fix(merge): page labels, retain-labels option, and workflow alignment with cpdf

src/js/workflow/nodes/merge-node.ts

@@ -3,7 +3,7 @@ import { BaseWorkflowNode } from './base-node';
 import { pdfSocket } from '../sockets';
 import type { SocketData } from '../types';
 import { extractAllPdfs } from '../types';
-import { mergePdfs } from '../../utils/pdf-operations';
+import { mergePdfsCpdf } from '../../utils/merge-cpdf';
 import { loadPdfDocument } from '../../utils/load-pdf-document.js';
 import { wfError } from '../errors';
 
@@ -16,6 +16,10 @@ export class MergeNode extends BaseWorkflowNode {
     super('Merge PDFs');
     this.addInput('pdf', new ClassicPreset.Input(pdfSocket, 'PDFs', true));
     this.addOutput('pdf', new ClassicPreset.Output(pdfSocket, 'Merged PDF'));
+    this.addControl(
+      'retainPageLabels',
+      new ClassicPreset.InputControl('text', { initial: 'false' })
+    );
   }
 
   async data(
@@ -26,7 +30,17 @@ export class MergeNode extends BaseWorkflowNode {
     if (allPdfs.length === 0)
       throw new Error(wfError('noPdfsConnected', { node: 'Merge' }));
 
-    const mergedBytes = await mergePdfs(allPdfs.map((p) => p.bytes));
+    const filesToMerge = allPdfs.map((p, idx) => ({
+      name: p.filename || `input-${idx}.pdf`,
+      data: p.bytes.slice().buffer as ArrayBuffer,
+    }));
+
+    const retainCtrl = this.controls['retainPageLabels'] as
+      | ClassicPreset.InputControl<'text'>
+      | undefined;
+    const retainPageLabels = (retainCtrl?.value ?? 'false') === 'true';
+
+    const mergedBytes = await mergePdfsCpdf(filesToMerge, { retainPageLabels });
     const mergedDoc = await loadPdfDocument(mergedBytes);
 
     return {