fix(grpc): preserve null values in protobuf Struct

Author: dazhi

src/grpc/buf.gen.yaml

@@ -11,7 +11,7 @@ inputs:
       - google/rpc/status.proto
       - google/rpc/error_details.proto
 plugins:
-  - remote: buf.build/community/stephenh-ts-proto:v2.6.1
+  - remote: buf.build/community/stephenh-ts-proto:v2.11.0
     opt: 
       - oneof=unions-value
       - importSuffix=.js
@@ -21,4 +21,4 @@ plugins:
       - outputJsonMethods=false
       - outputPartialMethods=false
       - useDate=string
-    out: ./pb
+    out: ./pb

src/grpc/pb/google/protobuf/struct.ts

@@ -0,0 +1,29 @@
+import { describe, expect, it } from 'vitest';
+import { A2AServiceService, SendMessageResponse } from '../../../src/grpc/pb/a2a.js';
+
+describe('gRPC protobuf serialization', () => {
+  it('preserves null values in task metadata', () => {
+    const response: SendMessageResponse = {
+      payload: {
+        $case: 'task',
+        value: {
+          id: 'task-1',
+          contextId: 'context-1',
+          status: undefined,
+          artifacts: [],
+          history: [],
+          metadata: {
+            direct: null,
+            nested: { value: null },
+            items: [null, 'present'],
+          },
+        },
+      },
+    };
+
+    const serialized = A2AServiceService.sendMessage.responseSerialize(response);
+    const deserialized = A2AServiceService.sendMessage.responseDeserialize(serialized);
+
+    expect(deserialized).toEqual(response);
+  });
+});