feat: Add SubscribeToTaskRequest mapper and ProtoUtils method

Added bidirectional mapping support for SubscribeToTaskRequest:

1. Created SubscribeToTaskRequestMapper:
   - toProto(): Converts domain SubscribeToTaskRequest to proto format
   - fromProto(): Converts proto SubscribeToTaskRequest to domain format
   - Handles conversion between TaskIdParams and "tasks/{task_id}" format
   - Uses ResourceNameParser for resource name formatting

2. Updated TaskIdParamsMapper:
   - Added toProtoSubscribeToTaskRequest() method to convert TaskIdParams
     to proto SubscribeToTaskRequest
   - Complements existing fromProtoSubscribeToTaskRequest() method
   - Uses ResourceNameParser.defineTaskName() for resource name creation

3. Updated ProtoUtils.ToProto:
   - Added subscribeToTaskRequest(TaskIdParams) method
   - Delegates to TaskIdParamsMapper.toProtoSubscribeToTaskRequest()
   - Follows existing pattern for cancelTaskRequest()

This enables proper handling of SubscribeToTaskRequest in the JSONRPC
transport layer, converting between domain JSONRPC requests and proto
gRPC requests.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: ehsavoie

spec-grpc/src/main/java/io/a2a/grpc/mapper/SubscribeToTaskRequestMapper.java

@@ -0,0 +1,54 @@
+package io.a2a.grpc.mapper;
+
+import org.mapstruct.Mapper;
+
+/**
+ * Mapper between {@link io.a2a.spec.SubscribeToTaskRequest} and {@link io.a2a.grpc.SubscribeToTaskRequest}.
+ * <p>
+ * The mapping handles the structural difference between domain and proto representations:
+ * <ul>
+ * <li>Domain: Full JSONRPC request with id, jsonrpc, method, and params (TaskIdParams)</li>
+ * <li>Proto: Simple request with name field in format "tasks/{task_id}"</li>
+ * </ul>
+ * <p>
+ * Note: The domain object is a complete JSONRPC request, while the proto is just the gRPC
+ * request parameters. The JSONRPC envelope (id, jsonrpc, method) is handled separately
+ * by the transport layer.
+ */
+@Mapper(config = A2AProtoMapperConfig.class, uses = {TaskIdParamsMapper.class})
+public interface SubscribeToTaskRequestMapper {
+
+    SubscribeToTaskRequestMapper INSTANCE = A2AMappers.getMapper(SubscribeToTaskRequestMapper.class);
+
+    /**
+     * Converts domain SubscribeToTaskRequest to proto SubscribeToTaskRequest.
+     * Extracts the task ID from params and formats it as "tasks/{task_id}".
+     *
+     * @param domain the domain SubscribeToTaskRequest
+     * @return the proto SubscribeToTaskRequest
+     */
+    default io.a2a.grpc.SubscribeToTaskRequest toProto(io.a2a.spec.SubscribeToTaskRequest domain) {
+        if (domain == null || domain.getParams() == null || domain.getParams().id() == null) {
+            return null;
+        }
+        return io.a2a.grpc.SubscribeToTaskRequest.newBuilder()
+                .setName(ResourceNameParser.defineTaskName(domain.getParams().id()))
+                .build();
+    }
+
+    /**
+     * Converts proto SubscribeToTaskRequest to domain SubscribeToTaskRequest.
+     * Extracts the task ID from the name field and creates a TaskIdParams.
+     *
+     * @param proto the proto SubscribeToTaskRequest
+     * @return the domain SubscribeToTaskRequest
+     */
+    default io.a2a.spec.SubscribeToTaskRequest fromProto(io.a2a.grpc.SubscribeToTaskRequest proto) {
+        if (proto == null || proto.getName() == null) {
+            return null;
+        }
+        return new io.a2a.spec.SubscribeToTaskRequest.Builder()
+                .params(new io.a2a.spec.TaskIdParams(ResourceNameParser.extractTaskId(proto.getName())))
+                .build();
+    }
+}

spec-grpc/src/main/java/io/a2a/grpc/mapper/TaskIdParamsMapper.java

@@ -42,4 +42,12 @@ public interface TaskIdParamsMapper {
     @Mapping(target = "id", expression = "java(ResourceNameParser.extractTaskId(proto.getName()))")
     @Mapping(target = "metadata", ignore = true)
     TaskIdParams fromProtoSubscribeToTaskRequest(io.a2a.grpc.SubscribeToTaskRequest proto);
+
+    /**
+     * Converts domain TaskIdParams to proto SubscribeToTaskRequest.
+     * Creates resource name from task ID.
+     */
+    @BeanMapping(builder = @Builder(buildMethod = "build"))
+    @Mapping(target = "name", expression = "java(ResourceNameParser.defineTaskName(domain.id()))")
+    io.a2a.grpc.SubscribeToTaskRequest toProtoSubscribeToTaskRequest(TaskIdParams domain);
 }

spec-grpc/src/main/java/io/a2a/grpc/utils/ProtoUtils.java

@@ -17,6 +17,7 @@
 import io.a2a.grpc.mapper.MessageSendParamsMapper;
 import io.a2a.grpc.mapper.SetTaskPushNotificationConfigMapper;
 import io.a2a.grpc.mapper.StreamResponseMapper;
+import io.a2a.grpc.mapper.SubscribeToTaskRequestMapper;
 import io.a2a.grpc.mapper.TaskArtifactUpdateEventMapper;
 import io.a2a.grpc.mapper.TaskIdParamsMapper;
 import io.a2a.grpc.mapper.TaskMapper;
@@ -66,6 +67,10 @@ public static io.a2a.grpc.CancelTaskRequest cancelTaskRequest(TaskIdParams param
             return TaskIdParamsMapper.INSTANCE.toProtoCancelTaskRequest(params);
         }
 
+        public static io.a2a.grpc.SubscribeToTaskRequest subscribeToTaskRequest(TaskIdParams params) {
+            return TaskIdParamsMapper.INSTANCE.toProtoSubscribeToTaskRequest(params);
+        }
+
         public static io.a2a.grpc.SetTaskPushNotificationConfigRequest setTaskPushNotificationConfigRequest(TaskPushNotificationConfig config) {
             return SetTaskPushNotificationConfigMapper.INSTANCE.toProto(config);
         }
@@ -162,6 +167,10 @@ public static io.a2a.grpc.StreamResponse taskOrMessageStream(StreamingEventKind
             }
         }
 
+        public static io.a2a.grpc.SubscribeToTaskRequest subscribeToTaskRequest(io.a2a.spec.SubscribeToTaskRequest request) {
+            return SubscribeToTaskRequestMapper.INSTANCE.toProto(request);
+        }
+
     }
 
     public static class FromProto {