args: simplify API + code

token/internal/envelope/ipld.go

@@ -187,6 +187,8 @@ func FromIPLD[T Tokener](node datamodel.Node) (T, error) {
 		return zero, errors.New("the VarsigHeader key type doesn't match the issuer's key type")
 	}
 
+	// TODO: this re-encode the payload! Is there a less wasteful way?
+
 	data, err := ipld.Encode(info.sigPayloadNode, dagcbor.Encode)
 	if err != nil {
 		return zero, err