refactor: clean up NodeService interface; move all integrity logic behind it

cmd/edit.go

@@ -45,17 +45,18 @@ var editCmd = &cobra.Command{
 			return
 		}
 
-		if content, err := os.ReadFile(tmp.Name()); err == nil {
-			n.Content = string(content)
-			if err := svc.Update(n); err != nil {
-				fmt.Fprintln(os.Stderr, "failed to update:", err)
-				return
-			}
-			n, _ = svc.GetByID(args[0])
-			output.PrintNode(cmd.OutOrStdout(), svc, n, jsonFlag)
-		} else {
+		content, err := os.ReadFile(tmp.Name())
+		if err != nil {
 			fmt.Fprintln(os.Stderr, "failed to read temp file:", err)
+			return
 		}
+		s := string(content)
+		n, err = svc.Update(args[0], service.UpdateInput{Content: &s})
+		if err != nil {
+			fmt.Fprintln(os.Stderr, "failed to update:", err)
+			return
+		}
+		output.PrintNode(cmd.OutOrStdout(), svc, n, jsonFlag)
 	},
 }