fix(cli): preserve root shell completion

tests/cli/test_entry.py

@@ -1,3 +1,8 @@
+import os
+import subprocess
+import sys
+from pathlib import Path
+
 from nanobot.cli import entry
 from nanobot.cli.entry import _agent_invocation_args, _native_tui_candidate
 
@@ -23,6 +28,36 @@ def test_root_metadata_and_subcommands_keep_the_root_cli() -> None:
         assert _agent_invocation_args(args) is None
 
 
+def test_root_shell_completion_keeps_root_subcommands() -> None:
+    env = os.environ.copy()
+    env.update(
+        {
+            "_NANOBOT_COMPLETE": "complete_bash",
+            "COMP_WORDS": "nanobot ",
+            "COMP_CWORD": "1",
+        }
+    )
+    script = (
+        "import sys; "
+        "from nanobot.cli.entry import main; "
+        "sys.argv = ['nanobot']; "
+        "main()"
+    )
+
+    result = subprocess.run(
+        [sys.executable, "-c", script],
+        cwd=Path(__file__).parents[2],
+        env=env,
+        capture_output=True,
+        text=True,
+        check=False,
+    )
+
+    assert result.returncode == 0, result.stderr
+    assert {"agent", "gateway", "webui"} <= set(result.stdout.splitlines())
+    assert "not supported" not in result.stderr
+
+
 def test_root_alias_dispatches_the_shared_agent_command(monkeypatch) -> None:
     calls: dict[str, object] = {}
     monkeypatch.setattr(entry.sys, "argv", ["nanobot", "-m", "hello"])