From f731514d7547fe721512a3661a444dcfcb938d7d Mon Sep 17 00:00:00 2001
From: Eugene Zagidullin <eugene@ecadlabs.com>
Date: Wed, 8 Apr 2026 00:14:29 +0300
Subject: [PATCH] core.Validator interface

---
 protocol/core/types.go                    |  5 +++++
 protocol/proto_023_PtSeouLo/operations.go | 10 ++++++++++
 2 files changed, 15 insertions(+)

diff --git a/protocol/core/types.go b/protocol/core/types.go
index b88c2ef..04adee3 100644
--- a/protocol/core/types.go
+++ b/protocol/core/types.go
@@ -314,3 +314,8 @@ type PackData struct {
 }
 
 func (PackData) SignRequestKind() string { return "pack" }
+
+// Validator interface may be implemented by some operations to allow pre-flight validation before signing/injection
+type Validator interface {
+	Validate() error
+}
diff --git a/protocol/proto_023_PtSeouLo/operations.go b/protocol/proto_023_PtSeouLo/operations.go
index a687dec..ef3040e 100644
--- a/protocol/proto_023_PtSeouLo/operations.go
+++ b/protocol/proto_023_PtSeouLo/operations.go
@@ -3,6 +3,7 @@ package proto_023_PtSeouLo
 //go:generate go run ../../cmd/genmarshaller.go
 
 import (
+	"errors"
 	"strconv"
 
 	tz "github.com/ecadlabs/gotez/v2"
@@ -125,6 +126,15 @@ type UpdateCompanionKey UpdateConsensusKey
 
 func (*UpdateCompanionKey) OperationKind() string { return "update_companion_key" }
 
+func (u *UpdateCompanionKey) Validate() error {
+	if _, ok := u.PublicKey.(*tz.BLSPublicKey); !ok {
+		return errors.New("companion key is not a BLS key")
+	}
+	return nil
+}
+
+var _ core.Validator = (*UpdateCompanionKey)(nil)
+
 //json:kind=OperationKind()
 type Attestation proto_022_PsRiotum.Attestation