T24: Use shared types, add 300ms debounce on Yjs updates in PropertiesPanel

frontend/src/components/PropertiesPanel/PropertiesPanel.tsx

@@ -1,39 +1,8 @@
 import React, { useState, useEffect, useCallback, useRef } from 'react';
+import type { CADLayer, CADProperties, CADElement } from '../../types/cad.types';
 import './PropertiesPanel.css';
 
-// ─── Types ───────────────────────────────────────────────────────────────────
-
-interface CADLayer {
-  id: string;
-  name: string;
-  visible: boolean;
-  locked: boolean;
-  color?: string;
-  lineType?: string;
-  transparency?: number;
-  sortOrder?: number;
-}
-
-interface CADProperties {
-  fill?: string;
-  stroke?: string;
-  strokeWidth?: number;
-  rotation?: number;
-  lineType?: 'solid' | 'dashed' | 'dotted';
-  radius?: number;
-  [key: string]: unknown;
-}
-
-interface CADElement {
-  id: string;
-  type: string;
-  layerId: string;
-  x: number;
-  y: number;
-  width: number;
-  height: number;
-  properties: CADProperties;
-}
+// ─── Types (local-only, not duplicated from cad.types.ts) ─────────────────────
 
 interface YjsDocumentLike {
   layers: {
@@ -112,6 +81,18 @@ const PropertiesPanel: React.FC<PropertiesPanelProps> = ({ canvasRef, yjsDocRef
   const [fabricObject, setFabricObject] = useState<FabricObjectLike | null>(null);
   const fabricCanvasRef = useRef<FabricCanvasLike | null>(null);
 
+  // Debounce timer for Yjs updates (300ms) — no new dependency needed
+  const yjsDebounceRef = useRef<ReturnType<typeof setTimeout> | null>(null);
+
+  // Clear debounce timer on unmount
+  useEffect(() => {
+    return () => {
+      if (yjsDebounceRef.current) {
+        clearTimeout(yjsDebounceRef.current);
+      }
+    };
+  }, []);
+
   // ── Sync layers from YjsDocument ──────────────────────────────────────────
   useEffect(() => {
     const yjsDoc = yjsDocRef?.current;
@@ -215,19 +196,26 @@ const PropertiesPanel: React.FC<PropertiesPanelProps> = ({ canvasRef, yjsDocRef
     };
   }, [canvasRef, yjsDocRef]);
 
-  // ── Update handlers (Panel → Canvas + YjsDocument) ─────────────────────────
+  // ── Update handlers (Panel → Canvas + YjsDocument) ──────────────────────────
 
   const updateFabricAndYjs = useCallback(
     (updates: Partial<CADElement> & { properties?: Partial<CADProperties> }) => {
       if (!selectedElement) return;
 
-      // Update YjsDocument
-      const yjsDoc = yjsDocRef?.current;
-      if (yjsDoc) {
-        yjsDoc.updateElement(selectedElement.id, updates);
+      // Debounce Yjs write (300ms) — only write after user pauses typing
+      if (yjsDebounceRef.current) {
+        clearTimeout(yjsDebounceRef.current);
       }
+      const elId = selectedElement.id;
+      yjsDebounceRef.current = setTimeout(() => {
+        const yjsDoc = yjsDocRef?.current;
+        if (yjsDoc) {
+          yjsDoc.updateElement(elId, updates);
+        }
+        yjsDebounceRef.current = null;
+      }, 300);
 
-      // Update fabric object directly
+      // Update fabric object directly (immediate, no debounce)
       const fabricObj = fabricObject;
       const fabricCanvas = fabricCanvasRef.current;
       if (fabricObj && fabricCanvas) {
@@ -251,7 +239,7 @@ const PropertiesPanel: React.FC<PropertiesPanelProps> = ({ canvasRef, yjsDocRef
         fabricCanvas.renderAll();
       }
 
-      // Update local state
+      // Update local state (immediate, no debounce)
       setSelectedElement((prev) => {
         if (!prev) return prev;
         return {
@@ -264,7 +252,7 @@ const PropertiesPanel: React.FC<PropertiesPanelProps> = ({ canvasRef, yjsDocRef
     [selectedElement, fabricObject, yjsDocRef]
   );
 
-  // ── Field change handlers ─────────────────────────────────────────────────
+  // ── Field change handlers ──────────────────────────────────────────────────
 
   const handleNumberChange = (field: 'x' | 'y' | 'width' | 'height', value: string) => {
     const n = clampNumber(value, -100000, 100000);
@@ -297,7 +285,7 @@ const PropertiesPanel: React.FC<PropertiesPanelProps> = ({ canvasRef, yjsDocRef
     updateFabricAndYjs({ layerId: value });
   };
 
-  // ── Render ────────────────────────────────────────────────────────────────
+  // ── Render ──────────────────────────────────────────────────────────────────
 
   if (!selectedElement) {
     return (