feat: add xhttp transport, network monitoring and kernel auto-switch

internal/model/validate.go

@@ -36,9 +36,38 @@ func ValidateNodeSpec(n *NodeSpec, kcfg config.KernelConfig) error {
 	if err := ValidateCustomRouteRules(n.CustomRouteRules, kernelType, availableTags); err != nil {
 		return fmt.Errorf("validate custom route rules: %w", err)
 	}
+	if err := validateTransportKernel(n.Network, kernelType); err != nil {
+		return err
+	}
 	return nil
 }
 
+// singboxUnsupportedTransports lists transport types that sing-box does not support.
+var singboxUnsupportedTransports = map[string]bool{
+	"xhttp":     true,
+	"splithttp": true,
+}
+
+func validateTransportKernel(network, kernelType string) error {
+	net := strings.ToLower(strings.TrimSpace(network))
+	if kernelType == "singbox" && singboxUnsupportedTransports[net] {
+		return fmt.Errorf("transport %q is not supported by sing-box kernel; use xray kernel instead", net)
+	}
+	return nil
+}
+
+// ResolveKernelForTransport returns the kernel type required by the given
+// transport. If the configured kernel cannot handle the transport, it returns
+// the kernel that can. Otherwise it returns configuredKernel unchanged.
+// This is used in machine mode to auto-switch kernel per node.
+func ResolveKernelForTransport(network, configuredKernel string) string {
+	net := strings.ToLower(strings.TrimSpace(network))
+	if configuredKernel == "singbox" && singboxUnsupportedTransports[net] {
+		return "xray"
+	}
+	return configuredKernel
+}
+
 func normalizeKernelType(value string) (string, error) {
 	switch strings.ToLower(strings.TrimSpace(value)) {
 	case "singbox", "sing-box":