fix: HIGH issues #13,#14,#18,#19,#20 — frontend state/sync: copy-paste selection, dynamic activeLayer, group creation, Yjs awareness protocol, connect sync

frontend/src/App.tsx

@@ -111,6 +111,7 @@ const CADEditor: React.FC<CADEditorProps> = ({ projectId, token, onNavigateBack
   // Right sidebar
   const [activeRightPanel, setActiveRightPanel] = useState<RightPanel>('tool');
   const [selectedElement, setSelectedElement] = useState<CADElement | null>(null);
+  const [selectedElementIds, setSelectedElementIds] = useState<string[]>([]);
   const [layers, setLayers] = useState<CADLayer[]>(initialLayers);
   const [activeLayerId, setActiveLayerId] = useState<string>('layer-0');
   const [blocks, setBlocks] = useState<BlockDefinition[]>(initialBlocks);
@@ -191,6 +192,8 @@ const CADEditor: React.FC<CADEditorProps> = ({ projectId, token, onNavigateBack
   bgConfigRef.current = bgConfig;
   const activeLayerIdRef = useRef(activeLayerId);
   activeLayerIdRef.current = activeLayerId;
+  const selectedElementIdsRef = useRef(selectedElementIds);
+  selectedElementIdsRef.current = selectedElementIds;
 
   // Clipboard (for copy/paste)
   const clipboardRef = React.useRef<CADElement[] | null>(null);
@@ -642,11 +645,16 @@ const CADEditor: React.FC<CADEditorProps> = ({ projectId, token, onNavigateBack
   }, [blocks, activeLayerId, collab, drawingId, token]);
 
   const handleSelectionChange = useCallback((selectedIds: string[]) => {
+    setSelectedElementIds(selectedIds);
     if (selectedIds.length === 1) {
       const el = elements.find(e => e.id === selectedIds[0]);
       setSelectedElement(el ?? null);
-    } else {
+    } else if (selectedIds.length === 0) {
       setSelectedElement(null);
+    } else {
+      // Multiple elements selected — keep the first one as a representative for the properties panel
+      const el = elements.find(e => e.id === selectedIds[0]);
+      setSelectedElement(el ?? null);
     }
   }, [elements]);
 
@@ -776,7 +784,8 @@ const CADEditor: React.FC<CADEditorProps> = ({ projectId, token, onNavigateBack
     if (action === 'undo') { handleUndo(); return; }
     if (action === 'redo') { handleRedo(); return; }
     if (action === 'copy') {
-      const selected = selectedElement ? [selectedElement] : [];
+      const ids = selectedElementIdsRef.current;
+      const selected = ids.length > 0 ? elements.filter(e => ids.includes(e.id)) : [];
       const clip = selected.length > 0 ? selected : elements.slice(0, 1);
       clipboardRef.current = clip;
       setCommandHistory((prev) => [...prev, { prefix: '·', text: `${clip.length} Element(e) kopiert`, type: 'info' }]);
@@ -1136,10 +1145,17 @@ const CADEditor: React.FC<CADEditorProps> = ({ projectId, token, onNavigateBack
     // Group command: create group from currently selected elements
     if (upper === 'GROUP' || upper === 'GRP') {
       const gm = groupManagerRef.current;
-      // For now, group all elements (selection state is in InteractionEngine, not accessible here)
-      // In a full implementation, we'd need selected IDs from the interaction engine
-      setCommandHistory((prev) => [...prev, { prefix: '·', text: 'Gruppe erstellt (Auswahl im Canvas erforderlich)', type: 'info' }]);
-      setGroups(gm.getGroups());
+      const ids = selectedElementIdsRef.current;
+      if (ids.length < 2) {
+        setCommandHistory((prev) => [...prev, { prefix: '·', text: 'Gruppe: Mindestens 2 Elemente auswählen', type: 'info' }]);
+        return;
+      }
+      const group = gm.createGroup(ids);
+      const newGroups = gm.getGroups();
+      setGroups(newGroups);
+      // Sync group to Yjs CRDT for real-time collaboration
+      collab.setGroup(group);
+      setCommandHistory((prev) => [...prev, { prefix: '·', text: `Gruppe erstellt: ${group.name} (${ids.length} Elemente)`, type: 'info' }]);
       return;
     }
 
@@ -1194,7 +1210,7 @@ const CADEditor: React.FC<CADEditorProps> = ({ projectId, token, onNavigateBack
         setCommandHistory((prev) => [...prev, { prefix: '·', text: `Unbekannter Befehl: ${cmd}`, type: 'info' }]);
       }
     }
-  }, [handleUndo, handleRedo, handleRibbonAction]);
+  }, [handleUndo, handleRedo, handleRibbonAction, collab]);
 
   const handleKISend = useCallback(async (text: string) => {
     const userMsg: KIMessage = { id: `ki-${Date.now()}`, role: 'user', content: text };
@@ -1249,7 +1265,7 @@ const CADEditor: React.FC<CADEditorProps> = ({ projectId, token, onNavigateBack
     handleKISend(suggestion.label);
   }, [handleKISend]);
 
-  const activeLayerName = layers.find((l) => l.id === 'layer-0')?.name ?? '—';
+  const activeLayerName = layers.find((l) => l.id === activeLayerId)?.name ?? '—';
 
   // ─── Render ─────────────────────────────────────────────
   return (

frontend/src/crdt/AwarenessManager.ts

@@ -1,9 +1,11 @@
 /**
  * AwarenessManager – Tracks user presence, cursor position, and selection.
- * Uses a Y.Map inside the shared doc so awareness state syncs via the same
- * raw-update WebSocket protocol as the rest of the document.
+ * Uses the Yjs awareness protocol (y-protocols/awareness) for ephemeral
+ * state that should NOT be persisted in the shared Y.Doc.
+ *
+ * Reference: https://docs.yjs.dev/ecosystem/awareness
  */
-import * as Y from 'yjs';
+import { Awareness, encodeAwarenessUpdate, applyAwarenessUpdate } from 'y-protocols/awareness';
 import type { YjsDocument } from './YjsDocument';
 
 export interface UserCursor {
@@ -20,13 +22,28 @@ export interface UserSelection {
   elementIds: string[];
 }
 
-export interface AwarenessState {
-  cursors: Y.Map<UserCursor>;
-  selections: Y.Map<UserSelection>;
+/**
+ * Payload stored under the 'cursor' field of each client's awareness state.
+ */
+interface CursorAwarenessPayload {
+  userId: string;
+  userName: string;
+  color: string;
+  x: number;
+  y: number;
+  visible: boolean;
+}
+
+/**
+ * Payload stored under the 'selection' field of each client's awareness state.
+ */
+interface SelectionAwarenessPayload {
+  userId: string;
+  elementIds: string[];
 }
 
 export class AwarenessManager {
-  readonly state: AwarenessState;
+  readonly awareness: Awareness;
   private yjsDoc: YjsDocument;
   private userId: string;
   private listeners: Set<() => void> = new Set();
@@ -34,85 +51,160 @@ export class AwarenessManager {
   constructor(yjsDoc: YjsDocument, userId: string) {
     this.yjsDoc = yjsDoc;
     this.userId = userId;
-    this.state = {
-      cursors: this.yjsDoc.doc.getMap<UserCursor>('awareness-cursors'),
-      selections: this.yjsDoc.doc.getMap<UserSelection>('awareness-selections'),
-    };
+    this.awareness = new Awareness(yjsDoc.doc);
   }
 
   /** Set the local user's cursor position */
   setCursor(x: number, y: number, userName: string, color: string): void {
-    this.state.cursors.set(this.userId, {
+    const payload: CursorAwarenessPayload = {
       userId: this.userId,
       userName,
       color,
       x,
       y,
       visible: true,
-    });
+    };
+    this.awareness.setLocalStateField('cursor', payload);
   }
 
   /** Hide the local user's cursor */
   hideCursor(): void {
-    const cur = this.state.cursors.get(this.userId);
-    if (cur) {
-      this.state.cursors.set(this.userId, { ...cur, visible: false });
+    const localState = this.awareness.getLocalState();
+    if (localState && localState.cursor) {
+      const cursor = localState.cursor as CursorAwarenessPayload;
+      this.awareness.setLocalStateField('cursor', {
+        ...cursor,
+        visible: false,
+      } as CursorAwarenessPayload);
     }
   }
 
   /** Set the local user's selection */
   setSelection(elementIds: string[]): void {
-    this.state.selections.set(this.userId, {
+    const payload: SelectionAwarenessPayload = {
       userId: this.userId,
       elementIds,
-    });
+    };
+    this.awareness.setLocalStateField('selection', payload);
   }
 
   /** Clear the local user's selection */
   clearSelection(): void {
-    this.state.selections.delete(this.userId);
+    this.awareness.setLocalStateField('selection', null);
   }
 
   /** Remove the local user from awareness (on disconnect) */
   removeSelf(): void {
-    this.state.cursors.delete(this.userId);
-    this.state.selections.delete(this.userId);
+    this.awareness.setLocalState(null);
   }
 
-  /** Get all active cursors */
+  /**
+   * Encode an awareness update for the local client.
+   * Used by WebSocketProvider to send awareness state over the wire.
+   */
+  encodeLocalState(): Uint8Array | null {
+    const localState = this.awareness.getLocalState();
+    if (!localState) return null;
+    return encodeAwarenessUpdate(this.awareness, [this.awareness.clientID]);
+  }
+
+  /**
+   * Apply a remote awareness update received from the server.
+   * Used by WebSocketProvider to process incoming awareness messages.
+   */
+  applyRemoteUpdate(update: Uint8Array, origin: unknown = 'remote'): void {
+    applyAwarenessUpdate(this.awareness, update, origin);
+    this.notifyListeners();
+  }
+
+  /** Get all active cursors from all connected clients */
   getAllCursors(): UserCursor[] {
-    return Array.from(this.state.cursors.values()).filter((c) => c.visible);
+    const cursors: UserCursor[] = [];
+    for (const [, state] of this.awareness.getStates()) {
+      if (state && state.cursor) {
+        const c = state.cursor as CursorAwarenessPayload;
+        if (c.visible) {
+          cursors.push({
+            userId: c.userId,
+            userName: c.userName,
+            color: c.color,
+            x: c.x,
+            y: c.y,
+            visible: c.visible,
+          });
+        }
+      }
+    }
+    return cursors;
   }
 
-  /** Get all selections */
+  /** Get all selections from all connected clients */
   getAllSelections(): UserSelection[] {
-    return Array.from(this.state.selections.values());
+    const selections: UserSelection[] = [];
+    for (const [, state] of this.awareness.getStates()) {
+      if (state && state.selection) {
+        const s = state.selection as SelectionAwarenessPayload;
+        selections.push({
+          userId: s.userId,
+          elementIds: s.elementIds,
+        });
+      }
+    }
+    return selections;
   }
 
   /** Get a specific user's cursor */
   getCursor(userId: string): UserCursor | undefined {
-    return this.state.cursors.get(userId);
+    for (const [, state] of this.awareness.getStates()) {
+      if (state && state.cursor) {
+        const c = state.cursor as CursorAwarenessPayload;
+        if (c.userId === userId) {
+          return {
+            userId: c.userId,
+            userName: c.userName,
+            color: c.color,
+            x: c.x,
+            y: c.y,
+            visible: c.visible,
+          };
+        }
+      }
+    }
+    return undefined;
   }
 
   /** Get a specific user's selection */
   getSelection(userId: string): UserSelection | undefined {
-    return this.state.selections.get(userId);
+    for (const [, state] of this.awareness.getStates()) {
+      if (state && state.selection) {
+        const s = state.selection as SelectionAwarenessPayload;
+        if (s.userId === userId) {
+          return {
+            userId: s.userId,
+            elementIds: s.elementIds,
+          };
+        }
+      }
+    }
+    return undefined;
   }
 
   /** Register a callback for awareness changes */
   onChange(callback: () => void): () => void {
     this.listeners.add(callback);
-    const cursorObserver = () => this.notifyListeners();
-    const selectionObserver = () => this.notifyListeners();
-    this.state.cursors.observe(cursorObserver);
-    this.state.selections.observe(selectionObserver);
+    const observer = () => this.notifyListeners();
+    this.awareness.on('change', observer);
     return () => {
       this.listeners.delete(callback);
-      this.state.cursors.unobserve(cursorObserver);
-      this.state.selections.unobserve(selectionObserver);
+      this.awareness.off('change', observer);
     };
   }
 
+  /** Destroy the awareness instance */
+  destroy(): void {
+    this.awareness.destroy();
+  }
+
   private notifyListeners(): void {
     for (const cb of this.listeners) {
       cb();

frontend/src/crdt/WebSocketProvider.ts

@@ -1,9 +1,14 @@
 /**
  * WebSocketProvider – Custom WebSocket provider matching the backend raw-update protocol.
  * Backend sends Y.encodeStateAsUpdate on connect and applies raw updates on message.
+ *
+ * Issue #20: On connect, the client must NOT send its local state immediately.
+ * Instead, the server sends its state first (Y.encodeStateAsUpdate). The client
+ * applies that update to sync, then sends only incremental local updates.
  */
 import * as Y from 'yjs';
 import type { YjsDocument } from './YjsDocument';
+import type { AwarenessManager } from './AwarenessManager';
 
 export type ConnectionStatus = 'disconnected' | 'connecting' | 'connected' | 'error';
 
@@ -11,15 +16,22 @@ export interface WebSocketProviderOptions {
   url: string;
   docName: string;
   yjsDoc: YjsDocument;
+  awareness?: AwarenessManager;
   onStatusChange?: (status: ConnectionStatus) => void;
   onSync?: () => void;
 }
 
+// Message type prefixes for multiplexing Y.Doc updates and awareness updates
+// Using a simple byte-prefix scheme: 0 = Y.Doc update, 1 = awareness update
+const MSG_DOC_UPDATE = 0;
+const MSG_AWARENESS = 1;
+
 export class WebSocketProvider {
   private ws: WebSocket | null = null;
   private url: string;
   private docName: string;
   private yjsDoc: YjsDocument;
+  private awareness?: AwarenessManager;
   private status: ConnectionStatus = 'disconnected';
   private onStatusChange?: (status: ConnectionStatus) => void;
   private onSync?: () => void;
@@ -28,11 +40,13 @@ export class WebSocketProvider {
   private maxReconnectDelay = 30000;
   private shouldReconnect = true;
   private authToken: string | undefined;
+  private synced = false;
 
   constructor(opts: WebSocketProviderOptions) {
     this.url = opts.url;
     this.docName = opts.docName;
     this.yjsDoc = opts.yjsDoc;
+    this.awareness = opts.awareness;
     this.onStatusChange = opts.onStatusChange;
     this.onSync = opts.onSync;
   }
@@ -44,6 +58,7 @@ export class WebSocketProvider {
 
     this.authToken = token;
     this.shouldReconnect = true;
+    this.synced = false;
     this.setStatus('connecting');
 
     const tokenParam = token ? `?token=${encodeURIComponent(token)}` : '';
@@ -61,20 +76,50 @@ export class WebSocketProvider {
     this.ws.onopen = () => {
       this.setStatus('connected');
       this.reconnectDelay = 1000;
-      // Send local state to server for initial sync
-      const stateUpdate = Y.encodeStateAsUpdate(this.yjsDoc.doc);
-      if (stateUpdate.length > 0) {
-        this.ws?.send(stateUpdate);
+      // Issue #20: Do NOT send local state on connect.
+      // The server sends its state (Y.encodeStateAsUpdate) to new clients.
+      // We wait for that server state, apply it, then mark as synced.
+      // Only after sync do we forward incremental local updates.
+      //
+      // If we have awareness, send our local awareness state after connect.
+      if (this.awareness) {
+        const awarenessUpdate = this.awareness.encodeLocalState();
+        if (awarenessUpdate && awarenessUpdate.length > 0) {
+          this.sendAwarenessUpdate(awarenessUpdate);
+        }
       }
-      this.onSync?.();
     };
 
     this.ws.onmessage = (event: MessageEvent) => {
       try {
         const data = new Uint8Array(event.data as ArrayBuffer);
-        this.yjsDoc.applyUpdate(data);
+        if (data.length === 0) return;
+
+        // Check message type prefix (first byte)
+        const msgType = data[0];
+        const payload = data.slice(1);
+
+        if (msgType === MSG_AWARENESS) {
+          // Awareness update — apply to awareness manager
+          if (this.awareness) {
+            this.awareness.applyRemoteUpdate(payload, 'remote');
+          }
+        } else {
+          // Y.Doc update — apply to Y.Doc
+          // Support both prefixed and non-prefixed messages for backward compatibility
+          // If the first byte looks like a valid Y.Doc update, use the full data;
+          // otherwise treat the whole message as the Y.Doc update (legacy mode).
+          const updateData = msgType === MSG_DOC_UPDATE ? payload : data;
+          this.yjsDoc.applyUpdate(updateData);
+
+          // Mark as synced after receiving the first server state
+          if (!this.synced) {
+            this.synced = true;
+            this.onSync?.();
+          }
+        }
       } catch (err) {
-        console.warn('[WebSocketProvider] Failed to apply update:', err);
+        console.warn('[WebSocketProvider] Failed to process message:', err);
       }
     };
 
@@ -84,6 +129,7 @@ export class WebSocketProvider {
 
     this.ws.onclose = () => {
       this.ws = null;
+      this.synced = false;
       this.setStatus('disconnected');
       if (this.shouldReconnect) {
         this.scheduleReconnect();
@@ -93,8 +139,22 @@ export class WebSocketProvider {
 
   /** Send a local Y.Doc update to the server */
   sendUpdate(update: Uint8Array): void {
+    if (this.ws && this.ws.readyState === WebSocket.OPEN && this.synced) {
+      // Prefix with MSG_DOC_UPDATE byte
+      const msg = new Uint8Array(update.length + 1);
+      msg[0] = MSG_DOC_UPDATE;
+      msg.set(update, 1);
+      this.ws.send(msg);
+    }
+  }
+
+  /** Send a local awareness update to the server */
+  sendAwarenessUpdate(update: Uint8Array): void {
     if (this.ws && this.ws.readyState === WebSocket.OPEN) {
-      this.ws.send(update);
+      const msg = new Uint8Array(update.length + 1);
+      msg[0] = MSG_AWARENESS;
+      msg.set(update, 1);
+      this.ws.send(msg);
     }
   }
 
@@ -112,6 +172,25 @@ export class WebSocketProvider {
     };
   }
 
+  /** Listen for local awareness changes and forward to server */
+  bindAwarenessUpdates(): () => void {
+    if (!this.awareness) return () => {};
+    const handler = () => {
+      const update = this.awareness!.encodeLocalState();
+      if (update && update.length > 0) {
+        this.sendAwarenessUpdate(update);
+      }
+    };
+    this.awareness.awareness.on('update', handler);
+    return () => {
+      this.awareness!.awareness.off('update', handler);
+    };
+  }
+
+  isSynced(): boolean {
+    return this.synced;
+  }
+
   getStatus(): ConnectionStatus {
     return this.status;
   }
@@ -126,6 +205,7 @@ export class WebSocketProvider {
       this.ws.close();
       this.ws = null;
     }
+    this.synced = false;
     this.setStatus('disconnected');
   }
 

frontend/src/crdt/index.ts

@@ -3,5 +3,5 @@
  */
 export { YjsDocument, type YjsDocumentData } from './YjsDocument';
 export { WebSocketProvider, type ConnectionStatus, type WebSocketProviderOptions } from './WebSocketProvider';
-export { AwarenessManager, type UserCursor, type UserSelection, type AwarenessState } from './AwarenessManager';
+export { AwarenessManager, type UserCursor, type UserSelection } from './AwarenessManager';
 export { useYjsBinding, type UseYjsBindingOptions, type UseYjsBindingResult } from './useYjsBinding';

frontend/src/crdt/useYjsBinding.ts

@@ -82,17 +82,18 @@ export function useYjsBinding(opts: UseYjsBindingOptions): UseYjsBindingResult {
     const doc = new YjsDocument();
     yjsDocRef.current = doc;
 
+    const awareness = new AwarenessManager(doc, userId);
+    awarenessRef.current = awareness;
+
     const provider = new WebSocketProvider({
       url: wsUrl,
       docName,
       yjsDoc: doc,
+      awareness,
       onStatusChange: (s) => setStatus(s),
     });
     providerRef.current = provider;
 
-    const awareness = new AwarenessManager(doc, userId);
-    awarenessRef.current = awareness;
-
     // Sync local state from Y.Doc on changes
     const syncState = () => {
       setElements(doc.getElements());
@@ -123,6 +124,8 @@ export function useYjsBinding(opts: UseYjsBindingOptions): UseYjsBindingResult {
 
     // Forward local updates to server
     const unbindLocal = provider.bindLocalUpdates();
+    // Forward local awareness updates to server
+    const unbindAwarenessUpdates = provider.bindAwarenessUpdates();
 
     // Connect
     provider.connect(token);
@@ -135,7 +138,9 @@ export function useYjsBinding(opts: UseYjsBindingOptions): UseYjsBindingResult {
       unbindDoc();
       unbindAwareness();
       unbindLocal();
+      unbindAwarenessUpdates();
       awareness.removeSelf();
+      awareness.destroy();
       provider.disconnect();
       doc.destroy();
       yjsDocRef.current = null;