From 90703002c9ab593a9c9a576a1d83a21a9a1976d0 Mon Sep 17 00:00:00 2001
From: Xubin Ren <52506698+Re-bin@users.noreply.github.com>
Date: Mon, 22 Jun 2026 22:41:48 +0800
Subject: [PATCH] fix(gateway): restore tty signal mode for ctrl-c

---
 nanobot/cli/commands.py    | 24 ++++++++++++++++++++++++
 tests/cli/test_commands.py | 31 +++++++++++++++++++++++++++++++
 2 files changed, 55 insertions(+)

diff --git a/nanobot/cli/commands.py b/nanobot/cli/commands.py
index 4acf8c38..aab27242 100644
--- a/nanobot/cli/commands.py
+++ b/nanobot/cli/commands.py
@@ -80,6 +80,29 @@ def _signal_name(signum: int) -> str:
     return f"signal {signum}"
 
 
+def _ensure_gateway_tty_signal_mode() -> None:
+    """Keep foreground gateway Ctrl+C usable even after a raw-mode TTY leak."""
+    try:
+        fd = sys.stdin.fileno()
+        if not os.isatty(fd):
+            return
+    except Exception:
+        return
+
+    with suppress(Exception):
+        import termios
+
+        attrs = termios.tcgetattr(fd)
+        lflag = attrs[3]
+        required = termios.ISIG | termios.ICANON | termios.ECHO
+        if (lflag & required) == required:
+            return
+        attrs[3] = lflag | required
+        termios.tcsetattr(fd, termios.TCSANOW, attrs)
+        termios.tcflush(fd, termios.TCIFLUSH)
+        logger.debug("Restored foreground gateway TTY signal mode")
+
+
 def _install_gateway_shutdown_handlers(
     loop: asyncio.AbstractEventLoop,
     shutdown_event: asyncio.Event,
@@ -1166,6 +1189,7 @@ def _run_gateway(
         runtime_tasks: asyncio.Future | None = None
         runtime_tasks_drained = False
         shutdown_event = asyncio.Event()
+        _ensure_gateway_tty_signal_mode()
         restore_shutdown_handlers = _install_gateway_shutdown_handlers(
             asyncio.get_running_loop(),
             shutdown_event,
diff --git a/tests/cli/test_commands.py b/tests/cli/test_commands.py
index 0e92fdc8..aeb67e8b 100644
--- a/tests/cli/test_commands.py
+++ b/tests/cli/test_commands.py
@@ -109,6 +109,37 @@ def test_gateway_signal_handler_first_signal_stops_and_second_forces() -> None:
     asyncio.run(_run())
 
 
+def test_gateway_tty_signal_mode_restores_ctrl_c(monkeypatch) -> None:
+    try:
+        import os
+        import pty
+        import termios
+    except ImportError:  # pragma: no cover - platform without POSIX termios
+        pytest.skip("termios unavailable")
+
+    master_fd, slave_fd = pty.openpty()
+
+    class _Stdin:
+        def fileno(self) -> int:
+            return slave_fd
+
+    try:
+        attrs = termios.tcgetattr(slave_fd)
+        attrs[3] &= ~(termios.ISIG | termios.ICANON | termios.ECHO)
+        termios.tcsetattr(slave_fd, termios.TCSANOW, attrs)
+
+        monkeypatch.setattr(cli_commands.sys, "stdin", _Stdin())
+        cli_commands._ensure_gateway_tty_signal_mode()
+
+        restored = termios.tcgetattr(slave_fd)
+        assert restored[3] & termios.ISIG
+        assert restored[3] & termios.ICANON
+        assert restored[3] & termios.ECHO
+    finally:
+        os.close(master_fd)
+        os.close(slave_fd)
+
+
 @pytest.fixture
 def mock_paths():
     """Mock config/workspace paths for test isolation."""