feat(cli): make nanobot launch the terminal agent

nanobot/cli/commands.py

@@ -87,7 +87,12 @@ app = typer.Typer(
     name="nanobot",
     context_settings={"help_option_names": ["-h", "--help"]},
     help=f"{__logo__} nanobot - Personal AI Assistant",
-    no_args_is_help=True,
+    epilog=(
+        "Run `nanobot` without a subcommand to start the terminal agent. "
+        "Use `nanobot agent --help` for agent options."
+    ),
+    invoke_without_command=True,
+    no_args_is_help=False,
 )
 
 console = Console()
@@ -98,7 +103,7 @@ def version_callback(value: bool):
         raise typer.Exit()
 
 
-@app.callback()
+@app.callback(invoke_without_command=True)
 def main(
     ctx: typer.Context,
     version: bool = typer.Option(
@@ -110,7 +115,11 @@ def main(
     # imports this Typer app directly instead of ``nanobot.cli.entry``. Keep the
     # role identity correct until that launcher is regenerated.
     command = ctx.invoked_subcommand
-    set_cli_process_identity([command] if command else sys.argv[1:])
+    set_cli_process_identity([command] if command else ["agent"])
+    if command is None:
+        from nanobot.cli.entry import _run_agent
+
+        _run_agent([], prog_name="nanobot")
 
 
 # ============================================================================

nanobot/cli/entry.py

@@ -8,6 +8,28 @@ from contextlib import suppress
 
 from nanobot.cli.process_identity import set_cli_process_identity
 
+_ROOT_OPTIONS = frozenset(
+    {
+        "-h",
+        "--help",
+        "-v",
+        "--version",
+        "--install-completion",
+        "--show-completion",
+    }
+)
+
+
+def _agent_invocation_args(args: list[str]) -> list[str] | None:
+    """Return agent arguments when the root command should act as ``agent``."""
+    if not args:
+        return []
+    if args[0] == "agent":
+        return args[1:]
+    if args[0].startswith("-") and args[0].split("=", 1)[0] not in _ROOT_OPTIONS:
+        return args
+    return None
+
 
 def _native_tui_candidate(args: list[str]) -> bool:
     """Return whether ``agent`` can start without the classic agent stack."""
@@ -34,19 +56,31 @@ def _configure_windows_console() -> None:
                 reconfigure(encoding="utf-8", errors="replace")
 
 
+def _run_agent(args: list[str], *, prog_name: str) -> None:
+    """Run the shared agent command without importing the complete CLI graph."""
+    import typer
+
+    from nanobot.cli.agent import agent
+
+    agent_app = typer.Typer(add_completion=False)
+    agent_app.command()(agent)
+    command = typer.main.get_command(agent_app)
+    command.main(args=args, prog_name=prog_name)
+
+
 def main() -> None:
     """Dispatch native TUI startup without importing the complete CLI graph."""
-    set_cli_process_identity(sys.argv[1:])
+    raw_args = sys.argv[1:]
+    agent_args = _agent_invocation_args(raw_args)
+    dispatch_args = ["agent", *agent_args] if agent_args is not None else raw_args
+    set_cli_process_identity(dispatch_args)
     _configure_windows_console()
-    if _native_tui_candidate(sys.argv[1:]):
-        import typer
-
-        from nanobot.cli.agent import agent
-
-        fast_app = typer.Typer(add_completion=False)
-        fast_app.command()(agent)
-        command = typer.main.get_command(fast_app)
-        command.main(args=sys.argv[2:], prog_name="nanobot agent")
+    root_agent_alias = agent_args is not None and raw_args[:1] != ["agent"]
+    if agent_args is not None and (
+        root_agent_alias or _native_tui_candidate(dispatch_args)
+    ):
+        prog_name = "nanobot" if root_agent_alias else "nanobot agent"
+        _run_agent(agent_args, prog_name=prog_name)
         return
 
     from nanobot.cli.commands import app