fix: Return UnsupportedOperationError when extendedAgentCard capabili… (#736)

kabir · claude · web-flow · commit 5f742aef6cd0 · 2026-03-12T16:12:09.000Z
…ty is disabled GetExtendedAgentCard now checks if the capability is enabled before checking if the card is configured. When capability is false, returns 501/UNIMPLEMENTED with UnsupportedOperationError instead of 400/FAILED_PRECONDITION. Applied to all three transports: HTTP+JSON, JSON-RPC, and gRPC. Fixes #733 Co-authored-by: Claude Sonnet 4.5 <noreply@anthropic.com>
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
@@ -546,6 +546,10 @@ public void onComplete() {
     public void getExtendedAgentCard(io.a2a.grpc.GetExtendedAgentCardRequest request,
                            StreamObserver<io.a2a.grpc.AgentCard> responseObserver) {
         try {
+            if (!getAgentCard().capabilities().extendedAgentCard()) {
+                handleError(responseObserver, new UnsupportedOperationError());
+                return;
+            }
             AgentCard extendedAgentCard = getExtendedAgentCard();
             if (extendedAgentCard != null) {
                 responseObserver.onNext(ToProto.agentCard(extendedAgentCard));
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
@@ -47,6 +47,7 @@
 import io.a2a.spec.EventKind;
 import io.a2a.spec.InternalError;
 import io.a2a.spec.InvalidRequestError;
+import io.a2a.spec.UnsupportedOperationError;
 import io.a2a.spec.ListTaskPushNotificationConfigResult;
 import io.a2a.spec.PushNotificationNotSupportedError;
 import io.a2a.spec.StreamingEventKind;
@@ -667,7 +668,10 @@ public DeleteTaskPushNotificationConfigResponse deletePushNotificationConfig(
     // TODO: Add authentication (https://github.com/a2aproject/a2a-java/issues/77)
     public GetExtendedAgentCardResponse onGetExtendedCardRequest(
             GetExtendedAgentCardRequest request, ServerCallContext context) {
-        if (!agentCard.capabilities().extendedAgentCard() || extendedAgentCard == null || !extendedAgentCard.isResolvable()) {
+        if (!agentCard.capabilities().extendedAgentCard()) {
+            return new GetExtendedAgentCardResponse(request.getId(), new UnsupportedOperationError());
+        }
+        if (extendedAgentCard == null || !extendedAgentCard.isResolvable()) {
             return new GetExtendedAgentCardResponse(request.getId(),
                     new ExtendedAgentCardNotConfiguredError(null, "Extended Card not configured", null));
         }
diff --git a/transport/jsonrpc/src/test/java/io/a2a/transport/jsonrpc/handler/JSONRPCHandlerTest.java b/transport/jsonrpc/src/test/java/io/a2a/transport/jsonrpc/handler/JSONRPCHandlerTest.java
@@ -1541,7 +1541,7 @@ public void testOnGetExtendedAgentCard() throws Exception {
         GetExtendedAgentCardRequest request = new GetExtendedAgentCardRequest("1");
         GetExtendedAgentCardResponse response = handler.onGetExtendedCardRequest(request, callContext);
         assertEquals(request.getId(), response.getId());
-        assertInstanceOf(ExtendedAgentCardNotConfiguredError.class, response.getError());
+        assertInstanceOf(UnsupportedOperationError.class, response.getError());
         assertNull(response.getResult());
     }
 
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
@@ -794,7 +794,10 @@ private int mapErrorToHttpStatus(A2AError error) {
      */
     public HTTPRestResponse getExtendedAgentCard(ServerCallContext context, String tenant) {
         try {
-            if (!agentCard.capabilities().extendedAgentCard() || extendedAgentCard == null || !extendedAgentCard.isResolvable()) {
+            if (!agentCard.capabilities().extendedAgentCard()) {
+                throw new UnsupportedOperationError();
+            }
+            if (extendedAgentCard == null || !extendedAgentCard.isResolvable()) {
                 throw new ExtendedAgentCardNotConfiguredError(null, "Extended Card not configured", null);
             }
             return new HTTPRestResponse(200, APPLICATION_JSON, JsonUtil.toJson(extendedAgentCard.get()));

Original file line number	Diff line number	Diff line change
`@@ -1541,7 +1541,7 @@ public void testOnGetExtendedAgentCard() throws Exception {`
`1541`	`1541`	`GetExtendedAgentCardRequest request = new GetExtendedAgentCardRequest("1");`
`1542`	`1542`	`GetExtendedAgentCardResponse response = handler.onGetExtendedCardRequest(request, callContext);`
`1543`	`1543`	`assertEquals(request.getId(), response.getId());`
`1544`		`- assertInstanceOf(ExtendedAgentCardNotConfiguredError.class, response.getError());`
	`1544`	`+ assertInstanceOf(UnsupportedOperationError.class, response.getError());`
`1545`	`1545`	`assertNull(response.getResult());`
`1546`	`1546`	`}`
`1547`	`1547`