feat(mcp): auto-create blank documents when file doesn't exist

superdoc_open now creates a new blank document from the built-in
OOXML template when the target path doesn't exist, instead of failing.

Author: caio-pizzol

apps/mcp/src/session-manager.ts

@@ -1,9 +1,10 @@
-import { readFile, writeFile } from 'node:fs/promises';
+import { readFile, writeFile, access  } from 'node:fs/promises';
 import { randomBytes } from 'node:crypto';
 import { resolve, basename } from 'node:path';
 import { Editor } from 'superdoc/super-editor';
 import { getDocumentApiAdapters } from '@superdoc/super-editor/document-api-adapters';
 import { createDocumentApi, type DocumentApi } from '@superdoc/document-api';
+import { BLANK_DOCX_BASE64 } from '@superdoc/super-editor/blank-docx';
 
 export interface Session {
   id: string;
@@ -19,9 +20,17 @@ export class SessionManager {
   async open(filePath: string): Promise<Session> {
     const absolutePath = resolve(filePath);
 
-    const bytes = await readFile(absolutePath);
+    let bytes: Buffer;
 
-    const editor = await Editor.open(Buffer.from(bytes), {
+    try {
+      await access(absolutePath);
+      bytes = await readFile(absolutePath);
+    } catch {
+      // File doesn't exist — create a blank document from the built-in template
+      bytes = Buffer.from(BLANK_DOCX_BASE64, 'base64');
+    }
+
+    const editor = await Editor.open(bytes, {
       documentId: absolutePath,
       user: { id: 'mcp', name: 'MCP Server' },
     });

apps/mcp/src/tools/lifecycle.ts

@@ -8,7 +8,7 @@ export function registerLifecycleTools(server: McpServer, sessions: SessionManag
     {
       title: 'Open Document',
       description:
-        'Open a Word document (.docx) for reading and editing. Must be called before any other operation. Returns a session_id to use in subsequent calls.',
+        'Open a Word document (.docx) for reading and editing. If the file does not exist, a new blank document is created at that path. Must be called before any other operation. Returns a session_id to use in subsequent calls.',
       inputSchema: {
         path: z.string().describe('Absolute path to the .docx file.'),
       },

apps/mcp/tsconfig.json

@@ -7,7 +7,10 @@
     "skipLibCheck": true,
     "types": ["bun"],
     "paths": {
-      "@superdoc/super-editor/document-api-adapters": ["../../packages/super-editor/src/document-api-adapters/index.ts"]
+      "@superdoc/super-editor/document-api-adapters": [
+        "../../packages/super-editor/src/document-api-adapters/index.ts"
+      ],
+      "@superdoc/super-editor/blank-docx": ["../../packages/super-editor/src/core/blank-docx.ts"]
     }
   },
   "include": ["src"]