refactor: add argument validation and improve tests per review

- Add validation to reject unknown arguments with helpful error message
- Add test cases to verify status argument routing
- Add test case to verify unknown arguments are rejected
- Addresses review feedback from nikolasdehor

cmd/picoclaw/internal/gateway/command.go

@@ -1,6 +1,8 @@
 package gateway
 
 import (
+	"fmt"
+
 	"github.com/sipeed/picoclaw/cmd/picoclaw/internal/status"
 	"github.com/spf13/cobra"
 )
@@ -15,10 +17,14 @@ func NewGatewayCommand() *cobra.Command {
 		Args:    cobra.MaximumNArgs(1),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			// If "status" is provided as an argument, delegate to status command
-			if len(args) > 0 && args[0] == "status" {
+			if len(args) > 0 {
+				if args[0] == "status" {
 					status.StatusCmd()
 					return nil
 				}
+				// Reject unknown arguments
+				return fmt.Errorf("unknown argument: %s (did you mean 'picoclaw status'?)", args[0])
+			}
 			// Otherwise, start the gateway
 			return gatewayCmd(debug)
 		},

cmd/picoclaw/internal/gateway/command_test.go

@@ -30,3 +30,22 @@ func TestNewGatewayCommand(t *testing.T) {
 	assert.True(t, cmd.HasFlags())
 	assert.NotNil(t, cmd.Flags().Lookup("debug"))
 }
+
+func TestGatewayCommandStatusArgument(t *testing.T) {
+	cmd := NewGatewayCommand()
+
+	// Test that "status" argument is accepted and routes correctly
+	err := cmd.RunE(cmd, []string{"status"})
+	// StatusCmd() doesn't return an error, so this should succeed
+	assert.NoError(t, err)
+}
+
+func TestGatewayCommandUnknownArgument(t *testing.T) {
+	cmd := NewGatewayCommand()
+
+	// Test that unknown arguments are rejected
+	err := cmd.RunE(cmd, []string{"foo"})
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "unknown argument: foo")
+	assert.Contains(t, err.Error(), "did you mean 'picoclaw status'?")
+}