Exception when deserializing {"jsonrpc":"2.0","id":3,"result":null}

acp-ktor-test/src/commonTest/kotlin/com/agentclientprotocol/FeaturesTest.kt

@@ -192,6 +192,37 @@ abstract class FeaturesTest(protocolDriver: ProtocolDriver) : ProtocolDriver by
 
 
 
+    @Test
+    fun `authenticate returns null when agent returns null`() = testWithProtocols { clientProtocol, agentProtocol ->
+        val client = Client(protocol = clientProtocol)
+
+        val agentSupport = object : AgentSupport {
+            override suspend fun initialize(clientInfo: ClientInfo): AgentInfo {
+                return AgentInfo(clientInfo.protocolVersion)
+            }
+
+            override suspend fun authenticate(methodId: AuthMethodId, _meta: JsonElement?): AuthenticateResponse? {
+                // Return null to simulate {"jsonrpc":"2.0","id":3,"result":null} response
+                return null
+            }
+
+            override suspend fun createSession(sessionParameters: SessionCreationParameters): AgentSession {
+                return TestAgentSession()
+            }
+
+            override suspend fun loadSession(sessionId: SessionId, sessionParameters: SessionCreationParameters): AgentSession {
+                return TestAgentSession()
+            }
+        }
+        Agent(agentProtocol, agentSupport)
+
+        client.initialize(ClientInfo())
+
+        // This should correctly handle the null response without throwing an exception
+        val result = client.authenticate(AuthMethodId("test-auth"))
+        assertNull(result, "authenticate should return null when agent returns null")
+    }
+
 //    @Test
 //    fun `call agent extension from client`(): TestResult = testWithProtocols { clientProtocol, agentProtocol ->
 //

acp-model/api/acp-model.api

@@ -30,6 +30,12 @@ public class com/agentclientprotocol/model/AcpMethod$AcpRequestResponseMethod :
 	public final fun getResponseSerializer ()Lkotlinx/serialization/KSerializer;
 }
 
+public class com/agentclientprotocol/model/AcpMethod$AcpRequestResponseNullableMethod : com/agentclientprotocol/model/AcpMethod {
+	public fun <init> (Ljava/lang/String;Lkotlinx/serialization/KSerializer;Lkotlinx/serialization/KSerializer;)V
+	public final fun getRequestSerializer ()Lkotlinx/serialization/KSerializer;
+	public final fun getResponseSerializer ()Lkotlinx/serialization/KSerializer;
+}
+
 public class com/agentclientprotocol/model/AcpMethod$AcpSessionNotificationMethod : com/agentclientprotocol/model/AcpMethod$AcpNotificationMethod {
 	public fun <init> (Ljava/lang/String;Lkotlinx/serialization/KSerializer;)V
 }
@@ -38,11 +44,15 @@ public class com/agentclientprotocol/model/AcpMethod$AcpSessionRequestResponseMe
 	public fun <init> (Ljava/lang/String;Lkotlinx/serialization/KSerializer;Lkotlinx/serialization/KSerializer;)V
 }
 
+public class com/agentclientprotocol/model/AcpMethod$AcpSessionRequestResponseNullableMethod : com/agentclientprotocol/model/AcpMethod$AcpRequestResponseNullableMethod {
+	public fun <init> (Ljava/lang/String;Lkotlinx/serialization/KSerializer;Lkotlinx/serialization/KSerializer;)V
+}
+
 public final class com/agentclientprotocol/model/AcpMethod$AgentMethods {
 	public static final field INSTANCE Lcom/agentclientprotocol/model/AcpMethod$AgentMethods;
 }
 
-public final class com/agentclientprotocol/model/AcpMethod$AgentMethods$Authenticate : com/agentclientprotocol/model/AcpMethod$AcpRequestResponseMethod {
+public final class com/agentclientprotocol/model/AcpMethod$AgentMethods$Authenticate : com/agentclientprotocol/model/AcpMethod$AcpRequestResponseNullableMethod {
 	public static final field INSTANCE Lcom/agentclientprotocol/model/AcpMethod$AgentMethods$Authenticate;
 }
 
@@ -66,11 +76,11 @@ public final class com/agentclientprotocol/model/AcpMethod$AgentMethods$SessionP
 	public static final field INSTANCE Lcom/agentclientprotocol/model/AcpMethod$AgentMethods$SessionPrompt;
 }
 
-public final class com/agentclientprotocol/model/AcpMethod$AgentMethods$SessionSetMode : com/agentclientprotocol/model/AcpMethod$AcpSessionRequestResponseMethod {
+public final class com/agentclientprotocol/model/AcpMethod$AgentMethods$SessionSetMode : com/agentclientprotocol/model/AcpMethod$AcpSessionRequestResponseNullableMethod {
 	public static final field INSTANCE Lcom/agentclientprotocol/model/AcpMethod$AgentMethods$SessionSetMode;
 }
 
-public final class com/agentclientprotocol/model/AcpMethod$AgentMethods$SessionSetModel : com/agentclientprotocol/model/AcpMethod$AcpSessionRequestResponseMethod {
+public final class com/agentclientprotocol/model/AcpMethod$AgentMethods$SessionSetModel : com/agentclientprotocol/model/AcpMethod$AcpSessionRequestResponseNullableMethod {
 	public static final field INSTANCE Lcom/agentclientprotocol/model/AcpMethod$AgentMethods$SessionSetModel;
 }
 
@@ -82,7 +92,7 @@ public final class com/agentclientprotocol/model/AcpMethod$ClientMethods$FsReadT
 	public static final field INSTANCE Lcom/agentclientprotocol/model/AcpMethod$ClientMethods$FsReadTextFile;
 }
 
-public final class com/agentclientprotocol/model/AcpMethod$ClientMethods$FsWriteTextFile : com/agentclientprotocol/model/AcpMethod$AcpSessionRequestResponseMethod {
+public final class com/agentclientprotocol/model/AcpMethod$ClientMethods$FsWriteTextFile : com/agentclientprotocol/model/AcpMethod$AcpSessionRequestResponseNullableMethod {
 	public static final field INSTANCE Lcom/agentclientprotocol/model/AcpMethod$ClientMethods$FsWriteTextFile;
 }
 
@@ -98,19 +108,19 @@ public final class com/agentclientprotocol/model/AcpMethod$ClientMethods$Termina
 	public static final field INSTANCE Lcom/agentclientprotocol/model/AcpMethod$ClientMethods$TerminalCreate;
 }
 
-public final class com/agentclientprotocol/model/AcpMethod$ClientMethods$TerminalKill : com/agentclientprotocol/model/AcpMethod$AcpSessionRequestResponseMethod {
+public final class com/agentclientprotocol/model/AcpMethod$ClientMethods$TerminalKill : com/agentclientprotocol/model/AcpMethod$AcpSessionRequestResponseNullableMethod {
 	public static final field INSTANCE Lcom/agentclientprotocol/model/AcpMethod$ClientMethods$TerminalKill;
 }
 
 public final class com/agentclientprotocol/model/AcpMethod$ClientMethods$TerminalOutput : com/agentclientprotocol/model/AcpMethod$AcpSessionRequestResponseMethod {
 	public static final field INSTANCE Lcom/agentclientprotocol/model/AcpMethod$ClientMethods$TerminalOutput;
 }
 
-public final class com/agentclientprotocol/model/AcpMethod$ClientMethods$TerminalRelease : com/agentclientprotocol/model/AcpMethod$AcpSessionRequestResponseMethod {
+public final class com/agentclientprotocol/model/AcpMethod$ClientMethods$TerminalRelease : com/agentclientprotocol/model/AcpMethod$AcpSessionRequestResponseNullableMethod {
 	public static final field INSTANCE Lcom/agentclientprotocol/model/AcpMethod$ClientMethods$TerminalRelease;
 }
 
-public final class com/agentclientprotocol/model/AcpMethod$ClientMethods$TerminalWaitForExit : com/agentclientprotocol/model/AcpMethod$AcpSessionRequestResponseMethod {
+public final class com/agentclientprotocol/model/AcpMethod$ClientMethods$TerminalWaitForExit : com/agentclientprotocol/model/AcpMethod$AcpSessionRequestResponseNullableMethod {
 	public static final field INSTANCE Lcom/agentclientprotocol/model/AcpMethod$ClientMethods$TerminalWaitForExit;
 }
 

acp-model/src/commonMain/kotlin/com/agentclientprotocol/model/Methods.kt

@@ -20,12 +20,24 @@ public open class AcpMethod(public val methodName: MethodName) {
         public val responseSerializer: KSerializer<TResponse>
     ) : AcpMethod(MethodName(method))
 
+    public open class AcpRequestResponseNullableMethod<TRequest: AcpRequest, TResponse: AcpResponse>(
+        method: String,
+        public val requestSerializer: KSerializer<TRequest>,
+        public val responseSerializer: KSerializer<TResponse>
+    ) : AcpMethod(MethodName(method))
+
     public open class AcpSessionRequestResponseMethod<TRequest, TResponse: AcpResponse>(method: String,
                                                                                         requestSerializer: KSerializer<TRequest>,
                                                                                         responseSerializer: KSerializer<TResponse>
     ) : AcpRequestResponseMethod<TRequest, TResponse>(method, requestSerializer, responseSerializer)
             where TRequest : AcpRequest, TRequest : AcpWithSessionId
 
+    public open class AcpSessionRequestResponseNullableMethod<TRequest, TResponse: AcpResponse>(method: String,
+                                                                                        requestSerializer: KSerializer<TRequest>,
+                                                                                        responseSerializer: KSerializer<TResponse>
+    ) : AcpRequestResponseNullableMethod<TRequest, TResponse>(method, requestSerializer, responseSerializer)
+            where TRequest : AcpRequest, TRequest : AcpWithSessionId
+
     public open class AcpNotificationMethod<TNotification: AcpNotification>(
         method: String,
         public val serializer: KSerializer<TNotification>,
@@ -43,16 +55,16 @@ public open class AcpMethod(public val methodName: MethodName) {
     public object AgentMethods {
         // Agent-side operations (methods that agents can call on clients)
         public object Initialize : AcpRequestResponseMethod<InitializeRequest, InitializeResponse>("initialize", InitializeRequest.serializer(), InitializeResponse.serializer())
-        public object Authenticate : AcpRequestResponseMethod<AuthenticateRequest, AuthenticateResponse>("authenticate", AuthenticateRequest.serializer(), AuthenticateResponse.serializer())
+        public object Authenticate : AcpRequestResponseNullableMethod<AuthenticateRequest, AuthenticateResponse>("authenticate", AuthenticateRequest.serializer(), AuthenticateResponse.serializer())
         public object SessionNew : AcpRequestResponseMethod<NewSessionRequest, NewSessionResponse>("session/new", NewSessionRequest.serializer(), NewSessionResponse.serializer())
         public object SessionLoad : AcpRequestResponseMethod<LoadSessionRequest, LoadSessionResponse>("session/load", LoadSessionRequest.serializer(), LoadSessionResponse.serializer())
 
         // session specific
         public object SessionPrompt : AcpSessionRequestResponseMethod<PromptRequest, PromptResponse>("session/prompt", PromptRequest.serializer(), PromptResponse.serializer())
         public object SessionCancel : AcpSessionNotificationMethod<CancelNotification>("session/cancel", CancelNotification.serializer())
-        public object SessionSetMode : AcpSessionRequestResponseMethod<SetSessionModeRequest, SetSessionModeResponse>("session/set_mode", SetSessionModeRequest.serializer(), SetSessionModeResponse.serializer())
+        public object SessionSetMode : AcpSessionRequestResponseNullableMethod<SetSessionModeRequest, SetSessionModeResponse>("session/set_mode", SetSessionModeRequest.serializer(), SetSessionModeResponse.serializer())
         @UnstableApi
-        public object SessionSetModel : AcpSessionRequestResponseMethod<SetSessionModelRequest, SetSessionModelResponse>("session/set_model", SetSessionModelRequest.serializer(), SetSessionModelResponse.serializer())
+        public object SessionSetModel : AcpSessionRequestResponseNullableMethod<SetSessionModelRequest, SetSessionModelResponse>("session/set_model", SetSessionModelRequest.serializer(), SetSessionModelResponse.serializer())
     }
 
     public object ClientMethods {
@@ -62,12 +74,12 @@ public open class AcpMethod(public val methodName: MethodName) {
 
         // extensions
         public object FsReadTextFile : AcpSessionRequestResponseMethod<ReadTextFileRequest, ReadTextFileResponse>("fs/read_text_file", ReadTextFileRequest.serializer(), ReadTextFileResponse.serializer())
-        public object FsWriteTextFile : AcpSessionRequestResponseMethod<WriteTextFileRequest, WriteTextFileResponse>("fs/write_text_file", WriteTextFileRequest.serializer(), WriteTextFileResponse.serializer())
+        public object FsWriteTextFile : AcpSessionRequestResponseNullableMethod<WriteTextFileRequest, WriteTextFileResponse>("fs/write_text_file", WriteTextFileRequest.serializer(), WriteTextFileResponse.serializer())
         public object TerminalCreate : AcpSessionRequestResponseMethod<CreateTerminalRequest, CreateTerminalResponse>("terminal/create", CreateTerminalRequest.serializer(), CreateTerminalResponse.serializer())
         public object TerminalOutput : AcpSessionRequestResponseMethod<TerminalOutputRequest, TerminalOutputResponse>("terminal/output", TerminalOutputRequest.serializer(), TerminalOutputResponse.serializer())
-        public object TerminalRelease : AcpSessionRequestResponseMethod<ReleaseTerminalRequest, ReleaseTerminalResponse>("terminal/release", ReleaseTerminalRequest.serializer(), ReleaseTerminalResponse.serializer())
-        public object TerminalWaitForExit : AcpSessionRequestResponseMethod<WaitForTerminalExitRequest, WaitForTerminalExitResponse>("terminal/wait_for_exit", WaitForTerminalExitRequest.serializer(), WaitForTerminalExitResponse.serializer())
-        public object TerminalKill : AcpSessionRequestResponseMethod<KillTerminalCommandRequest, KillTerminalCommandResponse>("terminal/kill", KillTerminalCommandRequest.serializer(), KillTerminalCommandResponse.serializer())
+        public object TerminalRelease : AcpSessionRequestResponseNullableMethod<ReleaseTerminalRequest, ReleaseTerminalResponse>("terminal/release", ReleaseTerminalRequest.serializer(), ReleaseTerminalResponse.serializer())
+        public object TerminalWaitForExit : AcpSessionRequestResponseNullableMethod<WaitForTerminalExitRequest, WaitForTerminalExitResponse>("terminal/wait_for_exit", WaitForTerminalExitRequest.serializer(), WaitForTerminalExitResponse.serializer())
+        public object TerminalKill : AcpSessionRequestResponseNullableMethod<KillTerminalCommandRequest, KillTerminalCommandResponse>("terminal/kill", KillTerminalCommandRequest.serializer(), KillTerminalCommandResponse.serializer())
     }