fix(tui): prioritize interrupt and quit keys

Declare Ctrl+C and Ctrl+D as priority Textual bindings so the focused prompt cannot consume them. Drive exit and silent-stream cancellation regressions through Pilot key events instead of calling action handlers directly.

nexusos_cli/tui_app.py

@@ -27,13 +27,14 @@ _APPROVAL_TIMEOUT = httpx.Timeout(10.0, connect=5.0)
 def _require_textual():
     try:
         from textual.app import App
+        from textual.binding import Binding
         from textual.widgets import Footer, Header, Input, RichLog, Static
     except ImportError as e:  # pragma: no cover - optional extra
         raise ImportError(
             "The interactive TUI needs the 'tui' extra — "
             "pip install 'nexusos-ai[tui]' (or: pip install textual)."
         ) from e
-    return App, Footer, Header, Input, RichLog, Static
+    return App, Binding, Footer, Header, Input, RichLog, Static
 
 
 def _escape(text: str) -> str:
@@ -154,7 +155,7 @@ class NexusTUI:
 
     @staticmethod
     def build_app(*, api_url: str | None = None):
-        App, Footer, Header, Input, RichLog, Static = _require_textual()
+        App, Binding, Footer, Header, Input, RichLog, Static = _require_textual()
         base = (api_url or settings.api_url).rstrip("/")
 
         class AppImpl(App):
@@ -187,8 +188,8 @@ class NexusTUI:
             #prompt { dock: bottom; }
             """
             BINDINGS = [
-                ("ctrl+c", "interrupt", "Interrupt"),
+                Binding("ctrl+c", "interrupt", "Interrupt", priority=True),
-                ("ctrl+d", "quit", "Quit"),
+                Binding("ctrl+d", "quit", "Quit", priority=True),
             ]
 
             def __init__(self):

tests/test_tui.py

@@ -123,6 +123,23 @@ def test_stream_error_remains_visible_after_finish():
     asyncio.run(_run())
 
 
+@pytest.mark.parametrize("key", ["ctrl+c", "ctrl+d"])
+def test_priority_exit_bindings_reach_app_while_prompt_is_focused(key):
+    pytest.importorskip("textual")
+    from nexusos_cli.tui_app import NexusTUI
+
+    app = NexusTUI.build_app(api_url="http://127.0.0.1:9")
+
+    async def _run():
+        async with app.run_test() as pilot:
+            assert app.is_running
+            await pilot.press(key)
+            await pilot.pause()
+            assert not app.is_running
+
+    asyncio.run(_run())
+
+
 def test_tool_request_is_denied_with_stream_token():
     _ApprovalClient.calls.clear()
     names = _deny_tool_request(
@@ -262,13 +279,14 @@ def test_interrupt_cancels_silent_stream_and_accepts_next_message(monkeypatch):
         pytest.fail("stream did not become idle within one second")
 
     async def _run():
-        async with app.run_test():
+        async with app.run_test() as pilot:
             app._start_chat("first")
             assert await asyncio.to_thread(first_stream_started.wait, 2)
-            app.action_interrupt()
+            await pilot.press("ctrl+c")
             await _wait_until_idle()
 
             log = app.query_one("#log")
+            assert any("interrupt requested" in line.text for line in log.lines)
             assert not any("ReadTimeout" in line.text for line in log.lines)
 
             app._start_chat("second")