fix(browser): isolate daemon from shell process group

src/browser/daemon/process.rs

@@ -1,3 +1,4 @@
+use std::os::unix::process::CommandExt;
 use std::path::PathBuf;
 use std::time::Duration;
 
@@ -107,7 +108,10 @@ pub fn spawn_daemon(
 
     let params_json = serde_json::to_string(params)?;
 
+    // Shell tools may clean up their process group when a command returns.
+    // Keep the daemon reachable by subsequent CLI invocations in other tools.
     let child = std::process::Command::new(exe)
+        .process_group(0)
         .args(["__daemon", "--session-name", session_name])
         .env("STEEL_DAEMON_PARAMS", params_json)
         .stdin(std::process::Stdio::null())

tests/browser_device_auth.rs

@@ -46,6 +46,7 @@ impl Drop for Fixture {
 }
 
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+#[allow(unsafe_code)] // read-only process-group query for our own daemon PID
 async fn device_auth_uses_bearer_and_normalizes_root_query_before_native_cdp() {
     use std::os::unix::fs::PermissionsExt;
     let api = MockServer::start().await;
@@ -133,6 +134,18 @@ async fn device_auth_uses_bearer_and_normalizes_root_query_before_native_cdp() {
         "{}",
         String::from_utf8_lossy(&start.stdout)
     );
+    let daemon_pid: libc::pid_t =
+        std::fs::read_to_string(fixture.home.path().join("daemon-test.pid"))
+            .unwrap()
+            .trim()
+            .parse()
+            .unwrap();
+    // SAFETY: getpgid only queries the known child process; it sends no signal.
+    let daemon_group = unsafe { libc::getpgid(daemon_pid) };
+    assert_eq!(
+        daemon_group, daemon_pid,
+        "daemon must have its own group to survive shell-tool cleanup"
+    );
     assert_eq!(
         *seen.lock().unwrap(),
         ["/?sessionId=test-session&token=synthetic-connect-token"]