reorder received messages

client/helpers/bgPollHelper.go

@@ -1,10 +1,12 @@
 package helpers
 
 import (
+	"encoding/json"
 	"errors"
 	"fmt"
 	"os"
 	"path/filepath"
+	"sort"
 	"strconv"
 	"sync"
 	"time"
@@ -13,6 +15,7 @@ import (
 	"forge.redroom.link/yves/meowlib/client"
 	invmsgs "forge.redroom.link/yves/meowlib/client/invitation/messages"
 	invsrv "forge.redroom.link/yves/meowlib/client/invitation/server"
+	doubleratchet "github.com/status-im/doubleratchet"
 	"github.com/google/uuid"
 	"google.golang.org/protobuf/proto"
 )
@@ -154,6 +157,18 @@ func ConsumeInboxFile(messageFilename string) ([]string, []string, string, error
 	}
 	// Chat messages
 	if len(fromServerMessage.Chat) > 0 {
+		// Sort by DR chain sequence number so messages are decrypted in ratchet order,
+		// regardless of server delivery order.
+		sort.SliceStable(fromServerMessage.Chat, func(i, j int) bool {
+			var hi, hj doubleratchet.MessageHeader
+			if err := json.Unmarshal(fromServerMessage.Chat[i].DrHeader, &hi); err != nil {
+				return false
+			}
+			if err := json.Unmarshal(fromServerMessage.Chat[j].DrHeader, &hj); err != nil {
+				return false
+			}
+			return hi.N < hj.N
+		})
 		for _, packedUserMessage := range fromServerMessage.Chat {
 
 			// find the peer with that lookup key