diff --git a/src/grpc/buf.gen.yaml b/src/grpc/buf.gen.yaml
index 6ca9834e..8f6cd84f 100644
--- a/src/grpc/buf.gen.yaml
+++ b/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
\ No newline at end of file
+    out: ./pb
diff --git a/src/grpc/pb/google/protobuf/struct.ts b/src/grpc/pb/google/protobuf/struct.ts
index ba4120ec..aa801ddb 100644
--- a/src/grpc/pb/google/protobuf/struct.ts
+++ b/src/grpc/pb/google/protobuf/struct.ts
@@ -1,6 +1,6 @@
 // Code generated by protoc-gen-ts_proto. DO NOT EDIT.
 // versions:
-//   protoc-gen-ts_proto  v2.6.1
+//   protoc-gen-ts_proto  v2.11.0
 //   protoc               unknown
 // source: google/protobuf/struct.proto
 
@@ -89,7 +89,7 @@ function createBaseStruct(): Struct {
 
 export const Struct: MessageFns<Struct> & StructWrapperFns = {
   encode(message: Struct, writer: BinaryWriter = new BinaryWriter()): BinaryWriter {
-    Object.entries(message.fields).forEach(([key, value]) => {
+    globalThis.Object.entries(message.fields).forEach(([key, value]: [string, any | undefined]) => {
       if (value !== undefined) {
         Struct_FieldsEntry.encode({ key: key as any, value }, writer.uint32(10).fork()).join();
       }
@@ -99,7 +99,7 @@ export const Struct: MessageFns<Struct> & StructWrapperFns = {
 
   decode(input: BinaryReader | Uint8Array, length?: number): Struct {
     const reader = input instanceof BinaryReader ? input : new BinaryReader(input);
-    let end = length === undefined ? reader.len : reader.pos + length;
+    const end = length === undefined ? reader.len : reader.pos + length;
     const message = createBaseStruct();
     while (reader.pos < end) {
       const tag = reader.uint32();
@@ -128,7 +128,7 @@ export const Struct: MessageFns<Struct> & StructWrapperFns = {
     const struct = createBaseStruct();
 
     if (object !== undefined) {
-      for (const key of Object.keys(object)) {
+      for (const key of globalThis.Object.keys(object)) {
         struct.fields[key] = object[key];
       }
     }
@@ -138,7 +138,7 @@ export const Struct: MessageFns<Struct> & StructWrapperFns = {
   unwrap(message: Struct): { [key: string]: any } {
     const object: { [key: string]: any } = {};
     if (message.fields) {
-      for (const key of Object.keys(message.fields)) {
+      for (const key of globalThis.Object.keys(message.fields)) {
         object[key] = message.fields[key];
       }
     }
@@ -163,7 +163,7 @@ export const Struct_FieldsEntry: MessageFns<Struct_FieldsEntry> = {
 
   decode(input: BinaryReader | Uint8Array, length?: number): Struct_FieldsEntry {
     const reader = input instanceof BinaryReader ? input : new BinaryReader(input);
-    let end = length === undefined ? reader.len : reader.pos + length;
+    const end = length === undefined ? reader.len : reader.pos + length;
     const message = createBaseStruct_FieldsEntry();
     while (reader.pos < end) {
       const tag = reader.uint32();
@@ -225,7 +225,7 @@ export const Value: MessageFns<Value> & AnyValueWrapperFns = {
 
   decode(input: BinaryReader | Uint8Array, length?: number): Value {
     const reader = input instanceof BinaryReader ? input : new BinaryReader(input);
-    let end = length === undefined ? reader.len : reader.pos + length;
+    const end = length === undefined ? reader.len : reader.pos + length;
     const message = createBaseValue();
     while (reader.pos < end) {
       const tag = reader.uint32();
@@ -290,7 +290,7 @@ export const Value: MessageFns<Value> & AnyValueWrapperFns = {
   wrap(value: any): Value {
     const result = createBaseValue();
     if (value === null) {
-      result.kind = { $case: "nullValue", value };
+      result.kind = { $case: "nullValue", value: NullValue.NULL_VALUE };
     } else if (typeof value === "boolean") {
       result.kind = { $case: "boolValue", value };
     } else if (typeof value === "number") {
@@ -308,7 +308,7 @@ export const Value: MessageFns<Value> & AnyValueWrapperFns = {
   },
 
   unwrap(message: Value): string | number | boolean | Object | null | Array<any> | undefined {
-    return message.kind?.value;
+    return (message.kind?.$case === "nullValue") ? null : message.kind?.value;
   },
 };
 
@@ -326,7 +326,7 @@ export const ListValue: MessageFns<ListValue> & ListValueWrapperFns = {
 
   decode(input: BinaryReader | Uint8Array, length?: number): ListValue {
     const reader = input instanceof BinaryReader ? input : new BinaryReader(input);
-    let end = length === undefined ? reader.len : reader.pos + length;
+    const end = length === undefined ? reader.len : reader.pos + length;
     const message = createBaseListValue();
     while (reader.pos < end) {
       const tag = reader.uint32();
diff --git a/test/server/grpc/protobuf_serialization.spec.ts b/test/server/grpc/protobuf_serialization.spec.ts
new file mode 100644
index 00000000..6acadd93
--- /dev/null
+++ b/test/server/grpc/protobuf_serialization.spec.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);
+  });
+});