fix(super-editor): reconcile OPC package metadata during DOCX export

packages/super-editor/src/core/DocxZipper.js

@@ -4,6 +4,7 @@ import { getContentTypesFromXml, base64ToUint8Array, detectImageType } from './s
 import { ensureXmlString, isXmlLike } from './encoding-helpers.js';
 import { DOCX } from '@superdoc/common';
 import { COMMENT_FILE_BASENAMES } from './super-converter/constants.js';
+import { syncPackageMetadata } from './opc/sync-package-metadata.js';
 
 /** Image file extensions recognized during import and export. */
 const IMAGE_EXTS = new Set(['png', 'jpg', 'jpeg', 'gif', 'bmp', 'tiff', 'tif', 'emf', 'wmf', 'svg', 'webp']);
@@ -313,6 +314,47 @@ class DocxZipper {
     docx.file(contentTypesPath, updatedContentTypesXml);
   }
 
+  /**
+   * Run the OPC package metadata synchronizer against a JSZip instance.
+   *
+   * Reads [Content_Types].xml and _rels/.rels from the zip, reconciles
+   * managed package-level parts, and writes the corrected files back.
+   *
+   * The assembled zip is treated as the single source of truth — no stale
+   * updatedDocs are passed, so the synchronizer sees exactly what
+   * updateContentTypes() already wrote.
+   *
+   * @param {JSZip} zip - The fully assembled zip to reconcile.
+   */
+  async #syncPackageMetadataInZip(zip) {
+    // Build a base-files map from the zip's current listing.
+    // At this point the zip already contains all base + updated + media entries.
+    const baseForSync = {};
+    zip.forEach((path) => {
+      baseForSync[path] = ''; // non-null signals "exists"
+    });
+
+    // Read the two metadata files the synchronizer needs to parse.
+    // Use JSZip's async API to correctly handle all internal storage formats.
+    const ctEntry = zip.file('[Content_Types].xml');
+    if (ctEntry) {
+      baseForSync['[Content_Types].xml'] = await ctEntry.async('string');
+    }
+    const rlEntry = zip.file('_rels/.rels');
+    if (rlEntry) {
+      baseForSync['_rels/.rels'] = await rlEntry.async('string');
+    }
+
+    // Pass an empty updatedDocs — the zip is already the assembled truth.
+    const { contentTypesXml, relsXml } = syncPackageMetadata({
+      baseFiles: baseForSync,
+      updatedDocs: {},
+    });
+
+    zip.file('[Content_Types].xml', contentTypesXml);
+    zip.file('_rels/.rels', relsXml);
+  }
+
   async unzip(file) {
     const zip = await this.zip.loadAsync(file);
     return zip;
@@ -374,6 +416,10 @@ class DocxZipper {
     }
 
     await this.updateContentTypes(zip, media, false, updatedDocs);
+
+    // Reconcile package-level singleton metadata as a final safety pass.
+    await this.#syncPackageMetadataInZip(zip);
+
     return zip;
   }
 
@@ -413,6 +459,9 @@ class DocxZipper {
 
     await this.updateContentTypes(unzippedOriginalDocx, media, false, updatedDocs);
 
+    // Reconcile package-level singleton metadata as a final safety pass.
+    await this.#syncPackageMetadataInZip(unzippedOriginalDocx);
+
     return unzippedOriginalDocx;
   }
 

packages/super-editor/src/core/Editor.ts

@@ -62,6 +62,7 @@ import type { DocumentApi } from '@superdoc/document-api';
 import { createDocumentApi } from '@superdoc/document-api';
 import { getDocumentApiAdapters } from '../document-api-adapters/index.js';
 import { initPartsRuntime } from './parts/init-parts-runtime.js';
+import { syncPackageMetadata } from './opc/sync-package-metadata.js';
 
 declare const __APP_VERSION__: string;
 declare const version: string | undefined;
@@ -2742,6 +2743,20 @@ export class Editor extends EventEmitter<EditorEventMap> {
           true,
           updatedDocs,
         );
+
+        // Reconcile package-level singleton metadata (content-type overrides
+        // and root relationships) against the final set of output entries.
+        // this.options.content is DocxFileEntry[] | Record<string, unknown> | string | null.
+        // The synchronizer accepts an array of {name, content} or a key→content map.
+        const content = this.options.content;
+        const baseFiles = Array.isArray(content) || (content && typeof content === 'object') ? content : null;
+        const { contentTypesXml, relsXml } = syncPackageMetadata({
+          baseFiles: baseFiles as Parameters<typeof syncPackageMetadata>[0]['baseFiles'],
+          updatedDocs,
+        });
+        updatedDocs['[Content_Types].xml'] = contentTypesXml;
+        updatedDocs['_rels/.rels'] = relsXml;
+
         return updatedDocs;
       }
 

packages/super-editor/src/core/opc/managed-parts-registry.js

@@ -0,0 +1,37 @@
+/**
+ * Registry of OPC package-level singleton parts and their required metadata.
+ *
+ * Each entry defines a part that must have exactly one content-type Override in
+ * [Content_Types].xml and exactly one root Relationship in _rels/.rels when the
+ * part exists in the final package. When the part is absent, both registrations
+ * must be removed.
+ *
+ * Values sourced from ECMA-376 / ISO 29500 and verified against real DOCX
+ * fixtures produced by Microsoft Word.
+ */
+
+/** @typedef {import('./sync-package-metadata.js').ManagedPartEntry} ManagedPartEntry */
+
+/** @type {ManagedPartEntry[]} */
+export const MANAGED_PACKAGE_PARTS = [
+  {
+    zipPath: 'word/document.xml',
+    contentType: 'application/vnd.openxmlformats-officedocument.wordprocessingml.document.main+xml',
+    relationshipType: 'http://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument',
+  },
+  {
+    zipPath: 'docProps/core.xml',
+    contentType: 'application/vnd.openxmlformats-package.core-properties+xml',
+    relationshipType: 'http://schemas.openxmlformats.org/package/2006/relationships/metadata/core-properties',
+  },
+  {
+    zipPath: 'docProps/app.xml',
+    contentType: 'application/vnd.openxmlformats-officedocument.extended-properties+xml',
+    relationshipType: 'http://schemas.openxmlformats.org/officeDocument/2006/relationships/extended-properties',
+  },
+  {
+    zipPath: 'docProps/custom.xml',
+    contentType: 'application/vnd.openxmlformats-officedocument.custom-properties+xml',
+    relationshipType: 'http://schemas.openxmlformats.org/officeDocument/2006/relationships/custom-properties',
+  },
+];