Add Mosh parity hardening

tests/integration_smoke.rs

@@ -1330,13 +1330,16 @@ fn tui_control_sequences_survive_transport_verbatim() {
     let (socket, bootstrap, ok) = direct_attach(&config, port, "read-write");
 
     let sequences = concat!(
-        "\x1b[?1049h", // alternate screen on
-        "\x1b[?2004h", // bracketed paste on
-        "\x1b[?1000h", // mouse tracking on
-        "\x1b[?1006h", // SGR mouse encoding on
-        "\x1b[?25l",   // cursor hidden
-        "\x1b[12;34H", // absolute cursor movement
+        "\x1b[?1049h",           // alternate screen on
+        "\x1b[?2004h",           // bracketed paste on
+        "\x1b[?1000h",           // mouse tracking on
+        "\x1b[?1006h",           // SGR mouse encoding on
+        "\x1b]0;DOSH_TITLE\x07", // OSC title
+        "\x1b[?25l",             // cursor hidden
+        "\x1b[12;34H",           // absolute cursor movement
+        "\x1b[1;31m",            // bold red
         "DOSH_TUI_VERBATIM",
+        "\x1b[0m",
         "\x1b[?25h",
         "\x1b[?1006l",
         "\x1b[?1000l",
@@ -1366,9 +1369,12 @@ fn tui_control_sequences_survive_transport_verbatim() {
         "\x1b[?2004h",
         "\x1b[?1000h",
         "\x1b[?1006h",
+        "\x1b]0;DOSH_TITLE\x07",
         "\x1b[?25l",
         "\x1b[12;34H",
+        "\x1b[1;31m",
         "DOSH_TUI_VERBATIM",
+        "\x1b[0m",
         "\x1b[?25h",
         "\x1b[?1006l",
         "\x1b[?1000l",
@@ -1382,6 +1388,39 @@ fn tui_control_sequences_survive_transport_verbatim() {
     }
 }
 
+#[test]
+fn unicode_output_survives_transport() {
+    let dir = tempfile::tempdir().unwrap();
+    let port = free_udp_port();
+    let config = write_server_config(&dir, port);
+    let mut server = start_server(&dir, &config);
+    let (socket, bootstrap, ok) = direct_attach(&config, port, "read-write");
+
+    let marker = "DOSH_UNICODE 你 e\u{301} 🚀";
+    let input = Input {
+        bytes: format!("printf '{}\\n'\n", marker).into_bytes(),
+    };
+    send_encrypted(
+        &socket,
+        port,
+        PacketKind::Input,
+        ok.client_id,
+        2,
+        0,
+        &bootstrap.session_key,
+        &protocol::to_body(&input).unwrap(),
+    );
+    let text = collect_frame_text(&socket, &bootstrap.session_key, 2000);
+
+    let _ = server.kill();
+    let _ = server.wait();
+
+    assert!(
+        text.contains(marker),
+        "expected UTF-8 output marker to survive transport, got {text:?}"
+    );
+}
+
 #[test]
 fn large_tui_paint_is_delivered_in_mtu_safe_frames() {
     let dir = tempfile::tempdir().unwrap();