actor: take ValidatorsHistory into account for CalculateValidUntilBlock

Which makes permanent result.Version caching safe for all cases.

pkg/rpcclient/actor/maker.go

@@ -191,5 +191,14 @@ func (a *Actor) CalculateValidUntilBlock() (uint32, error) {
 	if err != nil {
 		return 0, fmt.Errorf("can't get block count: %w", err)
 	}
-	return blockCount + uint32(a.version.Protocol.ValidatorsCount) + 1, nil
+	var vc = int(a.version.Protocol.ValidatorsCount)
+	var bestH = uint32(0)
+	for h, n := range a.version.Protocol.ValidatorsHistory { // In case it's enabled.
+		if h >= bestH && h <= blockCount {
+			vc = n
+			bestH = h
+		}
+	}
+
+	return blockCount + uint32(vc+1), nil
 }

pkg/rpcclient/actor/maker_test.go

@@ -24,6 +24,23 @@ func TestCalculateValidUntilBlock(t *testing.T) {
 	vub, err := a.CalculateValidUntilBlock()
 	require.NoError(t, err)
 	require.Equal(t, uint32(42+7+1), vub)
+
+	client.version.Protocol.ValidatorsHistory = map[uint32]int{
+		0:  7,
+		40: 4,
+		80: 10,
+	}
+	a, err = NewSimple(client, acc)
+	require.NoError(t, err)
+
+	vub, err = a.CalculateValidUntilBlock()
+	require.NoError(t, err)
+	require.Equal(t, uint32(42+4+1), vub)
+
+	client.bCount = 101
+	vub, err = a.CalculateValidUntilBlock()
+	require.NoError(t, err)
+	require.Equal(t, uint32(101+10+1), vub)
 }
 
 func TestMakeUnsigned(t *testing.T) {