Add --new-session to bwrap invocation

tests/integration.rs

@@ -9,6 +9,28 @@ fn sandbox(extra_args: &[&str]) -> Command {
     cmd
 }
 
+fn read_sid_from_stat(stat: &str) -> u32 {
+    stat.trim()
+        .split_whitespace()
+        .nth(5)
+        .expect("missing field 6 in /proc/self/stat")
+        .parse()
+        .expect("failed to parse session ID")
+}
+
+fn read_sid_inside_sandbox(extra_args: &[&str]) -> u32 {
+    let output = sandbox(extra_args)
+        .args(["--", "bash", "-c", "cat /proc/self/stat"])
+        .output()
+        .expect("agent-sandbox binary failed to execute");
+    read_sid_from_stat(&String::from_utf8_lossy(&output.stdout))
+}
+
+fn read_sid_current_process() -> u32 {
+    let stat = fs::read_to_string("/proc/self/stat").expect("failed to read /proc/self/stat");
+    read_sid_from_stat(&stat)
+}
+
 struct CleanupFile(&'static str);
 
 impl Drop for CleanupFile {
@@ -303,6 +325,17 @@ fn empty_home_rejected() {
     );
 }
 
+#[test]
+fn new_session_isolates_sid() {
+    let inner_sid = read_sid_inside_sandbox(&[]);
+    let outer_sid = read_sid_current_process();
+
+    assert_ne!(
+        inner_sid, outer_sid,
+        "sandboxed process should have a different session ID (got {inner_sid} == {outer_sid})"
+    );
+}
+
 #[test]
 fn rw_missing_path_errors() {
     let output = sandbox(&["--rw", "/nonexistent/xyz"])