fix(client): avoid abort on terminal hangup (#2427)

* fix(client): avoid abort on terminal hangup

refs #2424

* test(client): gate PTY integration on unix

refs #2424

---------

Co-authored-by: akbash-bot <300245827+akbash-bot@users.noreply.github.com>
Co-authored-by: Can Celik <ogulcancelik@gmail.com>

src/client/mod.rs

@@ -606,7 +606,7 @@ fn restore_terminal_state(
         restore_windows_input_mode_value(mode);
     }
 
-    ratatui::restore();
+    let _ = ratatui::try_restore();
     let _ = write_terminal_restore_postlude(&mut io::stdout(), reset_host_color_scheme_reports);
 
     #[cfg(windows)]

tests/client_mode.rs

@@ -1,5 +1,7 @@
 //! Integration tests for thin client mode.
 
+#![cfg(unix)]
+
 mod support;
 
 use std::fs;
@@ -756,11 +758,9 @@ fn client_restores_terminal_on_server_eof() {
     });
 }
 
-/// The path this PR actually fixes: a direct SIGHUP/SIGTERM to the client (e.g.
-/// a terminal emulator SIGHUPing its foreground child on window close). With
-/// `ctrlc`'s `termination` feature the handler sets `should_quit`, the loop
-/// exits, and `TerminalGuard::Drop` restores the terminal. Without it the
-/// process would die un-unwound and leak mouse reporting.
+/// A direct SIGHUP/SIGTERM with a writable terminal follows the graceful quit
+/// path and emits the terminal teardown. Actual terminal-window closure also
+/// makes the PTY unwritable and is covered separately below.
 #[test]
 fn client_restores_terminal_on_sighup() {
     assert_client_restores_terminal(|_server, client| {
@@ -771,6 +771,88 @@ fn client_restores_terminal_on_sighup() {
     });
 }
 
+fn read_until_client_attaches(client: &SpawnedHerdr) -> String {
+    let master = client._master.as_ref().expect("thin client master");
+    let fd = master.as_raw_fd().expect("thin client PTY file descriptor");
+    let flags = unsafe { libc::fcntl(fd, libc::F_GETFL) };
+    assert_ne!(flags, -1, "read thin client PTY flags");
+    assert_ne!(
+        unsafe { libc::fcntl(fd, libc::F_SETFL, flags | libc::O_NONBLOCK) },
+        -1,
+        "make thin client PTY nonblocking"
+    );
+
+    let mut reader = master.try_clone_reader().expect("clone client PTY reader");
+    let mut output = String::new();
+    let deadline = Instant::now() + Duration::from_secs(8);
+    while Instant::now() < deadline {
+        let mut buf = [0u8; 4096];
+        match reader.read(&mut buf) {
+            Ok(0) => break,
+            Ok(n) => output.push_str(&String::from_utf8_lossy(&buf[..n])),
+            Err(err) if err.kind() == std::io::ErrorKind::WouldBlock => {
+                thread::sleep(Duration::from_millis(20));
+            }
+            Err(err) => panic!("read thin client PTY: {err}"),
+        }
+        if output.contains('\u{2500}')
+            || output.contains("workspace")
+            || output.contains("pane")
+            || output.contains("terminal")
+        {
+            return output;
+        }
+    }
+    panic!("thin client must attach and render a frame; output: {output:?}");
+}
+
+#[test]
+fn client_exits_cleanly_when_terminal_hangs_up() {
+    let _lock = test_lock();
+    let base = unique_test_dir();
+    let config_home = base.join("config");
+    let runtime_dir = base.join("runtime");
+    let api_socket = runtime_dir.join("herdr.sock");
+    let client_socket = runtime_dir.join("herdr-client.sock");
+
+    let spawned_server = spawn_server(&config_home, &runtime_dir, &api_socket, &client_socket);
+    wait_for_socket(&api_socket, Duration::from_secs(10));
+    wait_for_socket(&client_socket, Duration::from_secs(10));
+
+    let mut thin_client = spawn_client_process(&config_home, &runtime_dir, &api_socket);
+    let attached_output = read_until_client_attaches(&thin_client);
+
+    // Closing the final PTY master models the outer terminal disappearing: the
+    // foreground client receives SIGHUP and writes to stdout/stderr fail.
+    thin_client.close_master();
+    let deadline = Instant::now() + Duration::from_secs(12);
+    let status = loop {
+        if let Some(status) = thin_client.child.try_wait().expect("poll thin client") {
+            break Some(status);
+        }
+        if Instant::now() >= deadline {
+            break None;
+        }
+        thread::sleep(Duration::from_millis(20));
+    };
+    let server_response = ping_socket(&api_socket);
+
+    drop(spawned_server);
+    cleanup_spawned_herdr(thin_client, base);
+
+    let status = status.unwrap_or_else(|| {
+        panic!("thin client did not exit after PTY hangup; attach output: {attached_output:?}")
+    });
+    assert!(
+        status.success(),
+        "thin client should exit cleanly after PTY hangup, got {status}; attach output: {attached_output:?}"
+    );
+    assert!(
+        server_response.contains("pong"),
+        "server should survive client PTY hangup: {server_response}"
+    );
+}
+
 #[test]
 fn client_receives_frame_after_pane_output() {
     // End-to-end test: server renders, client receives Frame.