src/aegis_gitea_mcp/cli.py

@@ -17,6 +17,17 @@ from aegis_gitea_mcp.config import Settings, get_settings, reset_settings
 from aegis_gitea_mcp.logging_utils import configure_logging
 
 
+def _port(value: str) -> int:
+    """Parse ``--port`` (argparse ``type``): an integer from 1 to 65535."""
+    try:
+        port = int(value)
+    except ValueError:
+        raise argparse.ArgumentTypeError("must be an integer from 1 to 65535") from None
+    if not 1 <= port <= 65535:
+        raise argparse.ArgumentTypeError("must be between 1 and 65535")
+    return port
+
+
 def build_parser() -> argparse.ArgumentParser:
     """Build the argument parser."""
     parser = argparse.ArgumentParser(
@@ -35,9 +46,8 @@ def build_parser() -> argparse.ArgumentParser:
     serve.add_argument("--host", default=None, help="HTTP bind address (default: MCP_HOST)")
     serve.add_argument(
         "--port",
-        type=int,
+        type=_port,
         default=None,
-        choices=range(1, 65536),
         metavar="PORT",
         help="HTTP port (default: MCP_PORT)",
     )

tests/test_cli.py

@@ -33,3 +33,16 @@ def test_package_version_matches_pyproject() -> None:
 
     data = tomllib.loads((Path(__file__).parent.parent / "pyproject.toml").read_text())
     assert data["project"]["version"] == __version__
+
+
+@pytest.mark.parametrize("value", ["0", "65536", "-1", "http", "80.5"])
+def test_serve_rejects_bad_ports_with_a_short_message(
+    value: str, capsys: pytest.CaptureFixture[str]
+) -> None:
+    with pytest.raises(SystemExit) as exit_info:
+        build_parser().parse_args(["serve", "--port", value])
+
+    err = capsys.readouterr().err
+    assert exit_info.value.code == 2
+    assert "--port" in err and "65535" in err
+    assert len(err) < 500