fix(messages): normalize webhook reply references

backend/internal/handler/webhook/incoming_persister.go

@@ -3,7 +3,9 @@ package webhook
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
+	"strings"
 	"time"
 
 	"github.com/google/uuid"
@@ -538,8 +540,27 @@ func (p *IncomingPersister) createMessage(ctx context.Context, tx *gorm.DB, inbo
 	if len(msg.Attachments) > 0 {
 		contentAttrs["attachments"] = msg.Attachments
 	}
-	if msg.ReplyToID != "" {
-		contentAttrs["in_reply_to"] = msg.ReplyToID
+	if replyToExternalID := strings.TrimSpace(msg.ReplyToID); replyToExternalID != "" {
+		// Chatwoot stores provider reply references as in_reply_to_external_id,
+		// then resolves the same-conversation message by source_id before save.
+		// Keep in_reply_to strictly as the internal numeric message ID expected by
+		// the dashboard and its cursor-based message API.
+		var replyMessage model.Message
+		err := tx.WithContext(ctx).
+			Where("conversation_id = ? AND source_id = ?", conversation.ID, replyToExternalID).
+			First(&replyMessage).Error
+		if err == nil {
+			contentAttrs["in_reply_to"] = replyMessage.ID
+			contentAttrs["in_reply_to_external_id"] = replyMessage.SourceID
+		} else if errors.Is(err, gorm.ErrRecordNotFound) {
+			// Match Chatwoot's InReplyToMessageBuilder: unresolved references
+			// are normalized to null instead of being persisted as an invalid
+			// internal message ID.
+			contentAttrs["in_reply_to"] = nil
+			contentAttrs["in_reply_to_external_id"] = nil
+		} else {
+			return nil, err
+		}
 	}
 	message := model.Message{
 		ConversationID:       conversation.ID,

backend/internal/handler/webhook/webhook_lookup_test.go

@@ -575,6 +575,81 @@ func TestIncomingPersisterCreatesConversationMessageAndDedupes(t *testing.T) {
 	}
 }
 
+func TestIncomingPersisterNormalizesExternalReplyReference(t *testing.T) {
+	db := newWebhookLookupTestDB(t)
+	inbox := seedWebhookInbox(t, db, "telegram")
+	persister := NewIncomingPersister(db)
+
+	original, err := persister.PersistIncoming(t.Context(), &inbox, &channel.IncomingMessage{
+		ChannelType: channel.ChannelTelegram,
+		SourceID:    "tg-reply-source-1",
+		SenderID:    "tg-reply-user-1",
+		SenderName:  "Reply User",
+		SenderType:  channel.SenderContact,
+		Content:     "original",
+		ContentType: channel.ContentText,
+		InboxID:     inbox.ID,
+		AccountID:   inbox.AccountID,
+	})
+	if err != nil {
+		t.Fatalf("persist original message: %v", err)
+	}
+
+	reply, err := persister.PersistIncoming(t.Context(), &inbox, &channel.IncomingMessage{
+		ChannelType: channel.ChannelTelegram,
+		SourceID:    "tg-reply-source-2",
+		SenderID:    "tg-reply-user-1",
+		SenderName:  "Reply User",
+		SenderType:  channel.SenderContact,
+		Content:     "reply",
+		ContentType: channel.ContentText,
+		ReplyToID:   "tg-reply-source-1",
+		InboxID:     inbox.ID,
+		AccountID:   inbox.AccountID,
+	})
+	if err != nil {
+		t.Fatalf("persist reply message: %v", err)
+	}
+
+	attrs := map[string]interface{}{}
+	if err := json.Unmarshal(reply.Message.ContentAttributes, &attrs); err != nil {
+		t.Fatalf("decode reply content attributes: %v", err)
+	}
+	if got := uint(attrs["in_reply_to"].(float64)); got != original.Message.ID {
+		t.Fatalf("expected internal in_reply_to %d, got %#v", original.Message.ID, attrs["in_reply_to"])
+	}
+	if got := attrs["in_reply_to_external_id"]; got != original.Message.SourceID {
+		t.Fatalf("expected external reply id %q, got %#v", original.Message.SourceID, got)
+	}
+
+	unresolved, err := persister.PersistIncoming(t.Context(), &inbox, &channel.IncomingMessage{
+		ChannelType: channel.ChannelTelegram,
+		SourceID:    "tg-reply-source-3",
+		SenderID:    "tg-reply-user-1",
+		SenderName:  "Reply User",
+		SenderType:  channel.SenderContact,
+		Content:     "unresolved reply",
+		ContentType: channel.ContentText,
+		ReplyToID:   "tg-missing-source",
+		InboxID:     inbox.ID,
+		AccountID:   inbox.AccountID,
+	})
+	if err != nil {
+		t.Fatalf("persist unresolved reply message: %v", err)
+	}
+
+	unresolvedAttrs := map[string]interface{}{}
+	if err := json.Unmarshal(unresolved.Message.ContentAttributes, &unresolvedAttrs); err != nil {
+		t.Fatalf("decode unresolved reply content attributes: %v", err)
+	}
+	if got, ok := unresolvedAttrs["in_reply_to"]; !ok || got != nil {
+		t.Fatalf("expected unresolved internal reply id to be null, got %#v", unresolvedAttrs)
+	}
+	if got, ok := unresolvedAttrs["in_reply_to_external_id"]; !ok || got != nil {
+		t.Fatalf("expected unresolved external reply id to be null, got %#v", unresolvedAttrs)
+	}
+}
+
 func TestIncomingPersisterQueuesIncomingMessageWithWorker(t *testing.T) {
 	db := newWebhookLookupTestDB(t)
 	inbox := seedWebhookInbox(t, db, "telegram")