diff --git a/frontend/src/services/exportService.ts b/frontend/src/services/exportService.ts
index 5f5e102..0e4635c 100644
--- a/frontend/src/services/exportService.ts
+++ b/frontend/src/services/exportService.ts
@@ -1,64 +1,14 @@
 import type { YjsDocument } from '../crdt/YjsDocument';
+import type {
+  CADLayer,
+  CADProperties,
+  CADElement,
+  ExportData,
+  ExportOptions,
+  ExportResult,
+} from '../types/cad.types';
 
-// ── 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;
-  x1?: number;
-  y1?: number;
-  x2?: number;
-  y2?: number;
-  points?: Array<{ x: number; y: number }>;
-  text?: string;
-  fontSize?: number;
-  startAngle?: number;
-  endAngle?: number;
-  [key: string]: unknown;
-}
-
-interface CADElement {
-  id: string;
-  type: string;
-  layerId: string;
-  x: number;
-  y: number;
-  width: number;
-  height: number;
-  properties: CADProperties;
-}
-
-interface ExportData {
-  version: string;
-  exportedAt: number;
-  projectMeta: Record<string, unknown>;
-  layers: CADLayer[];
-  elements: CADElement[];
-}
-
-interface ExportOptions {
-  includeHiddenLayers?: boolean;
-  includeInvisibleElements?: boolean;
-  pageSize?: 'a4' | 'a3' | 'letter';
-  landscape?: boolean;
-}
-
-// ── Helpers ──────────────────────────────────────────────────────────────────
+// ── Helpers ───────────────────────────────────────────────────────────────────
 
 function hexToRgb(hex: string): { r: number; g: number; b: number } {
   const clean = hex.replace('#', '');
@@ -150,412 +100,452 @@ function downloadBlob(content: string | Blob, filename: string, mimeType: string
   URL.revokeObjectURL(url);
 }
 
-// ── JSON Export ──────────────────────────────────────────────────────────────
+// ── JSON Export ───────────────────────────────────────────────────────────────
 
-export function exportJSON(yjsDoc: YjsDocument, filename = 'cad-export.json'): void {
-  const data = collectExportData(yjsDoc, {});
-  const json = JSON.stringify(data, null, 2);
-  downloadBlob(json, filename, 'application/json');
+export function exportJSON(yjsDoc: YjsDocument, filename = 'cad-export.json'): ExportResult {
+  try {
+    const data = collectExportData(yjsDoc, {});
+    const json = JSON.stringify(data, null, 2);
+    downloadBlob(json, filename, 'application/json');
+    return { success: true, data: json };
+  } catch (e) {
+    return {
+      success: false,
+      error: `exportJSON failed: ${(e as Error).message}`,
+    };
+  }
 }
 
-export function exportJSONString(yjsDoc: YjsDocument): string {
-  const data = collectExportData(yjsDoc, {});
-  return JSON.stringify(data, null, 2);
+export function exportJSONString(yjsDoc: YjsDocument): ExportResult {
+  try {
+    const data = collectExportData(yjsDoc, {});
+    const json = JSON.stringify(data, null, 2);
+    return { success: true, data: json };
+  } catch (e) {
+    return {
+      success: false,
+      error: `exportJSONString failed: ${(e as Error).message}`,
+    };
+  }
 }
 
-// ── SVG Export ───────────────────────────────────────────────────────────────
+// ── SVG Export ────────────────────────────────────────────────────────────────
 
-export function exportSVG(yjsDoc: YjsDocument, filename = 'cad-export.svg', options: ExportOptions = {}): void {
-  const data = collectExportData(yjsDoc, options);
+export function exportSVG(yjsDoc: YjsDocument, filename = 'cad-export.svg', options: ExportOptions = {}): ExportResult {
+  try {
+    const data = collectExportData(yjsDoc, options);
 
-  let minX = Infinity, minY = Infinity, maxX = -Infinity, maxY = -Infinity;
-  for (const el of data.elements) {
-    minX = Math.min(minX, el.x);
-    minY = Math.min(minY, el.y);
-    maxX = Math.max(maxX, el.x + el.width);
-    maxY = Math.max(maxY, el.y + el.height);
-  }
-  if (data.elements.length === 0) {
-    minX = 0; minY = 0; maxX = 100; maxY = 100;
-  }
-
-  const padding = 10;
-  const vbX = minX - padding;
-  const vbY = minY - padding;
-  const vbW = (maxX - minX) + padding * 2;
-  const vbH = (maxY - minY) + padding * 2;
-
-  const svgParts: string[] = [];
-  svgParts.push(`<?xml version="1.0" encoding="UTF-8"?>`);
-  svgParts.push(`<svg xmlns="http://www.w3.org/2000/svg" viewBox="${vbX} ${vbY} ${vbW} ${vbH}" width="${vbW}" height="${vbH}">`);
-
-  svgParts.push('<defs><style>');
-  for (const layer of data.layers) {
-    const color = layer.color || '#000000';
-    const dash = layer.lineType === 'dashed' ? 'stroke-dasharray:8,4;' : layer.lineType === 'dotted' ? 'stroke-dasharray:2,3;' : '';
-    svgParts.push(`.layer-${layer.id} { stroke: ${color}; ${dash} }`);
-  }
-  svgParts.push('</style></defs>');
-
-  for (const el of data.elements) {
-    const layer = getLayerById(data.layers, el.layerId);
-    const stroke = el.properties.stroke || layer?.color || '#000000';
-    const fill = el.properties.fill || 'none';
-    const strokeWidth = el.properties.strokeWidth || 1;
-    const transform = el.properties.rotation ? ` transform="rotate(${el.properties.rotation} ${el.x + el.width / 2} ${el.y + el.height / 2})"` : '';
-
-    const svgY = (vbY + vbH) - el.y;
-
-    switch (el.type) {
-      case 'line': {
-        const x1 = el.properties.x1 ?? el.x;
-        const y1 = (vbY + vbH) - (el.properties.y1 ?? el.y);
-        const x2 = el.properties.x2 ?? (el.x + el.width);
-        const y2 = (vbY + vbH) - (el.properties.y2 ?? (el.y + el.height));
-        svgParts.push(`<line x1="${x1}" y1="${y1}" x2="${x2}" y2="${y2}" stroke="${stroke}" stroke-width="${strokeWidth}"${transform} />`);
-        break;
-      }
-      case 'circle': {
-        const radius = el.properties.radius ?? el.width / 2;
-        const cx = el.x + radius;
-        const cy = svgY - radius;
-        svgParts.push(`<circle cx="${cx}" cy="${cy}" r="${radius}" fill="${fill === 'transparent' ? 'none' : fill}" stroke="${stroke}" stroke-width="${strokeWidth}"${transform} />`);
-        break;
-      }
-      case 'rect': {
-        svgParts.push(`<rect x="${el.x}" y="${svgY - el.height}" width="${el.width}" height="${el.height}" fill="${fill === 'transparent' ? 'none' : fill}" stroke="${stroke}" stroke-width="${strokeWidth}"${transform} />`);
-        break;
-      }
-      case 'polyline': {
-        if (el.properties.points && el.properties.points.length > 0) {
-          const pts = el.properties.points.map(p => `${p.x},${(vbY + vbH) - p.y}`).join(' ');
-          svgParts.push(`<polyline points="${pts}" fill="none" stroke="${stroke}" stroke-width="${strokeWidth}"${transform} />`);
-        }
-        break;
-      }
-      case 'polygon': {
-        if (el.properties.points && el.properties.points.length > 0) {
-          const pts = el.properties.points.map(p => `${p.x},${(vbY + vbH) - p.y}`).join(' ');
-          svgParts.push(`<polygon points="${pts}" fill="${fill === 'transparent' ? 'none' : fill}" stroke="${stroke}" stroke-width="${strokeWidth}"${transform} />`);
-        }
-        break;
-      }
-      case 'text': {
-        const text = escapeXml(el.properties.text || '');
-        const fontSize = el.properties.fontSize || 14;
-        svgParts.push(`<text x="${el.x}" y="${svgY}" font-size="${fontSize}" fill="${stroke}"${transform}>${text}</text>`);
-        break;
-      }
-      case 'arc': {
-        const rx = el.width / 2;
-        const ry = el.height / 2;
-        const cx = el.x + rx;
-        const cy = svgY - ry;
-        svgParts.push(`<ellipse cx="${cx}" cy="${cy}" rx="${rx}" ry="${ry}" fill="none" stroke="${stroke}" stroke-width="${strokeWidth}"${transform} />`);
-        break;
-      }
-      default:
-        break;
+    let minX = Infinity, minY = Infinity, maxX = -Infinity, maxY = -Infinity;
+    for (const el of data.elements) {
+      minX = Math.min(minX, el.x);
+      minY = Math.min(minY, el.y);
+      maxX = Math.max(maxX, el.x + el.width);
+      maxY = Math.max(maxY, el.y + el.height);
+    }
+    if (data.elements.length === 0) {
+      minX = 0; minY = 0; maxX = 100; maxY = 100;
     }
-  }
 
-  svgParts.push('</svg>');
-  const svg = svgParts.join('\n');
-  downloadBlob(svg, filename, 'image/svg+xml');
+    const padding = 10;
+    const vbX = minX - padding;
+    const vbY = minY - padding;
+    const vbW = (maxX - minX) + padding * 2;
+    const vbH = (maxY - minY) + padding * 2;
+
+    const svgParts: string[] = [];
+    svgParts.push(`<?xml version="1.0" encoding="UTF-8"?>`);
+    svgParts.push(`<svg xmlns="http://www.w3.org/2000/svg" viewBox="${vbX} ${vbY} ${vbW} ${vbH}" width="${vbW}" height="${vbH}">`);
+
+    svgParts.push('<defs><style>');
+    for (const layer of data.layers) {
+      const color = layer.color || '#000000';
+      const dash = layer.lineType === 'dashed' ? 'stroke-dasharray:8,4;' : layer.lineType === 'dotted' ? 'stroke-dasharray:2,3;' : '';
+      svgParts.push(`.layer-${layer.id} { stroke: ${color}; ${dash} }`);
+    }
+    svgParts.push('</style></defs>');
+
+    for (const el of data.elements) {
+      const layer = getLayerById(data.layers, el.layerId);
+      const stroke = el.properties.stroke || layer?.color || '#000000';
+      const fill = el.properties.fill || 'none';
+      const strokeWidth = el.properties.strokeWidth || 1;
+      const transform = el.properties.rotation ? ` transform="rotate(${el.properties.rotation} ${el.x + el.width / 2} ${el.y + el.height / 2})"` : '';
+
+      const svgY = (vbY + vbH) - el.y;
+
+      switch (el.type) {
+        case 'line': {
+          const x1 = el.properties.x1 ?? el.x;
+          const y1 = (vbY + vbH) - (el.properties.y1 ?? el.y);
+          const x2 = el.properties.x2 ?? (el.x + el.width);
+          const y2 = (vbY + vbH) - (el.properties.y2 ?? (el.y + el.height));
+          svgParts.push(`<line x1="${x1}" y1="${y1}" x2="${x2}" y2="${y2}" stroke="${stroke}" stroke-width="${strokeWidth}"${transform} />`);
+          break;
+        }
+        case 'circle': {
+          const radius = el.properties.radius ?? el.width / 2;
+          const cx = el.x + radius;
+          const cy = svgY - radius;
+          svgParts.push(`<circle cx="${cx}" cy="${cy}" r="${radius}" fill="${fill === 'transparent' ? 'none' : fill}" stroke="${stroke}" stroke-width="${strokeWidth}"${transform} />`);
+          break;
+        }
+        case 'rect': {
+          svgParts.push(`<rect x="${el.x}" y="${svgY - el.height}" width="${el.width}" height="${el.height}" fill="${fill === 'transparent' ? 'none' : fill}" stroke="${stroke}" stroke-width="${strokeWidth}"${transform} />`);
+          break;
+        }
+        case 'polyline': {
+          if (el.properties.points && el.properties.points.length > 0) {
+            const pts = el.properties.points.map(p => `${p.x},${(vbY + vbH) - p.y}`).join(' ');
+            svgParts.push(`<polyline points="${pts}" fill="none" stroke="${stroke}" stroke-width="${strokeWidth}"${transform} />`);
+          }
+          break;
+        }
+        case 'polygon': {
+          if (el.properties.points && el.properties.points.length > 0) {
+            const pts = el.properties.points.map(p => `${p.x},${(vbY + vbH) - p.y}`).join(' ');
+            svgParts.push(`<polygon points="${pts}" fill="${fill === 'transparent' ? 'none' : fill}" stroke="${stroke}" stroke-width="${strokeWidth}"${transform} />`);
+          }
+          break;
+        }
+        case 'text': {
+          const text = escapeXml(el.properties.text || '');
+          const fontSize = el.properties.fontSize || 14;
+          svgParts.push(`<text x="${el.x}" y="${svgY}" font-size="${fontSize}" fill="${stroke}"${transform}>${text}</text>`);
+          break;
+        }
+        case 'arc': {
+          const rx = el.width / 2;
+          const ry = el.height / 2;
+          const cx = el.x + rx;
+          const cy = svgY - ry;
+          svgParts.push(`<ellipse cx="${cx}" cy="${cy}" rx="${rx}" ry="${ry}" fill="none" stroke="${stroke}" stroke-width="${strokeWidth}"${transform} />`);
+          break;
+        }
+        default:
+          break;
+      }
+    }
+
+    svgParts.push('</svg>');
+    const svg = svgParts.join('\n');
+    downloadBlob(svg, filename, 'image/svg+xml');
+    return { success: true, data: svg };
+  } catch (e) {
+    return {
+      success: false,
+      error: `exportSVG failed: ${(e as Error).message}`,
+    };
+  }
 }
 
-// ── DXF Export ───────────────────────────────────────────────────────────────
+// ── DXF Export ────────────────────────────────────────────────────────────────
 
-export function exportDXF(yjsDoc: YjsDocument, filename = 'cad-export.dxf', options: ExportOptions = {}): void {
-  const data = collectExportData(yjsDoc, options);
-  const lines: string[] = [];
+export function exportDXF(yjsDoc: YjsDocument, filename = 'cad-export.dxf', options: ExportOptions = {}): ExportResult {
+  try {
+    const data = collectExportData(yjsDoc, options);
+    const lines: string[] = [];
 
-  lines.push('0'); lines.push('SECTION');
-  lines.push('2'); lines.push('HEADER');
-  lines.push('9'); lines.push('$ACADVER');
-  lines.push('1'); lines.push('AC1009');
-  lines.push('9'); lines.push('$INSBASE');
-  lines.push('10'); lines.push('0.0');
-  lines.push('20'); lines.push('0.0');
-  lines.push('30'); lines.push('0.0');
-  lines.push('0'); lines.push('ENDSEC');
+    lines.push('0'); lines.push('SECTION');
+    lines.push('2'); lines.push('HEADER');
+    lines.push('9'); lines.push('$ACADVER');
+    lines.push('1'); lines.push('AC1009');
+    lines.push('9'); lines.push('$INSBASE');
+    lines.push('10'); lines.push('0.0');
+    lines.push('20'); lines.push('0.0');
+    lines.push('30'); lines.push('0.0');
+    lines.push('0'); lines.push('ENDSEC');
 
-  lines.push('0'); lines.push('SECTION');
-  lines.push('2'); lines.push('TABLES');
-  lines.push('0'); lines.push('TABLE');
-  lines.push('2'); lines.push('LAYER');
-  lines.push('70'); lines.push(String(data.layers.length));
+    lines.push('0'); lines.push('SECTION');
+    lines.push('2'); lines.push('TABLES');
+    lines.push('0'); lines.push('TABLE');
+    lines.push('2'); lines.push('LAYER');
+    lines.push('70'); lines.push(String(data.layers.length));
 
-  for (const layer of data.layers) {
-    const color = layer.color || '#000000';
-    const rgb = hexToRgb(color);
-    const aci = rgbToAci(rgb.r, rgb.g, rgb.b);
-    lines.push('0'); lines.push('LAYER');
-    lines.push('2'); lines.push(layer.name || layer.id);
-    lines.push('70'); lines.push('0');
-    lines.push('62'); lines.push(String(aci));
-    lines.push('6'); lines.push(layer.lineType || 'CONTINUOUS');
-  }
+    for (const layer of data.layers) {
+      const color = layer.color || '#000000';
+      const rgb = hexToRgb(color);
+      const aci = rgbToAci(rgb.r, rgb.g, rgb.b);
+      lines.push('0'); lines.push('LAYER');
+      lines.push('2'); lines.push(layer.name || layer.id);
+      lines.push('70'); lines.push('0');
+      lines.push('62'); lines.push(String(aci));
+      lines.push('6'); lines.push(layer.lineType || 'CONTINUOUS');
+    }
 
-  lines.push('0'); lines.push('ENDTAB');
-  lines.push('0'); lines.push('ENDSEC');
+    lines.push('0'); lines.push('ENDTAB');
+    lines.push('0'); lines.push('ENDSEC');
 
-  lines.push('0'); lines.push('SECTION');
-  lines.push('2'); lines.push('ENTITIES');
+    lines.push('0'); lines.push('SECTION');
+    lines.push('2'); lines.push('ENTITIES');
 
-  for (const el of data.elements) {
-    const layer = getLayerById(data.layers, el.layerId);
-    const layerName = layer?.name || layer?.id || '0';
-    const color = el.properties.stroke || layer?.color || '#000000';
-    const rgb = hexToRgb(color);
-    const aci = rgbToAci(rgb.r, rgb.g, rgb.b);
+    for (const el of data.elements) {
+      const layer = getLayerById(data.layers, el.layerId);
+      const layerName = layer?.name || layer?.id || '0';
+      const color = el.properties.stroke || layer?.color || '#000000';
+      const rgb = hexToRgb(color);
+      const aci = rgbToAci(rgb.r, rgb.g, rgb.b);
 
-    switch (el.type) {
-      case 'line': {
-        const x1 = el.properties.x1 ?? el.x;
-        const y1 = el.properties.y1 ?? el.y;
-        const x2 = el.properties.x2 ?? (el.x + el.width);
-        const y2 = el.properties.y2 ?? (el.y + el.height);
-        lines.push('0'); lines.push('LINE');
-        lines.push('8'); lines.push(layerName);
-        lines.push('62'); lines.push(String(aci));
-        lines.push('10'); lines.push(String(x1));
-        lines.push('20'); lines.push(String(y1));
-        lines.push('30'); lines.push('0.0');
-        lines.push('11'); lines.push(String(x2));
-        lines.push('21'); lines.push(String(y2));
-        lines.push('31'); lines.push('0.0');
-        break;
-      }
-      case 'circle': {
-        const radius = el.properties.radius ?? el.width / 2;
-        const cx = el.x + radius;
-        const cy = el.y + radius;
-        lines.push('0'); lines.push('CIRCLE');
-        lines.push('8'); lines.push(layerName);
-        lines.push('62'); lines.push(String(aci));
-        lines.push('10'); lines.push(String(cx));
-        lines.push('20'); lines.push(String(cy));
-        lines.push('30'); lines.push('0.0');
-        lines.push('40'); lines.push(String(radius));
-        break;
-      }
-      case 'rect': {
-        const x = el.x, y = el.y, w = el.width, h = el.height;
-        lines.push('0'); lines.push('LWPOLYLINE');
-        lines.push('8'); lines.push(layerName);
-        lines.push('62'); lines.push(String(aci));
-        lines.push('90'); lines.push('4');
-        lines.push('70'); lines.push('1');
-        lines.push('10'); lines.push(String(x)); lines.push('20'); lines.push(String(y));
-        lines.push('10'); lines.push(String(x + w)); lines.push('20'); lines.push(String(y));
-        lines.push('10'); lines.push(String(x + w)); lines.push('20'); lines.push(String(y + h));
-        lines.push('10'); lines.push(String(x)); lines.push('20'); lines.push(String(y + h));
-        break;
-      }
-      case 'text': {
-        const text = el.properties.text || '';
-        const fontSize = el.properties.fontSize || 14;
-        lines.push('0'); lines.push('TEXT');
-        lines.push('8'); lines.push(layerName);
-        lines.push('62'); lines.push(String(aci));
-        lines.push('10'); lines.push(String(el.x));
-        lines.push('20'); lines.push(String(el.y));
-        lines.push('30'); lines.push('0.0');
-        lines.push('40'); lines.push(String(fontSize));
-        lines.push('1'); lines.push(text);
-        break;
-      }
-      case 'polyline': {
-        if (el.properties.points && el.properties.points.length > 0) {
-          const pts = el.properties.points;
-          lines.push('0'); lines.push('LWPOLYLINE');
+      switch (el.type) {
+        case 'line': {
+          const x1 = el.properties.x1 ?? el.x;
+          const y1 = el.properties.y1 ?? el.y;
+          const x2 = el.properties.x2 ?? (el.x + el.width);
+          const y2 = el.properties.y2 ?? (el.y + el.height);
+          lines.push('0'); lines.push('LINE');
           lines.push('8'); lines.push(layerName);
           lines.push('62'); lines.push(String(aci));
-          lines.push('90'); lines.push(String(pts.length));
-          lines.push('70'); lines.push('0');
-          for (const p of pts) {
-            lines.push('10'); lines.push(String(p.x));
-            lines.push('20'); lines.push(String(p.y));
-          }
+          lines.push('10'); lines.push(String(x1));
+          lines.push('20'); lines.push(String(y1));
+          lines.push('30'); lines.push('0.0');
+          lines.push('11'); lines.push(String(x2));
+          lines.push('21'); lines.push(String(y2));
+          lines.push('31'); lines.push('0.0');
+          break;
         }
-        break;
-      }
-      case 'polygon': {
-        if (el.properties.points && el.properties.points.length > 0) {
-          const pts = el.properties.points;
+        case 'circle': {
+          const radius = el.properties.radius ?? el.width / 2;
+          const cx = el.x + radius;
+          const cy = el.y + radius;
+          lines.push('0'); lines.push('CIRCLE');
+          lines.push('8'); lines.push(layerName);
+          lines.push('62'); lines.push(String(aci));
+          lines.push('10'); lines.push(String(cx));
+          lines.push('20'); lines.push(String(cy));
+          lines.push('30'); lines.push('0.0');
+          lines.push('40'); lines.push(String(radius));
+          break;
+        }
+        case 'rect': {
+          const x = el.x, y = el.y, w = el.width, h = el.height;
           lines.push('0'); lines.push('LWPOLYLINE');
           lines.push('8'); lines.push(layerName);
           lines.push('62'); lines.push(String(aci));
-          lines.push('90'); lines.push(String(pts.length));
+          lines.push('90'); lines.push('4');
           lines.push('70'); lines.push('1');
-          for (const p of pts) {
-            lines.push('10'); lines.push(String(p.x));
-            lines.push('20'); lines.push(String(p.y));
-          }
+          lines.push('10'); lines.push(String(x)); lines.push('20'); lines.push(String(y));
+          lines.push('10'); lines.push(String(x + w)); lines.push('20'); lines.push(String(y));
+          lines.push('10'); lines.push(String(x + w)); lines.push('20'); lines.push(String(y + h));
+          lines.push('10'); lines.push(String(x)); lines.push('20'); lines.push(String(y + h));
+          break;
         }
-        break;
+        case 'text': {
+          const text = el.properties.text || '';
+          const fontSize = el.properties.fontSize || 14;
+          lines.push('0'); lines.push('TEXT');
+          lines.push('8'); lines.push(layerName);
+          lines.push('62'); lines.push(String(aci));
+          lines.push('10'); lines.push(String(el.x));
+          lines.push('20'); lines.push(String(el.y));
+          lines.push('30'); lines.push('0.0');
+          lines.push('40'); lines.push(String(fontSize));
+          lines.push('1'); lines.push(text);
+          break;
+        }
+        case 'polyline': {
+          if (el.properties.points && el.properties.points.length > 0) {
+            const pts = el.properties.points;
+            lines.push('0'); lines.push('LWPOLYLINE');
+            lines.push('8'); lines.push(layerName);
+            lines.push('62'); lines.push(String(aci));
+            lines.push('90'); lines.push(String(pts.length));
+            lines.push('70'); lines.push('0');
+            for (const p of pts) {
+              lines.push('10'); lines.push(String(p.x));
+              lines.push('20'); lines.push(String(p.y));
+            }
+          }
+          break;
+        }
+        case 'polygon': {
+          if (el.properties.points && el.properties.points.length > 0) {
+            const pts = el.properties.points;
+            lines.push('0'); lines.push('LWPOLYLINE');
+            lines.push('8'); lines.push(layerName);
+            lines.push('62'); lines.push(String(aci));
+            lines.push('90'); lines.push(String(pts.length));
+            lines.push('70'); lines.push('1');
+            for (const p of pts) {
+              lines.push('10'); lines.push(String(p.x));
+              lines.push('20'); lines.push(String(p.y));
+            }
+          }
+          break;
+        }
+        case 'arc': {
+          const radius = el.properties.radius ?? el.width / 2;
+          const cx = el.x + radius;
+          const cy = el.y + radius;
+          // M4 fix: Export actual startAngle (group code 50) and endAngle (group code 51)
+          const startAngle = el.properties.startAngle ?? 0;
+          const endAngle = el.properties.endAngle ?? 360;
+          lines.push('0'); lines.push('ARC');
+          lines.push('8'); lines.push(layerName);
+          lines.push('62'); lines.push(String(aci));
+          lines.push('10'); lines.push(String(cx));
+          lines.push('20'); lines.push(String(cy));
+          lines.push('30'); lines.push('0.0');
+          lines.push('40'); lines.push(String(radius));
+          lines.push('50'); lines.push(String(startAngle));
+          lines.push('51'); lines.push(String(endAngle));
+          break;
+        }
+        default:
+          break;
       }
-      case 'arc': {
-        const radius = el.properties.radius ?? el.width / 2;
-        const cx = el.x + radius;
-        const cy = el.y + radius;
-        // M4 fix: Export actual startAngle (group code 50) and endAngle (group code 51)
-        const startAngle = el.properties.startAngle ?? 0;
-        const endAngle = el.properties.endAngle ?? 360;
-        lines.push('0'); lines.push('ARC');
-        lines.push('8'); lines.push(layerName);
-        lines.push('62'); lines.push(String(aci));
-        lines.push('10'); lines.push(String(cx));
-        lines.push('20'); lines.push(String(cy));
-        lines.push('30'); lines.push('0.0');
-        lines.push('40'); lines.push(String(radius));
-        lines.push('50'); lines.push(String(startAngle));
-        lines.push('51'); lines.push(String(endAngle));
-        break;
-      }
-      default:
-        break;
     }
+
+    lines.push('0'); lines.push('ENDSEC');
+    lines.push('0'); lines.push('EOF');
+
+    const dxf = lines.join('\n');
+    downloadBlob(dxf, filename, 'application/dxf');
+    return { success: true, data: dxf };
+  } catch (e) {
+    return {
+      success: false,
+      error: `exportDXF failed: ${(e as Error).message}`,
+    };
   }
-
-  lines.push('0'); lines.push('ENDSEC');
-  lines.push('0'); lines.push('EOF');
-
-  const dxf = lines.join('\n');
-  downloadBlob(dxf, filename, 'application/dxf');
 }
 
-// ── PDF Export ───────────────────────────────────────────────────────────────
+// ── PDF Export ────────────────────────────────────────────────────────────────
 
 export async function exportPDF(
   yjsDoc: YjsDocument,
   filename = 'cad-export.pdf',
   options: ExportOptions = {}
-): Promise<void> {
-  const data = collectExportData(yjsDoc, options);
+): Promise<ExportResult> {
+  try {
+    const data = collectExportData(yjsDoc, options);
 
-  const { jsPDF } = await import('jspdf');
+    const { jsPDF } = await import('jspdf');
 
-  const pageSize = options.pageSize || 'a4';
-  const orientation = options.landscape ? 'landscape' : 'portrait';
-  const pdf = new jsPDF({
-    orientation,
-    unit: 'mm',
-    format: pageSize,
-  });
+    const pageSize = options.pageSize || 'a4';
+    const orientation = options.landscape ? 'landscape' : 'portrait';
+    const pdf = new jsPDF({
+      orientation,
+      unit: 'mm',
+      format: pageSize,
+    });
 
-  const pageWidth = pdf.internal.pageSize.getWidth();
-  const pageHeight = pdf.internal.pageSize.getHeight();
-  const margin = 10;
-  const drawableW = pageWidth - margin * 2;
-  const drawableH = pageHeight - margin * 2;
+    const pageWidth = pdf.internal.pageSize.getWidth();
+    const pageHeight = pdf.internal.pageSize.getHeight();
+    const margin = 10;
+    const drawableW = pageWidth - margin * 2;
+    const drawableH = pageHeight - margin * 2;
 
-  let minX = Infinity, minY = Infinity, maxX = -Infinity, maxY = -Infinity;
-  for (const el of data.elements) {
-    minX = Math.min(minX, el.x);
-    minY = Math.min(minY, el.y);
-    maxX = Math.max(maxX, el.x + el.width);
-    maxY = Math.max(maxY, el.y + el.height);
-  }
-  if (data.elements.length === 0) {
-    minX = 0; minY = 0; maxX = 100; maxY = 100;
-  }
-
-  const contentW = maxX - minX;
-  const contentH = maxY - minY;
-  const scale = Math.min(drawableW / contentW, drawableH / contentH, 1);
-  const offsetX = margin + (drawableW - contentW * scale) / 2;
-  const offsetY = margin + (drawableH - contentH * scale) / 2;
-
-  const tx = (x: number) => offsetX + (x - minX) * scale;
-  const ty = (y: number) => pageHeight - offsetY - (y - minY) * scale;
-
-  for (const el of data.elements) {
-    const layer = getLayerById(data.layers, el.layerId);
-    const strokeColor = el.properties.stroke || layer?.color || '#000000';
-    const rgb = hexToRgb(strokeColor);
-    pdf.setDrawColor(rgb.r, rgb.g, rgb.b);
-    pdf.setLineWidth((el.properties.strokeWidth || 1) * scale);
-
-    const fillColor = el.properties.fill;
-    if (fillColor && fillColor !== 'transparent') {
-      const fRgb = hexToRgb(fillColor);
-      pdf.setFillColor(fRgb.r, fRgb.g, fRgb.b);
+    let minX = Infinity, minY = Infinity, maxX = -Infinity, maxY = -Infinity;
+    for (const el of data.elements) {
+      minX = Math.min(minX, el.x);
+      minY = Math.min(minY, el.y);
+      maxX = Math.max(maxX, el.x + el.width);
+      maxY = Math.max(maxY, el.y + el.height);
+    }
+    if (data.elements.length === 0) {
+      minX = 0; minY = 0; maxX = 100; maxY = 100;
     }
 
-    switch (el.type) {
-      case 'line': {
-        const x1 = el.properties.x1 ?? el.x;
-        const y1 = el.properties.y1 ?? el.y;
-        const x2 = el.properties.x2 ?? (el.x + el.width);
-        const y2 = el.properties.y2 ?? (el.y + el.height);
-        pdf.line(tx(x1), ty(y1), tx(x2), ty(y2));
-        break;
+    const contentW = maxX - minX;
+    const contentH = maxY - minY;
+    const scale = Math.min(drawableW / contentW, drawableH / contentH, 1);
+    const offsetX = margin + (drawableW - contentW * scale) / 2;
+    const offsetY = margin + (drawableH - contentH * scale) / 2;
+
+    const tx = (x: number) => offsetX + (x - minX) * scale;
+    const ty = (y: number) => pageHeight - offsetY - (y - minY) * scale;
+
+    for (const el of data.elements) {
+      const layer = getLayerById(data.layers, el.layerId);
+      const strokeColor = el.properties.stroke || layer?.color || '#000000';
+      const rgb = hexToRgb(strokeColor);
+      pdf.setDrawColor(rgb.r, rgb.g, rgb.b);
+      pdf.setLineWidth((el.properties.strokeWidth || 1) * scale);
+
+      const fillColor = el.properties.fill;
+      if (fillColor && fillColor !== 'transparent') {
+        const fRgb = hexToRgb(fillColor);
+        pdf.setFillColor(fRgb.r, fRgb.g, fRgb.b);
       }
-      case 'circle': {
-        const radius = el.properties.radius ?? el.width / 2;
-        const cx = tx(el.x + radius);
-        const cy = ty(el.y + radius);
-        pdf.circle(cx, cy, radius * scale, fillColor && fillColor !== 'transparent' ? 'FD' : 'S');
-        break;
-      }
-      case 'rect': {
-        const x = tx(el.x);
-        const y = ty(el.y + el.height);
-        pdf.rect(x, y, el.width * scale, el.height * scale, fillColor && fillColor !== 'transparent' ? 'FD' : 'S');
-        break;
-      }
-      case 'polyline': {
-        if (el.properties.points && el.properties.points.length > 1) {
-          const pts = el.properties.points;
-          for (let i = 0; i < pts.length - 1; i++) {
-            pdf.line(tx(pts[i].x), ty(pts[i].y), tx(pts[i + 1].x), ty(pts[i + 1].y));
-          }
+
+      switch (el.type) {
+        case 'line': {
+          const x1 = el.properties.x1 ?? el.x;
+          const y1 = el.properties.y1 ?? el.y;
+          const x2 = el.properties.x2 ?? (el.x + el.width);
+          const y2 = el.properties.y2 ?? (el.y + el.height);
+          pdf.line(tx(x1), ty(y1), tx(x2), ty(y2));
+          break;
         }
-        break;
-      }
-      case 'polygon': {
-        if (el.properties.points && el.properties.points.length > 2) {
-          const pts = el.properties.points;
-          for (let i = 0; i < pts.length; i++) {
-            const next = (i + 1) % pts.length;
-            pdf.line(tx(pts[i].x), ty(pts[i].y), tx(pts[next].x), ty(pts[next].y));
-          }
+        case 'circle': {
+          const radius = el.properties.radius ?? el.width / 2;
+          const cx = tx(el.x + radius);
+          const cy = ty(el.y + radius);
+          pdf.circle(cx, cy, radius * scale, fillColor && fillColor !== 'transparent' ? 'FD' : 'S');
+          break;
         }
-        break;
+        case 'rect': {
+          const x = tx(el.x);
+          const y = ty(el.y + el.height);
+          pdf.rect(x, y, el.width * scale, el.height * scale, fillColor && fillColor !== 'transparent' ? 'FD' : 'S');
+          break;
+        }
+        case 'polyline': {
+          if (el.properties.points && el.properties.points.length > 1) {
+            const pts = el.properties.points;
+            for (let i = 0; i < pts.length - 1; i++) {
+              pdf.line(tx(pts[i].x), ty(pts[i].y), tx(pts[i + 1].x), ty(pts[i + 1].y));
+            }
+          }
+          break;
+        }
+        case 'polygon': {
+          if (el.properties.points && el.properties.points.length > 2) {
+            const pts = el.properties.points;
+            for (let i = 0; i < pts.length; i++) {
+              const next = (i + 1) % pts.length;
+              pdf.line(tx(pts[i].x), ty(pts[i].y), tx(pts[next].x), ty(pts[next].y));
+            }
+          }
+          break;
+        }
+        case 'text': {
+          const text = el.properties.text || '';
+          const fontSize = (el.properties.fontSize || 14) * scale;
+          pdf.setFontSize(fontSize);
+          pdf.text(text, tx(el.x), ty(el.y));
+          break;
+        }
+        case 'arc': {
+          const radius = el.properties.radius ?? el.width / 2;
+          const cx = tx(el.x + radius);
+          const cy = ty(el.y + radius);
+          pdf.circle(cx, cy, radius * scale, 'S');
+          break;
+        }
+        default:
+          break;
       }
-      case 'text': {
-        const text = el.properties.text || '';
-        const fontSize = (el.properties.fontSize || 14) * scale;
-        pdf.setFontSize(fontSize);
-        pdf.text(text, tx(el.x), ty(el.y));
-        break;
-      }
-      case 'arc': {
-        const radius = el.properties.radius ?? el.width / 2;
-        const cx = tx(el.x + radius);
-        const cy = ty(el.y + radius);
-        pdf.circle(cx, cy, radius * scale, 'S');
-        break;
-      }
-      default:
-        break;
     }
+
+    pdf.setFontSize(8);
+    pdf.setTextColor(128, 128, 128);
+    pdf.text(
+      `Exported: ${new Date().toISOString()} | Elements: ${data.elements.length} | Layers: ${data.layers.length}`,
+      margin,
+      pageHeight - 5
+    );
+
+    pdf.save(filename);
+    return { success: true };
+  } catch (e) {
+    return {
+      success: false,
+      error: `exportPDF failed: ${(e as Error).message}`,
+    };
   }
-
-  pdf.setFontSize(8);
-  pdf.setTextColor(128, 128, 128);
-  pdf.text(
-    `Exported: ${new Date().toISOString()} | Elements: ${data.elements.length} | Layers: ${data.layers.length}`,
-    margin,
-    pageHeight - 5
-  );
-
-  pdf.save(filename);
 }
 
-// ── Unified Export ───────────────────────────────────────────────────────────
+// ── Unified Export ─────────────────────────────────────────────────────────────
 
 export type ExportFormat = 'json' | 'svg' | 'dxf' | 'pdf';
 
@@ -564,7 +554,7 @@ export async function exportDrawing(
   format: ExportFormat,
   filename?: string,
   options?: ExportOptions
-): Promise<void> {
+): Promise<ExportResult> {
   const ext = format;
   const name = filename || `cad-export.${ext}`;
 
@@ -578,6 +568,9 @@ export async function exportDrawing(
     case 'pdf':
       return exportPDF(yjsDoc, name, options);
     default:
-      throw new Error(`Unsupported export format: ${format}`);
+      return {
+        success: false,
+        error: `Unsupported export format: ${format}`,
+      };
   }
 }