)
+	req = httptest.NewRequest(http.MethodPost, "/api/v1/folders", bytes.NewReader(createFolderBody))
+	req.Header.Set("Authorization", "Bearer "+token)
+	req.Header.Set("Content-Type", "application/json")
+	rec = httptest.NewRecorder()
+	router.ServeHTTP(rec, req)
+	if rec.Code != http.StatusCreated {
+		t.Fatalf("expected 201 Created from /api/v1/folders, got %d: %s", rec.Code, rec.Body.String())
+	}
+
+	// Get folders
+	req = httptest.NewRequest(http.MethodGet, "/api/v1/folders", nil)
+	req.Header.Set("Authorization", "Bearer "+token)
+	rec = httptest.NewRecorder()
+	router.ServeHTTP(rec, req)
+	if rec.Code != http.StatusOK {
+		t.Fatalf("expected 200 OK from /api/v1/folders, got %d", rec.Code)
+	}
+	var folders []string
+	_ = json.Unmarshal(rec.Body.Bytes(), &folders)
+	foundFolder := false
+	for _, f := range folders {
+		if f == "TestOrdner" {
+			foundFolder = true
+			break
+		}
+	}
+	if !foundFolder {
+		t.Fatalf("expected TestOrdner in folders list, got %v", folders)
+	}
+
+	// Delete folder
+	req = httptest.NewRequest(http.MethodDelete, "/api/v1/folders?path=TestOrdner", nil)
+	req.Header.Set("Authorization", "Bearer "+token)
+	rec = httptest.NewRecorder()
+	router.ServeHTTP(rec, req)
+	if rec.Code != http.StatusOK {
+		t.Fatalf("expected 200 OK from DELETE /api/v1/folders, got %d", rec.Code)
+	}
+}

internal/domain/models.go

@@ -262,6 +262,34 @@ type Document struct {
 	SharedWith []DocShare `json:"sharedWith,omitempty"`
 }
 
+type TagSummary struct {
+	Tag   string `json:"tag"`
+	Count int    `json:"count"`
+}
+
+type MatchedTagBlock struct {
+	RootBlock DocumentBlock   `json:"rootBlock"`
+	Children  []DocumentBlock `json:"children"`
+}
+
+type TagDocumentGroup struct {
+	DocID         string            `json:"docId"`
+	Title         string            `json:"title"`
+	Icon          string            `json:"icon"`
+	FolderPath    string            `json:"folderPath"`
+	UpdatedAt     string            `json:"updatedAt"`
+	IsOwner       bool              `json:"isOwner"`
+	Permission    string            `json:"permission"`
+	OwnerName     string            `json:"ownerName,omitempty"`
+	MatchedBlocks []MatchedTagBlock `json:"matchedBlocks"`
+}
+
+type TagDetails struct {
+	Tag          string             `json:"tag"`
+	Documents    []TagDocumentGroup `json:"documents"`
+	TotalMatches int                `json:"totalMatches"`
+}
+
 type SpaceMember struct {
 	SpaceID     string `json:"spaceId"`
 	UserID      string `json:"userId"`

internal/storage/sqlite.go

@@ -231,6 +231,22 @@ func (s *Store) migrate() error {
 	INSERT OR IGNORE INTO doc_pins (user_id, doc_id, created_at)
 	SELECT user_id, id, updated_at FROM documents WHERE is_pinned = 1;
 
+	CREATE TABLE IF NOT EXISTS doc_block_tags (
+		id TEXT PRIMARY KEY,
+		tag TEXT NOT NULL,
+		user_id TEXT NOT NULL,
+		doc_id TEXT NOT NULL,
+		block_id TEXT NOT NULL,
+		created_at TEXT NOT NULL,
+		UNIQUE(doc_id, block_id, tag),
+		FOREIGN KEY(doc_id) REFERENCES documents(id) ON DELETE CASCADE,
+		FOREIGN KEY(user_id) REFERENCES users(id) ON DELETE CASCADE
+	);
+
+	CREATE INDEX IF NOT EXISTS idx_doc_block_tags_tag ON doc_block_tags(tag);
+	CREATE INDEX IF NOT EXISTS idx_doc_block_tags_user_tag ON doc_block_tags(user_id, tag);
+	CREATE INDEX IF NOT EXISTS idx_doc_block_tags_doc ON doc_block_tags(doc_id);
+
 	CREATE TABLE IF NOT EXISTS lists (
 		id TEXT PRIMARY KEY,
 		space_id TEXT NOT NULL,
@@ -325,6 +341,13 @@ func (s *Store) migrate() error {
 		('smtp_from', ''),
 		('smtp_tls', 'true')`)
 
+	// Reindex block tags if table is newly added or empty
+	var tagCount int
+	_ = s.db.QueryRow(`SELECT COUNT(*) FROM doc_block_tags`).Scan(&tagCount)
+	if tagCount == 0 {
+		_ = s.reindexAllDocBlockTags()
+	}
+
 	return nil
 }
 
@@ -1184,6 +1207,7 @@ func (s *Store) CreateDocument(userID, spaceID, title, icon, folderPath string,
 		_, _ = s.db.Exec(`INSERT OR IGNORE INTO doc_pins (user_id, doc_id, created_at) VALUES (?, ?, ?)`, userID, doc.ID, doc.CreatedAt)
 	}
 	s.saveDocumentToDisk(doc)
+	_ = s.indexDocBlockTags(doc.ID, doc.UserID, doc.Blocks)
 	return doc, nil
 }
 
@@ -1417,6 +1441,9 @@ func (s *Store) UpdateDocument(userID, docID string, title, icon, folderPath *st
 		return nil, err
 	}
 	s.saveDocumentToDisk(doc)
+	if blocks != nil {
+		_ = s.indexDocBlockTags(doc.ID, doc.UserID, doc.Blocks)
+	}
 	return doc, nil
 }
 
@@ -1432,10 +1459,228 @@ func (s *Store) DeleteDocument(userID, docID string) error {
 	if doc != nil {
 		s.removeDocumentFromDisk(doc)
 	}
+	_, _ = s.db.Exec(`DELETE FROM doc_block_tags WHERE doc_id = ?`, docID)
 	_, err = s.db.Exec(`DELETE FROM documents WHERE id = ? AND user_id = ?`, docID, userID)
 	return err
 }
 
+func (s *Store) reindexAllDocBlockTags() error {
+	rows, err := s.db.Query(`SELECT id, user_id, blocks_json FROM documents WHERE is_archived = 0`)
+	if err != nil {
+		return err
+	}
+	defer rows.Close()
+
+	type docInfo struct {
+		id, userID, blocksJSON string
+	}
+	var docs []docInfo
+	for rows.Next() {
+		var d docInfo
+		if err := rows.Scan(&d.id, &d.userID, &d.blocksJSON); err == nil {
+			docs = append(docs, d)
+		}
+	}
+	_ = rows.Close()
+
+	for _, d := range docs {
+		var blocks []domain.DocumentBlock
+		if err := json.Unmarshal([]byte(d.blocksJSON), &blocks); err == nil && len(blocks) > 0 {
+			_ = s.indexDocBlockTags(d.id, d.userID, blocks)
+		}
+	}
+	return nil
+}
+
+func (s *Store) indexDocBlockTags(docID, userID string, blocks []domain.DocumentBlock) error {
+	_, _ = s.db.Exec(`DELETE FROM doc_block_tags WHERE doc_id = ?`, docID)
+	if len(blocks) == 0 {
+		return nil
+	}
+
+	stmt, err := s.db.Prepare(`INSERT OR IGNORE INTO doc_block_tags (id, tag, user_id, doc_id, block_id, created_at) VALUES (?, ?, ?, ?, ?, ?)`)
+	if err != nil {
+		return err
+	}
+	defer stmt.Close()
+
+	now := domain.NowISO()
+	for _, b := range blocks {
+		if b.Content == "" {
+			continue
+		}
+		tags := domain.ExtractTags(b.Content)
+		for _, tag := range tags {
+			tagID := domain.NewID("dbtag")
+			_, _ = stmt.Exec(tagID, tag, userID, docID, b.ID, now)
+		}
+	}
+	return nil
+}
+
+func (s *Store) GetWorkspaceTags(userID string) ([]domain.TagSummary, error) {
+	rows, err := s.db.Query(
+		`SELECT t.tag, COUNT(DISTINCT t.doc_id || ':' || t.block_id) as count
+		 FROM doc_block_tags t
+		 JOIN documents d ON t.doc_id = d.id
+		 LEFT JOIN doc_shares s ON s.doc_id = d.id AND s.user_id = ?
+		 WHERE (d.user_id = ? OR s.user_id = ?)
+		   AND d.is_archived = 0
+		 GROUP BY t.tag
+		 ORDER BY count DESC, t.tag ASC`,
+		userID, userID, userID,
+	)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	results := make([]domain.TagSummary, 0)
+	for rows.Next() {
+		var ts domain.TagSummary
+		if err := rows.Scan(&ts.Tag, &ts.Count); err == nil {
+			results = append(results, ts)
+		}
+	}
+	return results, nil
+}
+
+func (s *Store) GetTagDetails(userID, tag string) (*domain.TagDetails, error) {
+	cleanTag := strings.ToLower(strings.TrimPrefix(strings.TrimSpace(tag), "#"))
+	if cleanTag == "" {
+		return &domain.TagDetails{Tag: "", Documents: []domain.TagDocumentGroup{}, TotalMatches: 0}, nil
+	}
+
+	rows, err := s.db.Query(
+		`SELECT t.block_id, d.id, d.title, d.icon, d.folder_path, d.blocks_json, d.updated_at, d.user_id,
+		        COALESCE(u.display_name, '') as owner_name,
+		        COALESCE(s.permission, '') as shared_permission
+		 FROM doc_block_tags t
+		 JOIN documents d ON t.doc_id = d.id
+		 LEFT JOIN users u ON d.user_id = u.id
+		 LEFT JOIN doc_shares s ON s.doc_id = d.id AND s.user_id = ?
+		 WHERE (d.user_id = ? OR s.user_id = ?)
+		   AND t.tag = ?
+		   AND d.is_archived = 0
+		 ORDER BY d.updated_at DESC`,
+		userID, userID, userID, cleanTag,
+	)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	type rawMatch struct {
+		blockID          string
+		docID            string
+		title            string
+		icon             string
+		folderPath       string
+		blocksJSON       string
+		updatedAt        string
+		docUserID        string
+		ownerName        string
+		sharedPermission string
+	}
+
+	var rawMatches []rawMatch
+	for rows.Next() {
+		var rm rawMatch
+		if err := rows.Scan(&rm.blockID, &rm.docID, &rm.title, &rm.icon, &rm.folderPath, &rm.blocksJSON, &rm.updatedAt, &rm.docUserID, &rm.ownerName, &rm.sharedPermission); err == nil {
+			rawMatches = append(rawMatches, rm)
+		}
+	}
+	_ = rows.Close()
+
+	// Group rawMatches by docID
+	docMap := make(map[string][]rawMatch)
+	var docOrder []string
+	for _, rm := range rawMatches {
+		if _, exists := docMap[rm.docID]; !exists {
+			docOrder = append(docOrder, rm.docID)
+		}
+		docMap[rm.docID] = append(docMap[rm.docID], rm)
+	}
+
+	totalMatches := 0
+	docGroups := make([]domain.TagDocumentGroup, 0, len(docOrder))
+
+	for _, docID := range docOrder {
+		matches := docMap[docID]
+		first := matches[0]
+
+		var blocks []domain.DocumentBlock
+		_ = json.Unmarshal([]byte(first.blocksJSON), &blocks)
+
+		blockIdxMap := make(map[string]int, len(blocks))
+		for i, b := range blocks {
+			blockIdxMap[b.ID] = i
+		}
+
+		matchedBlocks := make([]domain.MatchedTagBlock, 0)
+		processedBlockIDs := make(map[string]bool)
+
+		for _, m := range matches {
+			if processedBlockIDs[m.blockID] {
+				continue
+			}
+			idx, ok := blockIdxMap[m.blockID]
+			if !ok {
+				continue
+			}
+			rootBlock := blocks[idx]
+			processedBlockIDs[rootBlock.ID] = true
+
+			children := make([]domain.DocumentBlock, 0)
+			rootLevel := rootBlock.Level
+			for i := idx + 1; i < len(blocks); i++ {
+				if blocks[i].Level > rootLevel {
+					children = append(children, blocks[i])
+					processedBlockIDs[blocks[i].ID] = true
+				} else {
+					break
+				}
+			}
+
+			matchedBlocks = append(matchedBlocks, domain.MatchedTagBlock{
+				RootBlock: rootBlock,
+				Children:  children,
+			})
+			totalMatches++
+		}
+
+		if len(matchedBlocks) == 0 {
+			continue
+		}
+
+		isOwner := first.docUserID == userID
+		permission := "read"
+		if isOwner {
+			permission = "owner"
+		} else if first.sharedPermission != "" {
+			permission = first.sharedPermission
+		}
+
+		docGroups = append(docGroups, domain.TagDocumentGroup{
+			DocID:         first.docID,
+			Title:         first.title,
+			Icon:          first.icon,
+			FolderPath:    first.folderPath,
+			UpdatedAt:     first.updatedAt,
+			IsOwner:       isOwner,
+			Permission:    permission,
+			OwnerName:     first.ownerName,
+			MatchedBlocks: matchedBlocks,
+		})
+	}
+
+	return &domain.TagDetails{
+		Tag:          cleanTag,
+		Documents:    docGroups,
+		TotalMatches: totalMatches,
+	}, nil
+}
+
 func (s *Store) GetFolders(userID string) ([]string, error) {
 	folderSet := make(map[string]bool)
 
@@ -1549,8 +1794,9 @@ func (s *Store) DeleteFolder(userID, folderPath string) ([]string, error) {
 	}
 	_ = rows.Close()
 
-	// Delete from SQLite, pins, shares
+	// Delete from SQLite, pins, shares, tags
 	for _, id := range deletedDocIDs {
+		_, _ = s.db.Exec(`DELETE FROM doc_block_tags WHERE doc_id = ?`, id)
 		_, _ = s.db.Exec(`DELETE FROM doc_pins WHERE doc_id = ?`, id)
 		_, _ = s.db.Exec(`DELETE FROM doc_shares WHERE doc_id = ?`, id)
 		_, _ = s.db.Exec(`DELETE FROM documents WHERE id = ? AND user_id = ?`, id, userID)

internal/storage/sqlite_test.go

@@ -398,3 +398,107 @@ func TestFolderManagementAndDeletion(t *testing.T) {
 		t.Fatalf("expected directory %s to be deleted on disk", diskFolder)
 	}
 }
+
+func TestWorkspaceBlockHashtagsAndDetails(t *testing.T) {
+	tmpDir := t.TempDir()
+	dbPath := filepath.Join(tmpDir, "tags_test.db")
+
+	store, err := NewStore(dbPath)
+	if err != nil {
+		t.Fatalf("NewStore failed: %v", err)
+	}
+	defer store.Close()
+
+	user, err := store.CreateUser("taguser@example.com", "hash", "Tag User", "member")
+	if err != nil {
+		t.Fatalf("CreateUser failed: %v", err)
+	}
+
+	// Create document with nested bullet points and hashtags
+	blocks := []domain.DocumentBlock{
+		{ID: "b0", Type: "bullet", Content: "Einleitung ohne Tag", Level: 0},
+		{ID: "b1", Type: "bullet", Content: "Einkauf planen #Kühlregal #Wocheneinkauf", Level: 0},
+		{ID: "b2", Type: "bullet", Content: "Milch 3.8%", Level: 1},
+		{ID: "b3", Type: "bullet", Content: "Gouda alt", Level: 1},
+		{ID: "b4", Type: "bullet", Content: "Zusatzinfo: Aus Weidemilch", Level: 2},
+		{ID: "b5", Type: "bullet", Content: "Anderes Thema ohne Bezug", Level: 0},
+	}
+
+	doc, err := store.CreateDocument(user.ID, "", "Einkaufszettel", "🛒", "Haushalt", blocks, nil, false)
+	if err != nil {
+		t.Fatalf("CreateDocument failed: %v", err)
+	}
+
+	// 1. Check GetWorkspaceTags
+	tags, err := store.GetWorkspaceTags(user.ID)
+	if err != nil {
+		t.Fatalf("GetWorkspaceTags failed: %v", err)
+	}
+	if len(tags) != 2 {
+		t.Fatalf("expected 2 tags, got %d (%v)", len(tags), tags)
+	}
+	tagMap := make(map[string]int)
+	for _, tg := range tags {
+		tagMap[tg.Tag] = tg.Count
+	}
+	if tagMap["kühlregal"] != 1 || tagMap["wocheneinkauf"] != 1 {
+		t.Fatalf("unexpected tag counts: %v", tagMap)
+	}
+
+	// 2. Check GetTagDetails for #Kühlregal
+	details, err := store.GetTagDetails(user.ID, "#Kühlregal")
+	if err != nil {
+		t.Fatalf("GetTagDetails failed: %v", err)
+	}
+	if details.Tag != "kühlregal" {
+		t.Fatalf("expected tag 'kühlregal', got %s", details.Tag)
+	}
+	if details.TotalMatches != 1 {
+		t.Fatalf("expected 1 match, got %d", details.TotalMatches)
+	}
+	if len(details.Documents) != 1 {
+		t.Fatalf("expected 1 document, got %d", len(details.Documents))
+	}
+	docGroup := details.Documents[0]
+	if docGroup.DocID != doc.ID || docGroup.Title != "Einkaufszettel" {
+		t.Fatalf("unexpected doc group: %+v", docGroup)
+	}
+	if len(docGroup.MatchedBlocks) != 1 {
+		t.Fatalf("expected 1 matched block, got %d", len(docGroup.MatchedBlocks))
+	}
+	matched := docGroup.MatchedBlocks[0]
+	if matched.RootBlock.ID != "b1" {
+		t.Fatalf("expected root block b1, got %s", matched.RootBlock.ID)
+	}
+	// Children should be b2, b3, b4 (all subsequent blocks with Level > 0 until b5 where Level == 0)
+	if len(matched.Children) != 3 {
+		t.Fatalf("expected 3 children (b2, b3, b4), got %d (%v)", len(matched.Children), matched.Children)
+	}
+	if matched.Children[0].ID != "b2" || matched.Children[1].ID != "b3" || matched.Children[2].ID != "b4" {
+		t.Fatalf("unexpected children IDs: %v", matched.Children)
+	}
+
+	// 3. Update document: remove #Wocheneinkauf, add #Vorrat
+	updatedBlocks := []domain.DocumentBlock{
+		{ID: "b1", Type: "bullet", Content: "Einkauf planen #Kühlregal #Vorrat", Level: 0},
+	}
+	_, err = store.UpdateDocument(user.ID, doc.ID, nil, nil, nil, &updatedBlocks, nil, nil)
+	if err != nil {
+		t.Fatalf("UpdateDocument failed: %v", err)
+	}
+
+	tagsAfter, err := store.GetWorkspaceTags(user.ID)
+	if err != nil {
+		t.Fatalf("GetWorkspaceTags after update failed: %v", err)
+	}
+	tagMapAfter := make(map[string]int)
+	for _, tg := range tagsAfter {
+		tagMapAfter[tg.Tag] = tg.Count
+	}
+	if tagMapAfter["wocheneinkauf"] != 0 {
+		t.Fatalf("expected wocheneinkauf to be removed, got %v", tagMapAfter)
+	}
+	if tagMapAfter["vorrat"] != 1 || tagMapAfter["kühlregal"] != 1 {
+		t.Fatalf("expected vorrat and kühlregal, got %v", tagMapAfter)
+	}
+}