refactor(tui): retire the direct session default

nanobot/cli/agent.py

@@ -73,7 +73,7 @@ def agent(
         help="Terminal UI appearance: auto, dark, or light",
     ),
 ):
-    """Interact with the agent directly."""
+    """Chat in the terminal or send one message non-interactively."""
     from nanobot.bus.queue import MessageBus
     from nanobot.cron.service import CronService
     from nanobot.providers.factory import make_provider
@@ -85,7 +85,7 @@ def agent(
         raise typer.BadParameter("must be auto, dark, or light", param_hint="--theme")
     native_tui = message is None and not classic
     if native_tui:
-        from nanobot.cli.tui_launcher import TuiUnavailableError, launch_tui
+        from nanobot.cli.tui_launcher import TuiSessionError, TuiUnavailableError, launch_tui
         from nanobot.config.loader import get_config_path
 
         if not sys.stdin.isatty() or not sys.stdout.isatty():
@@ -106,6 +106,8 @@ def agent(
                 session_id=session_id,
                 theme=theme,
             )
+        except TuiSessionError as exc:
+            raise typer.BadParameter(str(exc), param_hint="--session") from exc
         except TuiUnavailableError as exc:
             console.print(f"[red]Native TUI unavailable: {exc}[/red]")
             console.print("[dim]Use `nanobot agent --classic` only if you want the old prompt.[/dim]")
@@ -205,7 +207,7 @@ def agent(
 
         return _cli_progress
 
-    if message:
+    if message is not None:
         # Single message mode — direct call, no bus needed
         async def run_once() -> None:
             try:

nanobot/cli/tui_launcher.py

@@ -32,6 +32,10 @@ class TuiUnavailableError(RuntimeError):
     """Raised when the native TypeScript TUI cannot run on this installation."""
 
 
+class TuiSessionError(ValueError):
+    """Raised when a session selector cannot be opened by the native TUI."""
+
+
 @dataclass(frozen=True)
 class _GatewayHandle:
     base_url: str
@@ -46,6 +50,8 @@ def launch_tui(
     theme: str,
 ) -> int:
     """Run the native TUI against the shared local gateway."""
+    state_path = config_path.parent / "tui" / "state.json"
+    chat_id = _initial_tui_chat_id(session_id, state_path)
     command = _resolve_tui_command()
     gateway = _ensure_gateway(
         config,
@@ -72,9 +78,7 @@ def launch_tui(
             "NANOBOT_TUI_THEME": theme,
         }
     )
-    state_path = config_path.parent / "tui" / "state.json"
     env["NANOBOT_TUI_STATE_PATH"] = str(state_path)
-    chat_id = _initial_tui_chat_id(session_id, state_path)
     if chat_id:
         env["NANOBOT_TUI_CHAT_ID"] = chat_id
     else:
@@ -335,7 +339,7 @@ def _websocket_chat_id(session_id: str) -> str | None:
     if session_id.startswith("websocket:"):
         return session_id.split(":", 1)[1] or None
     if ":" in session_id:
-        raise TuiUnavailableError(
+        raise TuiSessionError(
             "the native TUI can open only WebSocket sessions; use --classic to resume "
             f"{session_id!r}"
         )
@@ -343,10 +347,10 @@ def _websocket_chat_id(session_id: str) -> str | None:
 
 
 def _initial_tui_chat_id(session_id: str | None, state_path: Path) -> str | None:
-    """Resume the default TUI, while keeping an explicit selector authoritative."""
+    """Resume the last TUI chat, while keeping an explicit selector authoritative."""
     if session_id is not None:
         return _websocket_chat_id(session_id)
-    return _read_tui_chat_id(state_path) or "tui-direct"
+    return _read_tui_chat_id(state_path)
 
 
 def _read_tui_chat_id(path: Path) -> str | None: