fix(server): cover direct request handler wiring

Start the main event bus processor from the public request handler constructor and verify the direct manual wiring path.\n\nThis fixes a2aproject#995

Author: 014-code

server-common/src/main/java/org/a2aproject/sdk/server/events/MainEventBusProcessor.java

@@ -159,7 +159,7 @@ int pushNotificationChainCount() {
     @SuppressWarnings("NullAway.Init")
     @PostConstruct
     synchronized void start() {
-        if (processorThread != null) {
+        if (processorThread != null && processorThread.isAlive()) {
             LOGGER.debug("MainEventBusProcessor already started");
             return;
         }

server-common/src/main/java/org/a2aproject/sdk/server/requesthandlers/DefaultRequestHandler.java

@@ -326,6 +326,7 @@ public DefaultRequestHandler(AgentExecutor agentExecutor, TaskStore taskStore,
         //  I am unsure about the correct scope.
         //  Also reworked to make a Supplier since otherwise the builder gets polluted with wrong tasks
         this.requestContextBuilder = () -> new SimpleRequestContextBuilder(taskStore, false, null);
+        this.mainEventBusProcessor.start();
     }
 
     @SuppressWarnings("NullAway.Init")

server-common/src/test/java/org/a2aproject/sdk/server/requesthandlers/DefaultRequestHandlerTest.java

@@ -187,7 +187,7 @@ void testInitConfigReadsBlockingTimeouts() {
     }
 
     @Test
-    void testCreateStartsManuallyConstructedMainEventBusProcessor() throws Exception {
+    void testConstructorStartsManuallyConstructedMainEventBusProcessor() throws Exception {
         InMemoryTaskStore manualTaskStore = new InMemoryTaskStore();
         PushNotificationConfigStore manualPushConfigStore = new InMemoryPushNotificationConfigStore();
         MainEventBus manualMainEventBus = new MainEventBus();
@@ -207,9 +207,12 @@ public void cancel(RequestContext context, AgentEmitter agentEmitter) {
                     throw new AssertionError("Cancel should not be invoked");
                 }
             };
-            RequestHandler manualRequestHandler = DefaultRequestHandler.create(
+            DefaultRequestHandler manualRequestHandler = new DefaultRequestHandler(
                 manualAgentExecutor, manualTaskStore, manualQueueManager, manualPushConfigStore,
                 manualProcessor, internalExecutor, internalExecutor);
+            manualRequestHandler.agentCompletionTimeoutSeconds = 5;
+            manualRequestHandler.consumptionCompletionTimeoutSeconds = 2;
+            manualRequestHandler.reconciliationTimeoutSeconds = 1;
 
             EventKind eventKind = manualRequestHandler.onMessageSend(
                 MessageSendParams.builder().message(MESSAGE).build(), NULL_CONTEXT);