fix(exec): 消除 stdin 管道竞态——执行器总是向子进程提供（可能为空的）即时关闭 stdin；替身脚本先排空 stdin 再回显

- CI 实证（JDK 8 + Ubuntu）：commons-exec 泵入 stdin 时，不读 stdin 的
  快退进程会触发 write-after-close（exit=-1，stderr=Stream closed），
  1.4.0 必现、1.6.0 仍抖动
- 修复后：消费型命令（codex login --with-api-key）读满载荷到 EOF；
  不消费的命令拿到立即 EOF 的空管道，泵不再有迟到写入
- 副作用说明：子进程 stdin 从"挂起管道"变为"关闭管道"，对非交互
  SDK 是更严格正确的语义

Author: loong10k

src/main/java/io/github/easy4j/codex/cli/CodexCliExecutor.java

@@ -120,12 +120,12 @@ private CodexCliResult runProcess(String stdin, String... args) {
         DefaultExecutor executor = new DefaultExecutor();
         ByteArrayOutputStream stdout = new ByteArrayOutputStream();
         ByteArrayOutputStream stderr = new ByteArrayOutputStream();
-        if (stdin != null && !stdin.isEmpty()) {
-            executor.setStreamHandler(new org.apache.commons.exec.PumpStreamHandler(stdout, stderr,
-                    new ByteArrayInputStream(stdin.getBytes(StandardCharsets.UTF_8))));
-        } else {
-            executor.setStreamHandler(new org.apache.commons.exec.PumpStreamHandler(stdout, stderr));
-        }
+        // Always hand the child a (possibly empty) stdin pipe that closes
+        // right after the payload: consumers like `codex login --with-api-key`
+        // read to EOF, and a closed pipe cannot race the input pump.
+        byte[] stdinBytes = stdin == null ? new byte[0] : stdin.getBytes(StandardCharsets.UTF_8);
+        executor.setStreamHandler(new org.apache.commons.exec.PumpStreamHandler(stdout, stderr,
+                new ByteArrayInputStream(stdinBytes)));
 
         long timeoutMs = config.getLocalTimeoutSeconds() * 1000L;
         ExecuteWatchdog watchdog = new ExecuteWatchdog(timeoutMs);

src/test/resources/echo-args.sh

@@ -6,4 +6,8 @@
 # coreutils echo (Linux) interprets --version/--help as flags while BSD echo
 # (macOS) prints them literally.
 #
+# Drain piped stdin first: real `codex login --with-api-key` consumes its
+# stdin payload; reading to EOF also keeps the executor's input pump race-free
+# (an immediately-closed pipe yields instant EOF here).
+cat > /dev/null 2>/dev/null
 printf '%s\n' "$*"