fix: unpack business-account send responses

A send on behalf of a business account returns the sent message wrapped in
updateBotNewBusinessMessage (or updateBotEditBusinessMessage), which
unpack.MessageClass rejects as a "bad updates result". Extract the message
from those update types in the single-send fallback and the album unpacker, so
SendMessage/SendPhoto/SendMediaGroup as the account return the sent message
instead of erroring. Tests now use the real business response shape.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: ernado

business_media_test.go

@@ -42,7 +42,7 @@ func businessAlbumHandler(t *testing.T, connSeen *string) func(*bin.Buffer) (bin
 
 			return m, nil
 		case tg.MessagesSendMultiMediaRequestTypeID:
-			return multiMessageUpdates(11, 12), nil
+			return multiBusinessMessageUpdates(11, 12), nil
 		default:
 			return nil, fmt.Errorf("unexpected inner request %#x", inner)
 		}
@@ -51,7 +51,7 @@ func businessAlbumHandler(t *testing.T, connSeen *string) func(*bin.Buffer) (bin
 
 func TestSendPhotoWithBusinessConnection(t *testing.T) {
 	inv := newMockInvoker()
-	inv.reply(tg.InvokeWithBusinessConnectionRequestTypeID, sendMediaOK())
+	inv.reply(tg.InvokeWithBusinessConnectionRequestTypeID, businessSendReply())
 
 	b := newMockBot(inv)
 
@@ -85,7 +85,7 @@ func TestSendPhotoWithBusinessConnection(t *testing.T) {
 
 func TestSendDocumentWithBusinessConnection(t *testing.T) {
 	inv := newMockInvoker()
-	inv.reply(tg.InvokeWithBusinessConnectionRequestTypeID, sendMediaOK())
+	inv.reply(tg.InvokeWithBusinessConnectionRequestTypeID, businessSendReply())
 
 	b := newMockBot(inv)
 
@@ -116,7 +116,7 @@ func TestSendPhotoByFileIDWithBusinessConnection(t *testing.T) {
 	fid := documentFileID(t, 0x91)
 
 	inv := newMockInvoker()
-	inv.reply(tg.InvokeWithBusinessConnectionRequestTypeID, sendMediaOK())
+	inv.reply(tg.InvokeWithBusinessConnectionRequestTypeID, businessSendReply())
 
 	b := newMockBot(inv)
 

business_send_test.go

@@ -7,8 +7,34 @@ import (
 	"github.com/gotd/td/tg"
 )
 
+// multiBusinessMessageUpdates is the response an album sent on behalf of a
+// business account returns: each message wrapped in updateBotNewBusinessMessage.
+func multiBusinessMessageUpdates(ids ...int) *tg.Updates {
+	upds := make([]tg.UpdateClass, 0, len(ids))
+
+	for _, id := range ids {
+		upds = append(upds, &tg.UpdateBotNewBusinessMessage{
+			ConnectionID: "bc1",
+			Message:      &tg.Message{ID: id, Out: true, PeerID: &tg.PeerUser{UserID: 10}},
+		})
+	}
+
+	return &tg.Updates{Updates: upds, Users: []tg.UserClass{&tg.User{ID: 10, AccessHash: 1}}}
+}
+
+// businessSendReply is the response a send on behalf of a business account
+// returns: the sent message wrapped in updateBotNewBusinessMessage (not the
+// updateNewMessage a normal send returns).
 func businessSendReply() *tg.Updates {
-	return messageUpdates(&tg.Message{ID: 1, Message: "hi", PeerID: &tg.PeerUser{UserID: 10}})
+	return &tg.Updates{
+		Updates: []tg.UpdateClass{
+			&tg.UpdateBotNewBusinessMessage{
+				ConnectionID: "bc1",
+				Message:      &tg.Message{ID: 1, Out: true, Message: "hi", PeerID: &tg.PeerUser{UserID: 10}},
+			},
+		},
+		Users: []tg.UserClass{&tg.User{ID: 10, AccessHash: 1}},
+	}
 }
 
 func TestSendMessageWithBusinessConnection(t *testing.T) {

edit.go

@@ -78,9 +78,10 @@ func (b *Bot) EditMessageReplyMarkup(ctx context.Context, chat ChatID, messageID
 	return b.sentMessage(ctx, peer, resp, err)
 }
 
-// editedMessageFromResp extracts the edited message from an edit response.
-// Edits return UpdateEditMessage/UpdateEditChannelMessage, which the generic
-// send unpacker does not handle.
+// editedMessageFromResp extracts the resulting message from a response the
+// generic send unpacker (unpack.MessageClass) does not handle: edits
+// (UpdateEditMessage/UpdateEditChannelMessage) and sends on behalf of a business
+// account (UpdateBotNew/EditBusinessMessage).
 func editedMessageFromResp(resp tg.UpdatesClass) (tg.MessageClass, bool) {
 	var updates []tg.UpdateClass
 
@@ -101,6 +102,10 @@ func editedMessageFromResp(resp tg.UpdatesClass) (tg.MessageClass, bool) {
 			return upd.Message, true
 		case *tg.UpdateEditChannelMessage:
 			return upd.Message, true
+		case *tg.UpdateBotNewBusinessMessage:
+			return upd.Message, true
+		case *tg.UpdateBotEditBusinessMessage:
+			return upd.Message, true
 		}
 	}
 

media_group.go

@@ -132,6 +132,10 @@ func (b *Bot) sentMessages(ctx context.Context, resp tg.UpdatesClass, sendErr er
 			msg = u.Message
 		case *tg.UpdateNewChannelMessage:
 			msg = u.Message
+		case *tg.UpdateBotNewBusinessMessage:
+			// A media group sent on behalf of a business account returns its
+			// messages as business message updates.
+			msg = u.Message
 		default:
 			continue
 		}