strom: fix RegisterUntilLow to panic on reverse range, use dual-range registrations

- RegisterUntilLow now panics if startIndex > endIndex (programmer
  must address version incompatibility explicitly, not silently skip)
- Replace per-version RegisterCritical handlers with dual-range
  RegisterUntil: modern range (v1_21_8->latest) + legacy range (v1_8->1.12.2)
- Remove v1_12_2 handler duplicates (covered by upward range from v1_8)
- Move legacy chat handling into chat.Module.SendMessage (protocol<764
  uses v1_8.PlayToServerPacketChat instead of v1_21_11)
- Skip chat signing init for pre-1.19 versions

mc/bot/chat/mod.go

@@ -15,6 +15,7 @@ import (
 	"github.com/admin-else/strom/mc/api"
 	"github.com/admin-else/strom/mc/proto"
 	"github.com/admin-else/strom/mc/proto_generated/v1_21_11"
+	"github.com/admin-else/strom/mc/proto_generated/v1_8"
 	"github.com/google/uuid"
 )
 
@@ -43,6 +44,9 @@ func Start(c *proto.Conn, acc *api.Account) (*Module, error) {
 }
 
 func (m *Module) initSigning(acc *api.Account) (err error) {
+	if m.Conn.ProtocolVersion < 764 {
+		return nil
+	}
 	keys, err := acc.FetchKeys()
 	if err != nil {
 		return fmt.Errorf("fetch profile keys: %w", err)
@@ -80,8 +84,12 @@ func (m *Module) initSigning(acc *api.Account) (err error) {
 }
 
 // SendMessage sends a chat message. If signing is enabled, the message is signed;
-// otherwise it is sent unsigned.
+// otherwise it is sent unsigned. For pre-1.19 protocol versions, uses the legacy
+// chat packet format (plain string).
 func (m *Module) SendMessage(message string) (err error) {
+	if m.Conn.ProtocolVersion < 764 {
+		return m.Conn.Send(&v1_8.PlayToServerPacketChat{Message: message})
+	}
 	if m.canSign {
 		return m.sendSigned(message)
 	}

mc/client/login.go

@@ -16,7 +16,6 @@ import (
 	"github.com/admin-else/strom/mc/proto_base"
 	"github.com/admin-else/strom/mc/proto_generated/v1_21_8"
 	"github.com/admin-else/strom/mc/proto_generated/v1_8"
-	"github.com/admin-else/strom/mc/proto_generated/v1_12_2"
 	"github.com/admin-else/strom/mc/proto_generated/v26_2"
 	"github.com/admin-else/strom/mc/text"
 	"github.com/google/uuid"
@@ -140,31 +139,6 @@ func (s *LoginClient) OnSuccessV1_8(success *v1_8.LoginToClientPacketSuccess) (e
 	return
 }
 
-func (s *LoginClient) OnDisconnectV1_12_2(packet *v1_12_2.LoginToClientPacketDisconnect) (err error) {
-	var reason text.Component
-	err = json.Unmarshal([]byte(packet.Reason), &reason)
-	if err != nil {
-		return
-	}
-	err = KickedDuringLoginErr{reason}
-	return
-}
-
-func (s *LoginClient) OnCompressV1_12_2(packet *v1_12_2.LoginToClientPacketCompress) (err error) {
-	s.SetCompressionThreshold(packet.Threshold)
-	return
-}
-
-func (s *LoginClient) OnSuccessV1_12_2(success *v1_12_2.LoginToClientPacketSuccess) (err error) {
-	s.GivenAccount = &v1_21_8.LoginToClientPacketSuccess{
-		Uuid:     uuid.MustParse(success.Uuid),
-		Username: success.Username,
-	}
-	s.SetState(proto_base.Play)
-	err = event.HandlerDoneErr{}
-	return
-}
-
 func (s *LoginClient) OnSuccess(success *v1_21_8.LoginToClientPacketSuccess) (err error) {
 	s.GivenAccount = success
 	if s.ProtocolVersion >= 764 {
@@ -207,17 +181,10 @@ func LoginRawAddr(c *proto.Conn, account *api.Account, hostAddr string) (err err
 	}
 	lc.RegisterCritical(lc.OnDefault)
 	lc.RegisterCritical(lc.OnClose)
-	lc.RegisterCriticalUntilLatest(lc.OnCompress)
+	lc.RegisterUntil("26.2", lc.OnCompress, lc.OnEncrypt, lc.OnDisconnect)
-	lc.RegisterCriticalUntilLatest(lc.OnEncrypt)
+	lc.RegisterUntil("26.1", lc.OnSuccess)
-	lc.RegisterCriticalUntilLatest(lc.OnDisconnect)
+	lc.RegisterUntilLatest(lc.OnSuccess26_2)
-	lc.RegisterCriticalUntil("26.1", lc.OnSuccess)
+	lc.RegisterUntil("1.12.2", lc.OnCompressV1_8, lc.OnDisconnectV1_8, lc.OnSuccessV1_8)
-	lc.RegisterCriticalUntilLatest(lc.OnSuccess26_2)
-	lc.RegisterCritical(lc.OnCompressV1_8)
-	lc.RegisterCritical(lc.OnDisconnectV1_8)
-	lc.RegisterCritical(lc.OnSuccessV1_8)
-	lc.RegisterCritical(lc.OnCompressV1_12_2)
-	lc.RegisterCritical(lc.OnDisconnectV1_12_2)
-	lc.RegisterCritical(lc.OnSuccessV1_12_2)
 
 	var p proto_base.EncodeDecodeAble
 	if hostAddr != "" {

mc/client/status.go

@@ -10,7 +10,6 @@ import (
 	"github.com/admin-else/strom/mc/proto_base"
 	"github.com/admin-else/strom/mc/proto_generated/v1_21_8"
 	"github.com/admin-else/strom/mc/proto_generated/v1_8"
-	"github.com/admin-else/strom/mc/proto_generated/v1_12_2"
 	"github.com/admin-else/strom/mc/server"
 )
 
@@ -55,23 +54,6 @@ func (s *StatusClient) OnPongV1_8(p *v1_8.StatusToClientPacketPing) (err error)
 	return
 }
 
-func (s *StatusClient) OnStatusV1_12_2(p *v1_12_2.StatusToClientPacketServerInfo) (err error) {
-	s.Status = p.Response
-	s.PingSendTime = time.Now()
-	if s.DoPingRoundTripTime {
-		err = s.Send(&v1_21_8.StatusToServerPacketPing{Time: s.PingSendTime.UnixMilli()})
-	} else {
-		err = event.HandlerDoneErr{}
-	}
-	return
-}
-
-func (s *StatusClient) OnPongV1_12_2(p *v1_12_2.StatusToClientPacketPing) (err error) {
-	s.PingReceiveTime = time.Now()
-	err = event.HandlerDoneErr{}
-	return
-}
-
 // StatusRaw returns a StatusClient that is not connected to a server.
 // So ignore the resource leak warning. And maybe attach a warn ignore comment.
 // It does not resolve SRV records.
@@ -93,12 +75,8 @@ func StatusRawWithVersion(ctx context.Context, addr, version string) (s *StatusC
 	s = &StatusClient{
 		Conn: c,
 	}
-	s.RegisterCriticalUntilLatest(s.OnStatus)
+	s.RegisterUntil("26.2", s.OnStatus, s.OnPong)
-	s.RegisterCriticalUntilLatest(s.OnPong)
+	s.RegisterUntil("1.12.2", s.OnStatusV1_8, s.OnPongV1_8)
-	s.RegisterCritical(s.OnStatusV1_8)
-	s.RegisterCritical(s.OnPongV1_8)
-	s.RegisterCritical(s.OnStatusV1_12_2)
-	s.RegisterCritical(s.OnPongV1_12_2)
 
 	p, err := MakeHandshakePacketAddr(s.Conn, proto_base.Status, addr)
 	if err != nil {

mc/proto/smart_convert.go

@@ -116,6 +116,9 @@ func (c *Conn) RegisterUntilLow(eventType reflect.Type, hv reflect.Value, until
 	}
 	startIndex := slices.Index(proto_generated.SupportedVersions, versionInfo.MinecraftVersion)
 	endIndex := slices.Index(proto_generated.SupportedVersions, until)
+	if startIndex > endIndex {
+		panic(fmt.Sprintf("handler version %s is above until version %s", versionInfo.MinecraftVersion, until))
+	}
 	for i := startIndex + 1; i <= endIndex; i++ {
 		versionName := proto_generated.SupportedVersions[i]
 		versionInfo, err = data.LookUpVersionByName(versionName)
@@ -125,7 +128,7 @@ func (c *Conn) RegisterUntilLow(eventType reflect.Type, hv reflect.Value, until
 		var newPacketInfo proto_base.PacketInfo
 		newPacketInfo, found = LookupPacketInfoByNameProtocolVersionStateAndDirection(packetInfo.Name, versionInfo.Version, packetInfo.State, packetInfo.Direction)
 		if !found {
-			panic("packet not found in future version")
+			panic("packet not found in version " + versionName)
 		}
 		newT := reflect.TypeOf(newPacketInfo.Type)
 		if !SmartConvertibleTo(newT, reflect.TypeOf(packetInfo.Type)) {