Question: Clarify difference between StdioAcpAgentTransport and StdioAcpClientTransport ?

[cmoulliard]

Question

What is the difference between the StdioAcpAgentTransport and StdioAcpClientTransport as the class definition looks very similar ?
Is it because when we use StdioAcpAgentTransport, the JSON RPC ACP server is already running and the agent will read the messages from it ? How then can it read such messages ?

Is the main purpose of the StdioAcpAgent instead to create for testing purposes ACP agent replying the JSON RPC prompts, messages, etc. Example: https://github.com/markpollack/acp-java-tutorial/blob/main/module-12-echo-agent/src/main/java/com/acptutorial/module12/EchoAgent.java ?

/**
 * Implementation of the ACP Stdio transport for agents that communicates with clients
 * using standard input/output streams. Messages are exchanged as newline-delimited JSON-RPC
 * messages over stdin/stdout, with errors and debug information sent to stderr.
 *
 * <p>
 * This is the agent-side counterpart to {@code StdioAcpClientTransport}. While the client
 * spawns an agent process and connects to its stdin/stdout, the agent transport reads from
 * the process's System.in and writes to System.out.
 * </p>
 *
 * <p>
 * Key features:
 * <ul>
 * <li>Thread-safe message processing with dedicated schedulers</li>
 * <li>Proper resource management and graceful shutdown</li>
 * <li>Backpressure support via Reactor Sinks</li>
 * </ul>
 *
 * @author Mark Pollack
 */
public class StdioAcpAgentTransport implements AcpAgentTransport {

vs

/**
 * Implementation of the ACP Stdio transport that communicates with an agent process using
 * standard input/output streams. Messages are exchanged as newline-delimited JSON-RPC
 * messages over stdin/stdout, with errors and debug information sent to stderr.
 *
 * <p>
 * This is a full-featured transport with:
 * <ul>
 * <li>Thread-safe message processing with dedicated schedulers</li>
 * <li>Proper resource management and graceful shutdown</li>
 * <li>Error stream handling</li>
 * <li>Backpressure support via Reactor Sinks</li>
 * </ul>
 *
 * @author Mark Pollack
 * @author Christian Tzolov (MCP Java SDK)
 * @author Dariusz Jędrzejczyk (MCP Java SDK)
 */
public class StdioAcpClientTransport implements AcpClientTransport {