task(A2): tool dispatcher behind flag

frontend/src/components/CanvasArea.tsx

@@ -12,6 +12,8 @@ import { SpatialIndex } from '../canvas/SpatialIndex';
 import { LayerManager } from '../canvas/LayerManager';
 import { GroupManager } from '../tools/modification/GroupTool';
 import { formatCoordinate } from '../utils/format';
+import { InteractionDispatcher } from '../interaction/dispatcher';
+import { logger } from '../utils/logger';
 
 const CanvasArea: React.FC<CanvasAreaProps> = ({
   cursorPos, viewMode, onViewChange, gridEnabled, orthoEnabled, snapEnabled,
@@ -26,6 +28,7 @@ const CanvasArea: React.FC<CanvasAreaProps> = ({
   const zoomPanRef = useRef<ZoomPanController | null>(null);
   const renderEngineRef = useRef<RenderEngine | null>(null);
   const interactionRef = useRef<InteractionEngine | null>(null);
+  const dispatcherRef = useRef<InteractionDispatcher | null>(null);
   const spatialIndexRef = useRef<SpatialIndex | null>(null);
   const layerManagerRef = useRef<LayerManager | null>(null);
   const selectionEngineRef = useRef<SelectionEngine | null>(null);
@@ -44,6 +47,21 @@ const CanvasArea: React.FC<CanvasAreaProps> = ({
       canvas, zoomPan, renderEngine, snapEngine, selectionEngine, spatialIndex, layerManager,
     );
 
+    // ── Task A2: V2-Tool-Dispatcher hinter Feature-Flag ──
+    // Flag VITE_TOOL_DISPATCHER=v2 (in .env / Shell): aktiviert den neuen
+    // InteractionDispatcher parallel zur Legacy InteractionEngine.
+    // Tools mit handlers werden dann über die Plugin-API v2 geroutet.
+    if (import.meta.env.VITE_TOOL_DISPATCHER === 'v2') {
+      dispatcherRef.current = new InteractionDispatcher(canvas, {
+        zoomPan,
+        setStatus: (msg) => {
+          /* StatusBar-Bridge folgt in A3 */
+        },
+        setPreview: (el) => renderEngine.setPreviewElement(el as CADElement | null),
+      });
+      logger.info('InteractionDispatcher v2 aktiviert (VITE_TOOL_DISPATCHER=v2)');
+    }
+
     zoomPanRef.current = zoomPan;
     renderEngineRef.current = renderEngine;
     interactionRef.current = interaction;
@@ -66,6 +84,8 @@ const CanvasArea: React.FC<CanvasAreaProps> = ({
 
     return () => {
       interaction.detach();
+      dispatcherRef.current?.destroy();
+      dispatcherRef.current = null;
       zoomPanRef.current = null;
       renderEngineRef.current = null;
       interactionRef.current = null;