diff --git a/acp-websocket-jetty/src/test/java/com/agentclientprotocol/sdk/integration/WebSocketClientInboundEchoReproTest.java b/acp-websocket-jetty/src/test/java/com/agentclientprotocol/sdk/integration/WebSocketClientInboundEchoReproTest.java new file mode 100644 index 0000000..3178b7e --- /dev/null +++ b/acp-websocket-jetty/src/test/java/com/agentclientprotocol/sdk/integration/WebSocketClientInboundEchoReproTest.java @@ -0,0 +1,153 @@ +/* + * Copyright 2025-2026 the original author or authors. + */ + +package com.agentclientprotocol.sdk.integration; + +import java.io.IOException; +import java.net.ServerSocket; +import java.net.URI; +import java.time.Duration; +import java.util.HashMap; +import java.util.List; +import java.util.Map; +import java.util.concurrent.CountDownLatch; +import java.util.concurrent.TimeUnit; +import java.util.concurrent.atomic.AtomicReference; + +import com.agentclientprotocol.sdk.agent.transport.WebSocketAcpAgentTransport; +import com.agentclientprotocol.sdk.client.AcpAsyncClient; +import com.agentclientprotocol.sdk.client.AcpClient; +import com.agentclientprotocol.sdk.client.transport.WebSocketAcpClientTransport; +import com.agentclientprotocol.sdk.json.AcpJsonMapper; +import com.agentclientprotocol.sdk.json.TypeRef; +import com.agentclientprotocol.sdk.spec.AcpAgentSession; +import com.agentclientprotocol.sdk.spec.AcpSchema; +import org.junit.jupiter.api.Test; +import reactor.core.publisher.Mono; + +import static org.assertj.core.api.Assertions.assertThat; + +/** + * Reproduces the WebSocket client transport echo bug on main. + * + *

+ * This test isolates the agent-request path: + *

+ *
    + *
  1. The agent receives {@code session/prompt} from the client.
    2. + *
  2. While handling that prompt, the agent sends {@code fs/read_text_file} to the + * client.
    3. + *
  3. The client has registered {@code readTextFileHandler}, so it should handle the + * request locally and send only a JSON-RPC response with the same id.
    4. + *
  4. The original {@code fs/read_text_file} request must not be sent back to the + * agent.
    5. + *
+ * + *

+ * On main, {@code AcpClientSession} wires the transport handler with + * {@code mono -> mono.doOnNext(this::handle)}. Reactor {@code doOnNext} preserves the + * original message downstream, and the WebSocket transport forwards handler-emitted + * messages back onto the socket. The result is that an inbound agent request can be + * echoed back to the agent after being handled by the client. + *

+ */ +class WebSocketClientInboundEchoReproTest { + + private static final Duration TIMEOUT = Duration.ofSeconds(5); + + @Test + void clientSessionShouldNotEchoAgentRequestsBackToAgent() throws Exception { + AcpJsonMapper jsonMapper = AcpJsonMapper.createDefault(); + int port = findFreePort(); + + WebSocketAcpAgentTransport agentTransport = new WebSocketAcpAgentTransport(port, jsonMapper); + AtomicReference agentSessionRef = new AtomicReference<>(); + CountDownLatch echoedRequestReceived = new CountDownLatch(1); + + AcpAgentSession agentSession = null; + AcpAsyncClient client = null; + + try { + Map> requestHandlers = new HashMap<>(); + requestHandlers.put(AcpSchema.METHOD_INITIALIZE, + params -> Mono.just(new AcpSchema.InitializeResponse(1, new AcpSchema.AgentCapabilities(), List.of()))); + requestHandlers.put(AcpSchema.METHOD_SESSION_NEW, + params -> Mono.just(new AcpSchema.NewSessionResponse("echo-session", null, null))); + + // The prompt handler deliberately sends an agent->client request. The expected + // protocol flow is: + // + // agent -> client: request id=N, method=fs/read_text_file + // client -> agent: response id=N, result={ content: "client content" } + // + // The original request is not a client->agent message and should never be + // observed by the agent's inbound request router. + requestHandlers.put(AcpSchema.METHOD_SESSION_PROMPT, params -> agentSessionRef.get() + .sendRequest(AcpSchema.METHOD_FS_READ_TEXT_FILE, + new AcpSchema.ReadTextFileRequest("echo-session", "/tmp/input.txt", null, null), + new TypeRef() { + }) + .thenReturn(AcpSchema.PromptResponse.endTurn())); + + // Trap the agent->client method on the agent side. This handler should never run: + // fs/read_text_file is a client method, so if the agent receives it here, the + // client has echoed the inbound agent request back over the WebSocket transport. + // Returning "unexpected echo" makes the trap harmless to the rest of the prompt + // flow while the latch records that the invalid path happened. + requestHandlers.put(AcpSchema.METHOD_FS_READ_TEXT_FILE, params -> { + echoedRequestReceived.countDown(); + return Mono.just(new AcpSchema.ReadTextFileResponse("unexpected echo")); + }); + + agentSession = new AcpAgentSession(TIMEOUT, agentTransport, requestHandlers, Map.of()); + agentSessionRef.set(agentSession); + Thread.sleep(300); + + WebSocketAcpClientTransport clientTransport = new WebSocketAcpClientTransport( + URI.create("ws://localhost:" + port + "/acp"), jsonMapper); + client = AcpClient.async(clientTransport) + .requestTimeout(TIMEOUT) + // Registering this handler means the client can satisfy fs/read_text_file + // locally. It has no reason to route the request back to the agent. + .readTextFileHandler(params -> Mono.just(new AcpSchema.ReadTextFileResponse("client content"))) + .build(); + + // Advertise the matching client capability so the agent is allowed to make the + // fs/read_text_file request during prompt handling. + client.initialize(new AcpSchema.InitializeRequest(1, + new AcpSchema.ClientCapabilities(new AcpSchema.FileSystemCapability(true, false), false))) + .block(TIMEOUT); + client.newSession(new AcpSchema.NewSessionRequest("/workspace", List.of())).block(TIMEOUT); + + AcpSchema.PromptResponse response = client + .prompt(new AcpSchema.PromptRequest("echo-session", List.of(new AcpSchema.TextContent("read file")))) + .block(TIMEOUT); + + assertThat(response).isNotNull(); + assertThat(response.stopReason()).isEqualTo(AcpSchema.StopReason.END_TURN); + + // This should remain false. On main it becomes true, proving that the + // WebSocket client transport echoed the inbound fs/read_text_file request back + // to the agent. + assertThat(echoedRequestReceived.await(1, TimeUnit.SECONDS)) + .as("WebSocket client session must not send inbound agent requests back to the agent") + .isFalse(); + } + finally { + if (client != null) { + client.closeGracefully().block(TIMEOUT); + } + if (agentSession != null) { + agentSession.closeGracefully().block(TIMEOUT); + } + } + } + + private static int findFreePort() throws IOException { + try (ServerSocket socket = new ServerSocket(0)) { + return socket.getLocalPort(); + } + } + +}