fix(mindspace): map publication RPC errors to HTTP status codes

Return 404/401/403 from MindSpace RPC for known publication errors and
preserve error codes through the Portal remote adapter.

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

mindspace-remote-server-adapter.test.mjs

@@ -133,3 +133,26 @@ test('createMindSpaceRemoteServerAdapter surfaces remote conversation package er
     /conversationPackageRegistry\.readManifestForSession\(\) failed with 502: upstream manifest missing/,
   );
 });
+
+test('createMindSpaceRemoteServerAdapter preserves publication error codes from rpc payload', async () => {
+  const adapter = createMindSpaceRemoteServerAdapter({
+    endpoint: 'https://mindspace.example.com/',
+    authToken: 'secret-token',
+    fetchFn: async () => ({
+      ok: false,
+      status: 404,
+      async text() {
+        return JSON.stringify({
+          message: '公开页面不存在',
+          code: 'publication_not_found',
+        });
+      },
+    }),
+    logger: { log() {}, warn() {}, error() {} },
+  });
+
+  await assert.rejects(
+    () => adapter.publicationService.resolvePublic('john', 'missing-page', null, null, {}),
+    (error) => error instanceof Error && error.code === 'publication_not_found',
+  );
+});