diff --git a/extras/queue-manager-replicated/core/src/main/java/io/a2a/extras/queuemanager/replicated/core/ReplicatedQueueManager.java b/extras/queue-manager-replicated/core/src/main/java/io/a2a/extras/queuemanager/replicated/core/ReplicatedQueueManager.java
index 88c0c75ab..586ab11a7 100644
--- a/extras/queue-manager-replicated/core/src/main/java/io/a2a/extras/queuemanager/replicated/core/ReplicatedQueueManager.java
+++ b/extras/queue-manager-replicated/core/src/main/java/io/a2a/extras/queuemanager/replicated/core/ReplicatedQueueManager.java
@@ -24,12 +24,26 @@
 public class ReplicatedQueueManager implements QueueManager {
     private static final Logger LOGGER = LoggerFactory.getLogger(ReplicatedQueueManager.class);
 
-    private final InMemoryQueueManager delegate;
-
+    // Fields set by constructor injection cannot be final. We need a noargs constructor for
+    // Jakarta compatibility, and it seems that making fields set by constructor injection
+    // final, is not proxyable in all runtimes
+    private InMemoryQueueManager delegate;
     private ReplicationStrategy replicationStrategy;
-
     private TaskStateProvider taskStateProvider;
 
+    /**
+     * No-args constructor for CDI proxy creation.
+     * CDI requires a non-private constructor to create proxies for @ApplicationScoped beans.
+     * All fields are initialized by the @Inject constructor during actual bean creation.
+     */
+    @SuppressWarnings("NullAway")
+    protected ReplicatedQueueManager() {
+        // For CDI proxy creation
+        this.delegate = null;
+        this.replicationStrategy = null;
+        this.taskStateProvider = null;
+    }
+
     @Inject
     public ReplicatedQueueManager(ReplicationStrategy replicationStrategy, TaskStateProvider taskStateProvider) {
         this.replicationStrategy = replicationStrategy;
diff --git a/server-common/src/main/java/io/a2a/server/events/InMemoryQueueManager.java b/server-common/src/main/java/io/a2a/server/events/InMemoryQueueManager.java
index 19179f50d..e5a17e0e7 100644
--- a/server-common/src/main/java/io/a2a/server/events/InMemoryQueueManager.java
+++ b/server-common/src/main/java/io/a2a/server/events/InMemoryQueueManager.java
@@ -16,8 +16,23 @@ public class InMemoryQueueManager implements QueueManager {
     private static final Logger LOGGER = LoggerFactory.getLogger(InMemoryQueueManager.class);
 
     private final ConcurrentMap<String, EventQueue> queues = new ConcurrentHashMap<>();
-    private final EventQueueFactory factory;
-    private final TaskStateProvider taskStateProvider;
+    // Fields set by constructor injection cannot be final. We need a noargs constructor for
+    // Jakarta compatibility, and it seems that making fields set by constructor injection
+    // final, is not proxyable in all runtimes
+    private EventQueueFactory factory;
+    private TaskStateProvider taskStateProvider;
+
+    /**
+     * No-args constructor for CDI proxy creation.
+     * CDI requires a non-private constructor to create proxies for @ApplicationScoped beans.
+     * All fields are initialized by the @Inject constructor during actual bean creation.
+     */
+    @SuppressWarnings("NullAway")
+    protected InMemoryQueueManager() {
+        // For CDI proxy creation
+        this.factory = null;
+        this.taskStateProvider = null;
+    }
 
     @Inject
     public InMemoryQueueManager(TaskStateProvider taskStateProvider) {
diff --git a/server-common/src/main/java/io/a2a/server/requesthandlers/DefaultRequestHandler.java b/server-common/src/main/java/io/a2a/server/requesthandlers/DefaultRequestHandler.java
index 61af1d43e..e19f7920d 100644
--- a/server-common/src/main/java/io/a2a/server/requesthandlers/DefaultRequestHandler.java
+++ b/server-common/src/main/java/io/a2a/server/requesthandlers/DefaultRequestHandler.java
@@ -56,7 +56,6 @@
 import io.a2a.spec.Message;
 import io.a2a.spec.MessageSendParams;
 import io.a2a.spec.PushNotificationConfig;
-import io.a2a.spec.PushNotificationNotSupportedError;
 import io.a2a.spec.StreamingEventKind;
 import io.a2a.spec.Task;
 import io.a2a.spec.TaskIdParams;
@@ -208,17 +207,37 @@ public class DefaultRequestHandler implements RequestHandler {
      */
     int consumptionCompletionTimeoutSeconds;
 
-    private final AgentExecutor agentExecutor;
-    private final TaskStore taskStore;
-    private final QueueManager queueManager;
-    private final PushNotificationConfigStore pushConfigStore;
-    private final PushNotificationSender pushSender;
-    private final Supplier<RequestContext.Builder> requestContextBuilder;
+    // Fields set by constructor injection cannot be final. We need a noargs constructor for
+    // Jakarta compatibility, and it seems that making fields set by constructor injection
+    // final, is not proxyable in all runtimes
+    private AgentExecutor agentExecutor;
+    private TaskStore taskStore;
+    private QueueManager queueManager;
+    private PushNotificationConfigStore pushConfigStore;
+    private PushNotificationSender pushSender;
+    private Supplier<RequestContext.Builder> requestContextBuilder;
 
     private final ConcurrentMap<String, CompletableFuture<Void>> runningAgents = new ConcurrentHashMap<>();
     private final Set<CompletableFuture<Void>> backgroundTasks = ConcurrentHashMap.newKeySet();
 
-    private final Executor executor;
+    private Executor executor;
+
+    /**
+     * No-args constructor for CDI proxy creation.
+     * CDI requires a non-private constructor to create proxies for @ApplicationScoped beans.
+     * All fields are initialized by the @Inject constructor during actual bean creation.
+     */
+    @SuppressWarnings("NullAway")
+    protected DefaultRequestHandler() {
+        // For CDI proxy creation
+        this.agentExecutor = null;
+        this.taskStore = null;
+        this.queueManager = null;
+        this.pushConfigStore = null;
+        this.pushSender = null;
+        this.requestContextBuilder = null;
+        this.executor = null;
+    }
 
     @Inject
     public DefaultRequestHandler(AgentExecutor agentExecutor, TaskStore taskStore,
diff --git a/server-common/src/main/java/io/a2a/server/tasks/BasePushNotificationSender.java b/server-common/src/main/java/io/a2a/server/tasks/BasePushNotificationSender.java
index 35a248373..a59767d8f 100644
--- a/server-common/src/main/java/io/a2a/server/tasks/BasePushNotificationSender.java
+++ b/server-common/src/main/java/io/a2a/server/tasks/BasePushNotificationSender.java
@@ -27,8 +27,24 @@ public class BasePushNotificationSender implements PushNotificationSender {
 
     private static final Logger LOGGER = LoggerFactory.getLogger(BasePushNotificationSender.class);
 
-    private final A2AHttpClient httpClient;
-    private final PushNotificationConfigStore configStore;
+    // Fields set by constructor injection cannot be final. We need a noargs constructor for
+    // Jakarta compatibility, and it seems that making fields set by constructor injection
+    // final, is not proxyable in all runtimes
+    private A2AHttpClient httpClient;
+    private PushNotificationConfigStore configStore;
+
+
+    /**
+     * No-args constructor for CDI proxy creation.
+     * CDI requires a non-private constructor to create proxies for @ApplicationScoped beans.
+     * All fields are initialized by the @Inject constructor during actual bean creation.
+     */
+    @SuppressWarnings("NullAway")
+    protected BasePushNotificationSender() {
+        // For CDI proxy creation
+        this.httpClient = null;
+        this.configStore = null;
+    }
 
     @Inject
     public BasePushNotificationSender(PushNotificationConfigStore configStore) {
diff --git a/transport/grpc/src/main/java/io/a2a/transport/grpc/handler/GrpcHandler.java b/transport/grpc/src/main/java/io/a2a/transport/grpc/handler/GrpcHandler.java
index 7a1e0a912..2998965ea 100644
--- a/transport/grpc/src/main/java/io/a2a/transport/grpc/handler/GrpcHandler.java
+++ b/transport/grpc/src/main/java/io/a2a/transport/grpc/handler/GrpcHandler.java
@@ -67,7 +67,7 @@ public abstract class GrpcHandler extends A2AServiceGrpc.A2AServiceImplBase {
     // Without this we get intermittent failures
     private static volatile Runnable streamingSubscribedRunnable;
 
-    private AtomicBoolean initialised = new AtomicBoolean(false);
+    private final AtomicBoolean initialised = new AtomicBoolean(false);
 
     private static final Logger LOGGER = Logger.getLogger(GrpcHandler.class.getName());
 
diff --git a/transport/jsonrpc/src/main/java/io/a2a/transport/jsonrpc/handler/JSONRPCHandler.java b/transport/jsonrpc/src/main/java/io/a2a/transport/jsonrpc/handler/JSONRPCHandler.java
index 06de11dcd..ca8149099 100644
--- a/transport/jsonrpc/src/main/java/io/a2a/transport/jsonrpc/handler/JSONRPCHandler.java
+++ b/transport/jsonrpc/src/main/java/io/a2a/transport/jsonrpc/handler/JSONRPCHandler.java
@@ -60,10 +60,27 @@
 @ApplicationScoped
 public class JSONRPCHandler {
 
+    // Fields set by constructor injection cannot be final. We need a noargs constructor for
+    // Jakarta compatibility, and it seems that making fields set by constructor injection
+    // final, is not proxyable in all runtimes
     private AgentCard agentCard;
     private @Nullable Instance<AgentCard> extendedAgentCard;
     private RequestHandler requestHandler;
-    private final Executor executor;
+    private Executor executor;
+
+    /**
+     * No-args constructor for CDI proxy creation.
+     * CDI requires a non-private constructor to create proxies for @ApplicationScoped beans.
+     * All fields are initialized by the @Inject constructor during actual bean creation.
+     */
+    @SuppressWarnings("NullAway")
+    protected JSONRPCHandler() {
+        // For CDI proxy creation
+        this.agentCard = null;
+        this.extendedAgentCard = null;
+        this.requestHandler = null;
+        this.executor = null;
+    }
 
     @Inject
     public JSONRPCHandler(@PublicAgentCard AgentCard agentCard, @Nullable @ExtendedAgentCard Instance<AgentCard> extendedAgentCard,
diff --git a/transport/rest/src/main/java/io/a2a/transport/rest/handler/RestHandler.java b/transport/rest/src/main/java/io/a2a/transport/rest/handler/RestHandler.java
index 8c4050fd9..489bf909b 100644
--- a/transport/rest/src/main/java/io/a2a/transport/rest/handler/RestHandler.java
+++ b/transport/rest/src/main/java/io/a2a/transport/rest/handler/RestHandler.java
@@ -67,11 +67,20 @@
 public class RestHandler {
 
     private static final Logger log = Logger.getLogger(RestHandler.class.getName());
+
+    // Fields set by constructor injection cannot be final. We need a noargs constructor for
+    // Jakarta compatibility, and it seems that making fields set by constructor injection
+    // final, is not proxyable in all runtimes
     private AgentCard agentCard;
     private @Nullable Instance<AgentCard> extendedAgentCard;
     private RequestHandler requestHandler;
-    private final Executor executor;
+    private Executor executor;
 
+    /**
+     * No-args constructor for CDI proxy creation.
+     * CDI requires a non-private constructor to create proxies for @ApplicationScoped beans.
+     * All fields are initialized by the @Inject constructor during actual bean creation.
+     */
     @SuppressWarnings("NullAway")
     protected RestHandler() {
         // For CDI