fix(logging): 重定向 JS 日志到 stderr 以避免污染 stdout #536

在 ACP 代理模式下，stdout 专用于 JSON-RPC 通信。修改 Kotlin 和 TypeScript 代码，将所有 console 方法重定向到 console.error（stderr），防止日志输出干扰 JSON-RPC 消息。

Author: phodal

mpp-core/src/jsMain/kotlin/cc/unitmesh/agent/logging/PlatformLogging.js.kt

@@ -3,10 +3,14 @@ package cc.unitmesh.agent.logging
 /**
  * JavaScript implementation of platform-specific logging initialization
  * JS uses console logging, no file storage needed
+ *
+ * IMPORTANT: For ACP agent mode, all logs should go to stderr (console.error)
+ * to avoid polluting stdout which is used for JSON-RPC communication.
  */
 actual fun initializePlatformLogging(config: LoggingConfig) {
-    // JavaScript platform uses console logging by default
-    // No additional configuration needed
+    // Redirect all console.log/info/warn to console.error for stderr output
+    // This ensures that only JSON-RPC messages go to stdout
+    redirectConsoleToStderr()
 }
 
 /**
@@ -16,3 +20,22 @@ actual fun initializePlatformLogging(config: LoggingConfig) {
 actual fun getPlatformLogDirectory(): String {
     return "console-only" // JS platform doesn't support file logging
 }
+
+/**
+ * Redirect console logging to stderr
+ * This is critical for ACP agent mode where stdout is used for JSON-RPC
+ */
+@Suppress("UNUSED_VARIABLE")
+private fun redirectConsoleToStderr() {
+    // Use js() to execute raw JavaScript code
+    val result = js("""
+        (function() {
+            // Redirect all console methods to console.error (stderr)
+            console.log = console.error;
+            console.info = console.error;
+            console.warn = console.error;
+            console.debug = console.error;
+            return true;
+        })()
+    """)
+}

mpp-ui/src/jsMain/typescript/agents/acp/AcpAgentServer.ts

@@ -335,6 +335,10 @@ class AcpSessionRenderer {
  * This is the entry point for `xiuper acp` command.
  */
 export async function startAcpAgentServer(): Promise<void> {
+  // CRITICAL: Redirect all console output to stderr BEFORE any Kotlin code runs
+  // This prevents Kotlin logging from polluting stdout (which is used for JSON-RPC)
+  redirectConsoleToStderr();
+
   console.error('[ACP Agent] Starting AutoDev Xiuper ACP Agent Server...');
 
   // For ACP ndJsonStream: first param is output (where we write), second is input (where we read)
@@ -355,3 +359,20 @@ export async function startAcpAgentServer(): Promise<void> {
   await connection.closed;
   console.error('[ACP Agent] Connection closed.');
 }
+
+/**
+ * Redirect all console methods to stderr.
+ * This is critical for ACP mode where stdout is reserved for JSON-RPC messages.
+ */
+function redirectConsoleToStderr(): void {
+  // Save original console.error
+  const originalError = console.error;
+
+  // Redirect all console methods to stderr
+  console.log = originalError;
+  console.info = originalError;
+  console.warn = originalError;
+  console.debug = originalError;
+
+  // console.error already goes to stderr
+}