all: add tests; imp errors

internal/next/websvc/websvc.go

@@ -24,10 +24,21 @@ import (
 	httptreemux "github.com/dimfeld/httptreemux/v5"
 )
 
+// ServiceWithConfig is an extension of the [agh.Service] interface for services
+// that can return their configuration.
+//
+// TODO(a.garipov): Consider removing this generic interface if we figure out
+// how to make it testable in a better way.
+type ServiceWithConfig[ConfigType any] interface {
+	agh.Service
+
+	Config() (c ConfigType)
+}
+
 // ConfigManager is the configuration manager interface.
 type ConfigManager interface {
-	DNS() (svc *dnssvc.Service)
-	Web() (svc *Service)
+	DNS() (svc ServiceWithConfig[*dnssvc.Config])
+	Web() (svc ServiceWithConfig[*Config])
 
 	UpdateDNS(ctx context.Context, c *dnssvc.Config) (err error)
 	UpdateWeb(ctx context.Context, c *Config) (err error)