fix(mindspace): expose findPageBySourceMessage on remote pageService adapter.

Quick Plaza publish resolves existing chat pages by session/message id; production remote adapter rejected the RPC because the binding contract omitted this method.

Co-authored-by: Cursor <cursoragent@cursor.com>

mindspace-chat-plaza.test.mjs

@@ -1,6 +1,11 @@
 import test from 'node:test';
 import assert from 'node:assert/strict';
 import { slugFromPageTitle } from './mindspace-chat-plaza.mjs';
+import { MINDSPACE_SERVER_ADAPTER_BINDINGS } from './mindspace-server-adapter-contract.mjs';
+
+test('adapter contract exposes findPageBySourceMessage for quick plaza', () => {
+  assert.ok(MINDSPACE_SERVER_ADAPTER_BINDINGS.pageService.includes('findPageBySourceMessage'));
+});
 
 test('slugFromPageTitle falls back to page when title has no ascii', () => {
   assert.equal(slugFromPageTitle('春江花月夜', '1c99b83b-0454-474f-a5d2-129d34506a32'), 'page-1c99b83b');

mindspace-server-adapter-contract.mjs

@@ -30,6 +30,7 @@ export const MINDSPACE_SERVER_ADAPTER_BINDINGS = Object.freeze({
     'deletePage',
     'findPageByRelativePath',
     'findPageBySourceAsset',
+    'findPageBySourceMessage',
     'getDeletePreview',
     'getPage',
     'listPages',