Publish harness and TUI open-source

initial sync from the monorepo

crates/codegen/xai-grok-test-support/src/process.rs

@@ -0,0 +1,46 @@
+//! General subprocess plumbing shared by the harnesses in this crate.
+
+use std::sync::Arc;
+
+/// Pipe all three stdio handles, `kill_on_drop`, spawn, and drain the child's
+/// stderr into the returned buffer on a background task. The one spawn path
+/// shared by every subprocess harness in this crate (`GrokStdioClient`,
+/// `RawStdioClient`, `leader::LeaderStdioClient`); env/args stay with the
+/// callers, whose hermeticity models differ (sandbox-inherit vs `env_clear`).
+/// The drain future is `Send`, so this works on and off a `LocalSet`.
+pub(crate) fn spawn_piped_with_stderr_capture(
+    mut cmd: tokio::process::Command,
+) -> (tokio::process::Child, Arc<std::sync::Mutex<Vec<u8>>>) {
+    cmd.stdin(std::process::Stdio::piped())
+        .stdout(std::process::Stdio::piped())
+        .stderr(std::process::Stdio::piped())
+        .kill_on_drop(true);
+
+    // Derived from `cmd` itself so the panic can never name a different binary
+    // than the one actually spawned.
+    let program = cmd.as_std().get_program().to_string_lossy().into_owned();
+    let mut child = cmd
+        .spawn()
+        .unwrap_or_else(|e| panic!("failed to spawn grok at {program}: {e}"));
+
+    let stderr = Arc::new(std::sync::Mutex::new(Vec::new()));
+    let stderr_capture = stderr.clone();
+    let mut child_stderr = child.stderr.take().expect("child stderr missing");
+    tokio::spawn(async move {
+        use tokio::io::AsyncReadExt as _;
+
+        let mut buf = [0_u8; 1024];
+        loop {
+            match child_stderr.read(&mut buf).await {
+                Ok(0) => break,
+                Ok(read) => stderr_capture
+                    .lock()
+                    .unwrap()
+                    .extend_from_slice(&buf[..read]),
+                Err(_) => break,
+            }
+        }
+    });
+
+    (child, stderr)
+}