fix(exec): 子进程输出按 UTF-8 解码——toString() 用平台默认字符集，GBK 默认字符集的 Windows 上会把 CLI 的 UTF-8 输出解成乱码；附 POSIX printf 八进制转义回归测试

Author: loong10k

src/main/java/io/github/easy4j/claudecode/cli/ClaudeCodeCliExecutor.java

@@ -125,8 +125,8 @@ private ClaudeCodeCliResult runProcess(String stdin, String... args) {
             int exitCode = environment == null
                     ? executor.execute(cmd)
                     : executor.execute(cmd, environment);
-            String out = stdout.toString().trim();
-            String err = stderr.toString().trim();
+            String out = stdout.toString(java.nio.charset.StandardCharsets.UTF_8).trim();
+            String err = stderr.toString(java.nio.charset.StandardCharsets.UTF_8).trim();
             log.debug("claude CLI executed: exitCode={}, stdout.len={}", exitCode, out.length());
             if (watchdog.killedProcess()) {
                 return new ClaudeCodeCliResult(-1, out, "claude CLI timed out after " + timeoutMs + " ms\n" + err);
@@ -139,8 +139,8 @@ private ClaudeCodeCliResult runProcess(String stdin, String... args) {
             // with the real exit code instead of discarding the output. The
             // deadline check makes the timeout verdict race-free even when
             // {@code watchdog.killedProcess()} has not observed the kill yet.
-            String out = stdout.toString().trim();
-            String err = stderr.toString().trim();
+            String out = stdout.toString(java.nio.charset.StandardCharsets.UTF_8).trim();
+            String err = stderr.toString(java.nio.charset.StandardCharsets.UTF_8).trim();
             boolean timedOut = watchdog.killedProcess()
                     || System.nanoTime() - startNanos >= timeoutMs * 1_000_000L;
             if (timedOut) {

src/test/java/io/github/easy4j/claudecode/cli/ClaudeCodeCliExecutorTest.java

@@ -161,6 +161,19 @@ void shouldPassEnvironmentOverridesToChildProcess() {
                 "configured environment overrides must reach the child process");
     }
 
+    @Test
+    void shouldDecodeChildOutputAsUtf8() {
+        // The CLIs emit UTF-8 regardless of platform; decoding with the
+        // platform default charset would mojibake on GBK-default Windows.
+        // 你 = \344\275\240, 好 = \345\245\275 (POSIX printf octal escapes).
+        ClaudeCodeCliExecutor exec = newExecutorFor("/bin/sh");
+
+        ClaudeCodeCliResult result = exec.execute("-c", "printf '\\344\\275\\240\\345\\245\\275'");
+
+        assertEquals("你好", result.getStdout(),
+                "child output must be decoded as UTF-8, not the platform default charset");
+    }
+
     @Test
     void shouldExposeConfigBehaviourOnSuccessAndFailure() {
         ClaudeCodeClientConfig config = new ClaudeCodeClientConfig();