diff --git a/Telegram/CMakeLists.txt b/Telegram/CMakeLists.txt
index 23b203112..fe7d9a9b0 100644
--- a/Telegram/CMakeLists.txt
+++ b/Telegram/CMakeLists.txt
@@ -755,8 +755,6 @@ PRIVATE
     mtproto/connection_tcp.cpp
     mtproto/connection_tcp.h
     mtproto/core_types.h
-    mtproto/dc_options.cpp
-    mtproto/dc_options.h
     mtproto/dedicated_file_loader.cpp
     mtproto/dedicated_file_loader.h
     mtproto/facade.cpp
@@ -912,6 +910,8 @@ PRIVATE
     storage/serialize_common.h
     storage/serialize_document.cpp
     storage/serialize_document.h
+    storage/serialize_peer.cpp
+    storage/serialize_peer.h
     storage/storage_account.cpp
     storage/storage_account.h
     storage/storage_accounts.cpp
diff --git a/Telegram/SourceFiles/api/api_self_destruct.cpp b/Telegram/SourceFiles/api/api_self_destruct.cpp
index 80ae25186..64cf1a5b2 100644
--- a/Telegram/SourceFiles/api/api_self_destruct.cpp
+++ b/Telegram/SourceFiles/api/api_self_destruct.cpp
@@ -12,7 +12,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 namespace Api {
 
 SelfDestruct::SelfDestruct(not_null<ApiWrap*> api)
-: _api(api->instance()) {
+: _api(&api->instance()) {
 }
 
 void SelfDestruct::reload() {
diff --git a/Telegram/SourceFiles/api/api_sensitive_content.cpp b/Telegram/SourceFiles/api/api_sensitive_content.cpp
index 7ff3dd610..02fea25ba 100644
--- a/Telegram/SourceFiles/api/api_sensitive_content.cpp
+++ b/Telegram/SourceFiles/api/api_sensitive_content.cpp
@@ -21,7 +21,7 @@ constexpr auto kRefreshAppConfigTimeout = 3 * crl::time(1000);
 
 SensitiveContent::SensitiveContent(not_null<ApiWrap*> api)
 : _session(&api->session())
-, _api(api->instance())
+, _api(&api->instance())
 , _appConfigReloadTimer([=] { _session->account().appConfig().refresh(); }) {
 }
 
diff --git a/Telegram/SourceFiles/api/api_updates.cpp b/Telegram/SourceFiles/api/api_updates.cpp
index f2f879beb..d693d1280 100644
--- a/Telegram/SourceFiles/api/api_updates.cpp
+++ b/Telegram/SourceFiles/api/api_updates.cpp
@@ -11,7 +11,8 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "main/main_session.h"
 #include "main/main_account.h"
 #include "mtproto/mtp_instance.h"
-#include "mtproto/dc_options.h"
+#include "mtproto/mtproto_config.h"
+#include "mtproto/mtproto_dc_options.h"
 #include "data/stickers/data_stickers.h"
 #include "data/data_session.h"
 #include "data/data_user.h"
@@ -39,7 +40,6 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "boxes/confirm_box.h"
 #include "apiwrap.h"
 #include "app.h" // App::formatPhone
-#include "facades.h"
 
 namespace Api {
 namespace {
@@ -340,7 +340,9 @@ void Updates::channelDifferenceDone(
 	channel->ptsSetRequesting(false);
 
 	if (!isFinal) {
-		MTP_LOG(0, ("getChannelDifference { good - after not final channelDifference was received }%1").arg(cTestMode() ? " TESTMODE" : ""));
+		MTP_LOG(0, ("getChannelDifference "
+			"{ good - after not final channelDifference was received }%1"
+			).arg(_session->mtp().isTestMode() ? " TESTMODE" : ""));
 		getChannelDifference(channel);
 	} else if (ranges::contains(
 			_activeChats,
@@ -410,7 +412,9 @@ void Updates::differenceDone(const MTPupdates_Difference &result) {
 
 		_ptsWaiter.setRequesting(false);
 
-		MTP_LOG(0, ("getDifference { good - after a slice of difference was received }%1").arg(cTestMode() ? " TESTMODE" : ""));
+		MTP_LOG(0, ("getDifference "
+			"{ good - after a slice of difference was received }%1"
+			).arg(_session->mtp().isTestMode() ? " TESTMODE" : ""));
 		getDifference();
 	} break;
 	case mtpc_updates_difference: {
@@ -566,7 +570,9 @@ void Updates::getDifferenceAfterFail() {
 			wait = _getDifferenceTimeAfterFail - now;
 		} else {
 			_ptsWaiter.setRequesting(false);
-			MTP_LOG(0, ("getDifference { force - after get difference failed }%1").arg(cTestMode() ? " TESTMODE" : ""));
+			MTP_LOG(0, ("getDifference "
+				"{ force - after get difference failed }%1"
+				).arg(_session->mtp().isTestMode() ? " TESTMODE" : ""));
 			getDifference();
 		}
 	}
@@ -650,7 +656,7 @@ void Updates::getChannelDifference(
 }
 
 void Updates::sendPing() {
-	_session->mtp()->ping();
+	_session->mtp().ping();
 }
 
 void Updates::addActiveChat(rpl::producer<PeerData*> chat) {
@@ -680,9 +686,10 @@ void Updates::requestChannelRangeDifference(not_null<History*> history) {
 		return;
 	}
 
-	MTP_LOG(0, ("getChannelDifference { good - "
-		"after channelDifferenceTooLong was received, "
-		"validating history part }%1").arg(cTestMode() ? " TESTMODE" : ""));
+	MTP_LOG(0, ("getChannelDifference "
+		"{ good - after channelDifferenceTooLong was received, "
+		"validating history part }%1"
+		).arg(_session->mtp().isTestMode() ? " TESTMODE" : ""));
 	channelRangeDifferenceSend(channel, range, channel->pts());
 }
 
@@ -752,10 +759,10 @@ void Updates::channelRangeDifferenceDone(
 	}
 
 	if (!isFinal && nextRequestPts) {
-		MTP_LOG(0, ("getChannelDifference { "
-			"good - after not final channelDifference was received, "
+		MTP_LOG(0, ("getChannelDifference "
+			"{ good - after not final channelDifference was received, "
 			"validating history part }%1"
-			).arg(cTestMode() ? " TESTMODE" : ""));
+			).arg(_session->mtp().isTestMode() ? " TESTMODE" : ""));
 		channelRangeDifferenceSend(channel, range, nextRequestPts);
 	}
 }
@@ -764,7 +771,7 @@ void Updates::mtpNewSessionCreated() {
 	Core::App().checkAutoLock();
 	_updatesSeq = 0;
 	MTP_LOG(0, ("getDifference { after new_session_created }%1"
-		).arg(cTestMode() ? " TESTMODE" : ""));
+		).arg(_session->mtp().isTestMode() ? " TESTMODE" : ""));
 	getDifference();
 }
 
@@ -789,25 +796,26 @@ bool Updates::isIdle() const {
 void Updates::updateOnline(bool gotOtherOffline) {
 	crl::on_main(&session(), [] { Core::App().checkAutoLock(); });
 
+	const auto &config = _session->serverConfig();
 	bool isOnline = Core::App().hasActiveWindow(&session());
-	int updateIn = Global::OnlineUpdatePeriod();
+	int updateIn = config.onlineUpdatePeriod;
 	Assert(updateIn >= 0);
 	if (isOnline) {
 		const auto idle = crl::now() - Core::App().lastNonIdleTime();
-		if (idle >= Global::OfflineIdleTimeout()) {
+		if (idle >= config.offlineIdleTimeout) {
 			isOnline = false;
 			if (!_isIdle) {
 				_isIdle = true;
 				_idleFinishTimer.callOnce(900);
 			}
 		} else {
-			updateIn = qMin(updateIn, int(Global::OfflineIdleTimeout() - idle));
+			updateIn = qMin(updateIn, int(config.offlineIdleTimeout - idle));
 			Assert(updateIn >= 0);
 		}
 	}
 	auto ms = crl::now();
 	if (isOnline != _lastWasOnline
-		|| (isOnline && _lastSetOnline + Global::OnlineUpdatePeriod() <= ms)
+		|| (isOnline && _lastSetOnline + config.onlineUpdatePeriod <= ms)
 		|| (isOnline && gotOtherOffline)) {
 		api().request(base::take(_onlineRequest)).cancel();
 
@@ -828,7 +836,7 @@ void Updates::updateOnline(bool gotOtherOffline) {
 		}
 
 		const auto self = session().user();
-		self->onlineTill = base::unixtime::now() + (isOnline ? (Global::OnlineUpdatePeriod() / 1000) : -1);
+		self->onlineTill = base::unixtime::now() + (isOnline ? (config.onlineUpdatePeriod / 1000) : -1);
 		session().changes().peerUpdated(
 			self,
 			Data::PeerUpdate::Flag::OnlineStatus);
@@ -838,7 +846,7 @@ void Updates::updateOnline(bool gotOtherOffline) {
 
 		_lastSetOnline = ms;
 	} else if (isOnline) {
-		updateIn = qMin(updateIn, int(_lastSetOnline + Global::OnlineUpdatePeriod() - ms));
+		updateIn = qMin(updateIn, int(_lastSetOnline + config.onlineUpdatePeriod - ms));
 		Assert(updateIn >= 0);
 	}
 	_onlineTimer.callOnce(updateIn);
@@ -846,7 +854,7 @@ void Updates::updateOnline(bool gotOtherOffline) {
 
 void Updates::checkIdleFinish() {
 	if (crl::now() - Core::App().lastNonIdleTime()
-		< Global::OfflineIdleTimeout()) {
+		< _session->serverConfig().offlineIdleTimeout) {
 		_idleFinishTimer.cancel();
 		_isIdle = false;
 		updateOnline();
@@ -1153,7 +1161,9 @@ void Updates::applyUpdates(
 			|| (viaBotId && !session().data().userLoaded(viaBotId->v))
 			|| (entities && !MentionUsersLoaded(&session(), *entities))
 			|| (fwd && !ForwardedInfoDataLoaded(&session(), *fwd))) {
-			MTP_LOG(0, ("getDifference { good - getting user for updateShortMessage }%1").arg(cTestMode() ? " TESTMODE" : ""));
+			MTP_LOG(0, ("getDifference "
+				"{ good - getting user for updateShortMessage }%1"
+				).arg(_session->mtp().isTestMode() ? " TESTMODE" : ""));
 			return getDifference();
 		}
 		if (updateAndApply(d.vpts().v, d.vpts_count().v, updates)) {
@@ -1174,7 +1184,9 @@ void Updates::applyUpdates(
 			|| (viaBotId && !session().data().userLoaded(viaBotId->v))
 			|| (entities && !MentionUsersLoaded(&session(), *entities))
 			|| (fwd && !ForwardedInfoDataLoaded(&session(), *fwd))) {
-			MTP_LOG(0, ("getDifference { good - getting user for updateShortChatMessage }%1").arg(cTestMode() ? " TESTMODE" : ""));
+			MTP_LOG(0, ("getDifference "
+				"{ good - getting user for updateShortChatMessage }%1"
+				).arg(_session->mtp().isTestMode() ? " TESTMODE" : ""));
 			if (chat && noFrom) {
 				session().api().requestFullPeer(chat);
 			}
@@ -1232,7 +1244,9 @@ void Updates::applyUpdates(
 	} break;
 
 	case mtpc_updatesTooLong: {
-		MTP_LOG(0, ("getDifference { good - updatesTooLong received }%1").arg(cTestMode() ? " TESTMODE" : ""));
+		MTP_LOG(0, ("getDifference "
+			"{ good - updatesTooLong received }%1"
+			).arg(_session->mtp().isTestMode() ? " TESTMODE" : ""));
 		return getDifference();
 	} break;
 	}
@@ -1248,9 +1262,9 @@ void Updates::feedUpdate(const MTPUpdate &update) {
 
 		const auto isDataLoaded = AllDataLoadedForMessage(&session(), d.vmessage());
 		if (!requestingDifference() && isDataLoaded != DataIsLoadedResult::Ok) {
-			MTP_LOG(0, ("getDifference { good - "
-				"after not all data loaded in updateNewMessage }%1"
-				).arg(cTestMode() ? " TESTMODE" : ""));
+			MTP_LOG(0, ("getDifference "
+				"{ good - after not all data loaded in updateNewMessage }%1"
+				).arg(_session->mtp().isTestMode() ? " TESTMODE" : ""));
 
 			// This can be if this update was created by grouping
 			// some short message update into an updates vector.
@@ -1265,14 +1279,16 @@ void Updates::feedUpdate(const MTPUpdate &update) {
 		auto channel = session().data().channelLoaded(peerToChannel(PeerFromMessage(d.vmessage())));
 		const auto isDataLoaded = AllDataLoadedForMessage(&session(), d.vmessage());
 		if (!requestingDifference() && (!channel || isDataLoaded != DataIsLoadedResult::Ok)) {
-			MTP_LOG(0, ("getDifference { good - "
-				"after not all data loaded in updateNewChannelMessage }%1"
-				).arg(cTestMode() ? " TESTMODE" : ""));
+			MTP_LOG(0, ("getDifference "
+				"{ good - after not all data loaded in updateNewChannelMessage }%1"
+				).arg(_session->mtp().isTestMode() ? " TESTMODE" : ""));
 
 			// Request last active supergroup participants if the 'from' user was not loaded yet.
 			// This will optimize similar getDifference() calls for almost all next messages.
 			if (isDataLoaded == DataIsLoadedResult::FromNotLoaded && channel && channel->isMegagroup()) {
-				if (channel->mgInfo->lastParticipants.size() < Global::ChatSizeMax() && (channel->mgInfo->lastParticipants.empty() || channel->mgInfo->lastParticipants.size() < channel->membersCount())) {
+				if (channel->mgInfo->lastParticipants.size() < _session->serverConfig().chatSizeMax
+					&& (channel->mgInfo->lastParticipants.empty()
+						|| channel->mgInfo->lastParticipants.size() < channel->membersCount())) {
 					session().api().requestLastParticipants(channel);
 				}
 			}
@@ -1657,11 +1673,11 @@ void Updates::feedUpdate(const MTPUpdate &update) {
 
 	case mtpc_updateDcOptions: {
 		auto &d = update.c_updateDcOptions();
-		Core::App().dcOptions()->addFromList(d.vdc_options());
+		session().mtp().dcOptions().addFromList(d.vdc_options());
 	} break;
 
 	case mtpc_updateConfig: {
-		session().mtp()->requestConfig();
+		session().mtp().requestConfig();
 	} break;
 
 	case mtpc_updateUserPhone: {
diff --git a/Telegram/SourceFiles/apiwrap.cpp b/Telegram/SourceFiles/apiwrap.cpp
index e60b9d0ed..bcb3aaedb 100644
--- a/Telegram/SourceFiles/apiwrap.cpp
+++ b/Telegram/SourceFiles/apiwrap.cpp
@@ -43,6 +43,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "mainwindow.h"
 #include "mainwidget.h"
 #include "boxes/add_contact_box.h"
+#include "mtproto/mtproto_config.h"
 #include "history/history.h"
 #include "history/history_message.h"
 #include "history/history_item_components.h"
@@ -231,7 +232,7 @@ bool ApiWrap::BlockedUsersSlice::operator!=(const BlockedUsersSlice &other) cons
 }
 
 ApiWrap::ApiWrap(not_null<Main::Session*> session)
-: MTP::Sender(session->account().mtp())
+: MTP::Sender(&session->account().mtp())
 , _session(session)
 , _messageDataResolveDelayed([=] { resolveMessageDatas(); })
 , _webPagesTimer([=] { resolveWebPages(); })
@@ -572,10 +573,10 @@ void ApiWrap::sendMessageFail(
 		FullMsgId itemId) {
 	if (error.type() == qstr("PEER_FLOOD")) {
 		Ui::show(Box<InformBox>(
-			PeerFloodErrorText(PeerFloodType::Send)));
+			PeerFloodErrorText(&session(), PeerFloodType::Send)));
 	} else if (error.type() == qstr("USER_BANNED_IN_CHANNEL")) {
 		const auto link = textcmdLink(
-			Core::App().createInternalLinkFull(qsl("spambot")),
+			session().createInternalLinkFull(qsl("spambot")),
 			tr::lng_cant_more_info(tr::now));
 		Ui::show(Box<InformBox>(tr::lng_error_public_groups_denied(
 			tr::now,
@@ -754,7 +755,7 @@ QString ApiWrap::exportDirectMessageLink(not_null<HistoryItem*> item) {
 				}
 			}
 		}
-		return Core::App().createInternalLinkFull(query);
+		return session().createInternalLinkFull(query);
 	};
 	const auto i = _unlikelyMessageLinks.find(itemId);
 	const auto current = (i != end(_unlikelyMessageLinks))
@@ -1450,7 +1451,7 @@ void ApiWrap::requestLastParticipants(not_null<ChannelData*> channel) {
 		channel->inputChannel,
 		MTP_channelParticipantsRecent(),
 		MTP_int(offset),
-		MTP_int(Global::ChatSizeMax()),
+		MTP_int(_session->serverConfig().chatSizeMax),
 		MTP_int(participantsHash)
 	)).done([=](const MTPchannels_ChannelParticipants &result) {
 		_participantsRequests.remove(channel);
@@ -1480,7 +1481,7 @@ void ApiWrap::requestBots(not_null<ChannelData*> channel) {
 		channel->inputChannel,
 		MTP_channelParticipantsBots(),
 		MTP_int(offset),
-		MTP_int(Global::ChatSizeMax()),
+		MTP_int(_session->serverConfig().chatSizeMax),
 		MTP_int(participantsHash)
 	)).done([this, channel](const MTPchannels_ChannelParticipants &result) {
 		_botsRequests.remove(channel);
@@ -1510,7 +1511,7 @@ void ApiWrap::requestAdmins(not_null<ChannelData*> channel) {
 		channel->inputChannel,
 		MTP_channelParticipantsAdmins(),
 		MTP_int(offset),
-		MTP_int(Global::ChatSizeMax()),
+		MTP_int(_session->serverConfig().chatSizeMax),
 		MTP_int(participantsHash)
 	)).done([this, channel](const MTPchannels_ChannelParticipants &result) {
 		_adminsRequests.remove(channel);
@@ -1820,7 +1821,7 @@ void ApiWrap::requestChannelMembersForAdd(
 		channel->inputChannel,
 		MTP_channelParticipantsRecent(),
 		MTP_int(offset),
-		MTP_int(Global::ChatSizeMax()),
+		MTP_int(_session->serverConfig().chatSizeMax),
 		MTP_int(participantsHash)
 	)).done([this](const MTPchannels_ChannelParticipants &result) {
 		base::take(_channelMembersForAddRequestId);
@@ -5038,7 +5039,10 @@ FileLoadTo ApiWrap::fileLoadTaskOptions(const SendAction &action) const {
 
 void ApiWrap::uploadPeerPhoto(not_null<PeerData*> peer, QImage &&image) {
 	peer = peer->migrateToOrMe();
-	const auto ready = PreparePeerPhoto(instance()->mainDcId(), peer->id, std::move(image));
+	const auto ready = PreparePeerPhoto(
+		instance().mainDcId(),
+		peer->id,
+		std::move(image));
 
 	const auto fakeId = FullMsgId(
 		peerToChannel(peer->id),
diff --git a/Telegram/SourceFiles/boxes/add_contact_box.cpp b/Telegram/SourceFiles/boxes/add_contact_box.cpp
index 8db083635..fce87ac94 100644
--- a/Telegram/SourceFiles/boxes/add_contact_box.cpp
+++ b/Telegram/SourceFiles/boxes/add_contact_box.cpp
@@ -118,9 +118,11 @@ style::InputField CreateBioFieldStyle() {
 	return result;
 }
 
-QString PeerFloodErrorText(PeerFloodType type) {
-	auto link = textcmdLink(
-		Core::App().createInternalLinkFull(qsl("spambot")),
+QString PeerFloodErrorText(
+		not_null<Main::Session*> session,
+		PeerFloodType type) {
+	const auto link = textcmdLink(
+		session->createInternalLinkFull(qsl("spambot")),
 		tr::lng_cant_more_info(tr::now));
 	if (type == PeerFloodType::InviteGroup) {
 		return tr::lng_cant_invite_not_contact(tr::now, lt_more_info, link);
@@ -190,10 +192,10 @@ void ShowAddParticipantsError(
 		} else if (error == qstr("BOT_GROUPS_BLOCKED")) {
 			return tr::lng_error_cant_add_bot(tr::now);
 		} else if (error == qstr("PEER_FLOOD")) {
-			const auto isGroup = (chat->isChat() || chat->isMegagroup());
-			return PeerFloodErrorText(isGroup
+			const auto type = (chat->isChat() || chat->isMegagroup())
 				? PeerFloodType::InviteGroup
-				: PeerFloodType::InviteChannel);
+				: PeerFloodType::InviteChannel;
+			return PeerFloodErrorText(&chat->session(), type);
 		} else if (error == qstr("ADMINS_TOO_MUCH")) {
 			return ((chat->isChat() || chat->isMegagroup())
 				? tr::lng_error_admin_limit
@@ -453,7 +455,7 @@ GroupInfoBox::GroupInfoBox(
 	const QString &title,
 	Fn<void(not_null<ChannelData*>)> channelDone)
 : _navigation(navigation)
-, _api(_navigation->session().mtp())
+, _api(&_navigation->session().mtp())
 , _type(type)
 , _initialTitle(title)
 , _channelDone(std::move(channelDone)) {
@@ -598,7 +600,9 @@ void GroupInfoBox::createGroup(
 		} else if (error.type() == qstr("PEER_FLOOD")) {
 			Ui::show(
 				Box<InformBox>(
-					PeerFloodErrorText(PeerFloodType::InviteGroup)),
+					PeerFloodErrorText(
+						&_navigation->session(),
+						PeerFloodType::InviteGroup)),
 				Ui::LayerOption::KeepOther);
 		} else if (error.type() == qstr("USER_RESTRICTED")) {
 			Ui::show(
@@ -750,7 +754,7 @@ SetupChannelBox::SetupChannelBox(
 	bool existing)
 : _navigation(navigation)
 , _channel(channel)
-, _api(_channel->session().mtp())
+, _api(&_channel->session().mtp())
 , _existing(existing)
 , _privacyGroup(
 	std::make_shared<Ui::RadioenumGroup<Privacy>>(Privacy::Public))
@@ -790,7 +794,12 @@ SetupChannelBox::SetupChannelBox(
 		: tr::lng_create_private_channel_about)(tr::now),
 	_defaultOptions,
 	_aboutPublicWidth)
-, _link(this, st::setupChannelLink, nullptr, channel->username, true) {
+, _link(
+	this,
+	st::setupChannelLink,
+	nullptr,
+	channel->username,
+	channel->session().createInternalLink(QString())) {
 }
 
 void SetupChannelBox::prepare() {
@@ -1168,7 +1177,7 @@ void SetupChannelBox::firstCheckFail(const RPCError &error) {
 
 EditNameBox::EditNameBox(QWidget*, not_null<UserData*> user)
 : _user(user)
-, _api(_user->session().mtp())
+, _api(&_user->session().mtp())
 , _first(this, st::defaultInputField, tr::lng_signup_firstname(), _user->firstName)
 , _last(this, st::defaultInputField, tr::lng_signup_lastname(), _user->lastName)
 , _invertOrder(langFirstNameGoesSecond()) {
@@ -1292,7 +1301,7 @@ RevokePublicLinkBox::Inner::Inner(
 	Fn<void()> revokeCallback)
 : TWidget(parent)
 , _session(session)
-, _api(_session->mtp())
+, _api(&_session->mtp())
 , _rowHeight(st::contactsPadding.top() + st::contactsPhotoSize + st::contactsPadding.bottom())
 , _revokeWidth(st::normalFont->width(tr::lng_channels_too_much_public_revoke(tr::now)))
 , _revokeCallback(std::move(revokeCallback)) {
@@ -1320,7 +1329,7 @@ RevokePublicLinkBox::Inner::Inner(
 					Ui::NameTextOptions());
 				row.status.setText(
 					st::defaultTextStyle,
-					Core::App().createInternalLink(
+					_session->createInternalLink(
 						textcmdLink(1, peer->userName())),
 					Ui::DialogTextOptions());
 				_rows.push_back(std::move(row));
@@ -1401,7 +1410,7 @@ void RevokePublicLinkBox::Inner::mouseReleaseEvent(QMouseEvent *e) {
 		auto text = text_method(
 			tr::now,
 			lt_link,
-			Core::App().createInternalLink(pressed->userName()),
+			_session->createInternalLink(pressed->userName()),
 			lt_group,
 			pressed->name);
 		auto confirmText = tr::lng_channels_too_much_public_revoke(tr::now);
diff --git a/Telegram/SourceFiles/boxes/add_contact_box.h b/Telegram/SourceFiles/boxes/add_contact_box.h
index e72a2fd20..d28e57450 100644
--- a/Telegram/SourceFiles/boxes/add_contact_box.h
+++ b/Telegram/SourceFiles/boxes/add_contact_box.h
@@ -46,9 +46,11 @@ enum class PeerFloodType {
 	InviteChannel,
 };
 
-style::InputField CreateBioFieldStyle();
+[[nodiscard]] style::InputField CreateBioFieldStyle();
 
-QString PeerFloodErrorText(PeerFloodType type);
+[[nodiscard]] QString PeerFloodErrorText(
+	not_null<Main::Session*> session,
+	PeerFloodType type);
 void ShowAddParticipantsError(
 	const QString &error,
 	not_null<PeerData*> chat,
diff --git a/Telegram/SourceFiles/boxes/background_box.cpp b/Telegram/SourceFiles/boxes/background_box.cpp
index a39256c42..9ead668bb 100644
--- a/Telegram/SourceFiles/boxes/background_box.cpp
+++ b/Telegram/SourceFiles/boxes/background_box.cpp
@@ -193,7 +193,7 @@ BackgroundBox::Inner::Inner(
 	not_null<Main::Session*> session)
 : RpWidget(parent)
 , _session(session)
-, _api(_session->mtp())
+, _api(&_session->mtp())
 , _check(std::make_unique<Ui::RoundCheckbox>(st::overviewCheck, [=] { update(); })) {
 	_check->setChecked(true, anim::type::instant);
 	if (_session->data().wallpapers().empty()) {
diff --git a/Telegram/SourceFiles/boxes/background_preview_box.cpp b/Telegram/SourceFiles/boxes/background_preview_box.cpp
index 7a368677f..4d0a4c993 100644
--- a/Telegram/SourceFiles/boxes/background_preview_box.cpp
+++ b/Telegram/SourceFiles/boxes/background_preview_box.cpp
@@ -514,7 +514,8 @@ void BackgroundPreviewBox::apply() {
 }
 
 void BackgroundPreviewBox::share() {
-	QGuiApplication::clipboard()->setText(_paper.shareUrl());
+	QGuiApplication::clipboard()->setText(
+		_paper.shareUrl(&_controller->session()));
 	Ui::Toast::Show(tr::lng_background_link_copied(tr::now));
 }
 
diff --git a/Telegram/SourceFiles/boxes/change_phone_box.cpp b/Telegram/SourceFiles/boxes/change_phone_box.cpp
index 9369fa04b..65dcc5834 100644
--- a/Telegram/SourceFiles/boxes/change_phone_box.cpp
+++ b/Telegram/SourceFiles/boxes/change_phone_box.cpp
@@ -140,7 +140,7 @@ ChangePhoneBox::EnterPhone::EnterPhone(
 	QWidget*,
 	not_null<Main::Session*> session)
 : _session(session)
-, _api(session->mtp()) {
+, _api(&session->mtp()) {
 }
 
 void ChangePhoneBox::EnterPhone::prepare() {
@@ -257,7 +257,7 @@ ChangePhoneBox::EnterCode::EnterCode(
 	int codeLength,
 	int callTimeout)
 : _session(session)
-, _api(session->mtp())
+, _api(&session->mtp())
 , _phone(phone)
 , _hash(hash)
 , _codeLength(codeLength)
diff --git a/Telegram/SourceFiles/boxes/confirm_box.cpp b/Telegram/SourceFiles/boxes/confirm_box.cpp
index 67f6872c3..0de763d7b 100644
--- a/Telegram/SourceFiles/boxes/confirm_box.cpp
+++ b/Telegram/SourceFiles/boxes/confirm_box.cpp
@@ -36,7 +36,8 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "data/data_changes.h"
 #include "base/unixtime.h"
 #include "main/main_session.h"
-#include "facades.h"
+#include "mtproto/mtproto_config.h"
+#include "facades.h" // Ui::showChatsList
 #include "app.h"
 #include "styles/style_layers.h"
 #include "styles/style_boxes.h"
@@ -351,7 +352,7 @@ MaxInviteBox::MaxInviteBox(QWidget*, not_null<ChannelData*> channel) : BoxConten
 	tr::lng_participant_invite_sorry(
 		tr::now,
 		lt_count,
-		Global::ChatSizeMax()),
+		channel->session().serverConfig().chatSizeMax),
 	kInformBoxTextOptions,
 	(st::boxWidth
 		- st::boxPadding.left()
@@ -433,7 +434,7 @@ PinMessageBox::PinMessageBox(
 	not_null<PeerData*> peer,
 	MsgId msgId)
 : _peer(peer)
-, _api(peer->session().mtp())
+, _api(&peer->session().mtp())
 , _msgId(msgId)
 , _text(this, tr::lng_pinned_pin_sure(tr::now), st::boxLabel) {
 }
diff --git a/Telegram/SourceFiles/boxes/confirm_phone_box.cpp b/Telegram/SourceFiles/boxes/confirm_phone_box.cpp
index 336a9aca9..ab96d75f3 100644
--- a/Telegram/SourceFiles/boxes/confirm_phone_box.cpp
+++ b/Telegram/SourceFiles/boxes/confirm_phone_box.cpp
@@ -225,7 +225,7 @@ ConfirmPhoneBox::ConfirmPhoneBox(
 	const QString &phone,
 	const QString &hash)
 : _session(session)
-, _api(session->mtp())
+, _api(&session->mtp())
 , _phone(phone)
 , _hash(hash)
 , _call([this] { sendCall(); }, [this] { update(); }) {
diff --git a/Telegram/SourceFiles/boxes/connection_box.cpp b/Telegram/SourceFiles/boxes/connection_box.cpp
index eff5032e0..ac25ca944 100644
--- a/Telegram/SourceFiles/boxes/connection_box.cpp
+++ b/Telegram/SourceFiles/boxes/connection_box.cpp
@@ -1059,9 +1059,7 @@ void ProxiesBoxController::refreshChecker(Item &item) {
 	const auto type = (item.data.type == Type::Http)
 		? Variants::Http
 		: Variants::Tcp;
-	const auto mtproto = _account->mtp();
-	Assert(mtproto != nullptr);
-
+	const auto mtproto = &_account->mtp();
 	const auto dcId = mtproto->mainDcId();
 
 	item.state = ItemState::Checking;
@@ -1084,7 +1082,7 @@ void ProxiesBoxController::refreshChecker(Item &item) {
 			dcId);
 		item.checkerv6 = nullptr;
 	} else {
-		const auto options = mtproto->dcOptions()->lookup(
+		const auto options = mtproto->dcOptions().lookup(
 			dcId,
 			MTP::DcType::Regular,
 			true);
@@ -1376,9 +1374,7 @@ void ProxiesBoxController::setTryIPv6(bool enabled) {
 		return;
 	}
 	Global::SetTryIPv6(enabled);
-	if (const auto mtproto = _account->mtp()) {
-		mtproto->restart();
-	}
+	_account->mtp().restart();
 	Global::RefConnectionTypeChanged().notify();
 	saveDelayed();
 }
@@ -1410,8 +1406,7 @@ void ProxiesBoxController::updateView(const Item &item) {
 		if (!selected
 			|| (Global::ProxySettings() != ProxyData::Settings::Enabled)) {
 			return item.state;
-		} else if (_account->mtp()
-			&& _account->mtp()->dcstate() == MTP::ConnectedState) {
+		} else if (_account->mtp().dcstate() == MTP::ConnectedState) {
 			return ItemState::Online;
 		}
 		return ItemState::Connecting;
diff --git a/Telegram/SourceFiles/boxes/edit_caption_box.cpp b/Telegram/SourceFiles/boxes/edit_caption_box.cpp
index df5b732c8..ad2cf53d9 100644
--- a/Telegram/SourceFiles/boxes/edit_caption_box.cpp
+++ b/Telegram/SourceFiles/boxes/edit_caption_box.cpp
@@ -37,6 +37,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "media/streaming/media_streaming_loader_local.h"
 #include "storage/localimageloader.h"
 #include "storage/storage_media_prepare.h"
+#include "mtproto/mtproto_config.h"
 #include "ui/image/image.h"
 #include "ui/widgets/input_fields.h"
 #include "ui/widgets/checkbox.h"
@@ -46,7 +47,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "window/window_session_controller.h"
 #include "confirm_box.h"
 #include "apiwrap.h"
-#include "facades.h"
+#include "facades.h" // App::LambdaDelayed.
 #include "app.h"
 #include "styles/style_layers.h"
 #include "styles/style_boxes.h"
@@ -67,7 +68,7 @@ EditCaptionBox::EditCaptionBox(
 	not_null<Window::SessionController*> controller,
 	not_null<HistoryItem*> item)
 : _controller(controller)
-, _api(controller->session().mtp())
+, _api(&controller->session().mtp())
 , _msgId(item->fullId()) {
 	Expects(item->media() != nullptr);
 	Expects(item->media()->allowsEditCaption());
@@ -304,8 +305,10 @@ EditCaptionBox::EditCaptionBox(
 		Ui::InputField::Mode::MultiLine,
 		tr::lng_photo_caption(),
 		editData);
-	_field->setMaxLength(Global::CaptionLengthMax());
-	_field->setSubmitSettings(_controller->session().settings().sendSubmitWay());
+	_field->setMaxLength(
+		_controller->session().serverConfig().captionLengthMax);
+	_field->setSubmitSettings(
+		_controller->session().settings().sendSubmitWay());
 	_field->setInstantReplaces(Ui::InstantReplaces::Default());
 	_field->setInstantReplacesEnabled(
 		_controller->session().settings().replaceEmojiValue());
diff --git a/Telegram/SourceFiles/boxes/passcode_box.cpp b/Telegram/SourceFiles/boxes/passcode_box.cpp
index 865cf1235..166062615 100644
--- a/Telegram/SourceFiles/boxes/passcode_box.cpp
+++ b/Telegram/SourceFiles/boxes/passcode_box.cpp
@@ -50,7 +50,7 @@ PasscodeBox::PasscodeBox(
 	not_null<Main::Session*> session,
 	bool turningOff)
 : _session(session)
-, _api(_session->mtp())
+, _api(&_session->mtp())
 , _turningOff(turningOff)
 , _about(st::boxWidth - st::boxPadding.left() * 1.5)
 , _oldPasscode(this, st::defaultInputField, tr::lng_passcode_enter_old())
@@ -66,7 +66,7 @@ PasscodeBox::PasscodeBox(
 	not_null<Main::Session*> session,
 	const CloudFields &fields)
 : _session(session)
-, _api(_session->mtp())
+, _api(&_session->mtp())
 , _turningOff(fields.turningOff)
 , _cloudPwd(true)
 , _cloudFields(fields)
@@ -929,7 +929,7 @@ RecoverBox::RecoverBox(
 	not_null<Main::Session*> session,
 	const QString &pattern,
 	bool notEmptyPassport)
-: _api(session->mtp())
+: _api(&session->mtp())
 , _pattern(st::normalFont->elided(tr::lng_signin_recover_hint(tr::now, lt_recover_email, pattern), st::boxWidth - st::boxPadding.left() * 1.5))
 , _notEmptyPassport(notEmptyPassport)
 , _recoverCode(this, st::defaultInputField, tr::lng_signin_code()) {
diff --git a/Telegram/SourceFiles/boxes/peer_list_controllers.cpp b/Telegram/SourceFiles/boxes/peer_list_controllers.cpp
index 007da687a..bf400ead7 100644
--- a/Telegram/SourceFiles/boxes/peer_list_controllers.cpp
+++ b/Telegram/SourceFiles/boxes/peer_list_controllers.cpp
@@ -146,7 +146,7 @@ void PeerListRowWithLink::paintAction(
 PeerListGlobalSearchController::PeerListGlobalSearchController(
 	not_null<Window::SessionNavigation*> navigation)
 : _navigation(navigation)
-, _api(_navigation->session().mtp()) {
+, _api(&_navigation->session().mtp()) {
 	_timer.setCallback([this] { searchOnServer(); });
 }
 
diff --git a/Telegram/SourceFiles/boxes/peers/add_participants_box.cpp b/Telegram/SourceFiles/boxes/peers/add_participants_box.cpp
index fd2bd3ecc..5395084ef 100644
--- a/Telegram/SourceFiles/boxes/peers/add_participants_box.cpp
+++ b/Telegram/SourceFiles/boxes/peers/add_participants_box.cpp
@@ -20,11 +20,12 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "dialogs/dialogs_indexed_list.h"
 #include "base/unixtime.h"
 #include "main/main_session.h"
+#include "mtproto/mtproto_config.h"
 #include "mainwidget.h"
 #include "mainwindow.h"
 #include "window/window_session_controller.h"
 #include "apiwrap.h"
-#include "facades.h"
+#include "facades.h" // Ui::showPeerHistory
 #include "app.h"
 
 namespace {
@@ -87,10 +88,11 @@ void AddParticipantsBoxController::subscribeToMigration() {
 }
 
 void AddParticipantsBoxController::rowClicked(not_null<PeerListRow*> row) {
+	const auto &serverConfig = _peer->session().serverConfig();
 	auto count = fullCount();
 	auto limit = _peer && (_peer->isChat() || _peer->isMegagroup())
-		? Global::MegagroupSizeMax()
-		: Global::ChatSizeMax();
+		? serverConfig.megagroupSizeMax
+		: serverConfig.chatSizeMax;
 	if (count < limit || row->checked()) {
 		delegate()->peerListSetRowChecked(row, !row->checked());
 		updateTitle();
@@ -100,8 +102,8 @@ void AddParticipantsBoxController::rowClicked(not_null<PeerListRow*> row) {
 				Box<MaxInviteBox>(_peer->asChannel()),
 				Ui::LayerOption::KeepOther);
 		}
-	} else if (count >= Global::ChatSizeMax()
-		&& count < Global::MegagroupSizeMax()) {
+	} else if (count >= serverConfig.chatSizeMax
+		&& count < serverConfig.megagroupSizeMax) {
 		Ui::show(
 			Box<InformBox>(tr::lng_profile_add_more_after_create(tr::now)),
 			Ui::LayerOption::KeepOther);
@@ -166,7 +168,9 @@ void AddParticipantsBoxController::updateTitle() {
 		&& _peer->isChannel()
 		&& !_peer->isMegagroup())
 		? QString()
-		: qsl("%1 / %2").arg(fullCount()).arg(Global::MegagroupSizeMax());
+		: qsl("%1 / %2"
+		).arg(fullCount()
+		).arg(session().serverConfig().megagroupSizeMax);
 	delegate()->peerListSetTitle(tr::lng_profile_add_participant());
 	delegate()->peerListSetAdditionalTitle(rpl::single(additional));
 }
@@ -276,7 +280,7 @@ AddSpecialBoxController::AddSpecialBoxController(
 	peer,
 	&_additional))
 , _peer(peer)
-, _api(_peer->session().mtp())
+, _api(&_peer->session().mtp())
 , _role(role)
 , _additional(peer, Role::Members)
 , _adminDoneCallback(std::move(adminDoneCallback))
@@ -829,7 +833,7 @@ AddSpecialBoxSearchController::AddSpecialBoxSearchController(
 	not_null<ParticipantsAdditionalData*> additional)
 : _peer(peer)
 , _additional(additional)
-, _api(_peer->session().mtp())
+, _api(&_peer->session().mtp())
 , _timer([=] { searchOnServer(); }) {
 	subscribeToMigration();
 }
diff --git a/Telegram/SourceFiles/boxes/peers/edit_participants_box.cpp b/Telegram/SourceFiles/boxes/peers/edit_participants_box.cpp
index 43185f80d..28426dc15 100644
--- a/Telegram/SourceFiles/boxes/peers/edit_participants_box.cpp
+++ b/Telegram/SourceFiles/boxes/peers/edit_participants_box.cpp
@@ -13,6 +13,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "boxes/confirm_box.h"
 #include "boxes/add_contact_box.h"
 #include "main/main_session.h"
+#include "mtproto/mtproto_config.h"
 #include "apiwrap.h"
 #include "lang/lang_keys.h"
 #include "mainwidget.h"
@@ -28,7 +29,6 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "ui/ui_utility.h"
 #include "window/window_session_controller.h"
 #include "history/history.h"
-#include "facades.h"
 
 namespace {
 
@@ -707,7 +707,8 @@ void ParticipantsOnlineSorter::sort() {
 	const auto channel = _peer->asChannel();
 	if (channel
 		&& (!channel->isMegagroup()
-			|| channel->membersCount() > Global::ChatSizeMax())) {
+			|| (channel->membersCount()
+				> channel->session().serverConfig().chatSizeMax))) {
 		_onlineCount = 0;
 		return;
 	}
@@ -752,7 +753,7 @@ ParticipantsBoxController::ParticipantsBoxController(
 : PeerListController(CreateSearchController(peer, role, &_additional))
 , _navigation(navigation)
 , _peer(peer)
-, _api(_peer->session().mtp())
+, _api(&_peer->session().mtp())
 , _role(role)
 , _additional(peer, _role) {
 	subscribeToMigration();
@@ -844,8 +845,9 @@ void ParticipantsBoxController::Start(
 				return chat
 					? chat->canAddMembers()
 					: (channel->canAddMembers()
-						&& (channel->membersCount() < Global::ChatSizeMax()
-							|| channel->isMegagroup()));
+						&& (channel->isMegagroup()
+							|| (channel->membersCount()
+								< channel->session().serverConfig().chatSizeMax)));
 			case Role::Admins:
 				return chat
 					? chat->canAddAdmins()
@@ -924,7 +926,8 @@ void ParticipantsBoxController::addNewParticipants() {
 	if (chat) {
 		AddParticipantsBoxController::Start(_navigation, chat);
 	} else if (channel->isMegagroup()
-		|| channel->membersCount() < Global::ChatSizeMax()) {
+		|| (channel->membersCount()
+			< channel->session().serverConfig().chatSizeMax)) {
 		const auto count = delegate()->peerListFullRowsCount();
 		auto already = std::vector<not_null<UserData*>>();
 		already.reserve(count);
@@ -1887,7 +1890,7 @@ void ParticipantsBoxController::subscribeToCreatorChange(
 			channel->inputChannel,
 			MTP_channelParticipantsRecent(),
 			MTP_int(0),
-			MTP_int(Global::ChatSizeMax()),
+			MTP_int(channel->session().serverConfig().chatSizeMax),
 			MTP_int(0)
 		)).done([=](const MTPchannels_ChannelParticipants &result) {
 			if (channel->amCreator()) {
@@ -1922,7 +1925,7 @@ ParticipantsBoxSearchController::ParticipantsBoxSearchController(
 : _channel(channel)
 , _role(role)
 , _additional(additional)
-, _api(_channel->session().mtp()) {
+, _api(&_channel->session().mtp()) {
 	_timer.setCallback([=] { searchOnServer(); });
 }
 
diff --git a/Telegram/SourceFiles/boxes/peers/edit_peer_info_box.cpp b/Telegram/SourceFiles/boxes/peers/edit_peer_info_box.cpp
index a0a390fe3..ff154168e 100644
--- a/Telegram/SourceFiles/boxes/peers/edit_peer_info_box.cpp
+++ b/Telegram/SourceFiles/boxes/peers/edit_peer_info_box.cpp
@@ -355,7 +355,7 @@ Controller::Controller(
 : _navigation(navigation)
 , _box(box)
 , _peer(peer)
-, _api(_peer->session().mtp())
+, _api(&_peer->session().mtp())
 , _isGroup(_peer->isChat() || _peer->isMegagroup()) {
 	_box->setTitle(_isGroup
 		? tr::lng_edit_group()
diff --git a/Telegram/SourceFiles/boxes/peers/edit_peer_type_box.cpp b/Telegram/SourceFiles/boxes/peers/edit_peer_type_box.cpp
index 4476fce8d..a0c331060 100644
--- a/Telegram/SourceFiles/boxes/peers/edit_peer_type_box.cpp
+++ b/Telegram/SourceFiles/boxes/peers/edit_peer_type_box.cpp
@@ -168,7 +168,7 @@ Controller::Controller(
 	std::optional<Privacy> privacySavedValue,
 	std::optional<QString> usernameSavedValue)
 : _peer(peer)
-, _api(_peer->session().mtp())
+, _api(&_peer->session().mtp())
 , _privacySavedValue(privacySavedValue)
 , _usernameSavedValue(usernameSavedValue)
 , _useLocationPhrases(useLocationPhrases)
@@ -335,7 +335,7 @@ object_ptr<Ui::RpWidget> Controller::createUsernameEdit() {
 			st::setupChannelLink,
 			nullptr,
 			username,
-			true));
+			_peer->session().createInternalLink(QString())));
 	_controls.usernameInput->heightValue(
 	) | rpl::start_with_next([placeholder](int height) {
 		placeholder->resize(placeholder->width(), height);
diff --git a/Telegram/SourceFiles/boxes/rate_call_box.cpp b/Telegram/SourceFiles/boxes/rate_call_box.cpp
index aa6e72b2c..999eb93aa 100644
--- a/Telegram/SourceFiles/boxes/rate_call_box.cpp
+++ b/Telegram/SourceFiles/boxes/rate_call_box.cpp
@@ -31,7 +31,7 @@ RateCallBox::RateCallBox(
 	uint64 callId,
 	uint64 callAccessHash)
 : _session(session)
-, _api(_session->mtp())
+, _api(&_session->mtp())
 , _callId(callId)
 , _callAccessHash(callAccessHash) {
 }
diff --git a/Telegram/SourceFiles/boxes/report_box.cpp b/Telegram/SourceFiles/boxes/report_box.cpp
index a55ab4835..0c6fb1b03 100644
--- a/Telegram/SourceFiles/boxes/report_box.cpp
+++ b/Telegram/SourceFiles/boxes/report_box.cpp
@@ -28,12 +28,12 @@ constexpr auto kReportReasonLengthMax = 200;
 
 ReportBox::ReportBox(QWidget*, not_null<PeerData*> peer)
 : _peer(peer)
-, _api(_peer->session().mtp()) {
+, _api(&_peer->session().mtp()) {
 }
 
 ReportBox::ReportBox(QWidget*, not_null<PeerData*> peer, MessageIdsList ids)
 : _peer(peer)
-, _api(_peer->session().mtp())
+, _api(&_peer->session().mtp())
 , _ids(std::move(ids)) {
 }
 
diff --git a/Telegram/SourceFiles/boxes/send_files_box.cpp b/Telegram/SourceFiles/boxes/send_files_box.cpp
index e3c6570b9..3893ef1a1 100644
--- a/Telegram/SourceFiles/boxes/send_files_box.cpp
+++ b/Telegram/SourceFiles/boxes/send_files_box.cpp
@@ -12,6 +12,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "storage/localstorage.h"
 #include "storage/storage_media_prepare.h"
 #include "mainwidget.h"
+#include "mtproto/mtproto_config.h"
 #include "chat_helpers/message_field.h"
 #include "chat_helpers/emoji_suggestions_widget.h"
 #include "chat_helpers/tabbed_panel.h"
@@ -36,7 +37,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "api/api_common.h"
 #include "window/window_session_controller.h"
 #include "layout.h"
-#include "facades.h"
+#include "facades.h" // App::LambdaDelayed.
 #include "app.h"
 #include "styles/style_history.h"
 #include "styles/style_layers.h"
@@ -2041,8 +2042,10 @@ void SendFilesBox::applyAlbumOrder() {
 }
 
 void SendFilesBox::setupCaption() {
-	_caption->setMaxLength(Global::CaptionLengthMax());
-	_caption->setSubmitSettings(_controller->session().settings().sendSubmitWay());
+	_caption->setMaxLength(
+		_controller->session().serverConfig().captionLengthMax);
+	_caption->setSubmitSettings(
+		_controller->session().settings().sendSubmitWay());
 	connect(_caption, &Ui::InputField::resized, [=] {
 		captionResized();
 	});
diff --git a/Telegram/SourceFiles/boxes/sessions_box.cpp b/Telegram/SourceFiles/boxes/sessions_box.cpp
index ff494213b..23e07688e 100644
--- a/Telegram/SourceFiles/boxes/sessions_box.cpp
+++ b/Telegram/SourceFiles/boxes/sessions_box.cpp
@@ -77,7 +77,7 @@ private:
 
 SessionsBox::SessionsBox(QWidget*, not_null<Main::Session*> session)
 : _session(session)
-, _api(_session->mtp())
+, _api(&_session->mtp())
 , _shortPollTimer([=] { shortPollSessions(); }) {
 }
 
diff --git a/Telegram/SourceFiles/boxes/share_box.cpp b/Telegram/SourceFiles/boxes/share_box.cpp
index 3f333a498..8c6d0a5fd 100644
--- a/Telegram/SourceFiles/boxes/share_box.cpp
+++ b/Telegram/SourceFiles/boxes/share_box.cpp
@@ -159,7 +159,7 @@ ShareBox::ShareBox(
 	SubmitCallback &&submitCallback,
 	FilterCallback &&filterCallback)
 : _navigation(navigation)
-, _api(_navigation->session().mtp())
+, _api(&_navigation->session().mtp())
 , _copyCallback(std::move(copyCallback))
 , _submitCallback(std::move(submitCallback))
 , _filterCallback(std::move(filterCallback))
diff --git a/Telegram/SourceFiles/boxes/sticker_set_box.cpp b/Telegram/SourceFiles/boxes/sticker_set_box.cpp
index 980c84b26..7359a6e00 100644
--- a/Telegram/SourceFiles/boxes/sticker_set_box.cpp
+++ b/Telegram/SourceFiles/boxes/sticker_set_box.cpp
@@ -190,7 +190,8 @@ void StickerSetBox::addStickers() {
 }
 
 void StickerSetBox::shareStickers() {
-	auto url = Core::App().createInternalLinkFull(qsl("addstickers/") + _inner->shortName());
+	const auto url = _controller->session().createInternalLinkFull(
+		qsl("addstickers/") + _inner->shortName());
 	QGuiApplication::clipboard()->setText(url);
 	Ui::show(Box<InformBox>(tr::lng_stickers_copied(tr::now)));
 }
@@ -229,7 +230,7 @@ StickerSetBox::Inner::Inner(
 	const MTPInputStickerSet &set)
 : RpWidget(parent)
 , _controller(controller)
-, _api(_controller->session().mtp())
+, _api(&_controller->session().mtp())
 , _input(set)
 , _previewTimer([=] { showPreview(); }) {
 	set.match([&](const MTPDinputStickerSetID &data) {
diff --git a/Telegram/SourceFiles/boxes/stickers_box.cpp b/Telegram/SourceFiles/boxes/stickers_box.cpp
index 5638570f3..3ebeb1053 100644
--- a/Telegram/SourceFiles/boxes/stickers_box.cpp
+++ b/Telegram/SourceFiles/boxes/stickers_box.cpp
@@ -363,7 +363,7 @@ StickersBox::StickersBox(
 	not_null<Main::Session*> session,
 	Section section)
 : _session(session)
-, _api(session->mtp())
+, _api(&session->mtp())
 , _tabs(this, st::stickersTabs)
 , _unreadBadge(
 	this,
@@ -377,7 +377,7 @@ StickersBox::StickersBox(
 
 StickersBox::StickersBox(QWidget*, not_null<ChannelData*> megagroup)
 : _session(&megagroup->session())
-, _api(_session->mtp())
+, _api(&_session->mtp())
 , _section(Section::Installed)
 , _installed(0, this, megagroup)
 , _megagroupSet(megagroup) {
@@ -391,7 +391,7 @@ StickersBox::StickersBox(
 	not_null<Main::Session*> session,
 	const MTPVector<MTPStickerSetCovered> &attachedSets)
 : _session(session)
-, _api(session->mtp())
+, _api(&session->mtp())
 , _section(Section::Attached)
 , _attached(0, this, session, Section::Attached)
 , _attachedSets(attachedSets) {
@@ -928,7 +928,7 @@ StickersBox::Inner::Inner(
 	StickersBox::Section section)
 : RpWidget(parent)
 , _session(session)
-, _api(_session->mtp())
+, _api(&_session->mtp())
 , _section(section)
 , _rowHeight(st::contactsPadding.top() + st::contactsPhotoSize + st::contactsPadding.bottom())
 , _shiftingAnimation([=](crl::time now) {
@@ -945,7 +945,7 @@ StickersBox::Inner::Inner(
 StickersBox::Inner::Inner(QWidget *parent, not_null<ChannelData*> megagroup)
 : RpWidget(parent)
 , _session(&megagroup->session())
-, _api(_session->mtp())
+, _api(&_session->mtp())
 , _section(StickersBox::Section::Installed)
 , _rowHeight(st::contactsPadding.top() + st::contactsPhotoSize + st::contactsPadding.bottom())
 , _shiftingAnimation([=](crl::time now) {
@@ -954,10 +954,16 @@ StickersBox::Inner::Inner(QWidget *parent, not_null<ChannelData*> megagroup)
 , _itemsTop(st::membersMarginTop)
 , _megagroupSet(megagroup)
 , _megagroupSetInput(_megagroupSet->mgInfo->stickerSet)
-, _megagroupSetField(this, st::groupStickersField, rpl::single(qsl("stickerset")), QString(), true)
+, _megagroupSetField(
+	this,
+	st::groupStickersField,
+	rpl::single(qsl("stickerset")),
+	QString(),
+	_session->createInternalLink(QString()))
 , _megagroupDivider(this)
 , _megagroupSubTitle(this, tr::lng_stickers_group_from_your(tr::now), st::boxTitle) {
-	_megagroupSetField->setLinkPlaceholder(Core::App().createInternalLink(qsl("addstickers/")));
+	_megagroupSetField->setLinkPlaceholder(
+		_session->createInternalLink(qsl("addstickers/")));
 	_megagroupSetField->setPlaceholderHidden(false);
 	_megagroupSetAddressChangedTimer.setCallback([this] { handleMegagroupSetAddressChange(); });
 	connect(
diff --git a/Telegram/SourceFiles/boxes/username_box.cpp b/Telegram/SourceFiles/boxes/username_box.cpp
index d592cea8b..537e65429 100644
--- a/Telegram/SourceFiles/boxes/username_box.cpp
+++ b/Telegram/SourceFiles/boxes/username_box.cpp
@@ -31,13 +31,13 @@ constexpr auto kMinUsernameLength = 5;
 
 UsernameBox::UsernameBox(QWidget*, not_null<Main::Session*> session)
 : _session(session)
-, _api(_session->mtp())
+, _api(&_session->mtp())
 , _username(
 	this,
 	st::defaultInputField,
 	rpl::single(qsl("@username")),
 	session->user()->username,
-	false)
+	QString())
 , _link(this, QString(), st::boxLinkButton)
 , _about(st::boxWidth - st::usernamePadding.left())
 , _checkTimer(this) {
@@ -94,7 +94,8 @@ void UsernameBox::paintEvent(QPaintEvent *e) {
 	if (_link->isHidden()) {
 		p.drawTextLeft(st::usernamePadding.left(), linky, width(), tr::lng_username_link_willbe(tr::now));
 		p.setPen(st::usernameDefaultFg);
-		p.drawTextLeft(st::usernamePadding.left(), linky + st::usernameTextStyle.lineHeight + ((st::usernameTextStyle.lineHeight - st::boxTextFont->height) / 2), width(), Core::App().createInternalLinkFull(qsl("username")));
+		const auto link = _session->createInternalLinkFull(qsl("username"));
+		p.drawTextLeft(st::usernamePadding.left(), linky + st::usernameTextStyle.lineHeight + ((st::usernameTextStyle.lineHeight - st::boxTextFont->height) / 2), width(), link);
 	} else {
 		p.drawTextLeft(st::usernamePadding.left(), linky, width(), tr::lng_username_link(tr::now));
 	}
@@ -179,7 +180,8 @@ void UsernameBox::changed() {
 }
 
 void UsernameBox::linkClick() {
-	QGuiApplication::clipboard()->setText(Core::App().createInternalLinkFull(getName()));
+	QGuiApplication::clipboard()->setText(
+		_session->createInternalLinkFull(getName()));
 	Ui::Toast::Show(tr::lng_username_copied(tr::now));
 }
 
@@ -251,7 +253,7 @@ QString UsernameBox::getName() const {
 
 void UsernameBox::updateLinkText() {
 	QString uname = getName();
-	_link->setText(st::boxTextFont->elided(Core::App().createInternalLinkFull(uname), st::boxWidth - st::usernamePadding.left() - st::usernamePadding.right()));
+	_link->setText(st::boxTextFont->elided(_session->createInternalLinkFull(uname), st::boxWidth - st::usernamePadding.left() - st::usernamePadding.right()));
 	if (uname.isEmpty()) {
 		if (!_link->isHidden()) {
 			_link->hide();
diff --git a/Telegram/SourceFiles/calls/calls_box_controller.cpp b/Telegram/SourceFiles/calls/calls_box_controller.cpp
index 3f7dd8c38..b3eb152be 100644
--- a/Telegram/SourceFiles/calls/calls_box_controller.cpp
+++ b/Telegram/SourceFiles/calls/calls_box_controller.cpp
@@ -216,7 +216,7 @@ void BoxController::Row::stopLastActionRipple() {
 
 BoxController::BoxController(not_null<Window::SessionController*> window)
 : _window(window)
-, _api(_window->session().mtp()) {
+, _api(&_window->session().mtp()) {
 }
 
 Main::Session &BoxController::session() const {
diff --git a/Telegram/SourceFiles/calls/calls_call.cpp b/Telegram/SourceFiles/calls/calls_call.cpp
index 25cc94531..27079ffad 100644
--- a/Telegram/SourceFiles/calls/calls_call.cpp
+++ b/Telegram/SourceFiles/calls/calls_call.cpp
@@ -15,6 +15,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "calls/calls_instance.h"
 #include "base/openssl_help.h"
 #include "mtproto/mtproto_dh_utils.h"
+#include "mtproto/mtproto_config.h"
 #include "media/audio/media_audio_track.h"
 #include "base/platform/base_platform_info.h"
 #include "calls/calls_panel.h"
@@ -96,7 +97,7 @@ Call::Call(
 	Type type)
 : _delegate(delegate)
 , _user(user)
-, _api(_user->session().mtp())
+, _api(&_user->session().mtp())
 , _type(type) {
 	_discardByTimeoutTimer.setCallback([this] { hangup(); });
 
@@ -193,7 +194,8 @@ void Call::startOutgoing() {
 			return;
 		}
 
-		_discardByTimeoutTimer.callOnce(Global::CallReceiveTimeoutMs());
+		const auto &config = _user->session().serverConfig();
+		_discardByTimeoutTimer.callOnce(config.callReceiveTimeoutMs);
 		handleUpdate(phoneCall);
 	}).fail([this](const RPCError &error) {
 		handleRequestError(error);
@@ -382,7 +384,8 @@ bool Call::handleUpdate(const MTPPhoneCall &call) {
 		if (_type == Type::Outgoing
 			&& _state == State::Waiting
 			&& data.vreceive_date().value_or_empty() != 0) {
-			_discardByTimeoutTimer.callOnce(Global::CallRingTimeoutMs());
+			const auto &config = _user->session().serverConfig();
+			_discardByTimeoutTimer.callOnce(config.callRingTimeoutMs);
 			setState(State::Ringing);
 			startWaitingTrack();
 		}
@@ -534,6 +537,7 @@ void Call::createAndStartController(const MTPDphoneCall &call) {
 	}
 
 	const auto &protocol = call.vprotocol().c_phoneCallProtocol();
+	const auto &serverConfig = _user->session().serverConfig();
 
 	TgVoipConfig config;
 	config.dataSaving = TgVoipDataSaving::Never;
@@ -541,8 +545,8 @@ void Call::createAndStartController(const MTPDphoneCall &call) {
 	config.enableNS = true;
 	config.enableAGC = true;
 	config.enableVolumeControl = true;
-	config.initializationTimeout = Global::CallConnectTimeoutMs() / 1000.;
-	config.receiveTimeout = Global::CallPacketTimeoutMs() / 1000.;
+	config.initializationTimeout = serverConfig.callConnectTimeoutMs / 1000.;
+	config.receiveTimeout = serverConfig.callPacketTimeoutMs / 1000.;
 	config.enableP2P = call.is_p2p_allowed();
 	config.maxApiLayer = protocol.vmax_layer().v;
 	if (Logs::DebugEnabled()) {
diff --git a/Telegram/SourceFiles/calls/calls_instance.cpp b/Telegram/SourceFiles/calls/calls_instance.cpp
index 4809102ae..2916f073b 100644
--- a/Telegram/SourceFiles/calls/calls_instance.cpp
+++ b/Telegram/SourceFiles/calls/calls_instance.cpp
@@ -21,8 +21,8 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "platform/platform_specific.h"
 #include "base/unixtime.h"
 #include "mainwidget.h"
+#include "mtproto/mtproto_config.h"
 #include "boxes/rate_call_box.h"
-#include "facades.h"
 #include "app.h"
 
 namespace Calls {
@@ -34,7 +34,7 @@ constexpr auto kServerConfigUpdateTimeoutMs = 24 * 3600 * crl::time(1000);
 
 Instance::Instance(not_null<Main::Session*> session)
 : _session(session)
-, _api(_session->mtp()) {
+, _api(&_session->mtp()) {
 }
 
 void Instance::startOutgoingCall(not_null<UserData*> user) {
@@ -248,6 +248,7 @@ void Instance::handleCallUpdate(const MTPPhoneCall &call) {
 		} else if (user->isSelf()) {
 			LOG(("API Error: Self found in phoneCallRequested."));
 		}
+		const auto &config = _session->serverConfig();
 		if (alreadyInCall() || !user || user->isSelf()) {
 			_api.request(MTPphone_DiscardCall(
 				MTP_flags(0),
@@ -256,7 +257,7 @@ void Instance::handleCallUpdate(const MTPPhoneCall &call) {
 				MTP_phoneCallDiscardReasonBusy(),
 				MTP_long(0)
 			)).send();
-		} else if (phoneCall.vdate().v + (Global::CallRingTimeoutMs() / 1000)
+		} else if (phoneCall.vdate().v + (config.callRingTimeoutMs / 1000)
 			< base::unixtime::now()) {
 			LOG(("Ignoring too old call."));
 		} else {
diff --git a/Telegram/SourceFiles/chat_helpers/gifs_list_widget.cpp b/Telegram/SourceFiles/chat_helpers/gifs_list_widget.cpp
index 70d7cb756..6fb082fc0 100644
--- a/Telegram/SourceFiles/chat_helpers/gifs_list_widget.cpp
+++ b/Telegram/SourceFiles/chat_helpers/gifs_list_widget.cpp
@@ -134,7 +134,7 @@ GifsListWidget::GifsListWidget(
 	QWidget *parent,
 	not_null<Window::SessionController*> controller)
 : Inner(parent, controller)
-, _api(controller->session().mtp())
+, _api(&controller->session().mtp())
 , _section(Section::Gifs)
 , _updateInlineItems([=] { updateInlineItems(); })
 , _previewTimer([=] { showPreview(); }) {
diff --git a/Telegram/SourceFiles/chat_helpers/stickers_list_widget.cpp b/Telegram/SourceFiles/chat_helpers/stickers_list_widget.cpp
index ea87276a8..d82fbddee 100644
--- a/Telegram/SourceFiles/chat_helpers/stickers_list_widget.cpp
+++ b/Telegram/SourceFiles/chat_helpers/stickers_list_widget.cpp
@@ -873,7 +873,7 @@ StickersListWidget::StickersListWidget(
 	QWidget *parent,
 	not_null<Window::SessionController*> controller)
 : Inner(parent, controller)
-, _api(controller->session().mtp())
+, _api(&controller->session().mtp())
 , _section(Section::Stickers)
 , _megagroupSetAbout(st::columnMinimalWidthThird - st::emojiScroll.width - st::emojiPanHeaderLeft)
 , _addText(tr::lng_stickers_featured_add(tr::now).toUpper())
diff --git a/Telegram/SourceFiles/core/application.cpp b/Telegram/SourceFiles/core/application.cpp
index ba1ffae8a..cd8f4eaef 100644
--- a/Telegram/SourceFiles/core/application.cpp
+++ b/Telegram/SourceFiles/core/application.cpp
@@ -39,7 +39,8 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "main/main_accounts.h"
 #include "main/main_session.h"
 #include "media/view/media_view_overlay_widget.h"
-#include "mtproto/dc_options.h"
+#include "mtproto/mtproto_dc_options.h"
+#include "mtproto/mtproto_config.h"
 #include "mtproto/mtp_instance.h"
 #include "media/audio/media_audio.h"
 #include "media/audio/media_audio_track.h"
@@ -95,7 +96,8 @@ Application::Application(not_null<Launcher*> launcher)
 , _private(std::make_unique<Private>())
 , _databases(std::make_unique<Storage::Databases>())
 , _animationsManager(std::make_unique<Ui::Animations::Manager>())
-, _dcOptions(std::make_unique<MTP::DcOptions>())
+, _fallbackProductionConfig(
+	std::make_unique<MTP::Config>(MTP::Environment::Production))
 , _accounts(std::make_unique<Main::Accounts>(cDataFile()))
 , _langpack(std::make_unique<Lang::Instance>())
 , _langCloudManager(std::make_unique<Lang::CloudManager>(langpack()))
@@ -122,12 +124,8 @@ Application::Application(not_null<Launcher*> launcher)
 	}, _lifetime);
 
 	accounts().activeValue(
-	) | rpl::map([=](Main::Account *account) {
-		return account ? account->mtpValue() : rpl::never<MTP::Instance*>();
-	}) | rpl::flatten_latest(
-	) | rpl::filter([=](MTP::Instance *instance) {
-		return instance != nullptr;
-	}) | rpl::start_with_next([=] {
+	) | rpl::filter(rpl::mappers::_1 != nullptr
+	) | rpl::take(1) | rpl::start_with_next([=] {
 		if (_window) {
 			// Global::DesktopNotify is used in updateTrayMenu.
 			// This should be called when user settings are read.
@@ -149,14 +147,7 @@ Application::~Application() {
 	}
 
 	unlockTerms();
-	for (const auto &[index, account] : accounts().list()) {
-		if (account->sessionExists()) {
-			account->session().saveSettingsNowIfNeeded();
-		}
-		// Some MTP requests can be cancelled from data clearing.
-		account->destroySession();
-		account->clearMtp();
-	}
+	accounts().finish();
 
 	Local::finish();
 
@@ -269,7 +260,7 @@ void Application::run() {
 		_window->showSettings();
 	}
 
-	_window->updateIsActive(Global::OnlineFocusTimeout());
+	_window->updateIsActiveFocus();
 
 	for (const auto &error : Shortcuts::Errors()) {
 		LOG(("Shortcuts Error: %1").arg(error));
@@ -399,6 +390,30 @@ void Application::saveSettingsDelayed(crl::time delay) {
 	_saveSettingsTimer.callOnce(delay);
 }
 
+MTP::Config &Application::fallbackProductionConfig() const {
+	if (!_fallbackProductionConfig) {
+		_fallbackProductionConfig = std::make_unique<MTP::Config>(
+			MTP::Environment::Production);
+	}
+	return *_fallbackProductionConfig;
+}
+
+void Application::refreshFallbackProductionConfig(
+		const MTP::Config &config) {
+	if (config.environment() == MTP::Environment::Production) {
+		_fallbackProductionConfig = std::make_unique<MTP::Config>(config);
+	}
+}
+
+void Application::constructFallbackProductionConfig(
+		const QByteArray &serialized) {
+	if (auto config = MTP::Config::FromSerialized(serialized)) {
+		if (config->environment() == MTP::Environment::Production) {
+			_fallbackProductionConfig = std::move(config);
+		}
+	}
+}
+
 void Application::setCurrentProxy(
 		const MTP::ProxyData &proxy,
 		MTP::ProxyData::Settings settings) {
@@ -436,18 +451,6 @@ void Application::badMtprotoConfigurationError() {
 
 void Application::startLocalStorage() {
 	Local::start();
-
-	const auto writing = _lifetime.make_state<bool>(false);
-	_dcOptions->changed(
-	) | rpl::filter([=] {
-		return !*writing;
-	}) | rpl::start_with_next([=] {
-		*writing = true;
-		Ui::PostponeCall(this, [=] {
-			Local::writeSettings();
-		});
-	}, _lifetime);
-
 	_saveSettingsTimer.setCallback([=] { Local::writeSettings(); });
 }
 
@@ -498,13 +501,13 @@ void Application::stateChanged(Qt::ApplicationState state) {
 void Application::handleAppActivated() {
 	checkLocalTime();
 	if (_window) {
-		_window->updateIsActive(Global::OnlineFocusTimeout());
+		_window->updateIsActiveFocus();
 	}
 }
 
 void Application::handleAppDeactivated() {
 	if (_window) {
-		_window->updateIsActive(Global::OfflineBlurTimeout());
+		_window->updateIsActiveBlur();
 	}
 	Ui::Tooltip::Hide();
 }
@@ -530,21 +533,6 @@ void Application::switchDebugMode() {
 	}
 }
 
-void Application::switchTestMode() {
-	if (cTestMode()) {
-		QFile(cWorkingDir() + qsl("tdata/withtestmode")).remove();
-		cSetTestMode(false);
-	} else {
-		QFile f(cWorkingDir() + qsl("tdata/withtestmode"));
-		if (f.open(QIODevice::WriteOnly)) {
-			f.write("1");
-			f.close();
-		}
-		cSetTestMode(true);
-	}
-	App::restart();
-}
-
 void Application::switchFreeType() {
 	if (cUseFreeType()) {
 		QFile(cWorkingDir() + qsl("tdata/withfreetype")).remove();
@@ -613,45 +601,6 @@ bool Application::canApplyLangPackWithoutRestart() const {
 	return true;
 }
 
-void Application::setInternalLinkDomain(const QString &domain) const {
-	// This domain should start with 'http[s]://' and end with '/'.
-	// Like 'https://telegram.me/' or 'https://t.me/'.
-	auto validate = [](const auto &domain) {
-		const auto prefixes = {
-			qstr("https://"),
-			qstr("http://"),
-		};
-		for (const auto &prefix : prefixes) {
-			if (domain.startsWith(prefix, Qt::CaseInsensitive)) {
-				return domain.endsWith('/');
-			}
-		}
-		return false;
-	};
-	if (validate(domain) && domain != Global::InternalLinksDomain()) {
-		Global::SetInternalLinksDomain(domain);
-	}
-}
-
-QString Application::createInternalLink(const QString &query) const {
-	auto result = createInternalLinkFull(query);
-	auto prefixes = {
-		qstr("https://"),
-		qstr("http://"),
-	};
-	for (auto &prefix : prefixes) {
-		if (result.startsWith(prefix, Qt::CaseInsensitive)) {
-			return result.mid(prefix.size());
-		}
-	}
-	LOG(("Warning: bad internal url '%1'").arg(result));
-	return result;
-}
-
-QString Application::createInternalLinkFull(const QString &query) const {
-	return Global::InternalLinksDomain() + query;
-}
-
 void Application::checkStartUrl() {
 	if (!cStartUrl().isEmpty() && !locked()) {
 		const auto url = cStartUrl();
diff --git a/Telegram/SourceFiles/core/application.h b/Telegram/SourceFiles/core/application.h
index fb39c552c..e85a3e49b 100644
--- a/Telegram/SourceFiles/core/application.h
+++ b/Telegram/SourceFiles/core/application.h
@@ -49,7 +49,7 @@ class BoxContent;
 } // namespace Ui
 
 namespace MTP {
-class DcOptions;
+class Config;
 class Instance;
 class AuthKey;
 using AuthKeyPtr = std::shared_ptr<AuthKey>;
@@ -82,6 +82,11 @@ struct LocalUrlHandler;
 
 class Application final : public QObject, private base::Subscriber {
 public:
+	struct ProxyChange {
+		MTP::ProxyData was;
+		MTP::ProxyData now;
+	};
+
 	Application(not_null<Launcher*> launcher);
 	Application(const Application &other) = delete;
 	Application &operator=(const Application &other) = delete;
@@ -132,14 +137,10 @@ public:
 	}
 	void saveSettingsDelayed(crl::time delay = kDefaultSaveDelay);
 
-	// Dc options and proxy.
-	[[nodiscard]] not_null<MTP::DcOptions*> dcOptions() {
-		return _dcOptions.get();
-	}
-	struct ProxyChange {
-		MTP::ProxyData was;
-		MTP::ProxyData now;
-	};
+	// Fallback config and proxy.
+	[[nodiscard]] MTP::Config &fallbackProductionConfig() const;
+	void refreshFallbackProductionConfig(const MTP::Config &config);
+	void constructFallbackProductionConfig(const QByteArray &serialized);
 	void setCurrentProxy(
 		const MTP::ProxyData &proxy,
 		MTP::ProxyData::Settings settings);
@@ -183,9 +184,6 @@ public:
 	}
 
 	// Internal links.
-	void setInternalLinkDomain(const QString &domain) const;
-	[[nodiscard]] QString createInternalLink(const QString &query) const;
-	[[nodiscard]] QString createInternalLinkFull(const QString &query) const;
 	void checkStartUrl();
 	bool openLocalUrl(const QString &url, QVariant context);
 	bool openInternalUrl(const QString &url, QVariant context);
@@ -231,7 +229,6 @@ public:
 	void handleAppDeactivated();
 
 	void switchDebugMode();
-	void switchTestMode();
 	void switchFreeType();
 	void writeInstallBetaVersionsSetting();
 
@@ -284,7 +281,7 @@ private:
 
 	const std::unique_ptr<Storage::Databases> _databases;
 	const std::unique_ptr<Ui::Animations::Manager> _animationsManager;
-	const std::unique_ptr<MTP::DcOptions> _dcOptions;
+	mutable std::unique_ptr<MTP::Config> _fallbackProductionConfig;
 	const std::unique_ptr<Main::Accounts> _accounts;
 	std::unique_ptr<Window::Controller> _window;
 	std::unique_ptr<Media::View::OverlayWidget> _mediaView;
diff --git a/Telegram/SourceFiles/core/launcher.cpp b/Telegram/SourceFiles/core/launcher.cpp
index b15a25c40..85ef0654e 100644
--- a/Telegram/SourceFiles/core/launcher.cpp
+++ b/Telegram/SourceFiles/core/launcher.cpp
@@ -97,12 +97,6 @@ void ComputeDebugMode() {
 	}
 }
 
-void ComputeTestMode() {
-	if (QFile::exists(cWorkingDir() + qsl("tdata/withtestmode"))) {
-		cSetTestMode(true);
-	}
-}
-
 void ComputeExternalUpdater() {
 	QFile file(qsl("/etc/tdesktop/externalupdater"));
 
@@ -350,7 +344,6 @@ int Launcher::exec() {
 void Launcher::workingFolderReady() {
 	srand((unsigned int)time(nullptr));
 
-	ComputeTestMode();
 	ComputeDebugMode();
 	ComputeExternalUpdater();
 	ComputeFreeType();
@@ -476,7 +469,6 @@ void Launcher::processArguments() {
 	if (parseResult.contains("-externalupdater")) {
 		SetUpdaterDisabledAtStartup();
 	}
-	gTestMode = parseResult.contains("-testmode");
 	gUseFreeType = parseResult.contains("-freetype");
 	Logs::SetDebugEnabled(parseResult.contains("-debug"));
 	gManyInstance = parseResult.contains("-many");
diff --git a/Telegram/SourceFiles/data/data_folder.cpp b/Telegram/SourceFiles/data/data_folder.cpp
index 06ef2d1fa..9d0065dff 100644
--- a/Telegram/SourceFiles/data/data_folder.cpp
+++ b/Telegram/SourceFiles/data/data_folder.cpp
@@ -20,9 +20,9 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "main/main_account.h"
 //#include "storage/storage_feed_messages.h" // #feed
 #include "main/main_session.h"
+#include "mtproto/mtproto_config.h"
 #include "apiwrap.h"
 #include "mainwidget.h"
-#include "facades.h"
 #include "styles/style_dialogs.h"
 
 namespace Data {
@@ -31,17 +31,6 @@ namespace {
 constexpr auto kLoadedChatsMinCount = 20;
 constexpr auto kShowChatNamesCount = 8;
 
-rpl::producer<int> PinnedDialogsInFolderMaxValue(
-		not_null<Main::Session*> session) {
-	return rpl::single(
-		rpl::empty_value()
-	) | rpl::then(
-		session->account().configUpdates()
-	) | rpl::map([=] {
-		return Global::PinnedDialogsInFolderMax();
-	});
-}
-
 } // namespace
 
 // #feed
@@ -60,7 +49,7 @@ Folder::Folder(not_null<Data::Session*> owner, FolderId id)
 , _chatsList(
 	&owner->session(),
 	FilterId(),
-	PinnedDialogsInFolderMaxValue(&owner->session()))
+	owner->session().serverConfig().pinnedDialogsInFolderMax.value())
 , _name(tr::lng_archived_name(tr::now)) {
 	indexNameParts();
 
diff --git a/Telegram/SourceFiles/data/data_peer.cpp b/Telegram/SourceFiles/data/data_peer.cpp
index 4b1aadc1c..6a50820ae 100644
--- a/Telegram/SourceFiles/data/data_peer.cpp
+++ b/Telegram/SourceFiles/data/data_peer.cpp
@@ -24,6 +24,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "main/main_session.h"
 #include "main/main_account.h"
 #include "main/main_app_config.h"
+#include "mtproto/mtproto_config.h"
 #include "core/application.h"
 #include "mainwindow.h"
 #include "window/window_session_controller.h"
@@ -34,7 +35,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "history/view/history_view_element.h"
 #include "history/history_item.h"
 #include "storage/file_download.h"
-#include "facades.h"
+#include "facades.h" // Ui::showPeerProfile
 #include "app.h"
 
 namespace {
@@ -763,8 +764,8 @@ Data::RestrictionCheckResult PeerData::amRestricted(
 bool PeerData::canRevokeFullHistory() const {
 	return isUser()
 		&& !isSelf()
-		&& Global::RevokePrivateInbox()
-		&& (Global::RevokePrivateTimeLimit() == 0x7FFFFFFF);
+		&& session().serverConfig().revokePrivateInbox
+		&& (session().serverConfig().revokePrivateTimeLimit == 0x7FFFFFFF);
 }
 
 bool PeerData::slowmodeApplied() const {
diff --git a/Telegram/SourceFiles/data/data_session.cpp b/Telegram/SourceFiles/data/data_session.cpp
index 56e5642a0..c4108d54d 100644
--- a/Telegram/SourceFiles/data/data_session.cpp
+++ b/Telegram/SourceFiles/data/data_session.cpp
@@ -18,6 +18,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "ui/image/image_location_factory.h" // Images::FromPhotoSize
 #include "export/export_controller.h"
 #include "export/view/export_view_panel_controller.h"
+#include "mtproto/mtproto_config.h"
 #include "window/notifications_manager.h"
 #include "history/history.h"
 #include "history/history_item_components.h"
@@ -54,7 +55,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "base/platform/base_platform_info.h"
 #include "base/unixtime.h"
 #include "base/call_delayed.h"
-#include "facades.h"
+#include "facades.h" // Notify::switchInlineBotButtonReceived
 #include "app.h"
 #include "styles/style_boxes.h" // st::backgroundSize
 
@@ -188,17 +189,6 @@ std::vector<UnavailableReason> ExtractUnavailableReasons(
 	return FindInlineThumbnail(data.vsizes().v);
 }
 
-[[nodiscard]] rpl::producer<int> PinnedDialogsCountMaxValue(
-		not_null<Main::Session*> session) {
-	return rpl::single(
-		rpl::empty_value()
-	) | rpl::then(
-		session->account().configUpdates()
-	) | rpl::map([=] {
-		return Global::PinnedDialogsCountMax();
-	});
-}
-
 } // namespace
 
 Session::Session(not_null<Main::Session*> session)
@@ -209,7 +199,10 @@ Session::Session(not_null<Main::Session*> session)
 , _bigFileCache(Core::App().databases().get(
 	_session->local().cacheBigFilePath(),
 	_session->local().cacheBigFileSettings()))
-, _chatsList(session, FilterId(), PinnedDialogsCountMaxValue(session))
+, _chatsList(
+	session,
+	FilterId(),
+	session->serverConfig().pinnedDialogsCountMax.value())
 , _contactsList(Dialogs::SortMode::Name)
 , _contactsNoChatsList(Dialogs::SortMode::Name)
 , _selfDestructTimer([=] { checkSelfDestructItems(); })
@@ -929,7 +922,7 @@ void Session::startExport(const MTPInputPeer &singlePeer) {
 		return;
 	}
 	_export = std::make_unique<Export::Controller>(
-		session().mtp().get(),
+		&session().mtp(),
 		singlePeer);
 	_exportPanel = std::make_unique<Export::View::PanelController>(
 		&session(),
@@ -1660,8 +1653,8 @@ int Session::pinnedChatsLimit(
 		FilterId filterId) const {
 	if (!filterId) {
 		return folder
-			? Global::PinnedDialogsInFolderMax()
-			: Global::PinnedDialogsCountMax();
+			? session().serverConfig().pinnedDialogsInFolderMax.current()
+			: session().serverConfig().pinnedDialogsCountMax.current();
 	}
 	const auto &list = chatsFilters().list();
 	const auto i = ranges::find(list, filterId, &Data::ChatFilter::id);
diff --git a/Telegram/SourceFiles/data/data_types.cpp b/Telegram/SourceFiles/data/data_types.cpp
index bd54884b8..39d845878 100644
--- a/Telegram/SourceFiles/data/data_types.cpp
+++ b/Telegram/SourceFiles/data/data_types.cpp
@@ -48,7 +48,7 @@ Storage::Cache::Key DocumentThumbCacheKey(int32 dcId, uint64 id) {
 }
 
 Storage::Cache::Key WebDocumentCacheKey(const WebFileLocation &location) {
-	const auto CacheDcId = cTestMode() ? 2 : 4;
+	const auto CacheDcId = 4; // The default production value. Doesn't matter.
 	const auto dcId = uint64(CacheDcId) & 0xFFULL;
 	const auto &url = location.url();
 	const auto hash = openssl::Sha256(bytes::make_span(url));
diff --git a/Telegram/SourceFiles/data/data_wall_paper.cpp b/Telegram/SourceFiles/data/data_wall_paper.cpp
index 0b54c0de7..e8437169c 100644
--- a/Telegram/SourceFiles/data/data_wall_paper.cpp
+++ b/Telegram/SourceFiles/data/data_wall_paper.cpp
@@ -154,11 +154,11 @@ bool WallPaper::hasShareUrl() const {
 	return !_slug.isEmpty();
 }
 
-QString WallPaper::shareUrl() const {
+QString WallPaper::shareUrl(not_null<Main::Session*> session) const {
 	if (!hasShareUrl()) {
 		return QString();
 	}
-	const auto base = Core::App().createInternalLinkFull("bg/" + _slug);
+	const auto base = session->createInternalLinkFull("bg/" + _slug);
 	auto params = QStringList();
 	if (isPattern()) {
 		if (_backgroundColor) {
diff --git a/Telegram/SourceFiles/data/data_wall_paper.h b/Telegram/SourceFiles/data/data_wall_paper.h
index 50fef65e0..98957c78e 100644
--- a/Telegram/SourceFiles/data/data_wall_paper.h
+++ b/Telegram/SourceFiles/data/data_wall_paper.h
@@ -35,7 +35,7 @@ public:
 	[[nodiscard]] bool isBlurred() const;
 	[[nodiscard]] int patternIntensity() const;
 	[[nodiscard]] bool hasShareUrl() const;
-	[[nodiscard]] QString shareUrl() const;
+	[[nodiscard]] QString shareUrl(not_null<Main::Session*> session) const;
 
 	void loadDocument() const;
 	void loadDocumentThumbnail() const;
diff --git a/Telegram/SourceFiles/data/stickers/data_stickers.cpp b/Telegram/SourceFiles/data/stickers/data_stickers.cpp
index 39bbcb5e5..e5daeb82c 100644
--- a/Telegram/SourceFiles/data/stickers/data_stickers.cpp
+++ b/Telegram/SourceFiles/data/stickers/data_stickers.cpp
@@ -19,10 +19,10 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "apiwrap.h"
 #include "storage/storage_account.h"
 #include "main/main_session.h"
+#include "mtproto/mtproto_config.h"
 #include "ui/toast/toast.h"
 #include "ui/image/image_location_factory.h"
 #include "base/unixtime.h"
-#include "facades.h"
 #include "styles/style_chat_helpers.h"
 
 namespace Data {
@@ -142,7 +142,9 @@ void Stickers::incrementSticker(not_null<DocumentData*> document) {
 			break;
 		}
 	}
-	while (!recent.isEmpty() && set->stickers.size() + recent.size() > Global::StickersRecentLimit()) {
+	while (!recent.isEmpty()
+		&& (set->stickers.size() + recent.size()
+			> session().serverConfig().stickersRecentLimit)) {
 		writeOldRecent = true;
 		recent.pop_back();
 	}
@@ -184,7 +186,7 @@ void Stickers::addSavedGif(not_null<DocumentData*> document) {
 		_savedGifs.remove(index);
 	}
 	_savedGifs.push_front(document);
-	if (_savedGifs.size() > Global::SavedGifsLimit()) {
+	if (_savedGifs.size() > session().serverConfig().savedGifsLimit) {
 		_savedGifs.pop_back();
 	}
 	session().local().writeSavedGifs();
@@ -387,7 +389,7 @@ bool Stickers::isFaved(not_null<const DocumentData*> document) {
 }
 
 void Stickers::checkFavedLimit(StickersSet &set) {
-	if (set.stickers.size() <= Global::StickersFavedLimit()) {
+	if (set.stickers.size() <= session().serverConfig().stickersFavedLimit) {
 		return;
 	}
 	auto removing = set.stickers.back();
diff --git a/Telegram/SourceFiles/export/view/export_view_panel_controller.cpp b/Telegram/SourceFiles/export/view/export_view_panel_controller.cpp
index 4c98e7f6c..c8435ce5c 100644
--- a/Telegram/SourceFiles/export/view/export_view_panel_controller.cpp
+++ b/Telegram/SourceFiles/export/view/export_view_panel_controller.cpp
@@ -12,6 +12,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "ui/widgets/labels.h"
 #include "ui/widgets/separate_panel.h"
 #include "ui/wrap/padding_wrap.h"
+#include "mtproto/mtproto_config.h"
 #include "boxes/confirm_box.h"
 #include "lang/lang_keys.h"
 #include "storage/storage_account.h"
@@ -20,7 +21,6 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "data/data_session.h"
 #include "base/platform/base_platform_info.h"
 #include "base/unixtime.h"
-#include "facades.h"
 #include "styles/style_export.h"
 #include "styles/style_layers.h"
 
@@ -77,9 +77,9 @@ void SuggestBox::prepare() {
 
 } // namespace
 
-Environment PrepareEnvironment() {
+Environment PrepareEnvironment(not_null<Main::Session*> session) {
 	auto result = Environment();
-	result.internalLinksDomain = Global::InternalLinksDomain();
+	result.internalLinksDomain = session->serverConfig().internalLinksDomain;
 	result.aboutTelegram = tr::lng_export_about_telegram(tr::now).toUtf8();
 	result.aboutContacts = tr::lng_export_about_contacts(tr::now).toUtf8();
 	result.aboutFrequent = tr::lng_export_about_frequent(tr::now).toUtf8();
@@ -188,7 +188,7 @@ void PanelController::showSettings() {
 	settings->startClicks(
 	) | rpl::start_with_next([=]() {
 		showProgress();
-		_process->startExport(*_settings, PrepareEnvironment());
+		_process->startExport(*_settings, PrepareEnvironment(_session));
 	}, settings->lifetime());
 
 	settings->cancelClicks(
diff --git a/Telegram/SourceFiles/export/view/export_view_panel_controller.h b/Telegram/SourceFiles/export/view/export_view_panel_controller.h
index ddcf2cba7..afed15f1b 100644
--- a/Telegram/SourceFiles/export/view/export_view_panel_controller.h
+++ b/Telegram/SourceFiles/export/view/export_view_panel_controller.h
@@ -22,12 +22,8 @@ class Session;
 } // namespace Main
 
 namespace Export {
-
-struct Environment;
-
 namespace View {
 
-Environment PrepareEnvironment();
 QPointer<Ui::BoxContent> SuggestStart(not_null<Main::Session*> session);
 void ClearSuggestStart(not_null<Main::Session*> session);
 bool IsDefaultPath(not_null<Main::Session*> session, const QString &path);
diff --git a/Telegram/SourceFiles/facades.cpp b/Telegram/SourceFiles/facades.cpp
index d101f9df6..8e72aed3d 100644
--- a/Telegram/SourceFiles/facades.cpp
+++ b/Telegram/SourceFiles/facades.cpp
@@ -356,43 +356,6 @@ struct Data {
 	float64 VideoVolume = kDefaultVolume;
 	base::Observable<void> VideoVolumeChanged;
 
-	// config
-	int32 ChatSizeMax = 200;
-	int32 MegagroupSizeMax = 10000;
-	int32 ForwardedCountMax = 100;
-	int32 OnlineUpdatePeriod = 120000;
-	int32 OfflineBlurTimeout = 5000;
-	int32 OfflineIdleTimeout = 30000;
-	int32 OnlineFocusTimeout = 1000;
-	int32 OnlineCloudTimeout = 300000;
-	int32 NotifyCloudDelay = 30000;
-	int32 NotifyDefaultDelay = 1500;
-	int32 PushChatPeriod = 60000;
-	int32 PushChatLimit = 2;
-	int32 SavedGifsLimit = 200;
-	int32 EditTimeLimit = 172800;
-	int32 RevokeTimeLimit = 172800;
-	int32 RevokePrivateTimeLimit = 172800;
-	bool RevokePrivateInbox = false;
-	int32 StickersRecentLimit = 30;
-	int32 StickersFavedLimit = 5;
-	int32 PinnedDialogsCountMax = 5;
-	int32 PinnedDialogsInFolderMax = 100;
-	QString InternalLinksDomain = qsl("https://t.me/");
-	int32 ChannelsReadMediaPeriod = 86400 * 7;
-	int32 CallReceiveTimeoutMs = 20000;
-	int32 CallRingTimeoutMs = 90000;
-	int32 CallConnectTimeoutMs = 30000;
-	int32 CallPacketTimeoutMs = 10000;
-	int32 WebFileDcId = cTestMode() ? 2 : 4;
-	QString TxtDomainString = cTestMode()
-		? qsl("tapv3.stel.com")
-		: qsl("apv3.stel.com");
-	bool PhoneCallsEnabled = true;
-	bool BlockedMode = false;
-	int32 CaptionLengthMax = 1024;
-	base::Observable<void> PhoneCallsEnabledChanged;
-
 	HiddenPinnedMessagesMap HiddenPinnedMessages;
 
 	bool AskDownloadPath = false;
@@ -475,41 +438,6 @@ DefineRefVar(Global, base::Observable<void>, SongVolumeChanged);
 DefineVar(Global, float64, VideoVolume);
 DefineRefVar(Global, base::Observable<void>, VideoVolumeChanged);
 
-// config
-DefineVar(Global, int32, ChatSizeMax);
-DefineVar(Global, int32, MegagroupSizeMax);
-DefineVar(Global, int32, ForwardedCountMax);
-DefineVar(Global, int32, OnlineUpdatePeriod);
-DefineVar(Global, int32, OfflineBlurTimeout);
-DefineVar(Global, int32, OfflineIdleTimeout);
-DefineVar(Global, int32, OnlineFocusTimeout);
-DefineVar(Global, int32, OnlineCloudTimeout);
-DefineVar(Global, int32, NotifyCloudDelay);
-DefineVar(Global, int32, NotifyDefaultDelay);
-DefineVar(Global, int32, PushChatPeriod);
-DefineVar(Global, int32, PushChatLimit);
-DefineVar(Global, int32, SavedGifsLimit);
-DefineVar(Global, int32, EditTimeLimit);
-DefineVar(Global, int32, RevokeTimeLimit);
-DefineVar(Global, int32, RevokePrivateTimeLimit);
-DefineVar(Global, bool, RevokePrivateInbox);
-DefineVar(Global, int32, StickersRecentLimit);
-DefineVar(Global, int32, StickersFavedLimit);
-DefineVar(Global, int32, PinnedDialogsCountMax);
-DefineVar(Global, int32, PinnedDialogsInFolderMax);
-DefineVar(Global, QString, InternalLinksDomain);
-DefineVar(Global, int32, ChannelsReadMediaPeriod);
-DefineVar(Global, int32, CallReceiveTimeoutMs);
-DefineVar(Global, int32, CallRingTimeoutMs);
-DefineVar(Global, int32, CallConnectTimeoutMs);
-DefineVar(Global, int32, CallPacketTimeoutMs);
-DefineVar(Global, int32, WebFileDcId);
-DefineVar(Global, QString, TxtDomainString);
-DefineVar(Global, bool, PhoneCallsEnabled);
-DefineVar(Global, bool, BlockedMode);
-DefineVar(Global, int32, CaptionLengthMax);
-DefineRefVar(Global, base::Observable<void>, PhoneCallsEnabledChanged);
-
 DefineVar(Global, HiddenPinnedMessagesMap, HiddenPinnedMessages);
 
 DefineVar(Global, bool, AskDownloadPath);
diff --git a/Telegram/SourceFiles/facades.h b/Telegram/SourceFiles/facades.h
index 7d5be71e5..f83201fac 100644
--- a/Telegram/SourceFiles/facades.h
+++ b/Telegram/SourceFiles/facades.h
@@ -166,41 +166,6 @@ DeclareRefVar(base::Observable<void>, SongVolumeChanged);
 DeclareVar(float64, VideoVolume);
 DeclareRefVar(base::Observable<void>, VideoVolumeChanged);
 
-// config
-DeclareVar(int32, ChatSizeMax);
-DeclareVar(int32, MegagroupSizeMax);
-DeclareVar(int32, ForwardedCountMax);
-DeclareVar(int32, OnlineUpdatePeriod);
-DeclareVar(int32, OfflineBlurTimeout);
-DeclareVar(int32, OfflineIdleTimeout);
-DeclareVar(int32, OnlineFocusTimeout); // not from config
-DeclareVar(int32, OnlineCloudTimeout);
-DeclareVar(int32, NotifyCloudDelay);
-DeclareVar(int32, NotifyDefaultDelay);
-DeclareVar(int32, PushChatPeriod);
-DeclareVar(int32, PushChatLimit);
-DeclareVar(int32, SavedGifsLimit);
-DeclareVar(int32, EditTimeLimit);
-DeclareVar(int32, RevokeTimeLimit);
-DeclareVar(int32, RevokePrivateTimeLimit);
-DeclareVar(bool, RevokePrivateInbox);
-DeclareVar(int32, StickersRecentLimit);
-DeclareVar(int32, StickersFavedLimit);
-DeclareVar(int32, PinnedDialogsCountMax);
-DeclareVar(int32, PinnedDialogsInFolderMax);
-DeclareVar(QString, InternalLinksDomain);
-DeclareVar(int32, ChannelsReadMediaPeriod);
-DeclareVar(int32, CallReceiveTimeoutMs);
-DeclareVar(int32, CallRingTimeoutMs);
-DeclareVar(int32, CallConnectTimeoutMs);
-DeclareVar(int32, CallPacketTimeoutMs);
-DeclareVar(int32, WebFileDcId);
-DeclareVar(QString, TxtDomainString);
-DeclareVar(bool, PhoneCallsEnabled);
-DeclareVar(bool, BlockedMode);
-DeclareVar(int32, CaptionLengthMax);
-DeclareRefVar(base::Observable<void>, PhoneCallsEnabledChanged);
-
 typedef QMap<PeerId, MsgId> HiddenPinnedMessagesMap;
 DeclareVar(HiddenPinnedMessagesMap, HiddenPinnedMessages);
 
diff --git a/Telegram/SourceFiles/history/admin_log/history_admin_log_inner.cpp b/Telegram/SourceFiles/history/admin_log/history_admin_log_inner.cpp
index 43d800cd3..4ab2d87c2 100644
--- a/Telegram/SourceFiles/history/admin_log/history_admin_log_inner.cpp
+++ b/Telegram/SourceFiles/history/admin_log/history_admin_log_inner.cpp
@@ -229,7 +229,7 @@ InnerWidget::InnerWidget(
 , _controller(controller)
 , _channel(channel)
 , _history(channel->owner().history(channel))
-, _api(_channel->session().mtp())
+, _api(&_channel->session().mtp())
 , _scrollDateCheck([=] { scrollDateCheck(); })
 , _emptyText(
 		st::historyAdminLogEmptyWidth
diff --git a/Telegram/SourceFiles/history/admin_log/history_admin_log_item.cpp b/Telegram/SourceFiles/history/admin_log/history_admin_log_item.cpp
index 97ab2bf4e..e3939d03c 100644
--- a/Telegram/SourceFiles/history/admin_log/history_admin_log_item.cpp
+++ b/Telegram/SourceFiles/history/admin_log/history_admin_log_item.cpp
@@ -472,7 +472,11 @@ void GenerateItems(
 		auto bodyClientFlags = MTPDmessage_ClientFlag::f_admin_log_entry;
 		auto bodyReplyTo = 0;
 		auto bodyViaBotId = 0;
-		auto newLink = newValue.isEmpty() ? TextWithEntities() : PrepareText(Core::App().createInternalLinkFull(newValue), QString());
+		auto newLink = newValue.isEmpty()
+			? TextWithEntities()
+			: PrepareText(
+				history->session().createInternalLinkFull(newValue),
+				QString());
 		auto body = history->makeMessage(
 			history->nextNonHistoryEntryId(),
 			bodyFlags,
@@ -484,7 +488,9 @@ void GenerateItems(
 			QString(),
 			newLink);
 		if (!oldValue.isEmpty()) {
-			auto oldLink = PrepareText(Core::App().createInternalLinkFull(oldValue), QString());
+			auto oldLink = PrepareText(
+				history->session().createInternalLinkFull(oldValue),
+				QString());
 			body->addLogEntryOriginal(id, tr::lng_admin_log_previous_link(tr::now), oldLink);
 		}
 		addPart(body);
diff --git a/Telegram/SourceFiles/history/history_item.cpp b/Telegram/SourceFiles/history/history_item.cpp
index eccfe232f..9d00e1a6f 100644
--- a/Telegram/SourceFiles/history/history_item.cpp
+++ b/Telegram/SourceFiles/history/history_item.cpp
@@ -17,6 +17,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "history/history_service.h"
 #include "history/history_message.h"
 #include "history/history.h"
+#include "mtproto/mtproto_config.h"
 #include "media/clip/media_clip_reader.h"
 #include "ui/effects/ripple_animation.h"
 #include "ui/text/text_isolated_emoji.h"
@@ -42,7 +43,6 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "data/data_channel.h"
 #include "data/data_chat.h"
 #include "data/data_user.h"
-#include "facades.h"
 #include "styles/style_dialogs.h"
 #include "styles/style_history.h"
 
@@ -289,7 +289,8 @@ void HistoryItem::finishEditionToEmpty() {
 bool HistoryItem::hasUnreadMediaFlag() const {
 	if (_history->peer->isChannel()) {
 		const auto passed = base::unixtime::now() - date();
-		if (passed >= Global::ChannelsReadMediaPeriod()) {
+		const auto &config = _history->session().serverConfig();
+		if (passed >= config.channelsReadMediaPeriod) {
 			return false;
 		}
 	}
@@ -566,12 +567,13 @@ bool HistoryItem::canDelete() const {
 
 bool HistoryItem::canDeleteForEveryone(TimeId now) const {
 	const auto peer = history()->peer;
+	const auto &config = history()->session().serverConfig();
 	const auto messageToMyself = peer->isSelf();
 	const auto messageTooOld = messageToMyself
 		? false
 		: peer->isUser()
-		? (now - date() >= Global::RevokePrivateTimeLimit())
-		: (now - date() >= Global::RevokeTimeLimit());
+		? (now - date() >= config.revokePrivateTimeLimit)
+		: (now - date() >= config.revokeTimeLimit);
 	if (id < 0 || messageToMyself || messageTooOld || isPost()) {
 		return false;
 	}
@@ -599,7 +601,7 @@ bool HistoryItem::canDeleteForEveryone(TimeId now) const {
 				return false;
 			}
 		} else if (peer->isUser()) {
-			return Global::RevokePrivateInbox();
+			return config.revokePrivateInbox;
 		} else {
 			return false;
 		}
diff --git a/Telegram/SourceFiles/history/history_message.cpp b/Telegram/SourceFiles/history/history_message.cpp
index 8e9baca51..b2b256276 100644
--- a/Telegram/SourceFiles/history/history_message.cpp
+++ b/Telegram/SourceFiles/history/history_message.cpp
@@ -33,6 +33,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "window/notifications_manager.h"
 #include "window/window_session_controller.h"
 #include "storage/storage_shared_media.h"
+#include "mtproto/mtproto_config.h"
 #include "data/data_session.h"
 #include "data/data_changes.h"
 #include "data/data_game.h"
@@ -40,7 +41,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "data/data_channel.h"
 #include "data/data_user.h"
 #include "data/data_histories.h"
-#include "facades.h"
+#include "facades.h" // Notify::replyMarkupUpdated
 #include "app.h"
 #include "styles/style_dialogs.h"
 #include "styles/style_widgets.h"
@@ -208,6 +209,7 @@ void FastShareMessage(not_null<HistoryItem*> item) {
 	};
 	const auto history = item->history();
 	const auto owner = &history->owner();
+	const auto session = &history->session();
 	const auto data = std::make_shared<ShareData>(
 		history->peer,
 		owner->itemOrItsGroup(item));
@@ -220,13 +222,11 @@ void FastShareMessage(not_null<HistoryItem*> item) {
 	auto copyCallback = [=]() {
 		if (const auto item = owner->message(data->msgIds[0])) {
 			if (item->hasDirectLink()) {
-				HistoryView::CopyPostLink(
-					&item->history()->session(),
-					item->fullId());
+				HistoryView::CopyPostLink(session, item->fullId());
 			} else if (const auto bot = item->getMessageBot()) {
 				if (const auto media = item->media()) {
 					if (const auto game = media->game()) {
-						const auto link = Core::App().createInternalLinkFull(
+						const auto link = session->createInternalLinkFull(
 							bot->username
 							+ qsl("?game=")
 							+ game->shortName);
@@ -782,7 +782,7 @@ bool HistoryMessage::allowsSendNow() const {
 
 bool HistoryMessage::isTooOldForEdit(TimeId now) const {
 	return !_history->peer->canEditMessagesIndefinitely()
-		&& (now - date() >= Global::EditTimeLimit());
+		&& (now - date() >= _history->session().serverConfig().editTimeLimit);
 }
 
 bool HistoryMessage::allowsEdit(TimeId now) const {
diff --git a/Telegram/SourceFiles/history/history_widget.cpp b/Telegram/SourceFiles/history/history_widget.cpp
index dc169c5ea..5f3630eec 100644
--- a/Telegram/SourceFiles/history/history_widget.cpp
+++ b/Telegram/SourceFiles/history/history_widget.cpp
@@ -65,6 +65,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "chat_helpers/bot_keyboard.h"
 #include "chat_helpers/message_field.h"
 #include "platform/platform_specific.h"
+#include "mtproto/mtproto_config.h"
 #include "lang/lang_keys.h"
 #include "mainwidget.h"
 #include "mainwindow.h"
@@ -6756,7 +6757,7 @@ void HistoryWidget::paintEditHeader(Painter &p, const QRect &rect, int left, int
 	QString editTimeLeftText;
 	int updateIn = -1;
 	auto timeSinceMessage = ItemDateTime(_replyEditMsg).msecsTo(QDateTime::currentDateTime());
-	auto editTimeLeft = (Global::EditTimeLimit() * 1000LL) - timeSinceMessage;
+	auto editTimeLeft = (session().serverConfig().editTimeLimit * 1000LL) - timeSinceMessage;
 	if (editTimeLeft < 2) {
 		editTimeLeftText = qsl("0:00");
 	} else if (editTimeLeft > kDisplayEditTimeWarningMs) {
diff --git a/Telegram/SourceFiles/history/view/history_view_top_bar_widget.cpp b/Telegram/SourceFiles/history/view/history_view_top_bar_widget.cpp
index 4d2fc67d8..94c5928be 100644
--- a/Telegram/SourceFiles/history/view/history_view_top_bar_widget.cpp
+++ b/Telegram/SourceFiles/history/view/history_view_top_bar_widget.cpp
@@ -18,6 +18,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "mainwidget.h"
 #include "mainwindow.h"
 #include "main/main_session.h"
+#include "mtproto/mtproto_config.h"
 #include "lang/lang_keys.h"
 #include "core/shortcuts.h"
 #include "ui/widgets/buttons.h"
@@ -129,9 +130,10 @@ TopBarWidget::TopBarWidget(
 		}
 	}, lifetime());
 
-	subscribe(Global::RefPhoneCallsEnabledChanged(), [this] {
+	session().serverConfig().phoneCallsEnabled.changes(
+	) | rpl::start_with_next([=] {
 		updateControlsVisibility();
-	});
+	}, lifetime());
 
 	rpl::combine(
 		session().settings().thirdSectionInfoEnabledValue(),
@@ -156,8 +158,8 @@ Main::Session &TopBarWidget::session() const {
 }
 
 void TopBarWidget::updateConnectingState() {
-	const auto mtp = _controller->session().mtp()->dcstate();
-	if (mtp == MTP::ConnectedState) {
+	const auto state = _controller->session().mtp().dcstate();
+	if (state == MTP::ConnectedState) {
 		if (_connecting) {
 			_connecting = nullptr;
 			update();
@@ -640,7 +642,8 @@ void TopBarWidget::updateControlsVisibility() {
 	const auto callsEnabled = [&] {
 		if (const auto peer = _activeChat.peer()) {
 			if (const auto user = peer->asUser()) {
-				return Global::PhoneCallsEnabled() && user->hasCalls();
+				return session().serverConfig().phoneCallsEnabled.current()
+					&& user->hasCalls();
 			}
 		}
 		return false;
@@ -663,7 +666,9 @@ void TopBarWidget::updateMembersShowArea() {
 			return chat->amIn();
 		}
 		if (auto megagroup = peer->asMegagroup()) {
-			return megagroup->canViewMembers() && (megagroup->membersCount() < Global::ChatSizeMax());
+			return megagroup->canViewMembers()
+				&& (megagroup->membersCount()
+					< megagroup->session().serverConfig().chatSizeMax);
 		}
 		return false;
 	}();
@@ -846,7 +851,10 @@ void TopBarWidget::updateOnlineDisplay() {
 			}
 		}
 	} else if (const auto channel = _activeChat.peer()->asChannel()) {
-		if (channel->isMegagroup() && channel->membersCount() > 0 && channel->membersCount() <= Global::ChatSizeMax()) {
+		if (channel->isMegagroup()
+			&& (channel->membersCount() > 0)
+			&& (channel->membersCount()
+				<= channel->session().serverConfig().chatSizeMax)) {
 			if (channel->lastParticipantsRequestNeeded()) {
 				session().api().requestLastParticipants(channel);
 			}
diff --git a/Telegram/SourceFiles/info/common_groups/info_common_groups_inner_widget.cpp b/Telegram/SourceFiles/info/common_groups/info_common_groups_inner_widget.cpp
index e68dc414e..f1905b000 100644
--- a/Telegram/SourceFiles/info/common_groups/info_common_groups_inner_widget.cpp
+++ b/Telegram/SourceFiles/info/common_groups/info_common_groups_inner_widget.cpp
@@ -68,7 +68,7 @@ ListController::ListController(
 	not_null<UserData*> user)
 : PeerListController()
 , _controller(controller)
-, _api(_controller->session().mtp())
+, _api(&_controller->session().mtp())
 , _user(user) {
 	_controller->setSearchEnabledByContent(false);
 }
diff --git a/Telegram/SourceFiles/info/info_wrap_widget.cpp b/Telegram/SourceFiles/info/info_wrap_widget.cpp
index c6bac04d4..73192e0dc 100644
--- a/Telegram/SourceFiles/info/info_wrap_widget.cpp
+++ b/Telegram/SourceFiles/info/info_wrap_widget.cpp
@@ -28,12 +28,12 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "boxes/peer_list_box.h"
 #include "boxes/confirm_box.h"
 #include "main/main_session.h"
+#include "mtproto/mtproto_config.h"
 #include "data/data_session.h"
 #include "data/data_changes.h"
 #include "data/data_user.h"
 #include "mainwidget.h"
 #include "lang/lang_keys.h"
-#include "facades.h"
 #include "styles/style_info.h"
 #include "styles/style_profile.h"
 
@@ -479,7 +479,9 @@ void WrapWidget::addProfileCallsButton() {
 
 	const auto peer = key().peer();
 	const auto user = peer ? peer->asUser() : nullptr;
-	if (!user || user->isSelf() || !Global::PhoneCallsEnabled()) {
+	if (!user
+		|| user->isSelf()
+		|| !user->session().serverConfig().phoneCallsEnabled.current()) {
 		return;
 	}
 
diff --git a/Telegram/SourceFiles/info/polls/info_polls_results_inner_widget.cpp b/Telegram/SourceFiles/info/polls/info_polls_results_inner_widget.cpp
index b25cb2570..4313c1865 100644
--- a/Telegram/SourceFiles/info/polls/info_polls_results_inner_widget.cpp
+++ b/Telegram/SourceFiles/info/polls/info_polls_results_inner_widget.cpp
@@ -232,7 +232,7 @@ ListController::ListController(
 , _poll(poll)
 , _context(context)
 , _option(option)
-, _api(_session->mtp()) {
+, _api(&_session->mtp()) {
 	const auto i = ranges::find(poll->answers, option, &PollAnswer::option);
 	Assert(i != poll->answers.end());
 	_fullCount = i->votes;
diff --git a/Telegram/SourceFiles/info/profile/info_profile_actions.cpp b/Telegram/SourceFiles/info/profile/info_profile_actions.cpp
index d3c704820..ad7d70d30 100644
--- a/Telegram/SourceFiles/info/profile/info_profile_actions.cpp
+++ b/Telegram/SourceFiles/info/profile/info_profile_actions.cpp
@@ -301,7 +301,7 @@ object_ptr<Ui::RpWidget> DetailsFiller::setupInfo() {
 			std::move(linkText),
 			QString());
 		link->setClickHandlerFilter([peer = _peer](auto&&...) {
-			const auto link = Core::App().createInternalLinkFull(
+			const auto link = peer->session().createInternalLinkFull(
 				peer->userName());
 			if (!link.isEmpty()) {
 				QGuiApplication::clipboard()->setText(link);
diff --git a/Telegram/SourceFiles/info/profile/info_profile_values.cpp b/Telegram/SourceFiles/info/profile/info_profile_values.cpp
index 9fdd180ef..6e1bbb549 100644
--- a/Telegram/SourceFiles/info/profile/info_profile_values.cpp
+++ b/Telegram/SourceFiles/info/profile/info_profile_values.cpp
@@ -133,10 +133,10 @@ rpl::producer<TextWithEntities> AboutValue(not_null<PeerData*> peer) {
 rpl::producer<QString> LinkValue(not_null<PeerData*> peer) {
 	return PlainUsernameValue(
 		peer
-	) | rpl::map([](QString &&username) {
+	) | rpl::map([=](QString &&username) {
 		return username.isEmpty()
 			? QString()
-			: Core::App().createInternalLinkFull(username);
+			: peer->session().createInternalLinkFull(username);
 	});
 }
 
diff --git a/Telegram/SourceFiles/inline_bots/inline_results_widget.cpp b/Telegram/SourceFiles/inline_bots/inline_results_widget.cpp
index 5c865404b..f8f3252a1 100644
--- a/Telegram/SourceFiles/inline_bots/inline_results_widget.cpp
+++ b/Telegram/SourceFiles/inline_bots/inline_results_widget.cpp
@@ -746,7 +746,7 @@ Widget::Widget(
 	not_null<Window::SessionController*> controller)
 : RpWidget(parent)
 , _controller(controller)
-, _api(_controller->session().mtp())
+, _api(&_controller->session().mtp())
 , _contentMaxHeight(st::emojiPanMaxHeight)
 , _contentHeight(_contentMaxHeight)
 , _scroll(this, st::inlineBotsScroll) {
diff --git a/Telegram/SourceFiles/intro/intro_code.cpp b/Telegram/SourceFiles/intro/intro_code.cpp
index b0e8ce2ae..24684ca48 100644
--- a/Telegram/SourceFiles/intro/intro_code.cpp
+++ b/Telegram/SourceFiles/intro/intro_code.cpp
@@ -211,9 +211,9 @@ void CodeWidget::finished() {
 }
 
 void CodeWidget::cancelled() {
-	api()->request(base::take(_sentRequest)).cancel();
-	api()->request(base::take(_callRequestId)).cancel();
-	api()->request(MTPauth_CancelCode(
+	api().request(base::take(_sentRequest)).cancel();
+	api().request(base::take(_callRequestId)).cancel();
+	api().request(MTPauth_CancelCode(
 		MTP_string(getData()->phone),
 		MTP_bytes(getData()->phoneHash)
 	)).send();
@@ -224,12 +224,12 @@ void CodeWidget::stopCheck() {
 }
 
 void CodeWidget::checkRequest() {
-	auto status = api()->instance()->state(_sentRequest);
+	auto status = api().instance().state(_sentRequest);
 	if (status < 0) {
 		auto leftms = -status;
 		if (leftms >= 1000) {
 			if (_sentRequest) {
-				api()->request(base::take(_sentRequest)).cancel();
+				api().request(base::take(_sentRequest)).cancel();
 				_sentCode.clear();
 			}
 		}
@@ -282,7 +282,7 @@ void CodeWidget::codeSubmitFail(const RPCError &error) {
 		showCodeError(tr::lng_bad_code());
 	} else if (err == qstr("SESSION_PASSWORD_NEEDED")) {
 		_checkRequestTimer.callEach(1000);
-		_sentRequest = api()->request(MTPaccount_GetPassword(
+		_sentRequest = api().request(MTPaccount_GetPassword(
 		)).done([=](const MTPaccount_Password &result) {
 			gotPassword(result);
 		}).fail([=](const RPCError &error) {
@@ -305,7 +305,7 @@ void CodeWidget::sendCall() {
 		if (--_callTimeout <= 0) {
 			_callStatus = CallStatus::Calling;
 			_callTimer.cancel();
-			_callRequestId = api()->request(MTPauth_ResendCode(
+			_callRequestId = api().request(MTPauth_ResendCode(
 				MTP_string(getData()->phone),
 				MTP_bytes(getData()->phoneHash)
 			)).done([=](const MTPauth_SentCode &result) {
@@ -383,7 +383,7 @@ void CodeWidget::submit() {
 	getData()->hasRecovery = false;
 	getData()->pwdHint = QString();
 	getData()->pwdNotEmptyPassport = false;
-	_sentRequest = api()->request(MTPauth_SignIn(
+	_sentRequest = api().request(MTPauth_SignIn(
 		MTP_string(getData()->phone),
 		MTP_bytes(getData()->phoneHash),
 		MTP_string(_sentCode)
@@ -398,7 +398,7 @@ void CodeWidget::noTelegramCode() {
 	if (_noTelegramCodeRequestId) {
 		return;
 	}
-	_noTelegramCodeRequestId = api()->request(MTPauth_ResendCode(
+	_noTelegramCodeRequestId = api().request(MTPauth_ResendCode(
 		MTP_string(getData()->phone),
 		MTP_bytes(getData()->phoneHash)
 	)).done([=](const MTPauth_SentCode &result) {
diff --git a/Telegram/SourceFiles/intro/intro_password_check.cpp b/Telegram/SourceFiles/intro/intro_password_check.cpp
index 76ac7b621..2a49f3255 100644
--- a/Telegram/SourceFiles/intro/intro_password_check.cpp
+++ b/Telegram/SourceFiles/intro/intro_password_check.cpp
@@ -114,7 +114,7 @@ void PasswordCheckWidget::activate() {
 }
 
 void PasswordCheckWidget::cancelled() {
-	api()->request(base::take(_sentRequest)).cancel();
+	api().request(base::take(_sentRequest)).cancel();
 }
 
 void PasswordCheckWidget::pwdSubmitDone(bool recover, const MTPauth_Authorization &result) {
@@ -181,8 +181,8 @@ void PasswordCheckWidget::checkPasswordHash() {
 }
 
 void PasswordCheckWidget::requestPasswordData() {
-	api()->request(base::take(_sentRequest)).cancel();
-	_sentRequest = api()->request(
+	api().request(base::take(_sentRequest)).cancel();
+	_sentRequest = api().request(
 		MTPaccount_GetPassword()
 	).done([=](const MTPaccount_Password &result) {
 		_sentRequest = 0;
@@ -204,7 +204,7 @@ void PasswordCheckWidget::passwordChecked() {
 		return serverError();
 	}
 	_request.id = 0;
-	_sentRequest = api()->request(
+	_sentRequest = api().request(
 		MTPauth_CheckPassword(check.result)
 	).done([=](const MTPauth_Authorization &result) {
 		pwdSubmitDone(false, result);
@@ -266,7 +266,7 @@ void PasswordCheckWidget::recoverStartFail(const RPCError &error) {
 void PasswordCheckWidget::toRecover() {
 	if (_hasRecovery) {
 		if (_sentRequest) {
-			api()->request(base::take(_sentRequest)).cancel();
+			api().request(base::take(_sentRequest)).cancel();
 		}
 		hideError();
 		_toRecover->hide();
@@ -278,7 +278,7 @@ void PasswordCheckWidget::toRecover() {
 		_codeField->setFocus();
 		updateDescriptionText();
 		if (_emailPattern.isEmpty()) {
-			api()->request(
+			api().request(
 				MTPauth_RequestPasswordRecovery()
 			).done([=](const MTPauth_PasswordRecovery &result) {
 				recoverStarted(result);
@@ -301,7 +301,7 @@ void PasswordCheckWidget::toPassword() {
 
 void PasswordCheckWidget::showReset() {
 	if (_sentRequest) {
-		api()->request(base::take(_sentRequest)).cancel();
+		api().request(base::take(_sentRequest)).cancel();
 	}
 	_toRecover->show();
 	_toPassword->hide();
@@ -334,7 +334,7 @@ void PasswordCheckWidget::submit() {
 			return;
 		}
 		const auto send = crl::guard(this, [=] {
-			_sentRequest = api()->request(
+			_sentRequest = api().request(
 				MTPauth_RecoverPassword(MTP_string(code))
 			).done([=](const MTPauth_Authorization &result) {
 				pwdSubmitDone(true, result);
diff --git a/Telegram/SourceFiles/intro/intro_phone.cpp b/Telegram/SourceFiles/intro/intro_phone.cpp
index 4e3d7cea9..9d250c47d 100644
--- a/Telegram/SourceFiles/intro/intro_phone.cpp
+++ b/Telegram/SourceFiles/intro/intro_phone.cpp
@@ -141,8 +141,8 @@ void PhoneWidget::submit() {
 	_checkRequestTimer.callEach(1000);
 
 	_sentPhone = phone;
-	api()->instance()->setUserPhone(_sentPhone);
-	_sentRequest = api()->request(MTPauth_SendCode(
+	api().instance().setUserPhone(_sentPhone);
+	_sentRequest = api().request(MTPauth_SendCode(
 		MTP_string(_sentPhone),
 		MTP_int(ApiId),
 		MTP_string(ApiHash),
@@ -159,11 +159,11 @@ void PhoneWidget::stopCheck() {
 }
 
 void PhoneWidget::checkRequest() {
-	auto status = api()->instance()->state(_sentRequest);
+	auto status = api().instance().state(_sentRequest);
 	if (status < 0) {
 		auto leftms = -status;
 		if (leftms >= 1000) {
-			api()->request(base::take(_sentRequest)).cancel();
+			api().request(base::take(_sentRequest)).cancel();
 		}
 	}
 	if (!_sentRequest && status == MTP::RequestSent) {
@@ -246,7 +246,7 @@ void PhoneWidget::finished() {
 }
 
 void PhoneWidget::cancelled() {
-	api()->request(base::take(_sentRequest)).cancel();
+	api().request(base::take(_sentRequest)).cancel();
 }
 
 } // namespace details
diff --git a/Telegram/SourceFiles/intro/intro_qr.cpp b/Telegram/SourceFiles/intro/intro_qr.cpp
index 84daee0b3..9cc11fbc1 100644
--- a/Telegram/SourceFiles/intro/intro_qr.cpp
+++ b/Telegram/SourceFiles/intro/intro_qr.cpp
@@ -308,7 +308,7 @@ void QrWidget::refreshCode() {
 	if (_requestId) {
 		return;
 	}
-	_requestId = api()->request(MTPauth_ExportLoginToken(
+	_requestId = api().request(MTPauth_ExportLoginToken(
 		MTP_int(ApiId),
 		MTP_string(ApiHash),
 		MTP_vector<MTPint>(0)
@@ -356,8 +356,8 @@ void QrWidget::showToken(const QByteArray &token) {
 void QrWidget::importTo(MTP::DcId dcId, const QByteArray &token) {
 	Expects(_requestId != 0);
 
-	api()->instance()->setMainDcId(dcId);
-	_requestId = api()->request(MTPauth_ImportLoginToken(
+	api().instance().setMainDcId(dcId);
+	_requestId = api().request(MTPauth_ImportLoginToken(
 		MTP_bytes(token)
 	)).done([=](const MTPauth_LoginToken &result) {
 		handleTokenResult(result);
@@ -382,7 +382,7 @@ void QrWidget::done(const MTPauth_Authorization &authorization) {
 }
 
 void QrWidget::sendCheckPasswordRequest() {
-	_requestId = api()->request(MTPaccount_GetPassword(
+	_requestId = api().request(MTPaccount_GetPassword(
 	)).done([=](const MTPaccount_Password &result) {
 		result.match([&](const MTPDaccount_password &data) {
 			getData()->pwdRequest = Core::ParseCloudPasswordCheckRequest(
@@ -426,7 +426,7 @@ void QrWidget::finished() {
 }
 
 void QrWidget::cancelled() {
-	api()->request(base::take(_requestId)).cancel();
+	api().request(base::take(_requestId)).cancel();
 }
 
 } // namespace details
diff --git a/Telegram/SourceFiles/intro/intro_signup.cpp b/Telegram/SourceFiles/intro/intro_signup.cpp
index f82a54576..df2d2c06d 100644
--- a/Telegram/SourceFiles/intro/intro_signup.cpp
+++ b/Telegram/SourceFiles/intro/intro_signup.cpp
@@ -101,7 +101,7 @@ void SignupWidget::activate() {
 }
 
 void SignupWidget::cancelled() {
-	api()->request(base::take(_sentRequest)).cancel();
+	api().request(base::take(_sentRequest)).cancel();
 }
 
 void SignupWidget::nameSubmitDone(const MTPauth_Authorization &result) {
@@ -181,7 +181,7 @@ void SignupWidget::submit() {
 
 		_firstName = _first->getLastText().trimmed();
 		_lastName = _last->getLastText().trimmed();
-		_sentRequest = api()->request(MTPauth_SignUp(
+		_sentRequest = api().request(MTPauth_SignUp(
 			MTP_string(getData()->phone),
 			MTP_bytes(getData()->phoneHash),
 			MTP_string(_firstName),
diff --git a/Telegram/SourceFiles/intro/intro_step.cpp b/Telegram/SourceFiles/intro/intro_step.cpp
index 1010b0beb..70c62b864 100644
--- a/Telegram/SourceFiles/intro/intro_step.cpp
+++ b/Telegram/SourceFiles/intro/intro_step.cpp
@@ -98,11 +98,11 @@ Step::Step(
 
 Step::~Step() = default;
 
-not_null<MTP::Sender*> Step::api() const {
+MTP::Sender &Step::api() const {
 	if (!_api) {
-		_api.emplace(_account->mtp());
+		_api.emplace(&_account->mtp());
 	}
-	return &*_api;
+	return *_api;
 }
 
 void Step::apiClear() {
diff --git a/Telegram/SourceFiles/intro/intro_step.h b/Telegram/SourceFiles/intro/intro_step.h
index 24b671196..1aa6c4a50 100644
--- a/Telegram/SourceFiles/intro/intro_step.h
+++ b/Telegram/SourceFiles/intro/intro_step.h
@@ -45,7 +45,7 @@ public:
 
 	// It should not be called in StartWidget, in other steps it should be
 	// present and not changing.
-	[[nodiscard]] not_null<MTP::Sender*> api() const;
+	[[nodiscard]] MTP::Sender &api() const;
 	void apiClear();
 
 	virtual void finishInit() {
diff --git a/Telegram/SourceFiles/intro/intro_widget.cpp b/Telegram/SourceFiles/intro/intro_widget.cpp
index 147efa6fb..33f1c3198 100644
--- a/Telegram/SourceFiles/intro/intro_widget.cpp
+++ b/Telegram/SourceFiles/intro/intro_widget.cpp
@@ -24,7 +24,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "ui/wrap/fade_wrap.h"
 #include "core/update_checker.h"
 #include "core/application.h"
-#include "mtproto/dc_options.h"
+#include "mtproto/mtproto_dc_options.h"
 #include "window/window_slide_animation.h"
 #include "window/window_connecting_widget.h"
 #include "base/platform/base_platform_info.h"
@@ -64,14 +64,11 @@ Widget::Widget(QWidget *parent, not_null<Main::Account*> account)
 	getData()->country = Platform::SystemCountry();
 
 	_account->mtpValue(
-	) | rpl::start_with_next([=](MTP::Instance *instance) {
-		if (instance) {
-			_api.emplace(instance);
-			createLanguageLink();
-		} else {
-			_api.reset();
-		}
+	) | rpl::start_with_next([=](not_null<MTP::Instance*> instance) {
+		_api.emplace(instance);
+		createLanguageLink();
 	}, lifetime());
+
 	subscribe(Lang::CurrentCloudManager().firstLanguageSuggestion(), [=] {
 		createLanguageLink();
 	});
@@ -141,9 +138,9 @@ void Widget::handleUpdates(const MTPUpdates &updates) {
 
 void Widget::handleUpdate(const MTPUpdate &update) {
 	update.match([&](const MTPDupdateDcOptions &data) {
-		Core::App().dcOptions()->addFromList(data.vdc_options());
+		_account->mtp().dcOptions().addFromList(data.vdc_options());
 	}, [&](const MTPDupdateConfig &data) {
-		_account->mtp()->requestConfig();
+		_account->mtp().requestConfig();
 	}, [&](const MTPDupdateServiceNotification &data) {
 		const auto text = TextWithEntities{
 			qs(data.vmessage()),
diff --git a/Telegram/SourceFiles/lang/lang_cloud_manager.cpp b/Telegram/SourceFiles/lang/lang_cloud_manager.cpp
index 61ae993dc..0351b03ea 100644
--- a/Telegram/SourceFiles/lang/lang_cloud_manager.cpp
+++ b/Telegram/SourceFiles/lang/lang_cloud_manager.cpp
@@ -160,15 +160,16 @@ CloudManager::CloudManager(Instance &langpack)
 : _langpack(langpack) {
 	Core::App().accounts().activeValue(
 	) | rpl::map([=](Main::Account *account) {
-		return account ? account->mtpValue() : rpl::never<MTP::Instance*>();
-	}) | rpl::flatten_latest(
-	) | rpl::start_with_next([=](MTP::Instance *instance) {
-		if (instance) {
-			_api.emplace(instance);
-			resendRequests();
-		} else {
+		if (!account) {
 			_api.reset();
 		}
+		return account
+			? account->mtpValue()
+			: rpl::never<not_null<MTP::Instance*>>();
+	}) | rpl::flatten_latest(
+	) | rpl::start_with_next([=](not_null<MTP::Instance*> instance) {
+		_api.emplace(instance);
+		resendRequests();
 	}, _lifetime);
 }
 
@@ -604,7 +605,7 @@ void CloudManager::switchLangPackId(const Language &data) {
 void CloudManager::changeIdAndReInitConnection(const Language &data) {
 	_langpack.switchToId(data);
 	if (_api) {
-		const auto mtproto = _api->instance();
+		const auto mtproto = &_api->instance();
 		mtproto->reInitConnection(mtproto->mainDcId());
 	}
 }
diff --git a/Telegram/SourceFiles/logs.cpp b/Telegram/SourceFiles/logs.cpp
index cfbc69a84..1c4bf00b6 100644
--- a/Telegram/SourceFiles/logs.cpp
+++ b/Telegram/SourceFiles/logs.cpp
@@ -414,16 +414,11 @@ void start(not_null<Core::Launcher*> launcher) {
 		LogsData = nullptr;
 	}
 
-	LOG(("Launched version: %1, "
-		"install beta: %2, "
-		"alpha: %3, "
-		"debug mode: %4, "
-		"test dc: %5"
+	LOG(("Launched version: %1, install beta: %2, alpha: %3, debug mode: %4"
 		).arg(AppVersion
 		).arg(Logs::b(cInstallBetaVersion())
 		).arg(cAlphaVersion()
-		).arg(Logs::b(DebugEnabled())
-		).arg(Logs::b(cTestMode())));
+		).arg(Logs::b(DebugEnabled())));
 	LOG(("Executable dir: %1, name: %2").arg(cExeDir()).arg(cExeName()));
 	LOG(("Initial working dir: %1").arg(initialWorkingDir));
 	LOG(("Working dir: %1").arg(cWorkingDir()));
diff --git a/Telegram/SourceFiles/main/main_account.cpp b/Telegram/SourceFiles/main/main_account.cpp
index cb51e9620..2e690139a 100644
--- a/Telegram/SourceFiles/main/main_account.cpp
+++ b/Telegram/SourceFiles/main/main_account.cpp
@@ -13,12 +13,16 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "storage/storage_account.h"
 #include "storage/storage_accounts.h" // Storage::StartResult.
 #include "storage/serialize_common.h"
+#include "storage/serialize_peer.h"
 #include "storage/localstorage.h"
 #include "data/data_session.h"
 #include "data/data_user.h"
 #include "data/data_changes.h"
 #include "window/window_controller.h"
 #include "media/audio/media_audio.h"
+#include "mtproto/mtproto_config.h"
+#include "mtproto/mtproto_dc_options.h"
+#include "mtproto/mtp_instance.h"
 #include "ui/image/image.h"
 #include "mainwidget.h"
 #include "api/api_updates.h"
@@ -46,7 +50,14 @@ Account::Account(const QString &dataName, int index)
 	ComposeDataString(dataName, index))) {
 }
 
-Account::~Account() = default;
+Account::~Account() {
+	if (sessionExists()) {
+		session().saveSettingsNowIfNeeded();
+	}
+	destroySession();
+	_mtpValue.reset(nullptr);
+	base::take(_mtp);
+}
 
 [[nodiscard]] Storage::StartResult Account::legacyStart(
 		const QByteArray &passcode) {
@@ -54,22 +65,27 @@ Account::~Account() = default;
 
 	const auto result = _local->legacyStart(passcode);
 	if (result == Storage::StartResult::Success) {
-		finishStarting();
+		finishStarting(nullptr);
 	}
 	return result;
 }
 
 void Account::start(std::shared_ptr<MTP::AuthKey> localKey) {
-	_local->start(std::move(localKey));
-	finishStarting();
+	finishStarting(_local->start(std::move(localKey)));
 }
 
-void Account::startAdded(std::shared_ptr<MTP::AuthKey> localKey) {
+void Account::startAdded(
+		std::shared_ptr<MTP::AuthKey> localKey,
+		std::unique_ptr<MTP::Config> config) {
 	_local->startAdded(std::move(localKey));
-	finishStarting();
+	finishStarting(std::move(config));
 }
 
-void Account::finishStarting() {
+void Account::finishStarting(std::unique_ptr<MTP::Config> config) {
+	startMtp(config
+		? std::move(config)
+		: std::make_unique<MTP::Config>(
+			Core::App().fallbackProductionConfig()));
 	_appConfig = std::make_unique<AppConfig>(this);
 	watchProxyChanges();
 	watchSessionChanges();
@@ -195,12 +211,10 @@ rpl::producer<Session*> Account::sessionChanges() const {
 	return _sessionValue.changes();
 }
 
-rpl::producer<MTP::Instance*> Account::mtpValue() const {
-	return _mtpValue.value();
-}
-
-rpl::producer<MTP::Instance*> Account::mtpChanges() const {
-	return _mtpValue.changes();
+rpl::producer<not_null<MTP::Instance*>> Account::mtpValue() const {
+	return _mtpValue.value() | rpl::map([](MTP::Instance *instance) {
+		return not_null{ instance };
+	});
 }
 
 rpl::producer<MTPUpdates> Account::mtpUpdates() const {
@@ -214,14 +228,14 @@ rpl::producer<> Account::mtpNewSessionCreated() const {
 void Account::setLegacyMtpMainDcId(MTP::DcId mainDcId) {
 	Expects(!_mtp);
 
-	_mtpConfig.mainDcId = mainDcId;
+	_mtpFields.mainDcId = mainDcId;
 }
 
 void Account::setLegacyMtpKey(std::shared_ptr<MTP::AuthKey> key) {
 	Expects(!_mtp);
 	Expects(key != nullptr);
 
-	_mtpConfig.keys.push_back(std::move(key));
+	_mtpFields.keys.push_back(std::move(key));
 }
 
 QByteArray Account::serializeMtpAuthorization() const {
@@ -270,9 +284,9 @@ QByteArray Account::serializeMtpAuthorization() const {
 			: MTP::AuthKeysList();
 		return serialize(_mtp->mainDcId(), keys, keysToDestroy);
 	}
-	const auto &keys = _mtpConfig.keys;
+	const auto &keys = _mtpFields.keys;
 	const auto &keysToDestroy = _mtpKeysToDestroy;
-	return serialize(_mtpConfig.mainDcId, keys, keysToDestroy);
+	return serialize(_mtpFields.mainDcId, keys, keysToDestroy);
 }
 
 void Account::setSessionUserId(UserId userId) {
@@ -319,9 +333,9 @@ void Account::setMtpAuthorization(const QByteArray &serialized) {
 	}
 
 	setSessionUserId(userId);
-	_mtpConfig.mainDcId = mainDcId;
+	_mtpFields.mainDcId = mainDcId;
 
-	const auto readKeys = [&stream](auto &keys) {
+	const auto readKeys = [&](auto &keys) {
 		const auto count = Serialize::read<qint32>(stream);
 		if (stream.status() != QDataStream::Ok) {
 			LOG(("MTP Error: "
@@ -340,29 +354,53 @@ void Account::setMtpAuthorization(const QByteArray &serialized) {
 			keys.push_back(std::make_shared<MTP::AuthKey>(MTP::AuthKey::Type::ReadFromFile, dcId, keyData));
 		}
 	};
-	readKeys(_mtpConfig.keys);
+	readKeys(_mtpFields.keys);
 	readKeys(_mtpKeysToDestroy);
 	LOG(("MTP Info: "
 		"read keys, current: %1, to destroy: %2"
-		).arg(_mtpConfig.keys.size()
+		).arg(_mtpFields.keys.size()
 		).arg(_mtpKeysToDestroy.size()));
 }
 
-void Account::startMtp() {
+void Account::startMtp(std::unique_ptr<MTP::Config> config) {
 	Expects(!_mtp);
 
-	auto config = base::take(_mtpConfig);
-	config.deviceModel = Core::App().launcher()->deviceModel();
-	config.systemVersion = Core::App().launcher()->systemVersion();
+	auto fields = base::take(_mtpFields);
+	fields.config = std::move(config);
+	fields.deviceModel = Core::App().launcher()->deviceModel();
+	fields.systemVersion = Core::App().launcher()->systemVersion();
 	_mtp = std::make_unique<MTP::Instance>(
-		Core::App().dcOptions(),
 		MTP::Instance::Mode::Normal,
-		std::move(config));
+		std::move(fields));
+
+	const auto writingKeys = _mtp->lifetime().make_state<bool>(false);
 	_mtp->writeKeysRequests(
-	) | rpl::start_with_next([=] {
-		local().writeMtpData();
+	) | rpl::filter([=] {
+		return !*writingKeys;
+	}) | rpl::start_with_next([=] {
+		*writingKeys = true;
+		Ui::PostponeCall(_mtp.get(), [=] {
+			local().writeMtpData();
+			*writingKeys = false;
+		});
 	}, _mtp->lifetime());
-	_mtpConfig.mainDcId = _mtp->mainDcId();
+
+	const auto writingConfig = _lifetime.make_state<bool>(false);
+	rpl::merge(
+		_mtp->config().updates(),
+		_mtp->dcOptions().changed(
+		) | rpl::map([] { return rpl::empty_value(); })
+	) | rpl::filter([=] {
+		return !*writingConfig;
+	}) | rpl::start_with_next([=] {
+		*writingConfig = true;
+		Ui::PostponeCall(_mtp.get(), [=] {
+			local().writeMtpConfig();
+			*writingConfig = false;
+		});
+	}, _lifetime);
+
+	_mtpFields.mainDcId = _mtp->mainDcId();
 
 	_mtp->setUpdatesHandler(::rpcDone([=](
 			const mtpPrime *from,
@@ -466,6 +504,8 @@ void Account::loggedOut() {
 }
 
 void Account::destroyMtpKeys(MTP::AuthKeysList &&keys) {
+	Expects(_mtp != nullptr);
+
 	if (keys.empty()) {
 		return;
 	}
@@ -474,15 +514,16 @@ void Account::destroyMtpKeys(MTP::AuthKeysList &&keys) {
 		local().writeMtpData();
 		return;
 	}
-	auto destroyConfig = MTP::Instance::Config();
-	destroyConfig.mainDcId = MTP::Instance::Config::kNoneMainDc;
-	destroyConfig.keys = std::move(keys);
-	destroyConfig.deviceModel = Core::App().launcher()->deviceModel();
-	destroyConfig.systemVersion = Core::App().launcher()->systemVersion();
+	auto destroyFields = MTP::Instance::Fields();
+
+	destroyFields.mainDcId = MTP::Instance::Fields::kNoneMainDc;
+	destroyFields.config = std::make_unique<MTP::Config>(_mtp->config());
+	destroyFields.keys = std::move(keys);
+	destroyFields.deviceModel = Core::App().launcher()->deviceModel();
+	destroyFields.systemVersion = Core::App().launcher()->systemVersion();
 	_mtpForKeysDestroy = std::make_unique<MTP::Instance>(
-		Core::App().dcOptions(),
 		MTP::Instance::Mode::KeysDestroyer,
-		std::move(destroyConfig));
+		std::move(destroyFields));
 	_mtpForKeysDestroy->writeKeysRequests(
 	) | rpl::start_with_next([=] {
 		local().writeMtpData();
@@ -501,8 +542,8 @@ void Account::suggestMainDcId(MTP::DcId mainDcId) {
 	Expects(_mtp != nullptr);
 
 	_mtp->suggestMainDcId(mainDcId);
-	if (_mtpConfig.mainDcId != MTP::Instance::Config::kNotSetMainDc) {
-		_mtpConfig.mainDcId = mainDcId;
+	if (_mtpFields.mainDcId != MTP::Instance::Fields::kNotSetMainDc) {
+		_mtpFields.mainDcId = mainDcId;
 	}
 }
 
@@ -521,25 +562,15 @@ void Account::destroyStaleAuthorizationKeys() {
 	}
 }
 
-void Account::configUpdated() {
-	_configUpdates.fire({});
-}
-
-rpl::producer<> Account::configUpdates() const {
-	return _configUpdates.events();
-}
-
 void Account::resetAuthorizationKeys() {
-	_mtpValue = nullptr;
-	_mtp = nullptr;
-	startMtp();
+	Expects(_mtp != nullptr);
+
+	{
+		const auto old = base::take(_mtp);
+		auto config = std::make_unique<MTP::Config>(old->config());
+		startMtp(std::move(config));
+	}
 	local().writeMtpData();
 }
 
-void Account::clearMtp() {
-	_mtpValue = nullptr;
-	_mtp = nullptr;
-	_mtpForKeysDestroy = nullptr;
-}
-
 } // namespace Main
diff --git a/Telegram/SourceFiles/main/main_account.h b/Telegram/SourceFiles/main/main_account.h
index be949af7a..eefdcd8a0 100644
--- a/Telegram/SourceFiles/main/main_account.h
+++ b/Telegram/SourceFiles/main/main_account.h
@@ -18,6 +18,7 @@ enum class StartResult : uchar;
 
 namespace MTP {
 class AuthKey;
+class Config;
 } // namespace MTP
 
 namespace Main {
@@ -37,7 +38,9 @@ public:
 	[[nodiscard]] Storage::StartResult legacyStart(
 		const QByteArray &passcode);
 	void start(std::shared_ptr<MTP::AuthKey> localKey);
-	void startAdded(std::shared_ptr<MTP::AuthKey> localKey);
+	void startAdded(
+		std::shared_ptr<MTP::AuthKey> localKey,
+		std::unique_ptr<MTP::Config> config);
 
 	[[nodiscard]] UserId willHaveUserId() const;
 	void createSession(const MTPUser &user);
@@ -67,11 +70,10 @@ public:
 	[[nodiscard]] rpl::producer<Session*> sessionValue() const;
 	[[nodiscard]] rpl::producer<Session*> sessionChanges() const;
 
-	[[nodiscard]] MTP::Instance *mtp() const {
-		return _mtp.get();
+	[[nodiscard]] MTP::Instance &mtp() const {
+		return *_mtp;
 	}
-	[[nodiscard]] rpl::producer<MTP::Instance*> mtpValue() const;
-	[[nodiscard]] rpl::producer<MTP::Instance*> mtpChanges() const;
+	[[nodiscard]] rpl::producer<not_null<MTP::Instance*>> mtpValue() const;
 
 	// Set from legacy storage.
 	void setLegacyMtpMainDcId(MTP::DcId mainDcId);
@@ -89,24 +91,21 @@ public:
 	[[nodiscard]] QByteArray serializeMtpAuthorization() const;
 	void setMtpAuthorization(const QByteArray &serialized);
 
-	void startMtp();
 	void suggestMainDcId(MTP::DcId mainDcId);
 	void destroyStaleAuthorizationKeys();
-	void configUpdated();
-	[[nodiscard]] rpl::producer<> configUpdates() const;
-	void clearMtp();
 
-	rpl::lifetime &lifetime() {
+	[[nodiscard]] rpl::lifetime &lifetime() {
 		return _lifetime;
 	}
 
 private:
+	void startMtp(std::unique_ptr<MTP::Config> config);
 	void createSession(
 		const MTPUser &user,
 		QByteArray serialized,
 		int streamVersion,
 		Settings &&settings);
-	void finishStarting();
+	void finishStarting(std::unique_ptr<MTP::Config> config);
 	void watchProxyChanges();
 	void watchSessionChanges();
 	bool checkForUpdates(const mtpPrime *from, const mtpPrime *end);
@@ -124,7 +123,6 @@ private:
 	std::unique_ptr<MTP::Instance> _mtpForKeysDestroy;
 	rpl::event_stream<MTPUpdates> _mtpUpdates;
 	rpl::event_stream<> _mtpNewSessionCreated;
-	rpl::event_stream<> _configUpdates;
 
 	std::unique_ptr<AppConfig> _appConfig;
 
@@ -135,7 +133,7 @@ private:
 	QByteArray _sessionUserSerialized;
 	int32 _sessionUserStreamVersion = 0;
 	std::unique_ptr<Settings> _storedSettings;
-	MTP::Instance::Config _mtpConfig;
+	MTP::Instance::Fields _mtpFields;
 	MTP::AuthKeysList _mtpKeysToDestroy;
 	bool _loggingOut = false;
 
diff --git a/Telegram/SourceFiles/main/main_accounts.cpp b/Telegram/SourceFiles/main/main_accounts.cpp
index bb0049887..27a86c356 100644
--- a/Telegram/SourceFiles/main/main_accounts.cpp
+++ b/Telegram/SourceFiles/main/main_accounts.cpp
@@ -11,6 +11,8 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "core/shortcuts.h"
 #include "main/main_account.h"
 #include "main/main_session.h"
+#include "mtproto/mtproto_config.h"
+#include "mtproto/mtproto_dc_options.h"
 #include "storage/storage_accounts.h"
 #include "storage/localstorage.h"
 #include "facades.h"
@@ -43,6 +45,12 @@ Storage::StartResult Accounts::start(const QByteArray &passcode) {
 	return result;
 }
 
+void Accounts::finish() {
+	_activeIndex = -1;
+	_active = nullptr;
+	base::take(_accounts);
+}
+
 void Accounts::accountAddedInStorage(
 		int index,
 		std::unique_ptr<Account> account) {
@@ -115,7 +123,28 @@ rpl::producer<Session*> Accounts::activeSessionValue() const {
 	return rpl::single(current) | rpl::then(_activeSessions.events());
 }
 
-int Accounts::add() {
+int Accounts::add(MTP::Environment environment) {
+	Expects(_active.current() != nullptr);
+
+	static const auto cloneConfig = [](const MTP::Config &config) {
+		return std::make_unique<MTP::Config>(config);
+	};
+	static const auto accountConfig = [](not_null<Account*> account) {
+		return cloneConfig(account->mtp().config());
+	};
+	auto config = [&] {
+		if (_active.current()->mtp().environment() == environment) {
+			return accountConfig(_active.current());
+		}
+		for (const auto &[index, account] : list()) {
+			if (account->mtp().environment() == environment) {
+				return accountConfig(account.get());
+			}
+		}
+		return (environment == MTP::Environment::Production)
+			? cloneConfig(Core::App().fallbackProductionConfig())
+			: std::make_unique<MTP::Config>(environment);
+	}();
 	auto index = 0;
 	while (_accounts.contains(index)) {
 		++index;
@@ -124,17 +153,16 @@ int Accounts::add() {
 		index,
 		std::make_unique<Account>(_dataName, index)
 	).first->second.get();
-	_local->startAdded(account);
+	_local->startAdded(account, std::move(config));
 	watchSession(account);
 	return index;
 }
 
 void Accounts::watchSession(not_null<Account*> account) {
-	account->startMtp();
 	account->sessionChanges(
 	) | rpl::filter([=](Session *session) {
 		return !session; // removeRedundantAccounts may remove passcode lock.
-	}) | rpl::start_with_next([=](Session *session) {
+	}) | rpl::start_with_next([=] {
 		if (account == _active.current()) {
 			activateAuthedAccount();
 		}
@@ -183,6 +211,7 @@ void Accounts::removeRedundantAccounts() {
 			++i;
 			continue;
 		}
+		checkForLastProductionConfig(i->second.get());
 		i = _accounts.erase(i);
 	}
 
@@ -191,6 +220,21 @@ void Accounts::removeRedundantAccounts() {
 	}
 }
 
+void Accounts::checkForLastProductionConfig(
+		not_null<Main::Account*> account) {
+	const auto mtp = &account->mtp();
+	if (mtp->environment() != MTP::Environment::Production) {
+		return;
+	}
+	for (const auto &[index, other] : _accounts) {
+		if (other.get() != account
+			&& other->mtp().environment() == MTP::Environment::Production) {
+			return;
+		}
+	}
+	Core::App().refreshFallbackProductionConfig(mtp->config());
+}
+
 void Accounts::activate(int index) {
 	Expects(_accounts.contains(index));
 
diff --git a/Telegram/SourceFiles/main/main_accounts.h b/Telegram/SourceFiles/main/main_accounts.h
index 555472cf8..e51d700d7 100644
--- a/Telegram/SourceFiles/main/main_accounts.h
+++ b/Telegram/SourceFiles/main/main_accounts.h
@@ -12,6 +12,10 @@ class Accounts;
 enum class StartResult : uchar;
 } // namespace Storage
 
+namespace MTP {
+enum class Environment : uchar;
+} // namespace MTP
+
 namespace Main {
 
 class Account;
@@ -25,6 +29,7 @@ public:
 	[[nodiscard]] bool started() const;
 	[[nodiscard]] Storage::StartResult start(const QByteArray &passcode);
 	void resetWithForgottenPasscode();
+	void finish();
 
 	[[nodiscard]] Storage::Accounts &local() const {
 		return *_local;
@@ -42,7 +47,7 @@ public:
 	[[nodiscard]] rpl::producer<Session*> activeSessionValue() const;
 	[[nodiscard]] rpl::producer<Session*> activeSessionChanges() const;
 
-	[[nodiscard]] int add();
+	[[nodiscard]] int add(MTP::Environment environment);
 	void activate(int index);
 
 	// Interface for Storage::Accounts.
@@ -55,6 +60,7 @@ private:
 	void removeRedundantAccounts();
 	void watchSession(not_null<Account*> account);
 	void scheduleWriteAccounts();
+	void checkForLastProductionConfig(not_null<Main::Account*> account);
 
 	const QString _dataName;
 	const std::unique_ptr<Storage::Accounts> _local;
diff --git a/Telegram/SourceFiles/main/main_app_config.cpp b/Telegram/SourceFiles/main/main_app_config.cpp
index 4057ed396..4f86f2bcf 100644
--- a/Telegram/SourceFiles/main/main_app_config.cpp
+++ b/Telegram/SourceFiles/main/main_app_config.cpp
@@ -20,14 +20,9 @@ constexpr auto kRefreshTimeout = 3600 * crl::time(1000);
 
 AppConfig::AppConfig(not_null<Account*> account) : _account(account) {
 	account->mtpValue(
-	) | rpl::start_with_next([=](MTP::Instance *instance) {
-		if (instance) {
-			_api.emplace(instance);
-			refresh();
-		} else {
-			_api.reset();
-			_requestId = 0;
-		}
+	) | rpl::start_with_next([=](not_null<MTP::Instance*> instance) {
+		_api.emplace(instance);
+		refresh();
 	}, _lifetime);
 }
 
diff --git a/Telegram/SourceFiles/main/main_session.cpp b/Telegram/SourceFiles/main/main_session.cpp
index 8b783124d..e9e72babe 100644
--- a/Telegram/SourceFiles/main/main_session.cpp
+++ b/Telegram/SourceFiles/main/main_session.cpp
@@ -12,6 +12,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "core/application.h"
 #include "core/changelogs.h"
 #include "main/main_account.h"
+#include "mtproto/mtproto_config.h"
 #include "chat_helpers/stickers_emoji_pack.h"
 #include "chat_helpers/stickers_dice_pack.h"
 #include "storage/file_download.h"
@@ -40,6 +41,25 @@ namespace {
 
 constexpr auto kLegacyCallsPeerToPeerNobody = 4;
 
+[[nodiscard]] QString ValidatedInternalLinksDomain(
+		not_null<const Main::Session*> session) {
+	// This domain should start with 'http[s]://' and end with '/'.
+	// Like 'https://telegram.me/' or 'https://t.me/'.
+	const auto &domain = session->serverConfig().internalLinksDomain;
+	const auto prefixes = {
+		qstr("https://"),
+		qstr("http://"),
+	};
+	for (const auto &prefix : prefixes) {
+		if (domain.startsWith(prefix, Qt::CaseInsensitive)) {
+			return domain.endsWith('/')
+				? domain
+				: MTP::ConfigFields().internalLinksDomain;
+		}
+	}
+	return MTP::ConfigFields().internalLinksDomain;
+}
+
 } // namespace
 
 Session::Session(
@@ -75,7 +95,7 @@ Session::Session(
 	_api->requestTermsUpdate();
 	_api->requestFullPeer(_user);
 
-	_api->instance()->setUserPhone(_user->phone());
+	_api->instance().setUserPhone(_user->phone());
 
 	crl::on_main(this, [=] {
 		using Flag = Data::PeerUpdate::Flag;
@@ -91,9 +111,9 @@ Session::Session(
 
 			if (update.flags & Flag::PhoneNumber) {
 				const auto phone = _user->phone();
-				_api->instance()->setUserPhone(phone);
+				_api->instance().setUserPhone(phone);
 				if (!phone.isEmpty()) {
-					_api->instance()->requestConfig();
+					_api->instance().requestConfig();
 				}
 			}
 		}, _lifetime);
@@ -156,19 +176,42 @@ void Session::saveSettingsDelayed(crl::time delay) {
 }
 
 MTP::DcId Session::mainDcId() const {
-	return _account->mtp()->mainDcId();
+	return _account->mtp().mainDcId();
 }
 
-not_null<MTP::Instance*> Session::mtp() const {
+MTP::Instance &Session::mtp() const {
 	return _account->mtp();
 }
 
+const MTP::ConfigFields &Session::serverConfig() const {
+	return _account->mtp().configValues();
+}
+
 void Session::termsDeleteNow() {
 	api().request(MTPaccount_DeleteAccount(
 		MTP_string("Decline ToS update")
 	)).send();
 }
 
+QString Session::createInternalLink(const QString &query) const {
+	auto result = createInternalLinkFull(query);
+	auto prefixes = {
+		qstr("https://"),
+		qstr("http://"),
+	};
+	for (auto &prefix : prefixes) {
+		if (result.startsWith(prefix, Qt::CaseInsensitive)) {
+			return result.mid(prefix.size());
+		}
+	}
+	LOG(("Warning: bad internal url '%1'").arg(result));
+	return result;
+}
+
+QString Session::createInternalLinkFull(const QString &query) const {
+	return ValidatedInternalLinksDomain(this) + query;
+}
+
 bool Session::supportMode() const {
 	return (_supportHelper != nullptr);
 }
diff --git a/Telegram/SourceFiles/main/main_session.h b/Telegram/SourceFiles/main/main_session.h
index 710e071f8..43d3cf47a 100644
--- a/Telegram/SourceFiles/main/main_session.h
+++ b/Telegram/SourceFiles/main/main_session.h
@@ -21,6 +21,7 @@ class Updates;
 
 namespace MTP {
 class Instance;
+struct ConfigFields;
 } // namespace MTP
 
 namespace Support {
@@ -127,7 +128,8 @@ public:
 	// Shortcuts.
 	[[nodiscard]] base::Observable<void> &downloaderTaskFinished();
 	[[nodiscard]] MTP::DcId mainDcId() const;
-	[[nodiscard]] not_null<MTP::Instance*> mtp() const;
+	[[nodiscard]] MTP::Instance &mtp() const;
+	[[nodiscard]] const MTP::ConfigFields &serverConfig() const;
 	[[nodiscard]] ApiWrap &api() {
 		return *_api;
 	}
@@ -138,6 +140,10 @@ public:
 
 	void termsDeleteNow();
 
+	void setInternalLinkDomain(const QString &domain) const;
+	[[nodiscard]] QString createInternalLink(const QString &query) const;
+	[[nodiscard]] QString createInternalLinkFull(const QString &query) const;
+
 	[[nodiscard]] rpl::lifetime &lifetime() {
 		return _lifetime;
 	}
diff --git a/Telegram/SourceFiles/mainwidget.cpp b/Telegram/SourceFiles/mainwidget.cpp
index 1baca05b8..0441df09f 100644
--- a/Telegram/SourceFiles/mainwidget.cpp
+++ b/Telegram/SourceFiles/mainwidget.cpp
@@ -85,7 +85,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "window/window_session_controller.h"
 #include "window/themes/window_theme.h"
 #include "window/window_history_hider.h"
-#include "mtproto/dc_options.h"
+#include "mtproto/mtproto_dc_options.h"
 #include "core/file_utilities.h"
 #include "core/update_checker.h"
 #include "core/shortcuts.h"
diff --git a/Telegram/SourceFiles/mainwindow.cpp b/Telegram/SourceFiles/mainwindow.cpp
index 07b286109..01d166aa7 100644
--- a/Telegram/SourceFiles/mainwindow.cpp
+++ b/Telegram/SourceFiles/mainwindow.cpp
@@ -516,7 +516,7 @@ bool MainWindow::doWeMarkAsRead() {
 	if (!_main || Ui::isLayerShown()) {
 		return false;
 	}
-	updateIsActive(0);
+	updateIsActive();
 	return isActive() && _main->doWeMarkAsRead();
 }
 
@@ -609,7 +609,7 @@ void MainWindow::updateTrayMenu(bool force) {
 		auto minimizeAction = actions.at(1);
 		minimizeAction->setEnabled(isVisible());
 	} else {
-		updateIsActive(0);
+		updateIsActive();
 		auto active = Platform::IsWayland() ? isVisible() : isActive();
 		auto toggleAction = actions.at(0);
 		disconnect(toggleAction, SIGNAL(triggered(bool)), this, SLOT(minimizeToTray()));
@@ -705,7 +705,7 @@ void MainWindow::activate() {
 	setVisible(true);
 	psActivateProcess();
 	activateWindow();
-	updateIsActive(Global::OnlineFocusTimeout());
+	controller().updateIsActiveFocus();
 	if (wasHidden) {
 		if (_main) {
 			_main->windowShown();
@@ -743,7 +743,7 @@ void MainWindow::showFromTray(QSystemTrayIcon::ActivationReason reason) {
 
 void MainWindow::handleTrayIconActication(
 		QSystemTrayIcon::ActivationReason reason) {
-	updateIsActive(0);
+	updateIsActive();
 	if (Platform::IsMac() && isActive()) {
 		if (trayIcon && !trayIcon->contextMenu()) {
 			showFromTray(reason);
diff --git a/Telegram/SourceFiles/media/streaming/media_streaming_loader_mtproto.cpp b/Telegram/SourceFiles/media/streaming/media_streaming_loader_mtproto.cpp
index d4b810fe8..2ed5bea92 100644
--- a/Telegram/SourceFiles/media/streaming/media_streaming_loader_mtproto.cpp
+++ b/Telegram/SourceFiles/media/streaming/media_streaming_loader_mtproto.cpp
@@ -27,7 +27,7 @@ LoaderMtproto::LoaderMtproto(
 	Data::FileOrigin origin)
 : DownloadMtprotoTask(owner, location, origin)
 , _size(size)
-, _api(api().instance()) {
+, _api(&api().instance()) {
 }
 
 Storage::Cache::Key LoaderMtproto::baseCacheKey() const {
diff --git a/Telegram/SourceFiles/media/view/media_view_overlay_widget.cpp b/Telegram/SourceFiles/media/view/media_view_overlay_widget.cpp
index 828fdc550..81cbe580b 100644
--- a/Telegram/SourceFiles/media/view/media_view_overlay_widget.cpp
+++ b/Telegram/SourceFiles/media/view/media_view_overlay_widget.cpp
@@ -2462,6 +2462,7 @@ void OverlayWidget::initThemePreview() {
 		return result;
 	}();
 
+	const auto weakSession = base::make_weak(&_document->session());
 	const auto path = _document->location().name();
 	const auto id = _themePreviewId = rand_value<uint64>();
 	const auto weak = Ui::MakeWeak(this);
@@ -2473,7 +2474,8 @@ void OverlayWidget::initThemePreview() {
 			std::move(data),
 			Window::Theme::PreviewType::Extended);
 		crl::on_main(weak, [=, result = std::move(preview)]() mutable {
-			if (id != _themePreviewId) {
+			const auto session = weakSession.get();
+			if (id != _themePreviewId || !session) {
 				return;
 			}
 			_themePreviewId = 0;
@@ -2509,7 +2511,7 @@ void OverlayWidget::initThemePreview() {
 					_themeShare->show();
 					_themeShare->setClickedCallback([=] {
 						QGuiApplication::clipboard()->setText(
-							Core::App().createInternalLinkFull("addtheme/" + slug));
+							session->createInternalLinkFull("addtheme/" + slug));
 						Ui::Toast::Show(
 							this,
 							tr::lng_background_link_copied(tr::now));
diff --git a/Telegram/SourceFiles/mtproto/config_loader.cpp b/Telegram/SourceFiles/mtproto/config_loader.cpp
index fc847c855..ef2151f50 100644
--- a/Telegram/SourceFiles/mtproto/config_loader.cpp
+++ b/Telegram/SourceFiles/mtproto/config_loader.cpp
@@ -9,7 +9,8 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 
 #include "mtproto/special_config_request.h"
 #include "mtproto/facade.h"
-#include "mtproto/dc_options.h"
+#include "mtproto/mtproto_dc_options.h"
+#include "mtproto/mtproto_config.h"
 #include "mtproto/mtp_instance.h"
 #include "facades.h"
 
@@ -40,7 +41,7 @@ void ConfigLoader::load() {
 		sendRequest(_instance->mainDcId());
 		_enumDCTimer.callOnce(kEnumerateDcTimeout);
 	} else {
-		auto ids = _instance->dcOptions()->configEnumDcIds();
+		auto ids = _instance->dcOptions().configEnumDcIds();
 		Assert(!ids.empty());
 		_enumCurrent = ids.front();
 		enumerate();
@@ -87,7 +88,7 @@ void ConfigLoader::enumerate() {
 	if (!_enumCurrent) {
 		_enumCurrent = _instance->mainDcId();
 	}
-	auto ids = _instance->dcOptions()->configEnumDcIds();
+	auto ids = _instance->dcOptions().configEnumDcIds();
 	Assert(!ids.empty());
 
 	auto i = std::find(ids.cbegin(), ids.cend(), _enumCurrent);
@@ -135,7 +136,7 @@ void ConfigLoader::createSpecialLoader() {
 		} else {
 			addSpecialEndpoint(dcId, ip, port, secret);
 		}
-	}, _phone);
+	}, _instance->configValues().txtDomainString, _phone);
 }
 
 void ConfigLoader::addSpecialEndpoint(
@@ -180,7 +181,7 @@ void ConfigLoader::sendSpecialRequest() {
 	using Flag = MTPDdcOption::Flag;
 	const auto flags = Flag::f_tcpo_only
 		| (endpoint->secret.empty() ? Flag(0) : Flag::f_secret);
-	_instance->dcOptions()->constructAddOne(
+	_instance->dcOptions().constructAddOne(
 		_specialEnumCurrent,
 		flags,
 		endpoint->ip,
@@ -212,7 +213,7 @@ void ConfigLoader::specialConfigLoaded(const MTPConfig &result) {
 
 	// We use special config only for dc options.
 	// For everything else we wait for normal config from main dc.
-	_instance->dcOptions()->setFromList(data.vdc_options());
+	_instance->dcOptions().setFromList(data.vdc_options());
 }
 
 } // namespace details
diff --git a/Telegram/SourceFiles/mtproto/connection_abstract.h b/Telegram/SourceFiles/mtproto/connection_abstract.h
index 695d83694..9437a4a42 100644
--- a/Telegram/SourceFiles/mtproto/connection_abstract.h
+++ b/Telegram/SourceFiles/mtproto/connection_abstract.h
@@ -7,7 +7,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 */
 #pragma once
 
-#include "mtproto/dc_options.h"
+#include "mtproto/mtproto_dc_options.h"
 #include "mtproto/mtproto_proxy_data.h"
 #include "base/bytes.h"
 
diff --git a/Telegram/SourceFiles/mtproto/dedicated_file_loader.cpp b/Telegram/SourceFiles/mtproto/dedicated_file_loader.cpp
index 2a6e573d6..7db41b7c3 100644
--- a/Telegram/SourceFiles/mtproto/dedicated_file_loader.cpp
+++ b/Telegram/SourceFiles/mtproto/dedicated_file_loader.cpp
@@ -84,7 +84,7 @@ std::optional<DedicatedLoader::File> ParseFile(
 
 WeakInstance::WeakInstance(base::weak_ptr<Main::Session> session)
 : _session(session)
-, _instance(_session ? _session->account().mtp() : nullptr) {
+, _instance(_session ? &_session->account().mtp() : nullptr) {
 	if (!valid()) {
 		return;
 	}
diff --git a/Telegram/SourceFiles/mtproto/details/mtproto_dcenter.cpp b/Telegram/SourceFiles/mtproto/details/mtproto_dcenter.cpp
index 7dbf0a602..7a1799f11 100644
--- a/Telegram/SourceFiles/mtproto/details/mtproto_dcenter.cpp
+++ b/Telegram/SourceFiles/mtproto/details/mtproto_dcenter.cpp
@@ -9,7 +9,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 
 #include "mtproto/facade.h"
 #include "mtproto/mtproto_auth_key.h"
-#include "mtproto/dc_options.h"
+#include "mtproto/mtproto_dc_options.h"
 #include "mtproto/mtp_instance.h"
 #include "mtproto/special_config_request.h"
 
diff --git a/Telegram/SourceFiles/mtproto/details/mtproto_domain_resolver.cpp b/Telegram/SourceFiles/mtproto/details/mtproto_domain_resolver.cpp
index b26308978..21c56003d 100644
--- a/Telegram/SourceFiles/mtproto/details/mtproto_domain_resolver.cpp
+++ b/Telegram/SourceFiles/mtproto/details/mtproto_domain_resolver.cpp
@@ -294,7 +294,7 @@ void DomainResolver::performRequest(
 			request.setRawHeader("Host", host.toLatin1());
 		}
 	} break;
-	default: Unexpected("Type in SpecialConfigRequest::performRequest.");
+	default: Unexpected("Type in DomainResolver::performRequest.");
 	}
 	request.setUrl(url);
 	request.setRawHeader("User-Agent", DnsUserAgent());
diff --git a/Telegram/SourceFiles/mtproto/facade.h b/Telegram/SourceFiles/mtproto/facade.h
index 6afce1e0d..c0892b3cb 100644
--- a/Telegram/SourceFiles/mtproto/facade.h
+++ b/Telegram/SourceFiles/mtproto/facade.h
@@ -63,17 +63,17 @@ inline bool isCdnDc(MTPDdcOption::Flags flags) {
 
 inline bool isTemporaryDcId(ShiftedDcId shiftedDcId) {
 	auto dcId = BareDcId(shiftedDcId);
-	return (dcId >= Instance::Config::kTemporaryMainDc);
+	return (dcId >= Instance::Fields::kTemporaryMainDc);
 }
 
 inline DcId getRealIdFromTemporaryDcId(ShiftedDcId shiftedDcId) {
 	auto dcId = BareDcId(shiftedDcId);
-	return (dcId >= Instance::Config::kTemporaryMainDc) ? (dcId - Instance::Config::kTemporaryMainDc) : 0;
+	return (dcId >= Instance::Fields::kTemporaryMainDc) ? (dcId - Instance::Fields::kTemporaryMainDc) : 0;
 }
 
 inline DcId getTemporaryIdFromRealDcId(ShiftedDcId shiftedDcId) {
 	auto dcId = BareDcId(shiftedDcId);
-	return (dcId < Instance::Config::kTemporaryMainDc) ? (dcId + Instance::Config::kTemporaryMainDc) : 0;
+	return (dcId < Instance::Fields::kTemporaryMainDc) ? (dcId + Instance::Fields::kTemporaryMainDc) : 0;
 }
 
 namespace details {
diff --git a/Telegram/SourceFiles/mtproto/mtp_instance.cpp b/Telegram/SourceFiles/mtproto/mtp_instance.cpp
index bf561124c..1b6de5a6d 100644
--- a/Telegram/SourceFiles/mtproto/mtp_instance.cpp
+++ b/Telegram/SourceFiles/mtproto/mtp_instance.cpp
@@ -11,7 +11,8 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "mtproto/details/mtproto_rsa_public_key.h"
 #include "mtproto/special_config_request.h"
 #include "mtproto/session.h"
-#include "mtproto/dc_options.h"
+#include "mtproto/mtproto_config.h"
+#include "mtproto/mtproto_dc_options.h"
 #include "mtproto/config_loader.h"
 #include "mtproto/sender.h"
 #include "storage/localstorage.h"
@@ -53,9 +54,18 @@ int GetNextRequestId() {
 
 class Instance::Private : private Sender {
 public:
-	Private(not_null<Instance*> instance, not_null<DcOptions*> options, Instance::Mode mode);
+	Private(
+		not_null<Instance*> instance,
+		Instance::Mode mode,
+		Fields &&fields);
 
-	void start(Config &&config);
+	void start();
+
+	[[nodiscard]] Config &config() const;
+	[[nodiscard]] const ConfigFields &configValues() const;
+	[[nodiscard]] DcOptions &dcOptions() const;
+	[[nodiscard]] Environment environment() const;
+	[[nodiscard]] bool isTestMode() const;
 
 	void resolveProxyDomain(const QString &host);
 	void setGoodProxyDomain(const QString &host, const QString &ip);
@@ -72,8 +82,6 @@ public:
 	void addKeysForDestroy(AuthKeysList &&keys);
 	[[nodiscard]] rpl::producer<> allKeysDestroyed() const;
 
-	[[nodiscard]] not_null<DcOptions*> dcOptions();
-
 	// Thread safe.
 	[[nodiscard]] QString deviceModel() const;
 	[[nodiscard]] QString systemVersion() const;
@@ -195,8 +203,8 @@ private:
 	void checkDelayedRequests();
 
 	const not_null<Instance*> _instance;
-	const not_null<DcOptions*> _dcOptions;
 	const Instance::Mode _mode = Instance::Mode::Normal;
+	const std::unique_ptr<Config> _config;
 
 	std::unique_ptr<QThread> _mainSessionThread;
 	std::unique_ptr<QThread> _otherSessionsThread;
@@ -205,7 +213,7 @@ private:
 	QString _deviceModel;
 	QString _systemVersion;
 
-	DcId _mainDcId = Config::kDefaultMainDc;
+	DcId _mainDcId = Fields::kDefaultMainDc;
 	bool _mainDcIdForced = false;
 	base::flat_map<DcId, std::unique_ptr<Dcenter>> _dcenters;
 	std::vector<std::unique_ptr<Dcenter>> _dcentersToDestroy;
@@ -261,27 +269,36 @@ private:
 
 };
 
+Instance::Fields::Fields() = default;
+
+Instance::Fields::Fields(Fields &&other) = default;
+
+auto Instance::Fields::operator=(Fields &&other) -> Fields & = default;
+
+Instance::Fields::~Fields() = default;
+
 Instance::Private::Private(
 	not_null<Instance*> instance,
-	not_null<DcOptions*> options,
-	Instance::Mode mode)
+	Instance::Mode mode,
+	Fields &&fields)
 : Sender(instance)
 , _instance(instance)
-, _dcOptions(options)
-, _mode(mode) {
+, _mode(mode)
+, _config(std::move(fields.config)) {
+	Expects(_config != nullptr);
+
 	const auto idealThreadPoolSize = QThread::idealThreadCount();
 	_fileSessionThreads.resize(2 * std::max(idealThreadPoolSize / 2, 1));
+
 	details::unpaused(
 	) | rpl::start_with_next([=] {
 		unpaused();
 	}, _lifetime);
-}
 
-void Instance::Private::start(Config &&config) {
-	_deviceModel = std::move(config.deviceModel);
-	_systemVersion = std::move(config.systemVersion);
+	_deviceModel = std::move(fields.deviceModel);
+	_systemVersion = std::move(fields.systemVersion);
 
-	for (auto &key : config.keys) {
+	for (auto &key : fields.keys) {
 		auto dcId = key->dcId();
 		auto shiftedDcId = dcId;
 		if (isKeysDestroyer()) {
@@ -297,22 +314,24 @@ void Instance::Private::start(Config &&config) {
 		addDc(shiftedDcId, std::move(key));
 	}
 
-	if (config.mainDcId != Config::kNotSetMainDc) {
-		_mainDcId = config.mainDcId;
+	if (fields.mainDcId != Fields::kNotSetMainDc) {
+		_mainDcId = fields.mainDcId;
 		_mainDcIdForced = true;
 	}
+}
 
+void Instance::Private::start() {
 	if (isKeysDestroyer()) {
 		for (const auto &[shiftedDcId, dc] : _dcenters) {
 			startSession(shiftedDcId);
 		}
-	} else if (_mainDcId != Config::kNoneMainDc) {
+	} else if (_mainDcId != Fields::kNoneMainDc) {
 		_mainSession = startSession(_mainDcId);
 	}
 
 	_checkDelayedTimer.setCallback([this] { checkDelayedRequests(); });
 
-	Assert((_mainDcId == Config::kNoneMainDc) == isKeysDestroyer());
+	Assert((_mainDcId == Fields::kNoneMainDc) == isKeysDestroyer());
 	requestConfig();
 }
 
@@ -418,7 +437,8 @@ void Instance::Private::setMainDcId(DcId mainDcId) {
 }
 
 DcId Instance::Private::mainDcId() const {
-	Expects(_mainDcId != Config::kNoneMainDc);
+	Expects(_mainDcId != Fields::kNoneMainDc);
+
 	return _mainDcId;
 }
 
@@ -457,7 +477,7 @@ void Instance::Private::syncHttpUnixtime() {
 		InvokeQueued(_instance, [=] {
 			_httpUnixtimeLoader = nullptr;
 		});
-	});
+	}, configValues().txtDomainString);
 }
 
 void Instance::Private::restartedByTimeout(ShiftedDcId shiftedDcId) {
@@ -469,7 +489,7 @@ rpl::producer<ShiftedDcId> Instance::Private::restartsByTimeout() const {
 }
 
 void Instance::Private::requestConfigIfOld() {
-	const auto timeout = Global::BlockedMode()
+	const auto timeout = _config->values().blockedMode
 		? kConfigBecomesOldForBlockedIn
 		: kConfigBecomesOldIn;
 	if (crl::now() - _lastConfigLoadedTime >= timeout) {
@@ -490,7 +510,7 @@ void Instance::Private::requestConfigIfExpired() {
 }
 
 void Instance::Private::requestCDNConfig() {
-	if (_cdnConfigLoadRequestId || _mainDcId == Config::kNoneMainDc) {
+	if (_cdnConfigLoadRequestId || _mainDcId == Fields::kNoneMainDc) {
 		return;
 	}
 	_cdnConfigLoadRequestId = request(
@@ -498,7 +518,7 @@ void Instance::Private::requestCDNConfig() {
 	).done([this](const MTPCdnConfig &result) {
 		_cdnConfigLoadRequestId = 0;
 		result.match([&](const MTPDcdnConfig &data) {
-			dcOptions()->setCDNConfig(data);
+			dcOptions().setCDNConfig(data);
 		});
 		Local::writeSettings();
 	}).send();
@@ -642,7 +662,7 @@ void Instance::Private::logoutGuestDcs() {
 		dcIds.push_back(key.first);
 	}
 	for (const auto dcId : dcIds) {
-		if (dcId == mainDcId() || dcOptions()->dcType(dcId) == DcType::Cdn) {
+		if (dcId == mainDcId() || dcOptions().dcType(dcId) == DcType::Cdn) {
 			continue;
 		}
 		const auto shiftedDcId = MTP::logoutDcId(dcId);
@@ -784,8 +804,24 @@ rpl::producer<> Instance::Private::writeKeysRequests() const {
 	return _writeKeysRequests.events();
 }
 
-not_null<DcOptions*> Instance::Private::dcOptions() {
-	return _dcOptions;
+Config &Instance::Private::config() const {
+	return *_config;
+}
+
+const ConfigFields &Instance::Private::configValues() const {
+	return _config->values();
+}
+
+DcOptions &Instance::Private::dcOptions() const {
+	return _config->dcOptions();
+}
+
+Environment Instance::Private::environment() const {
+	return _config->environment();
+}
+
+bool Instance::Private::isTestMode() const {
+	return _config->isTestMode();
 }
 
 QString Instance::Private::deviceModel() const {
@@ -809,58 +845,13 @@ void Instance::Private::configLoadDone(const MTPConfig &result) {
 	_lastConfigLoadedTime = crl::now();
 
 	const auto &data = result.c_config();
-	DEBUG_LOG(("MTP Info: got config, chat_size_max: %1, date: %2, test_mode: %3, this_dc: %4, dc_options.length: %5").arg(data.vchat_size_max().v).arg(data.vdate().v).arg(mtpIsTrue(data.vtest_mode())).arg(data.vthis_dc().v).arg(data.vdc_options().v.size()));
-	if (data.vdc_options().v.empty()) {
-		LOG(("MTP Error: config with empty dc_options received!"));
-	} else {
-		_dcOptions->setFromList(data.vdc_options());
-	}
-
-	Global::SetChatSizeMax(data.vchat_size_max().v);
-	Global::SetMegagroupSizeMax(data.vmegagroup_size_max().v);
-	Global::SetForwardedCountMax(data.vforwarded_count_max().v);
-	Global::SetOnlineUpdatePeriod(data.vonline_update_period_ms().v);
-	Global::SetOfflineBlurTimeout(data.voffline_blur_timeout_ms().v);
-	Global::SetOfflineIdleTimeout(data.voffline_idle_timeout_ms().v);
-	Global::SetOnlineCloudTimeout(data.vonline_cloud_timeout_ms().v);
-	Global::SetNotifyCloudDelay(data.vnotify_cloud_delay_ms().v);
-	Global::SetNotifyDefaultDelay(data.vnotify_default_delay_ms().v);
-	Global::SetPushChatPeriod(data.vpush_chat_period_ms().v);
-	Global::SetPushChatLimit(data.vpush_chat_limit().v);
-	Global::SetSavedGifsLimit(data.vsaved_gifs_limit().v);
-	Global::SetEditTimeLimit(data.vedit_time_limit().v);
-	Global::SetRevokeTimeLimit(data.vrevoke_time_limit().v);
-	Global::SetRevokePrivateTimeLimit(data.vrevoke_pm_time_limit().v);
-	Global::SetRevokePrivateInbox(data.is_revoke_pm_inbox());
-	Global::SetStickersRecentLimit(data.vstickers_recent_limit().v);
-	Global::SetStickersFavedLimit(data.vstickers_faved_limit().v);
-	Global::SetPinnedDialogsCountMax(
-		std::max(data.vpinned_dialogs_count_max().v, 1));
-	Global::SetPinnedDialogsInFolderMax(
-		std::max(data.vpinned_infolder_count_max().v, 1));
-	Core::App().setInternalLinkDomain(qs(data.vme_url_prefix()));
-	Global::SetChannelsReadMediaPeriod(data.vchannels_read_media_period().v);
-	Global::SetWebFileDcId(data.vwebfile_dc_id().v);
-	Global::SetTxtDomainString(qs(data.vdc_txt_domain_name()));
-	Global::SetCallReceiveTimeoutMs(data.vcall_receive_timeout_ms().v);
-	Global::SetCallRingTimeoutMs(data.vcall_ring_timeout_ms().v);
-	Global::SetCallConnectTimeoutMs(data.vcall_connect_timeout_ms().v);
-	Global::SetCallPacketTimeoutMs(data.vcall_packet_timeout_ms().v);
-	if (Global::PhoneCallsEnabled() != data.is_phonecalls_enabled()) {
-		Global::SetPhoneCallsEnabled(data.is_phonecalls_enabled());
-		Global::RefPhoneCallsEnabledChanged().notify();
-	}
-	Global::SetBlockedMode(data.is_blocked_mode());
-	Global::SetCaptionLengthMax(data.vcaption_length_max().v);
+	_config->apply(data);
 
 	const auto lang = qs(data.vsuggested_lang_code().value_or_empty());
 	Lang::CurrentCloudManager().setSuggestedLanguage(lang);
 	Lang::CurrentCloudManager().setCurrentVersions(
 		data.vlang_pack_version().value_or_empty(),
 		data.vbase_lang_pack_version().value_or_empty());
-
-	Core::App().activeAccount().configUpdated(); // #TODO multi
-
 	if (const auto prefix = data.vautoupdate_url_prefix()) {
 		Local::writeAutoupdatePrefix(qs(*prefix));
 	}
@@ -1520,7 +1511,7 @@ not_null<QThread*> Instance::Private::getThreadForDc(
 void Instance::Private::scheduleKeyDestroy(ShiftedDcId shiftedDcId) {
 	Expects(isKeysDestroyer());
 
-	if (dcOptions()->dcType(shiftedDcId) == DcType::Cdn) {
+	if (dcOptions().dcType(shiftedDcId) == DcType::Cdn) {
 		performKeyDestroy(shiftedDcId);
 	} else {
 		_instance->send(MTPauth_LogOut(), rpcDone([=](const MTPBool &) {
@@ -1643,10 +1634,10 @@ void Instance::Private::prepareToDestroy() {
 	}
 }
 
-Instance::Instance(not_null<DcOptions*> options, Mode mode, Config &&config)
+Instance::Instance(Mode mode, Fields &&fields)
 : QObject()
-, _private(std::make_unique<Private>(this, options, mode)) {
-	_private->start(std::move(config));
+, _private(std::make_unique<Private>(this, mode, std::move(fields))) {
+	_private->start();
 }
 
 void Instance::resolveProxyDomain(const QString &host) {
@@ -1787,10 +1778,26 @@ void Instance::addKeysForDestroy(AuthKeysList &&keys) {
 	_private->addKeysForDestroy(std::move(keys));
 }
 
-not_null<DcOptions*> Instance::dcOptions() {
+Config &Instance::config() const {
+	return _private->config();
+}
+
+const ConfigFields &Instance::configValues() const {
+	return _private->configValues();
+}
+
+DcOptions &Instance::dcOptions() const {
 	return _private->dcOptions();
 }
 
+Environment Instance::environment() const {
+	return _private->environment();
+}
+
+bool Instance::isTestMode() const {
+	return _private->isTestMode();
+}
+
 QString Instance::deviceModel() const {
 	return _private->deviceModel();
 }
diff --git a/Telegram/SourceFiles/mtproto/mtp_instance.h b/Telegram/SourceFiles/mtproto/mtp_instance.h
index 7e44f9553..8a0bd0c7d 100644
--- a/Telegram/SourceFiles/mtproto/mtp_instance.h
+++ b/Telegram/SourceFiles/mtproto/mtp_instance.h
@@ -21,20 +21,29 @@ class Session;
 } // namespace details
 
 class DcOptions;
+class Config;
+struct ConfigFields;
 class AuthKey;
 using AuthKeyPtr = std::shared_ptr<AuthKey>;
 using AuthKeysList = std::vector<AuthKeyPtr>;
+enum class Environment : uchar;
 
 class Instance : public QObject {
 	Q_OBJECT
 
 public:
-	struct Config {
+	struct Fields {
+		Fields();
+		Fields(Fields &&other);
+		Fields &operator=(Fields &&other);
+		~Fields();
+
 		static constexpr auto kNoneMainDc = -1;
 		static constexpr auto kNotSetMainDc = 0;
 		static constexpr auto kDefaultMainDc = 2;
 		static constexpr auto kTemporaryMainDc = 1000;
 
+		std::unique_ptr<Config> config;
 		DcId mainDcId = kNotSetMainDc;
 		AuthKeysList keys;
 		QString deviceModel;
@@ -46,7 +55,7 @@ public:
 		KeysDestroyer,
 	};
 
-	Instance(not_null<DcOptions*> options, Mode mode, Config &&config);
+	Instance(Mode mode, Fields &&fields);
 	Instance(const Instance &other) = delete;
 	Instance &operator=(const Instance &other) = delete;
 	~Instance();
@@ -64,6 +73,11 @@ public:
 	[[nodiscard]] rpl::producer<> allKeysDestroyed() const;
 
 	// Thread-safe.
+	[[nodiscard]] Config &config() const;
+	[[nodiscard]] const ConfigFields &configValues() const;
+	[[nodiscard]] DcOptions &dcOptions() const;
+	[[nodiscard]] Environment environment() const;
+	[[nodiscard]] bool isTestMode() const;
 	[[nodiscard]] QString deviceModel() const;
 	[[nodiscard]] QString systemVersion() const;
 
@@ -74,8 +88,6 @@ public:
 	[[nodiscard]] AuthKeysList getKeysForWrite() const;
 	void addKeysForDestroy(AuthKeysList &&keys);
 
-	[[nodiscard]] not_null<DcOptions*> dcOptions();
-
 	void restart();
 	void restart(ShiftedDcId shiftedDcId);
 	int32 dcstate(ShiftedDcId shiftedDcId = 0);
diff --git a/Telegram/SourceFiles/mtproto/mtproto_config.cpp b/Telegram/SourceFiles/mtproto/mtproto_config.cpp
new file mode 100644
index 000000000..8b862ac6d
--- /dev/null
+++ b/Telegram/SourceFiles/mtproto/mtproto_config.cpp
@@ -0,0 +1,259 @@
+/*
+This file is part of Telegram Desktop,
+the official desktop application for the Telegram messaging service.
+
+For license and copyright information please follow this link:
+https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
+*/
+#include "mtproto/mtproto_config.h"
+
+#include "storage/serialize_common.h"
+#include "mtproto/type_utils.h"
+#include "logs.h"
+
+namespace MTP {
+namespace {
+
+constexpr auto kVersion = 1;
+
+}
+Config::Config(Environment environment) : _dcOptions(environment) {
+	_fields.webFileDcId = _dcOptions.isTestMode() ? 2 : 4;
+	_fields.txtDomainString = _dcOptions.isTestMode()
+		? u"tapv3.stel.com"_q
+		: u"apv3.stel.com"_q;
+}
+
+Config::Config(const Config &other)
+: _dcOptions(other.dcOptions())
+, _fields(other._fields) {
+}
+
+QByteArray Config::serialize() const {
+	auto options = _dcOptions.serialize();
+	auto size = sizeof(qint32) * 2; // version + environment
+	size += Serialize::bytearraySize(options);
+	size += 28 * sizeof(qint32);
+	size += Serialize::stringSize(_fields.internalLinksDomain);
+	size += Serialize::stringSize(_fields.txtDomainString);
+
+	auto result = QByteArray();
+	result.reserve(size);
+	{
+		QDataStream stream(&result, QIODevice::WriteOnly);
+		stream.setVersion(QDataStream::Qt_5_1);
+		stream
+			<< qint32(kVersion)
+			<< qint32(_dcOptions.isTestMode()
+				? Environment::Test
+				: Environment::Production)
+			<< options
+			<< qint32(_fields.chatSizeMax)
+			<< qint32(_fields.megagroupSizeMax)
+			<< qint32(_fields.forwardedCountMax)
+			<< qint32(_fields.onlineUpdatePeriod)
+			<< qint32(_fields.offlineBlurTimeout)
+			<< qint32(_fields.offlineIdleTimeout)
+			<< qint32(_fields.onlineFocusTimeout)
+			<< qint32(_fields.onlineCloudTimeout)
+			<< qint32(_fields.notifyCloudDelay)
+			<< qint32(_fields.notifyDefaultDelay)
+			<< qint32(_fields.savedGifsLimit)
+			<< qint32(_fields.editTimeLimit)
+			<< qint32(_fields.revokeTimeLimit)
+			<< qint32(_fields.revokePrivateTimeLimit)
+			<< qint32(_fields.revokePrivateInbox ? 1 : 0)
+			<< qint32(_fields.stickersRecentLimit)
+			<< qint32(_fields.stickersFavedLimit)
+			<< qint32(_fields.pinnedDialogsCountMax.current())
+			<< qint32(_fields.pinnedDialogsInFolderMax.current())
+			<< _fields.internalLinksDomain
+			<< qint32(_fields.channelsReadMediaPeriod)
+			<< qint32(_fields.callReceiveTimeoutMs)
+			<< qint32(_fields.callRingTimeoutMs)
+			<< qint32(_fields.callConnectTimeoutMs)
+			<< qint32(_fields.callPacketTimeoutMs)
+			<< qint32(_fields.webFileDcId)
+			<< _fields.txtDomainString
+			<< qint32(_fields.phoneCallsEnabled.current() ? 1 : 0)
+			<< qint32(_fields.blockedMode ? 1 : 0)
+			<< qint32(_fields.captionLengthMax);
+	}
+	return result;
+}
+
+std::unique_ptr<Config> Config::FromSerialized(const QByteArray &serialized) {
+	auto result = std::unique_ptr<Config>();
+	auto raw = result.get();
+
+	QDataStream stream(serialized);
+	stream.setVersion(QDataStream::Qt_5_1);
+
+	auto version = qint32();
+	stream >> version;
+	if (version != kVersion) {
+		return result;
+	}
+	auto environment = qint32();
+	stream >> environment;
+	switch (environment) {
+	case qint32(Environment::Test):
+		result = std::make_unique<Config>(Environment::Test);
+		break;
+	case qint32(Environment::Production):
+		result = std::make_unique<Config>(Environment::Production);
+		break;
+	}
+	if (!(raw = result.get())) {
+		return result;
+	}
+
+	auto dcOptionsSerialized = QByteArray();
+	const auto read = [&](auto &field) {
+		using Type = std::decay_t<decltype(field)>();
+		if constexpr (std::is_same_v<Type, int>
+			|| std::is_same_v<Type, rpl::variable<int>>) {
+			auto value = qint32();
+			stream >> value;
+			field = value;
+		} else if constexpr (std::is_same_v<Type, bool>
+			|| std::is_same_v<Type, rpl::variable<bool>>) {
+			auto value = qint32();
+			stream >> value;
+			field = (value == 1);
+		} else if constexpr (std::is_same_v<Type, QByteArray>
+			|| std::is_same_v<Type, QString>) {
+			static_assert(false_(field), "Bad read() call.");
+		}
+	};
+
+	read(dcOptionsSerialized);
+	read(raw->_fields.chatSizeMax);
+	read(raw->_fields.megagroupSizeMax);
+	read(raw->_fields.forwardedCountMax);
+	read(raw->_fields.onlineUpdatePeriod);
+	read(raw->_fields.offlineBlurTimeout);
+	read(raw->_fields.offlineIdleTimeout);
+	read(raw->_fields.onlineFocusTimeout);
+	read(raw->_fields.onlineCloudTimeout);
+	read(raw->_fields.notifyCloudDelay);
+	read(raw->_fields.notifyDefaultDelay);
+	read(raw->_fields.savedGifsLimit);
+	read(raw->_fields.editTimeLimit);
+	read(raw->_fields.revokeTimeLimit);
+	read(raw->_fields.revokePrivateTimeLimit);
+	read(raw->_fields.revokePrivateInbox);
+	read(raw->_fields.stickersRecentLimit);
+	read(raw->_fields.stickersFavedLimit);
+	read(raw->_fields.pinnedDialogsCountMax);
+	read(raw->_fields.pinnedDialogsInFolderMax);
+	read(raw->_fields.internalLinksDomain);
+	read(raw->_fields.channelsReadMediaPeriod);
+	read(raw->_fields.callReceiveTimeoutMs);
+	read(raw->_fields.callRingTimeoutMs);
+	read(raw->_fields.callConnectTimeoutMs);
+	read(raw->_fields.callPacketTimeoutMs);
+	read(raw->_fields.webFileDcId);
+	read(raw->_fields.txtDomainString);
+	read(raw->_fields.phoneCallsEnabled);
+	read(raw->_fields.blockedMode);
+	read(raw->_fields.captionLengthMax);
+
+	if (stream.status() != QDataStream::Ok
+		|| !raw->_dcOptions.constructFromSerialized(dcOptionsSerialized)) {
+		return nullptr;
+	}
+	return result;
+}
+
+const ConfigFields &Config::values() const {
+	return _fields;
+}
+
+void Config::apply(const MTPDconfig &data) {
+	if (mtpIsTrue(data.vtest_mode()) != _dcOptions.isTestMode()) {
+		LOG(("MTP Error: config with wrong test mode field received!"));
+		return;
+	}
+
+	DEBUG_LOG(("MTP Info: got config, "
+		"chat_size_max: %1, "
+		"date: %2, "
+		"test_mode: %3, "
+		"this_dc: %4, "
+		"dc_options.length: %5"
+		).arg(data.vchat_size_max().v
+		).arg(data.vdate().v
+		).arg(mtpIsTrue(data.vtest_mode())
+		).arg(data.vthis_dc().v
+		).arg(data.vdc_options().v.size()));
+
+	_fields.chatSizeMax = data.vchat_size_max().v;
+	_fields.megagroupSizeMax = data.vmegagroup_size_max().v;
+	_fields.forwardedCountMax = data.vforwarded_count_max().v;
+	_fields.onlineUpdatePeriod = data.vonline_update_period_ms().v;
+	_fields.offlineBlurTimeout = data.voffline_blur_timeout_ms().v;
+	_fields.offlineIdleTimeout = data.voffline_idle_timeout_ms().v;
+	_fields.onlineCloudTimeout = data.vonline_cloud_timeout_ms().v;
+	_fields.notifyCloudDelay = data.vnotify_cloud_delay_ms().v;
+	_fields.notifyDefaultDelay = data.vnotify_default_delay_ms().v;
+	_fields.savedGifsLimit = data.vsaved_gifs_limit().v;
+	_fields.editTimeLimit = data.vedit_time_limit().v;
+	_fields.revokeTimeLimit = data.vrevoke_time_limit().v;
+	_fields.revokePrivateTimeLimit = data.vrevoke_pm_time_limit().v;
+	_fields.revokePrivateInbox = data.is_revoke_pm_inbox();
+	_fields.stickersRecentLimit = data.vstickers_recent_limit().v;
+	_fields.stickersFavedLimit = data.vstickers_faved_limit().v;
+	_fields.pinnedDialogsCountMax =
+		std::max(data.vpinned_dialogs_count_max().v, 1);
+	_fields.pinnedDialogsInFolderMax =
+		std::max(data.vpinned_infolder_count_max().v, 1);
+	_fields.internalLinksDomain = qs(data.vme_url_prefix());
+	_fields.channelsReadMediaPeriod = data.vchannels_read_media_period().v;
+	_fields.webFileDcId = data.vwebfile_dc_id().v;
+	_fields.callReceiveTimeoutMs = data.vcall_receive_timeout_ms().v;
+	_fields.callRingTimeoutMs = data.vcall_ring_timeout_ms().v;
+	_fields.callConnectTimeoutMs = data.vcall_connect_timeout_ms().v;
+	_fields.callPacketTimeoutMs = data.vcall_packet_timeout_ms().v;
+	_fields.phoneCallsEnabled = data.is_phonecalls_enabled();
+	_fields.blockedMode = data.is_blocked_mode();
+	_fields.captionLengthMax = data.vcaption_length_max().v;
+
+	if (data.vdc_options().v.empty()) {
+		LOG(("MTP Error: config with empty dc_options received!"));
+	} else {
+		dcOptions().setFromList(data.vdc_options());
+	}
+
+	_updates.fire({});
+}
+
+rpl::producer<> Config::updates() const {
+	return _updates.events();
+}
+
+void Config::setChatSizeMax(int value) {
+	_fields.chatSizeMax = value;
+}
+
+void Config::setSavedGifsLimit(int value) {
+	_fields.savedGifsLimit = value;
+}
+
+void Config::setStickersRecentLimit(int value) {
+	_fields.stickersRecentLimit = value;
+}
+
+void Config::setStickersFavedLimit(int value) {
+	_fields.stickersFavedLimit = value;
+}
+
+void Config::setMegagroupSizeMax(int value) {
+	_fields.megagroupSizeMax = value;
+}
+
+void Config::setTxtDomainString(const QString &value) {
+	_fields.txtDomainString = value;
+}
+
+} // namespace MTP
diff --git a/Telegram/SourceFiles/mtproto/mtproto_config.h b/Telegram/SourceFiles/mtproto/mtproto_config.h
new file mode 100644
index 000000000..6df4dd9c7
--- /dev/null
+++ b/Telegram/SourceFiles/mtproto/mtproto_config.h
@@ -0,0 +1,93 @@
+/*
+This file is part of Telegram Desktop,
+the official desktop application for the Telegram messaging service.
+
+For license and copyright information please follow this link:
+https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
+*/
+#pragma once
+
+#include "mtproto/mtproto_dc_options.h"
+
+namespace MTP {
+
+struct ConfigFields {
+	int chatSizeMax = 200;
+	int megagroupSizeMax = 10000;
+	int forwardedCountMax = 100;
+	int onlineUpdatePeriod = 120000;
+	int offlineBlurTimeout = 5000;
+	int offlineIdleTimeout = 30000;
+	int onlineFocusTimeout = 1000; // Not from the server config.
+	int onlineCloudTimeout = 300000;
+	int notifyCloudDelay = 30000;
+	int notifyDefaultDelay = 1500;
+	int savedGifsLimit = 200;
+	int editTimeLimit = 172800;
+	int revokeTimeLimit = 172800;
+	int revokePrivateTimeLimit = 172800;
+	bool revokePrivateInbox = false;
+	int stickersRecentLimit = 30;
+	int stickersFavedLimit = 5;
+	rpl::variable<int> pinnedDialogsCountMax = 5;
+	rpl::variable<int> pinnedDialogsInFolderMax = 100;
+	QString internalLinksDomain = u"https://t.me/"_q;
+	int channelsReadMediaPeriod = 86400 * 7;
+	int callReceiveTimeoutMs = 20000;
+	int callRingTimeoutMs = 90000;
+	int callConnectTimeoutMs = 30000;
+	int callPacketTimeoutMs = 10000;
+	int webFileDcId = 4;
+	QString txtDomainString;
+	rpl::variable<bool> phoneCallsEnabled = true;
+	bool blockedMode = false;
+	int captionLengthMax = 1024;
+};
+
+class Config final {
+	struct PrivateTag {
+	};
+
+public:
+	explicit Config(Environment environment);
+	Config(const Config &other);
+
+	[[nodiscard]] QByteArray serialize() const;
+	[[nodiscard]] static std::unique_ptr<Config> FromSerialized(
+		const QByteArray &serialized);
+
+	[[nodiscard]] DcOptions &dcOptions() {
+		return _dcOptions;
+	}
+	[[nodiscard]] const DcOptions &dcOptions() const {
+		return _dcOptions;
+	}
+	[[nodiscard]] MTP::Environment environment() const {
+		return _dcOptions.environment();
+	}
+	[[nodiscard]] bool isTestMode() const {
+		return _dcOptions.isTestMode();
+	}
+
+	void apply(const MTPDconfig &data);
+
+	[[nodiscard]] const ConfigFields &values() const;
+	[[nodiscard]] rpl::producer<> updates() const;
+
+	// Set from legacy local stored values.
+	void setChatSizeMax(int value);
+	void setSavedGifsLimit(int value);
+	void setStickersRecentLimit(int value);
+	void setStickersFavedLimit(int value);
+	void setMegagroupSizeMax(int value);
+	void setTxtDomainString(const QString &value);
+
+private:
+	DcOptions _dcOptions;
+	ConfigFields _fields;
+
+	rpl::event_stream<> _updates;
+
+};
+
+} // namespace MTP
\ No newline at end of file
diff --git a/Telegram/SourceFiles/mtproto/dc_options.cpp b/Telegram/SourceFiles/mtproto/mtproto_dc_options.cpp
similarity index 94%
rename from Telegram/SourceFiles/mtproto/dc_options.cpp
rename to Telegram/SourceFiles/mtproto/mtproto_dc_options.cpp
index 95f8a0e0a..d2a54fc8c 100644
--- a/Telegram/SourceFiles/mtproto/dc_options.cpp
+++ b/Telegram/SourceFiles/mtproto/mtproto_dc_options.cpp
@@ -5,13 +5,16 @@ the official desktop application for the Telegram messaging service.
 For license and copyright information please follow this link:
 https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 */
-#include "mtproto/dc_options.h"
+#include "mtproto/mtproto_dc_options.h"
 
 #include "mtproto/details/mtproto_rsa_public_key.h"
 #include "mtproto/facade.h"
 #include "mtproto/connection_tcp.h"
 #include "storage/serialize_common.h"
 
+#include <QtCore/QFile>
+#include <QtCore/QRegularExpression>
+
 namespace MTP {
 namespace {
 
@@ -136,10 +139,20 @@ private:
 
 };
 
-DcOptions::DcOptions() {
+DcOptions::DcOptions(Environment environment)
+: _environment(environment) {
 	constructFromBuiltIn();
 }
 
+DcOptions::DcOptions(const DcOptions &other)
+: _environment(other._environment)
+, _data(other._data)
+, _cdnDcIds(other._cdnDcIds)
+, _publicKeys(other._publicKeys)
+, _cdnPublicKeys(other._cdnPublicKeys)
+, _immutable(other._immutable) {
+}
+
 DcOptions::~DcOptions() = default;
 
 bool DcOptions::ValidateSecret(bytes::const_span secret) {
@@ -163,13 +176,21 @@ void DcOptions::readBuiltInPublicKeys() {
 	}
 }
 
+Environment DcOptions::environment() const {
+	return _environment;
+}
+
+bool DcOptions::isTestMode() const {
+	return (_environment != Environment::Production);
+}
+
 void DcOptions::constructFromBuiltIn() {
 	WriteLocker lock(this);
 	_data.clear();
 
 	readBuiltInPublicKeys();
 
-	const auto list = cTestMode()
+	const auto list = isTestMode()
 		? gsl::make_span(kBuiltInDcsTest)
 		: gsl::make_span(kBuiltInDcs).subspan(0);
 	for (const auto &entry : list) {
@@ -181,7 +202,7 @@ void DcOptions::constructFromBuiltIn() {
 			).arg(entry.port));
 	}
 
-	const auto listv6 = cTestMode()
+	const auto listv6 = isTestMode()
 		? gsl::make_span(kBuiltInDcsIPv6Test)
 		: gsl::make_span(kBuiltInDcsIPv6).subspan(0);
 	for (const auto &entry : listv6) {
@@ -204,7 +225,7 @@ void DcOptions::processFromList(
 
 	auto data = [&] {
 		if (overwrite) {
-			return std::map<DcId, std::vector<Endpoint>>();
+			return base::flat_map<DcId, std::vector<Endpoint>>();
 		}
 		ReadLocker lock(this);
 		return _data;
@@ -313,7 +334,7 @@ bool DcOptions::applyOneGuarded(
 }
 
 bool DcOptions::ApplyOneOption(
-		std::map<DcId, std::vector<Endpoint>> &data,
+		base::flat_map<DcId, std::vector<Endpoint>> &data,
 		DcId dcId,
 		Flags flags,
 		const std::string &ip,
@@ -336,8 +357,8 @@ bool DcOptions::ApplyOneOption(
 }
 
 std::vector<DcId> DcOptions::CountOptionsDifference(
-		const std::map<DcId, std::vector<Endpoint>> &a,
-		const std::map<DcId, std::vector<Endpoint>> &b) {
+		const base::flat_map<DcId, std::vector<Endpoint>> &a,
+		const base::flat_map<DcId, std::vector<Endpoint>> &b) {
 	auto result = std::vector<DcId>();
 	const auto find = [](
 			const std::vector<Endpoint> &where,
@@ -389,7 +410,7 @@ std::vector<DcId> DcOptions::CountOptionsDifference(
 QByteArray DcOptions::serialize() const {
 	if (_immutable) {
 		// Don't write the overriden options to our settings.
-		return DcOptions().serialize();
+		return DcOptions(_environment).serialize();
 	}
 
 	ReadLocker lock(this);
@@ -477,7 +498,7 @@ QByteArray DcOptions::serialize() const {
 	return result;
 }
 
-void DcOptions::constructFromSerialized(const QByteArray &serialized) {
+bool DcOptions::constructFromSerialized(const QByteArray &serialized) {
 	QDataStream stream(serialized);
 	stream.setVersion(QDataStream::Qt_5_1);
 
@@ -493,7 +514,7 @@ void DcOptions::constructFromSerialized(const QByteArray &serialized) {
 	}
 	if (stream.status() != QDataStream::Ok) {
 		LOG(("MTP Error: Bad data for DcOptions::constructFromSerialized()"));
-		return;
+		return false;
 	}
 
 	WriteLocker lock(this);
@@ -506,7 +527,7 @@ void DcOptions::constructFromSerialized(const QByteArray &serialized) {
 		constexpr auto kMaxIpSize = 45;
 		if (ipSize <= 0 || ipSize > kMaxIpSize) {
 			LOG(("MTP Error: Bad data inside DcOptions::constructFromSerialized()"));
-			return;
+			return false;
 		}
 
 		auto ip = std::string(ipSize, ' ');
@@ -519,7 +540,7 @@ void DcOptions::constructFromSerialized(const QByteArray &serialized) {
 			stream >> secretSize;
 			if (secretSize < 0 || secretSize > kMaxSecretSize) {
 				LOG(("MTP Error: Bad data inside DcOptions::constructFromSerialized()"));
-				return;
+				return false;
 			} else if (secretSize > 0) {
 				secret.resize(secretSize);
 				stream.readRawData(
@@ -530,7 +551,7 @@ void DcOptions::constructFromSerialized(const QByteArray &serialized) {
 
 		if (stream.status() != QDataStream::Ok) {
 			LOG(("MTP Error: Bad data inside DcOptions::constructFromSerialized()"));
-			return;
+			return false;
 		}
 
 		applyOneGuarded(
@@ -547,7 +568,7 @@ void DcOptions::constructFromSerialized(const QByteArray &serialized) {
 		stream >> count;
 		if (stream.status() != QDataStream::Ok) {
 			LOG(("MTP Error: Bad data for CDN config in DcOptions::constructFromSerialized()"));
-			return;
+			return false;
 		}
 
 		for (auto i = 0; i != count; ++i) {
@@ -556,7 +577,7 @@ void DcOptions::constructFromSerialized(const QByteArray &serialized) {
 			stream >> dcId >> Serialize::bytes(n) >> Serialize::bytes(e);
 			if (stream.status() != QDataStream::Ok) {
 				LOG(("MTP Error: Bad data for CDN config inside DcOptions::constructFromSerialized()"));
-				return;
+				return false;
 			}
 
 			auto key = RSAPublicKey(n, e);
@@ -564,9 +585,11 @@ void DcOptions::constructFromSerialized(const QByteArray &serialized) {
 				_cdnPublicKeys[dcId].emplace(key.fingerprint(), std::move(key));
 			} else {
 				LOG(("MTP Error: Could not read valid CDN public key."));
+				return false;
 			}
 		}
 	}
+	return true;
 }
 
 rpl::producer<DcId> DcOptions::changed() const {
@@ -640,7 +663,8 @@ bool DcOptions::hasCDNKeysForDc(DcId dcId) const {
 RSAPublicKey DcOptions::getDcRSAKey(
 		DcId dcId,
 		const QVector<MTPlong> &fingerprints) const {
-	const auto findKey = [&](const std::map<uint64, RSAPublicKey> &keys) {
+	const auto findKey = [&](
+			const base::flat_map<uint64, RSAPublicKey> &keys) {
 		for (const auto &fingerprint : fingerprints) {
 			const auto it = keys.find(static_cast<uint64>(fingerprint.v));
 			if (it != keys.cend()) {
diff --git a/Telegram/SourceFiles/mtproto/dc_options.h b/Telegram/SourceFiles/mtproto/mtproto_dc_options.h
similarity index 81%
rename from Telegram/SourceFiles/mtproto/dc_options.h
rename to Telegram/SourceFiles/mtproto/mtproto_dc_options.h
index 11449d3ea..26c6e0861 100644
--- a/Telegram/SourceFiles/mtproto/dc_options.h
+++ b/Telegram/SourceFiles/mtproto/mtproto_dc_options.h
@@ -27,6 +27,12 @@ enum class DcType {
 	MediaCluster,
 	Cdn,
 };
+
+enum class Environment : uchar {
+	Production,
+	Test,
+};
+
 class DcOptions {
 public:
 	using Flag = MTPDdcOption::Flag;
@@ -53,13 +59,17 @@ public:
 
 	};
 
-	DcOptions();
+	explicit DcOptions(Environment environment);
+	DcOptions(const DcOptions &other);
 	~DcOptions();
 
 	[[nodiscard]] static bool ValidateSecret(bytes::const_span secret);
 
+	[[nodiscard]] Environment environment() const;
+	[[nodiscard]] bool isTestMode() const;
+
 	// construct methods don't notify "changed" subscribers.
-	void constructFromSerialized(const QByteArray &serialized);
+	bool constructFromSerialized(const QByteArray &serialized);
 	void constructFromBuiltIn();
 	void constructAddOne(
 		int id,
@@ -114,15 +124,15 @@ private:
 		int port,
 		const bytes::vector &secret);
 	static bool ApplyOneOption(
-		std::map<DcId, std::vector<Endpoint>> &data,
+		base::flat_map<DcId, std::vector<Endpoint>> &data,
 		DcId dcId,
 		Flags flags,
 		const std::string &ip,
 		int port,
 		const bytes::vector &secret);
 	static std::vector<DcId> CountOptionsDifference(
-		const std::map<DcId, std::vector<Endpoint>> &a,
-		const std::map<DcId, std::vector<Endpoint>> &b);
+		const base::flat_map<DcId, std::vector<Endpoint>> &a,
+		const base::flat_map<DcId, std::vector<Endpoint>> &b);
 	static void FilterIfHasWithFlag(Variants &variants, Flag flag);
 
 	[[nodiscard]] bool hasMediaOnlyOptionsFor(DcId dcId) const;
@@ -138,10 +148,13 @@ private:
 	class ReadLocker;
 	friend class ReadLocker;
 
-	std::map<DcId, std::vector<Endpoint>> _data;
-	std::set<DcId> _cdnDcIds;
-	std::map<uint64, details::RSAPublicKey> _publicKeys;
-	std::map<DcId, std::map<uint64, details::RSAPublicKey>> _cdnPublicKeys;
+	const Environment _environment = Environment();
+	base::flat_map<DcId, std::vector<Endpoint>> _data;
+	base::flat_set<DcId> _cdnDcIds;
+	base::flat_map<uint64, details::RSAPublicKey> _publicKeys;
+	base::flat_map<
+		DcId,
+		base::flat_map<uint64, details::RSAPublicKey>> _cdnPublicKeys;
 	mutable QReadWriteLock _useThroughLockers;
 
 	rpl::event_stream<DcId> _changed;
diff --git a/Telegram/SourceFiles/mtproto/mtproto_pch.h b/Telegram/SourceFiles/mtproto/mtproto_pch.h
index 2804191f4..284089e7e 100644
--- a/Telegram/SourceFiles/mtproto/mtproto_pch.h
+++ b/Telegram/SourceFiles/mtproto/mtproto_pch.h
@@ -10,10 +10,14 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include <QtNetwork/QNetworkProxy>
 #include <QtNetwork/QTcpSocket>
 
+#include <range/v3/all.hpp>
+
 #include <rpl/rpl.h>
 #include <crl/crl.h>
 
 #include "base/bytes.h"
+#include "base/flat_map.h"
+#include "base/flat_set.h"
 
 #include "logs.h"
 #include "scheme.h"
diff --git a/Telegram/SourceFiles/mtproto/sender.h b/Telegram/SourceFiles/mtproto/sender.h
index 189121f1f..c9eaf23fe 100644
--- a/Telegram/SourceFiles/mtproto/sender.h
+++ b/Telegram/SourceFiles/mtproto/sender.h
@@ -196,8 +196,8 @@ public:
 	: _instance(instance) {
 	}
 
-	[[nodiscard]] not_null<Instance*> instance() const {
-		return _instance;
+	[[nodiscard]] Instance &instance() const {
+		return *_instance;
 	}
 
 	template <typename Request>
@@ -247,7 +247,7 @@ public:
 		}
 
 		mtpRequestId send() {
-			const auto id = sender()->instance()->send(
+			const auto id = sender()->_instance->send(
 				_request,
 				takeOnDone(),
 				takeOnFail(),
@@ -376,7 +376,7 @@ private:
 	};
 
 	template <typename Request>
-	friend class SpecialRequestBuilder;
+	friend class SpecificRequestBuilder;
 	friend class RequestBuilder;
 	friend class RequestWrap;
 	friend class SentRequestWrap;
diff --git a/Telegram/SourceFiles/mtproto/session.cpp b/Telegram/SourceFiles/mtproto/session.cpp
index f850e9956..b4f264662 100644
--- a/Telegram/SourceFiles/mtproto/session.cpp
+++ b/Telegram/SourceFiles/mtproto/session.cpp
@@ -195,7 +195,7 @@ void Session::watchDcKeyChanges() {
 }
 
 void Session::watchDcOptionsChanges() {
-	_instance->dcOptions()->changed(
+	_instance->dcOptions().changed(
 	) | rpl::filter([=](DcId dcId) {
 		return (BareDcId(_shiftedDcId) == dcId) && (_private != nullptr);
 	}) | rpl::start_with_next([=] {
@@ -204,8 +204,8 @@ void Session::watchDcOptionsChanges() {
 		});
 	}, _lifetime);
 
-	if (_instance->dcOptions()->dcType(_shiftedDcId) == DcType::Cdn) {
-		_instance->dcOptions()->cdnConfigChanged(
+	if (_instance->dcOptions().dcType(_shiftedDcId) == DcType::Cdn) {
+		_instance->dcOptions().cdnConfigChanged(
 		) | rpl::filter([=] {
 			return (_private != nullptr);
 		}) | rpl::start_with_next([=] {
diff --git a/Telegram/SourceFiles/mtproto/session_private.cpp b/Telegram/SourceFiles/mtproto/session_private.cpp
index 8f7aa7c59..b54b591b0 100644
--- a/Telegram/SourceFiles/mtproto/session_private.cpp
+++ b/Telegram/SourceFiles/mtproto/session_private.cpp
@@ -13,7 +13,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "mtproto/details/mtproto_rsa_public_key.h"
 #include "mtproto/session.h"
 #include "mtproto/mtproto_rpc_sender.h"
-#include "mtproto/dc_options.h"
+#include "mtproto/mtproto_dc_options.h"
 #include "mtproto/connection_abstract.h"
 #include "base/openssl_help.h"
 #include "base/qthelp_url.h"
@@ -117,7 +117,7 @@ SessionPrivate::SessionPrivate(
 : QObject(nullptr)
 , _instance(instance)
 , _shiftedDcId(shiftedDcId)
-, _realDcType(_instance->dcOptions()->dcType(_shiftedDcId))
+, _realDcType(_instance->dcOptions().dcType(_shiftedDcId))
 , _currentDcType(_realDcType)
 , _state(DisconnectedState)
 , _retryTimer(thread, [=] { retryByTimer(); })
@@ -203,7 +203,7 @@ int16 SessionPrivate::getProtocolDcId() const {
 	const auto simpleDcId = isTemporaryDcId(dcId)
 		? getRealIdFromTemporaryDcId(dcId)
 		: dcId;
-	const auto testedDcId = cTestMode()
+	const auto testedDcId = _instance->isTestMode()
 		? (kTestModeDcIdShift + simpleDcId)
 		: simpleDcId;
 	return (_currentDcType == DcType::MediaCluster)
@@ -374,7 +374,7 @@ uint32 SessionPrivate::nextRequestSeqNumber(bool needAck) {
 }
 
 bool SessionPrivate::realDcTypeChanged() {
-	const auto now = _instance->dcOptions()->dcType(_shiftedDcId);
+	const auto now = _instance->dcOptions().dcType(_shiftedDcId);
 	if (_realDcType == now) {
 		return false;
 	}
@@ -936,7 +936,7 @@ void SessionPrivate::connectToServer(bool afterConfig) {
 
 	_currentDcType = tryAcquireKeyCreation();
 	if (_currentDcType == DcType::Cdn && !_instance->isKeysDestroyer()) {
-		if (!_instance->dcOptions()->hasCDNKeysForDc(bareDc)) {
+		if (!_instance->dcOptions().hasCDNKeysForDc(bareDc)) {
 			requestCDNConfig();
 			return;
 		}
@@ -947,7 +947,7 @@ void SessionPrivate::connectToServer(bool afterConfig) {
 	} else {
 		using Variants = DcOptions::Variants;
 		const auto special = (_currentDcType == DcType::Temporary);
-		const auto variants = _instance->dcOptions()->lookup(
+		const auto variants = _instance->dcOptions().lookup(
 			bareDc,
 			_currentDcType,
 			_options->proxy.type != ProxyData::Type::None);
@@ -2366,7 +2366,7 @@ void SessionPrivate::applyAuthKey(AuthKeyPtr &&encryptionKey) {
 			BareDcId(_shiftedDcId),
 			getProtocolDcId(),
 			_connection.get(),
-			_instance->dcOptions());
+			&_instance->dcOptions());
 	} else {
 		DEBUG_LOG(("AuthKey Info: No key in updateAuthKey(), "
 			"but someone is creating already, waiting."));
diff --git a/Telegram/SourceFiles/mtproto/session_private.h b/Telegram/SourceFiles/mtproto/session_private.h
index 302067c65..cf7c68ab4 100644
--- a/Telegram/SourceFiles/mtproto/session_private.h
+++ b/Telegram/SourceFiles/mtproto/session_private.h
@@ -10,7 +10,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "mtproto/details/mtproto_received_ids_manager.h"
 #include "mtproto/details/mtproto_serialized_request.h"
 #include "mtproto/mtproto_auth_key.h"
-#include "mtproto/dc_options.h"
+#include "mtproto/mtproto_dc_options.h"
 #include "mtproto/connection_abstract.h"
 #include "mtproto/facade.h"
 #include "base/openssl_help.h"
diff --git a/Telegram/SourceFiles/mtproto/special_config_request.cpp b/Telegram/SourceFiles/mtproto/special_config_request.cpp
index 2bc5cae2a..ab8bd0c6a 100644
--- a/Telegram/SourceFiles/mtproto/special_config_request.cpp
+++ b/Telegram/SourceFiles/mtproto/special_config_request.cpp
@@ -8,7 +8,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "mtproto/special_config_request.h"
 
 #include "mtproto/details/mtproto_rsa_public_key.h"
-#include "mtproto/dc_options.h"
+#include "mtproto/mtproto_dc_options.h"
 #include "mtproto/mtproto_auth_key.h"
 #include "base/unixtime.h"
 #include "base/openssl_help.h"
@@ -189,9 +189,11 @@ SpecialConfigRequest::SpecialConfigRequest(
 		int port,
 		bytes::const_span secret)> callback,
 	Fn<void()> timeDoneCallback,
+	const QString &domainString,
 	const QString &phone)
 : _callback(std::move(callback))
 , _timeDoneCallback(std::move(timeDoneCallback))
+, _domainString(domainString)
 , _phone(phone) {
 	Expects((_callback == nullptr) != (_timeDoneCallback == nullptr));
 
@@ -251,12 +253,19 @@ SpecialConfigRequest::SpecialConfigRequest(
 		const std::string &ip,
 		int port,
 		bytes::const_span secret)> callback,
+	const QString &domainString,
 	const QString &phone)
-: SpecialConfigRequest(std::move(callback), nullptr, phone) {
+: SpecialConfigRequest(std::move(callback), nullptr, domainString, phone) {
 }
 
-SpecialConfigRequest::SpecialConfigRequest(Fn<void()> timeDoneCallback)
-: SpecialConfigRequest(nullptr, std::move(timeDoneCallback), QString()) {
+SpecialConfigRequest::SpecialConfigRequest(
+	Fn<void()> timeDoneCallback,
+	const QString &domainString)
+: SpecialConfigRequest(
+	nullptr,
+	std::move(timeDoneCallback),
+	domainString,
+	QString()) {
 }
 
 void SpecialConfigRequest::sendNextRequest() {
@@ -283,7 +292,7 @@ void SpecialConfigRequest::performRequest(const Attempt &attempt) {
 		url.setHost(attempt.data);
 		url.setPath(qsl("/dns-query"));
 		url.setQuery(qsl("name=%1&type=16&random_padding=%2"
-		).arg(Global::TxtDomainString()
+		).arg(_domainString
 		).arg(GenerateDnsRandomPadding()));
 		request.setRawHeader("accept", "application/dns-json");
 	} break;
@@ -291,7 +300,7 @@ void SpecialConfigRequest::performRequest(const Attempt &attempt) {
 		url.setHost(attempt.data);
 		url.setPath(qsl("/resolve"));
 		url.setQuery(qsl("name=%1&type=ANY&random_padding=%2"
-		).arg(Global::TxtDomainString()
+		).arg(_domainString
 		).arg(GenerateDnsRandomPadding()));
 		if (!attempt.host.isEmpty()) {
 			const auto host = attempt.host + ".google.com";
diff --git a/Telegram/SourceFiles/mtproto/special_config_request.h b/Telegram/SourceFiles/mtproto/special_config_request.h
index da4d27f4d..6962c04fe 100644
--- a/Telegram/SourceFiles/mtproto/special_config_request.h
+++ b/Telegram/SourceFiles/mtproto/special_config_request.h
@@ -25,8 +25,11 @@ public:
 			const std::string &ip,
 			int port,
 			bytes::const_span secret)> callback,
+		const QString &domainString,
 		const QString &phone);
-	explicit SpecialConfigRequest(Fn<void()> timeDoneCallback);
+	SpecialConfigRequest(
+		Fn<void()> timeDoneCallback,
+		const QString &domainString);
 
 private:
 	enum class Type {
@@ -49,6 +52,7 @@ private:
 			int port,
 			bytes::const_span secret)> callback,
 		Fn<void()> timeDoneCallback,
+		const QString &domainString,
 		const QString &phone);
 
 	void sendNextRequest();
@@ -65,6 +69,7 @@ private:
 		int port,
 		bytes::const_span secret)> _callback;
 	Fn<void()> _timeDoneCallback;
+	QString _domainString;
 	QString _phone;
 	MTPhelp_ConfigSimple _simpleConfig;
 
diff --git a/Telegram/SourceFiles/passport/passport_form_controller.cpp b/Telegram/SourceFiles/passport/passport_form_controller.cpp
index 386ae43a9..80d91a9d3 100644
--- a/Telegram/SourceFiles/passport/passport_form_controller.cpp
+++ b/Telegram/SourceFiles/passport/passport_form_controller.cpp
@@ -624,7 +624,7 @@ FormController::FormController(
 	not_null<Window::SessionController*> controller,
 	const FormRequest &request)
 : _controller(controller)
-, _api(_controller->session().mtp())
+, _api(&_controller->session().mtp())
 , _request(PreprocessRequest(request))
 , _shortPollTimer([=] { reloadPassword(); })
 , _view(std::make_unique<PanelController>(this)) {
diff --git a/Telegram/SourceFiles/platform/linux/launcher_linux.cpp b/Telegram/SourceFiles/platform/linux/launcher_linux.cpp
index 679f4864b..1d948fd19 100644
--- a/Telegram/SourceFiles/platform/linux/launcher_linux.cpp
+++ b/Telegram/SourceFiles/platform/linux/launcher_linux.cpp
@@ -67,9 +67,6 @@ bool Launcher::launchUpdater(UpdaterLaunch action) {
 	if (cStartInTray()) {
 		argumentsList.push("-startintray");
 	}
-	if (cTestMode()) {
-		argumentsList.push("-testmode");
-	}
 #ifndef TDESKTOP_DISABLE_AUTOUPDATE
 	if (Core::UpdaterDisabled()) {
 		argumentsList.push("-externalupdater");
diff --git a/Telegram/SourceFiles/platform/linux/main_window_linux.cpp b/Telegram/SourceFiles/platform/linux/main_window_linux.cpp
index 71f32f6be..fc5b3f140 100644
--- a/Telegram/SourceFiles/platform/linux/main_window_linux.cpp
+++ b/Telegram/SourceFiles/platform/linux/main_window_linux.cpp
@@ -1025,7 +1025,7 @@ void MainWindow::updateGlobalMenuHook() {
 		canCopy = list->canCopySelected();
 		canDelete = list->canDeleteSelected();
 	}
-	App::wnd()->updateIsActive(0);
+	App::wnd()->updateIsActive();
 	const auto logged = account().sessionExists();
 	const auto locked = Core::App().locked();
 	const auto inactive = !logged || locked;
diff --git a/Telegram/SourceFiles/platform/mac/launcher_mac.mm b/Telegram/SourceFiles/platform/mac/launcher_mac.mm
index 080f7471b..a8d0cb26b 100644
--- a/Telegram/SourceFiles/platform/mac/launcher_mac.mm
+++ b/Telegram/SourceFiles/platform/mac/launcher_mac.mm
@@ -63,7 +63,6 @@ bool Launcher::launchUpdater(UpdaterLaunch action) {
 		if (cLaunchMode() == LaunchModeAutoStart) [args addObject:@"-autostart"];
 		if (Logs::DebugEnabled()) [args addObject:@"-debug"];
 		if (cStartInTray()) [args addObject:@"-startintray"];
-		if (cTestMode()) [args addObject:@"-testmode"];
 		if (cUseFreeType()) [args addObject:@"-freetype"];
 #ifndef TDESKTOP_DISABLE_AUTOUPDATE
 		if (Core::UpdaterDisabled()) [args addObject:@"-externalupdater"];
diff --git a/Telegram/SourceFiles/platform/mac/mac_touchbar.mm b/Telegram/SourceFiles/platform/mac/mac_touchbar.mm
index feeec8ce8..c1b77c3d5 100644
--- a/Telegram/SourceFiles/platform/mac/mac_touchbar.mm
+++ b/Telegram/SourceFiles/platform/mac/mac_touchbar.mm
@@ -11,6 +11,7 @@
 
 #include "apiwrap.h"
 #include "main/main_session.h"
+#include "mtproto/mtproto_config.h"
 #include "api/api_sending.h"
 #include "boxes/confirm_box.h"
 #include "chat_helpers/emoji_list_widget.h"
@@ -39,7 +40,6 @@
 #include "window/window_session_controller.h"
 #include "ui/empty_userpic.h"
 #include "ui/widgets/input_fields.h"
-#include "facades.h"
 #include "app.h"
 #include "window/window_controller.h"
 
@@ -1233,7 +1233,8 @@ void AppendEmojiPacks(
 		_mainPinnedButtons = [[NSMutableArray alloc] init];
 		NSStackView *stackView = [[NSStackView alloc] init];
 
-		for (auto i = kArchiveId; i <= Global::PinnedDialogsCountMax(); i++) {
+		const auto &config = _session->serverConfig();
+		for (auto i = kArchiveId; i <= config.pinnedDialogsCountMax.current(); i++) {
 			PinnedDialogButton *button =
 				[[[PinnedDialogButton alloc]
 					init:i
diff --git a/Telegram/SourceFiles/platform/mac/main_window_mac.mm b/Telegram/SourceFiles/platform/mac/main_window_mac.mm
index 95341c679..64ee4253a 100644
--- a/Telegram/SourceFiles/platform/mac/main_window_mac.mm
+++ b/Telegram/SourceFiles/platform/mac/main_window_mac.mm
@@ -821,7 +821,7 @@ void MainWindow::updateGlobalMenuHook() {
 	if (_private->_touchBar) {
 		[_private->_touchBar showInputFieldItem:showTouchBarItem];
 	}
-	App::wnd()->updateIsActive(0);
+	App::wnd()->updateIsActive();
 	const auto logged = account().sessionExists();
 	const auto locked = Core::App().locked();
 	const auto inactive = !logged || locked;
diff --git a/Telegram/SourceFiles/platform/win/launcher_win.cpp b/Telegram/SourceFiles/platform/win/launcher_win.cpp
index b2584cd0c..20d530249 100644
--- a/Telegram/SourceFiles/platform/win/launcher_win.cpp
+++ b/Telegram/SourceFiles/platform/win/launcher_win.cpp
@@ -68,9 +68,6 @@ bool Launcher::launchUpdater(UpdaterLaunch action) {
 	if (cStartInTray()) {
 		pushArgument(qsl("-startintray"));
 	}
-	if (cTestMode()) {
-		pushArgument(qsl("-testmode"));
-	}
 	if (cUseFreeType()) {
 		pushArgument(qsl("-freetype"));
 	}
diff --git a/Telegram/SourceFiles/profile/profile_block_group_members.cpp b/Telegram/SourceFiles/profile/profile_block_group_members.cpp
index a67c574af..ab0711376 100644
--- a/Telegram/SourceFiles/profile/profile_block_group_members.cpp
+++ b/Telegram/SourceFiles/profile/profile_block_group_members.cpp
@@ -14,6 +14,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "boxes/peers/edit_participants_box.h"
 #include "base/unixtime.h"
 #include "ui/widgets/popup_menu.h"
+#include "mtproto/mtproto_config.h"
 #include "data/data_peer_values.h"
 #include "data/data_channel.h"
 #include "data/data_chat.h"
@@ -23,7 +24,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "apiwrap.h"
 #include "main/main_session.h"
 #include "lang/lang_keys.h"
-#include "facades.h"
+#include "facades.h" // Ui::showPeerProfile
 
 namespace Profile {
 namespace {
@@ -341,7 +342,8 @@ void GroupMembersWidget::fillMegagroupMembers(
 	}
 
 	_sortByOnline = (megagroup->membersCount() > 0)
-		&& (megagroup->membersCount() <= Global::ChatSizeMax());
+		&& (megagroup->membersCount()
+			<= megagroup->session().serverConfig().chatSizeMax);
 
 	auto &membersList = megagroup->mgInfo->lastParticipants;
 	if (_sortByOnline) {
diff --git a/Telegram/SourceFiles/settings.cpp b/Telegram/SourceFiles/settings.cpp
index 682f3ab83..4cdbbdded 100644
--- a/Telegram/SourceFiles/settings.cpp
+++ b/Telegram/SourceFiles/settings.cpp
@@ -24,7 +24,6 @@ uint64 gAlphaVersion = AppAlphaVersion;
 uint64 gRealAlphaVersion = AppAlphaVersion;
 QByteArray gAlphaPrivateKey;
 
-bool gTestMode = false;
 bool gManyInstance = false;
 QString gKeyFile;
 QString gWorkingDir, gExeDir, gExeName;
diff --git a/Telegram/SourceFiles/settings.h b/Telegram/SourceFiles/settings.h
index b87c300b1..2877f6504 100644
--- a/Telegram/SourceFiles/settings.h
+++ b/Telegram/SourceFiles/settings.h
@@ -35,7 +35,6 @@ DeclareSetting(uint64, AlphaVersion);
 DeclareSetting(uint64, RealAlphaVersion);
 DeclareSetting(QByteArray, AlphaPrivateKey);
 
-DeclareSetting(bool, TestMode);
 DeclareSetting(bool, AutoStart);
 DeclareSetting(bool, StartMinimized);
 DeclareSetting(bool, StartInTray);
diff --git a/Telegram/SourceFiles/settings/settings_advanced.cpp b/Telegram/SourceFiles/settings/settings_advanced.cpp
index c55b7047e..9ed96b9b8 100644
--- a/Telegram/SourceFiles/settings/settings_advanced.cpp
+++ b/Telegram/SourceFiles/settings/settings_advanced.cpp
@@ -57,9 +57,7 @@ void SetupConnectionType(
 	}
 #ifndef TDESKTOP_DISABLE_NETWORK_PROXY
 	const auto connectionType = [=] {
-		const auto transport = account->mtp()
-			? account->mtp()->dctransport()
-			: QString();
+		const auto transport = account->mtp().dctransport();
 		if (Global::ProxySettings() != MTP::ProxyData::Settings::Enabled) {
 			return transport.isEmpty()
 				? tr::lng_connection_auto_connecting(tr::now)
diff --git a/Telegram/SourceFiles/settings/settings_codes.cpp b/Telegram/SourceFiles/settings/settings_codes.cpp
index 930df4a17..a1d72d1f3 100644
--- a/Telegram/SourceFiles/settings/settings_codes.cpp
+++ b/Telegram/SourceFiles/settings/settings_codes.cpp
@@ -13,13 +13,14 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "mainwindow.h"
 #include "data/data_session.h"
 #include "main/main_session.h"
+#include "main/main_account.h"
 #include "main/main_accounts.h"
 #include "boxes/confirm_box.h"
 #include "lang/lang_cloud_manager.h"
 #include "lang/lang_instance.h"
 #include "core/application.h"
 #include "mtproto/mtp_instance.h"
-#include "mtproto/dc_options.h"
+#include "mtproto/mtproto_dc_options.h"
 #include "core/file_utilities.h"
 #include "core/update_checker.h"
 #include "window/themes/window_theme.h"
@@ -49,12 +50,6 @@ auto GenerateCodes() {
 	codes.emplace(qsl("viewlogs"), [](SessionController *window) {
 		File::ShowInFolder(cWorkingDir() + "log.txt");
 	});
-	codes.emplace(qsl("testmode"), [](SessionController *window) {
-		auto text = cTestMode() ? qsl("Do you want to disable TEST mode?") : qsl("Do you want to enable TEST mode?\n\nYou will be switched to test cloud.");
-		Ui::show(Box<ConfirmBox>(text, [] {
-			Core::App().switchTestMode();
-		}));
-	});
 	if (!Core::UpdaterDisabled()) {
 		codes.emplace(qsl("testupdate"), [](SessionController *window) {
 			Core::UpdateChecker().test();
@@ -112,10 +107,25 @@ auto GenerateCodes() {
 		}));
 	});
 	codes.emplace(qsl("endpoints"), [](SessionController *window) {
-		FileDialog::GetOpenPath(Core::App().getFileDialogParent(), "Open DC endpoints", "DC Endpoints (*.tdesktop-endpoints)", [](const FileDialog::OpenResult &result) {
+		if (!Core::App().accounts().started()) {
+			return;
+		}
+		const auto weak = window
+			? base::make_weak(&window->session().account())
+			: nullptr;
+		FileDialog::GetOpenPath(Core::App().getFileDialogParent(), "Open DC endpoints", "DC Endpoints (*.tdesktop-endpoints)", [weak](const FileDialog::OpenResult &result) {
 			if (!result.paths.isEmpty()) {
-				if (!Core::App().dcOptions()->loadFromFile(result.paths.front())) {
-					Ui::show(Box<InformBox>("Could not load endpoints :( Errors in 'log.txt'."));
+				const auto loadFor = [&](not_null<Main::Account*> account) {
+					if (!account->mtp().dcOptions().loadFromFile(result.paths.front())) {
+						Ui::show(Box<InformBox>("Could not load endpoints :( Errors in 'log.txt'."));
+					}
+				};
+				if (const auto strong = weak.get()) {
+					loadFor(strong);
+				} else {
+					for (const auto &[index, account] : Core::App().accounts().list()) {
+						loadFor(account.get());
+					}
 				}
 			}
 		});
@@ -130,11 +140,26 @@ auto GenerateCodes() {
 		crl::on_main(&Core::App(), [=] {
 			if (window
 				&& !Core::App().locked()
+				&& Core::App().accounts().started()
 				&& Core::App().accounts().list().size() < 3) {
-				Core::App().accounts().activate(Core::App().accounts().add());
+				Core::App().accounts().activate(
+					Core::App().accounts().add(MTP::Environment::Production));
 			}
 		});
 	});
+
+	codes.emplace(qsl("acctest"), [](SessionController *window) {
+		crl::on_main(&Core::App(), [=] {
+			if (window
+				&& !Core::App().locked()
+				&& Core::App().accounts().started()
+				&& Core::App().accounts().list().size() < 3) {
+				Core::App().accounts().activate(
+					Core::App().accounts().add(MTP::Environment::Test));
+			}
+		});
+	});
+
 	for (auto i = 0; i != 3; ++i) {
 		codes.emplace(qsl("account%1").arg(i + 1), [=](
 				SessionController *window) {
diff --git a/Telegram/SourceFiles/settings/settings_privacy_controllers.cpp b/Telegram/SourceFiles/settings/settings_privacy_controllers.cpp
index d946cb66c..e4b9f352c 100644
--- a/Telegram/SourceFiles/settings/settings_privacy_controllers.cpp
+++ b/Telegram/SourceFiles/settings/settings_privacy_controllers.cpp
@@ -182,7 +182,7 @@ AdminLog::OwnedItem GenerateForwardedItem(
 BlockedBoxController::BlockedBoxController(
 	not_null<Window::SessionController*> window)
 : _window(window)
-, _api(_window->session().mtp()) {
+, _api(&_window->session().mtp()) {
 }
 
 Main::Session &BlockedBoxController::session() const {
diff --git a/Telegram/SourceFiles/storage/details/storage_settings_scheme.cpp b/Telegram/SourceFiles/storage/details/storage_settings_scheme.cpp
index f4fc6e7a4..70686c5b3 100644
--- a/Telegram/SourceFiles/storage/details/storage_settings_scheme.cpp
+++ b/Telegram/SourceFiles/storage/details/storage_settings_scheme.cpp
@@ -9,8 +9,9 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 
 #include "storage/details/storage_file_utilities.h"
 #include "storage/cache/storage_cache_database.h"
-#include "core/application.h"
 #include "storage/serialize_common.h"
+#include "core/application.h"
+#include "mtproto/mtproto_config.h"
 #include "ui/effects/animation_value.h"
 #include "ui/widgets/input_fields.h"
 #include "window/themes/window_theme.h"
@@ -47,7 +48,7 @@ bool ReadSetting(
 		stream >> dcId >> host >> ip >> port;
 		if (!CheckStreamStatus(stream)) return false;
 
-		context.dcOptions.constructAddOne(
+		context.fallbackConfigLegacyDcOptions.constructAddOne(
 			dcId,
 			0,
 			ip.toStdString(),
@@ -62,7 +63,7 @@ bool ReadSetting(
 		stream >> dcIdWithShift >> flags >> ip >> port;
 		if (!CheckStreamStatus(stream)) return false;
 
-		context.dcOptions.constructAddOne(
+		context.fallbackConfigLegacyDcOptions.constructAddOne(
 			dcIdWithShift,
 			MTPDdcOption::Flags::from_raw(flags),
 			ip.toStdString(),
@@ -70,12 +71,13 @@ bool ReadSetting(
 			{});
 	} break;
 
-	case dbiDcOptions: {
+	case dbiDcOptionsOld: {
 		auto serialized = QByteArray();
 		stream >> serialized;
 		if (!CheckStreamStatus(stream)) return false;
 
-		context.dcOptions.constructFromSerialized(serialized);
+		context.fallbackConfigLegacyDcOptions.constructFromSerialized(
+			serialized);
 	} break;
 
 	case dbiApplicationSettings: {
@@ -86,44 +88,44 @@ bool ReadSetting(
 		Core::App().settings().constructFromSerialized(serialized);
 	} break;
 
-	case dbiChatSizeMax: {
+	case dbiChatSizeMaxOld: {
 		qint32 maxSize;
 		stream >> maxSize;
 		if (!CheckStreamStatus(stream)) return false;
 
-		Global::SetChatSizeMax(maxSize);
+		context.fallbackConfigLegacyChatSizeMax = maxSize;
 	} break;
 
-	case dbiSavedGifsLimit: {
+	case dbiSavedGifsLimitOld: {
 		qint32 limit;
 		stream >> limit;
 		if (!CheckStreamStatus(stream)) return false;
 
-		Global::SetSavedGifsLimit(limit);
+		context.fallbackConfigLegacySavedGifsLimit = limit;
 	} break;
 
-	case dbiStickersRecentLimit: {
+	case dbiStickersRecentLimitOld: {
 		qint32 limit;
 		stream >> limit;
 		if (!CheckStreamStatus(stream)) return false;
 
-		Global::SetStickersRecentLimit(limit);
+		context.fallbackConfigLegacyStickersRecentLimit = limit;
 	} break;
 
-	case dbiStickersFavedLimit: {
+	case dbiStickersFavedLimitOld: {
 		qint32 limit;
 		stream >> limit;
 		if (!CheckStreamStatus(stream)) return false;
 
-		Global::SetStickersFavedLimit(limit);
+		context.fallbackConfigLegacyStickersFavedLimit = limit;
 	} break;
 
-	case dbiMegagroupSizeMax: {
+	case dbiMegagroupSizeMaxOld: {
 		qint32 maxSize;
 		stream >> maxSize;
 		if (!CheckStreamStatus(stream)) return false;
 
-		Global::SetMegagroupSizeMax(maxSize);
+		context.fallbackConfigLegacyMegagroupSizeMax = maxSize;
 	} break;
 
 	case dbiUser: {
@@ -407,18 +409,18 @@ bool ReadSetting(
 		Global::RefWorkMode().set(newMode());
 	} break;
 
-	case dbiTxtDomainStringOld: {
+	case dbiTxtDomainStringOldOld: {
 		QString v;
 		stream >> v;
 		if (!CheckStreamStatus(stream)) return false;
 	} break;
 
-	case dbiTxtDomainString: {
+	case dbiTxtDomainStringOld: {
 		QString v;
 		stream >> v;
 		if (!CheckStreamStatus(stream)) return false;
 
-		Global::SetTxtDomainString(v);
+		context.fallbackConfigLegacyTxtDomainString = v;
 	} break;
 
 	case dbiConnectionTypeOld: {
@@ -659,13 +661,13 @@ bool ReadSetting(
 		}
 	} break;
 
-	case dbiLangOld: {
+	case dbiLangOld: { // deprecated
 		qint32 v;
 		stream >> v;
 		if (!CheckStreamStatus(stream)) return false;
 	} break;
 
-	case dbiLangFileOld: {
+	case dbiLangFileOld: { // deprecated
 		QString v;
 		stream >> v;
 		if (!CheckStreamStatus(stream)) return false;
@@ -681,19 +683,19 @@ bool ReadSetting(
 		cSetWindowPos(position);
 	} break;
 
-	case dbiLoggedPhoneNumber: { // deprecated
+	case dbiLoggedPhoneNumberOld: { // deprecated
 		QString v;
 		stream >> v;
 		if (!CheckStreamStatus(stream)) return false;
 	} break;
 
-	case dbiMutePeer: { // deprecated
+	case dbiMutePeerOld: { // deprecated
 		quint64 peerId;
 		stream >> peerId;
 		if (!CheckStreamStatus(stream)) return false;
 	} break;
 
-	case dbiMutedPeers: { // deprecated
+	case dbiMutedPeersOld: { // deprecated
 		quint32 count;
 		stream >> count;
 		if (!CheckStreamStatus(stream)) return false;
@@ -1001,6 +1003,14 @@ bool ReadSetting(
 		context.callSettings = callSettings;
 	} break;
 
+	case dbiFallbackProductionConfig: {
+		QByteArray config;
+		stream >> config;
+		if (!CheckStreamStatus(stream)) return false;
+
+		context.fallbackConfig = config;
+	} break;
+
 	default:
 		LOG(("App Error: unknown blockId in _readSetting: %1").arg(blockId));
 		return false;
@@ -1009,5 +1019,38 @@ bool ReadSetting(
 	return true;
 }
 
+void ApplyReadFallbackConfig(ReadSettingsContext &context) {
+	if (context.fallbackConfig.isEmpty()) {
+		auto &config = Core::App().fallbackProductionConfig();
+		config.dcOptions().addFromOther(
+			std::move(context.fallbackConfigLegacyDcOptions));
+		if (context.fallbackConfigLegacyChatSizeMax > 0) {
+			config.setChatSizeMax(context.fallbackConfigLegacyChatSizeMax);
+		}
+		if (context.fallbackConfigLegacySavedGifsLimit > 0) {
+			config.setSavedGifsLimit(
+				context.fallbackConfigLegacySavedGifsLimit);
+		}
+		if (context.fallbackConfigLegacyStickersRecentLimit > 0) {
+			config.setStickersRecentLimit(
+				context.fallbackConfigLegacyStickersRecentLimit);
+		}
+		if (context.fallbackConfigLegacyStickersFavedLimit > 0) {
+			config.setStickersFavedLimit(
+				context.fallbackConfigLegacyStickersFavedLimit);
+		}
+		if (context.fallbackConfigLegacyMegagroupSizeMax > 0) {
+			config.setMegagroupSizeMax(
+				context.fallbackConfigLegacyMegagroupSizeMax);
+		}
+		if (!context.fallbackConfigLegacyTxtDomainString.isEmpty()) {
+			config.setTxtDomainString(
+				context.fallbackConfigLegacyTxtDomainString);
+		}
+	} else {
+		Core::App().constructFallbackProductionConfig(context.fallbackConfig);
+	}
+}
+
 } // namespace details
 } // namespace Storage
diff --git a/Telegram/SourceFiles/storage/details/storage_settings_scheme.h b/Telegram/SourceFiles/storage/details/storage_settings_scheme.h
index 09f68ec72..654f23b2f 100644
--- a/Telegram/SourceFiles/storage/details/storage_settings_scheme.h
+++ b/Telegram/SourceFiles/storage/details/storage_settings_scheme.h
@@ -7,7 +7,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 */
 #pragma once
 
-#include "mtproto/dc_options.h"
+#include "mtproto/mtproto_dc_options.h"
 #include "main/main_settings.h"
 #include "storage/storage_account.h"
 
@@ -30,7 +30,15 @@ struct ReadSettingsContext {
 	bool hasCustomDayBackground = false;
 
 	// Those fields are written in ReadSetting.
-	MTP::DcOptions dcOptions;
+	MTP::DcOptions fallbackConfigLegacyDcOptions
+		= MTP::DcOptions(MTP::Environment::Production);
+	qint32 fallbackConfigLegacyChatSizeMax = 0;
+	qint32 fallbackConfigLegacySavedGifsLimit = 0;
+	qint32 fallbackConfigLegacyStickersRecentLimit = 0;
+	qint32 fallbackConfigLegacyStickersFavedLimit = 0;
+	qint32 fallbackConfigLegacyMegagroupSizeMax = 0;
+	QString fallbackConfigLegacyTxtDomainString;
+	QByteArray fallbackConfig;
 
 	qint64 cacheTotalSizeLimit = 0;
 	qint32 cacheTotalTimeLimit = 0;
@@ -62,12 +70,14 @@ struct ReadSettingsContext {
 	int version,
 	ReadSettingsContext &context);
 
+void ApplyReadFallbackConfig(ReadSettingsContext &context);
+
 enum {
 	dbiKey = 0x00,
 	dbiUser = 0x01,
 	dbiDcOptionOldOld = 0x02,
-	dbiChatSizeMax = 0x03,
-	dbiMutePeer = 0x04,
+	dbiChatSizeMaxOld = 0x03,
+	dbiMutePeerOld = 0x04,
 	dbiSendKeyOld = 0x05,
 	dbiAutoStart = 0x06,
 	dbiStartMinimized = 0x07,
@@ -88,8 +98,8 @@ enum {
 	dbiScaleOld = 0x16,
 	dbiEmojiTabOld = 0x17,
 	dbiRecentEmojiOldOld = 0x18,
-	dbiLoggedPhoneNumber = 0x19,
-	dbiMutedPeers = 0x1a,
+	dbiLoggedPhoneNumberOld = 0x19,
+	dbiMutedPeersOld = 0x1a,
 	// 0x1b reserved
 	dbiNotifyView = 0x1c,
 	dbiSendToMenu = 0x1d,
@@ -107,10 +117,10 @@ enum {
 	dbiSongVolume = 0x29,
 	dbiWindowsNotificationsOld = 0x30,
 	dbiIncludeMutedOld = 0x31,
-	dbiMegagroupSizeMax = 0x32,
+	dbiMegagroupSizeMaxOld = 0x32,
 	dbiDownloadPath = 0x33,
 	dbiAutoDownloadOld = 0x34,
-	dbiSavedGifsLimit = 0x35,
+	dbiSavedGifsLimitOld = 0x35,
 	dbiShowingSavedGifsOld = 0x36,
 	dbiAutoPlayOld = 0x37,
 	dbiAdaptiveForWide = 0x38,
@@ -120,23 +130,23 @@ enum {
 	dbiDialogsModeOld = 0x40,
 	dbiModerateMode = 0x41,
 	dbiVideoVolume = 0x42,
-	dbiStickersRecentLimit = 0x43,
+	dbiStickersRecentLimitOld = 0x43,
 	dbiNativeNotifications = 0x44,
 	dbiNotificationsCount = 0x45,
 	dbiNotificationsCorner = 0x46,
 	dbiThemeKeyOld = 0x47,
 	dbiDialogsWidthRatioOld = 0x48,
 	dbiUseExternalVideoPlayer = 0x49,
-	dbiDcOptions = 0x4a,
+	dbiDcOptionsOld = 0x4a,
 	dbiMtpAuthorization = 0x4b,
 	dbiLastSeenWarningSeenOld = 0x4c,
 	dbiSessionSettings = 0x4d,
 	dbiLangPackKey = 0x4e,
 	dbiConnectionType = 0x4f,
-	dbiStickersFavedLimit = 0x50,
+	dbiStickersFavedLimitOld = 0x50,
 	dbiSuggestStickersByEmojiOld = 0x51,
 	dbiSuggestEmojiOld = 0x52,
-	dbiTxtDomainStringOld = 0x53,
+	dbiTxtDomainStringOldOld = 0x53,
 	dbiThemeKey = 0x54,
 	dbiTileBackground = 0x55,
 	dbiCacheSettingsOld = 0x56,
@@ -146,9 +156,10 @@ enum {
 	dbiLanguagesKey = 0x5a,
 	dbiCallSettings = 0x5b,
 	dbiCacheSettings = 0x5c,
-	dbiTxtDomainString = 0x5d,
+	dbiTxtDomainStringOld = 0x5d,
 	dbiApplicationSettings = 0x5e,
 	dbiDialogsFilters = 0x5f,
+	dbiFallbackProductionConfig = 0x60,
 
 	dbiEncryptedWithSalt = 333,
 	dbiEncrypted = 444,
diff --git a/Telegram/SourceFiles/storage/download_manager_mtproto.cpp b/Telegram/SourceFiles/storage/download_manager_mtproto.cpp
index 621ec8e00..4dadef241 100644
--- a/Telegram/SourceFiles/storage/download_manager_mtproto.cpp
+++ b/Telegram/SourceFiles/storage/download_manager_mtproto.cpp
@@ -119,7 +119,7 @@ DownloadManagerMtproto::DownloadManagerMtproto(not_null<ApiWrap*> api)
 : _api(api)
 , _resetGenerationTimer([=] { resetGeneration(); })
 , _killSessionsTimer([=] { killSessions(); }) {
-	_api->instance()->restartsByTimeout(
+	_api->instance().restartsByTimeout(
 	) | rpl::filter([](MTP::ShiftedDcId shiftedDcId) {
 		return MTP::isDownloadDcId(shiftedDcId);
 	}) | rpl::start_with_next([=](MTP::ShiftedDcId shiftedDcId) {
@@ -353,7 +353,7 @@ void DownloadManagerMtproto::removeSession(MTP::DcId dcId) {
 	Assert(session.requested == kMaxWaitedInSession * kMaxSessionsCount);
 
 	dc.sessions.pop_back();
-	api().instance()->killSession(MTP::downloadDcId(dcId, index));
+	api().instance().killSession(MTP::downloadDcId(dcId, index));
 
 	dc.lastSessionRemove = crl::now();
 }
@@ -403,7 +403,7 @@ void DownloadManagerMtproto::killSessions(MTP::DcId dcId) {
 		for (auto j = 0; j != int(sessions.size()); ++j) {
 			Assert(sessions[j].requested == 0);
 			sessions[j] = DcSessionBalanceData();
-			api().instance()->stopSession(MTP::downloadDcId(dcId, j));
+			api().instance().stopSession(MTP::downloadDcId(dcId, j));
 		}
 		dc.sessions = base::take(sessions);
 	}
diff --git a/Telegram/SourceFiles/storage/file_download_mtproto.cpp b/Telegram/SourceFiles/storage/file_download_mtproto.cpp
index fccedf0af..02098d83b 100644
--- a/Telegram/SourceFiles/storage/file_download_mtproto.cpp
+++ b/Telegram/SourceFiles/storage/file_download_mtproto.cpp
@@ -13,9 +13,9 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "main/main_session.h"
 #include "apiwrap.h"
 #include "mtproto/mtp_instance.h"
+#include "mtproto/mtproto_config.h"
 #include "mtproto/mtproto_auth_key.h"
 #include "base/openssl_help.h"
-#include "facades.h"
 
 mtpFileLoader::mtpFileLoader(
 	not_null<Main::Session*> session,
@@ -58,7 +58,7 @@ mtpFileLoader::mtpFileLoader(
 	cacheTag)
 , DownloadMtprotoTask(
 	&session->downloader(),
-	Global::WebFileDcId(),
+	session->serverConfig().webFileDcId,
 	{ location }) {
 }
 
@@ -80,7 +80,7 @@ mtpFileLoader::mtpFileLoader(
 	cacheTag)
 , DownloadMtprotoTask(
 	&session->downloader(),
-	Global::WebFileDcId(),
+	session->serverConfig().webFileDcId,
 	{ location }) {
 }
 
diff --git a/Telegram/SourceFiles/storage/file_upload.cpp b/Telegram/SourceFiles/storage/file_upload.cpp
index ea43f9335..ccaefa2c4 100644
--- a/Telegram/SourceFiles/storage/file_upload.cpp
+++ b/Telegram/SourceFiles/storage/file_upload.cpp
@@ -277,7 +277,7 @@ void Uploader::currentFailed() {
 
 void Uploader::stopSessions() {
 	for (int i = 0; i < MTP::kUploadSessionsCount; ++i) {
-		_api->instance()->stopSession(MTP::uploadDcId(i));
+		_api->instance().stopSession(MTP::uploadDcId(i));
 	}
 }
 
@@ -524,7 +524,7 @@ void Uploader::clear() {
 	dcMap.clear();
 	sentSize = 0;
 	for (int i = 0; i < MTP::kUploadSessionsCount; ++i) {
-		_api->instance()->stopSession(MTP::uploadDcId(i));
+		_api->instance().stopSession(MTP::uploadDcId(i));
 		sentSizes[i] = 0;
 	}
 	stopSessionsTimer.stop();
diff --git a/Telegram/SourceFiles/storage/localstorage.cpp b/Telegram/SourceFiles/storage/localstorage.cpp
index 9af3578de..9d88cd77e 100644
--- a/Telegram/SourceFiles/storage/localstorage.cpp
+++ b/Telegram/SourceFiles/storage/localstorage.cpp
@@ -18,8 +18,11 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "ui/effects/animation_value.h"
 #include "core/update_checker.h"
 #include "media/audio/media_audio.h"
-#include "mtproto/dc_options.h"
+#include "mtproto/mtproto_config.h"
+#include "mtproto/mtproto_dc_options.h"
 #include "core/application.h"
+#include "main/main_accounts.h"
+#include "main/main_account.h"
 #include "main/main_session.h"
 #include "window/themes/window_theme.h"
 #include "facades.h"
@@ -52,18 +55,6 @@ QString _basePath, _userBasePath, _userDbPath;
 bool _started = false;
 TaskQueue *_localLoader = nullptr;
 
-bool _working() {
-	return !_basePath.isEmpty();
-}
-
-bool CheckStreamStatus(QDataStream &stream) {
-	if (stream.status() != QDataStream::Ok) {
-		LOG(("Bad data stream status: %1").arg(stream.status()));
-		return false;
-	}
-	return true;
-}
-
 QByteArray _settingsSalt;
 
 auto OldKey = MTP::AuthKeyPtr();
@@ -87,8 +78,44 @@ enum class WriteMapWhen {
 	Soon,
 };
 
+bool _working() {
+	return !_basePath.isEmpty();
+}
+
+bool CheckStreamStatus(QDataStream &stream) {
+	if (stream.status() != QDataStream::Ok) {
+		LOG(("Bad data stream status: %1").arg(stream.status()));
+		return false;
+	}
+	return true;
+}
+
+[[nodiscard]] const MTP::Config &LookupFallbackConfig() {
+	static const auto lookupConfig = [](not_null<Main::Account*> account) {
+		const auto mtp = &account->mtp();
+		return (mtp->environment() == MTP::Environment::Production)
+			? &mtp->config()
+			: nullptr;
+	};
+	const auto &app = Core::App();
+	const auto &accounts = app.accounts();
+	const auto production = MTP::Environment::Production;
+	if (!accounts.started()) {
+		return app.fallbackProductionConfig();
+	}
+	if (const auto result = lookupConfig(&app.activeAccount())) {
+		return *result;
+	}
+	for (const auto &[_, account] : accounts.list()) {
+		if (const auto result = lookupConfig(account.get())) {
+			return *result;
+		}
+	}
+	return app.fallbackProductionConfig();
+}
+
 void applyReadContext(ReadSettingsContext &&context) {
-	Core::App().dcOptions()->addFromOther(std::move(context.dcOptions));
+	ApplyReadFallbackConfig(context);
 
 	_themeKeyLegacy = context.themeKeyLegacy;
 	_themeKeyDay = context.themeKeyDay;
@@ -195,7 +222,10 @@ void _readOldUserSettingsFields(
 
 bool _readOldUserSettings(bool remove, ReadSettingsContext &context) {
 	bool result = false;
-	QFile file(cWorkingDir() + cDataFile() + (cTestMode() ? qsl("_test") : QString()) + qsl("_config"));
+	// We dropped old test authorizations when migrated to multi auth.
+	//const auto testPrefix = (cTestMode() ? qsl("_test") : QString());
+	const auto testPrefix = QString();
+	QFile file(cWorkingDir() + cDataFile() + testPrefix + qsl("_config"));
 	if (file.open(QIODevice::ReadOnly)) {
 		LOG(("App Info: reading old user config..."));
 		qint32 version = 0;
@@ -273,7 +303,9 @@ void _readOldMtpDataFields(
 
 bool _readOldMtpData(bool remove, ReadSettingsContext &context) {
 	bool result = false;
-	const auto testPostfix = (cTestMode() ? qsl("_test") : QString());
+	// We dropped old test authorizations when migrated to multi auth.
+	//const auto testPostfix = (cTestMode() ? qsl("_test") : QString());
+	const auto testPostfix = QString();
 	QFile file(cWorkingDir() + cDataFile() + testPostfix);
 	if (file.open(QIODevice::ReadOnly)) {
 		LOG(("App Info: reading old keys..."));
@@ -306,7 +338,10 @@ void start() {
 
 	ReadSettingsContext context;
 	FileReadDescriptor settingsData;
-	if (!ReadFile(settingsData, cTestMode() ? qsl("settings_test") : qsl("settings"), _basePath)) {
+	// We dropped old test authorizations when migrated to multi auth.
+	//const auto name = cTestMode() ? qsl("settings_test") : qsl("settings");
+	const auto name = u"settings"_q;
+	if (!ReadFile(settingsData, name, _basePath)) {
 		_readOldSettings(true, context);
 		_readOldUserSettings(false, context); // needed further in _readUserSettings
 		_readOldMtpData(false, context); // needed further in _readMtpData
@@ -367,9 +402,10 @@ void writeSettings() {
 
 	if (!QDir().exists(_basePath)) QDir().mkpath(_basePath);
 
-	FileWriteDescriptor settings(
-		cTestMode() ? qsl("settings_test") : qsl("settings"),
-		_basePath);
+	// We dropped old test authorizations when migrated to multi auth.
+	//const auto name = cTestMode() ? qsl("settings_test") : qsl("settings");
+	const auto name = u"settings"_q;
+	FileWriteDescriptor settings(name, _basePath);
 	if (_settingsSalt.isEmpty() || !SettingsKey) {
 		_settingsSalt.resize(LocalEncryptSaltSize);
 		memset_rand(_settingsSalt.data(), _settingsSalt.size());
@@ -377,13 +413,12 @@ void writeSettings() {
 	}
 	settings.writeData(_settingsSalt);
 
-	const auto dcOptionsSerialized = Core::App().dcOptions()->serialize();
+	const auto configSerialized = LookupFallbackConfig().serialize();
 	const auto applicationSettings = Core::App().settings().serialize();
 
-	quint32 size = 12 * (sizeof(quint32) + sizeof(qint32));
-	size += sizeof(quint32) + Serialize::bytearraySize(dcOptionsSerialized);
+	quint32 size = 9 * (sizeof(quint32) + sizeof(qint32));
+	size += sizeof(quint32) + Serialize::bytearraySize(configSerialized);
 	size += sizeof(quint32) + Serialize::bytearraySize(applicationSettings);
-	size += sizeof(quint32) + Serialize::stringSize(Global::TxtDomainString());
 	size += sizeof(quint32) + Serialize::stringSize(cDialogLastPath());
 
 	auto &proxies = Global::RefProxiesList();
@@ -407,11 +442,6 @@ void writeSettings() {
 	size += sizeof(quint32) + sizeof(qint32) * 8;
 
 	EncryptedDescriptor data(size);
-	data.stream << quint32(dbiChatSizeMax) << qint32(Global::ChatSizeMax());
-	data.stream << quint32(dbiMegagroupSizeMax) << qint32(Global::MegagroupSizeMax());
-	data.stream << quint32(dbiSavedGifsLimit) << qint32(Global::SavedGifsLimit());
-	data.stream << quint32(dbiStickersRecentLimit) << qint32(Global::StickersRecentLimit());
-	data.stream << quint32(dbiStickersFavedLimit) << qint32(Global::StickersFavedLimit());
 	data.stream << quint32(dbiAutoStart) << qint32(cAutoStart());
 	data.stream << quint32(dbiStartMinimized) << qint32(cStartMinimized());
 	data.stream << quint32(dbiSendToMenu) << qint32(cSendToMenu());
@@ -420,9 +450,8 @@ void writeSettings() {
 	data.stream << quint32(dbiAutoUpdate) << qint32(cAutoUpdate());
 	data.stream << quint32(dbiLastUpdateCheck) << qint32(cLastUpdateCheck());
 	data.stream << quint32(dbiScalePercent) << qint32(cConfigScale());
-	data.stream << quint32(dbiDcOptions) << dcOptionsSerialized;
+	data.stream << quint32(dbiFallbackProductionConfig) << configSerialized;
 	data.stream << quint32(dbiApplicationSettings) << applicationSettings;
-	data.stream << quint32(dbiTxtDomainString) << Global::TxtDomainString();
 	data.stream << quint32(dbiDialogLastPath) << cDialogLastPath();
 	data.stream << quint32(dbiAnimationsDisabled) << qint32(anim::Disabled() ? 1 : 0);
 
diff --git a/Telegram/SourceFiles/storage/serialize_common.cpp b/Telegram/SourceFiles/storage/serialize_common.cpp
index 93f249ba8..d3f7ec8ad 100644
--- a/Telegram/SourceFiles/storage/serialize_common.cpp
+++ b/Telegram/SourceFiles/storage/serialize_common.cpp
@@ -7,20 +7,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 */
 #include "storage/serialize_common.h"
 
-#include "main/main_session.h"
-#include "data/data_channel.h"
-#include "data/data_chat.h"
-#include "data/data_user.h"
-#include "data/data_session.h"
-#include "ui/image/image.h"
-#include "app.h"
-
 namespace Serialize {
-namespace {
-
-constexpr auto kModernImageLocationTag = std::numeric_limits<qint32>::min();
-
-} // namespace
 
 void writeColor(QDataStream &stream, const QColor &color) {
 	stream << (quint32(uchar(color.red()))
@@ -39,323 +26,4 @@ QColor readColor(QDataStream &stream) {
 		int((value >> 24) & 0xFFU));
 }
 
-std::optional<StorageImageLocation> readLegacyStorageImageLocationOrTag(
-		int streamAppVersion,
-		QDataStream &stream) {
-	qint32 width, height, dc, local;
-	quint64 volume, secret;
-	QByteArray fileReference;
-	stream >> width;
-	if (width == kModernImageLocationTag) {
-		return std::nullopt;
-	}
-	stream >> height >> dc >> volume >> local >> secret;
-	if (streamAppVersion >= 1003013) {
-		stream >> fileReference;
-	}
-	if (stream.status() != QDataStream::Ok) {
-		return std::nullopt;
-	}
-	return StorageImageLocation(
-		StorageFileLocation(
-			dc,
-			UserId(0),
-			MTP_inputFileLocation(
-				MTP_long(volume),
-				MTP_int(local),
-				MTP_long(secret),
-				MTP_bytes(fileReference))),
-		width,
-		height);
-}
-
-int storageImageLocationSize(const StorageImageLocation &location) {
-	// Modern image location tag + (size + content) of the serialization.
-	return sizeof(qint32) * 2 + location.serializeSize();
-}
-
-void writeStorageImageLocation(
-		QDataStream &stream,
-		const StorageImageLocation &location) {
-	stream << kModernImageLocationTag << location.serialize();
-}
-
-std::optional<StorageImageLocation> readStorageImageLocation(
-		int streamAppVersion,
-		QDataStream &stream) {
-	const auto legacy = readLegacyStorageImageLocationOrTag(
-		streamAppVersion,
-		stream);
-	if (legacy) {
-		return legacy;
-	}
-	auto serialized = QByteArray();
-	stream >> serialized;
-	return (stream.status() == QDataStream::Ok)
-		? StorageImageLocation::FromSerialized(serialized)
-		: std::nullopt;
-}
-
-int imageLocationSize(const ImageLocation &location) {
-	// Modern image location tag + (size + content) of the serialization.
-	return sizeof(qint32) * 2 + location.serializeSize();
-}
-
-void writeImageLocation(QDataStream &stream, const ImageLocation &location) {
-	stream << kModernImageLocationTag << location.serialize();
-}
-
-std::optional<ImageLocation> readImageLocation(
-		int streamAppVersion,
-		QDataStream &stream) {
-	const auto legacy = readLegacyStorageImageLocationOrTag(
-		streamAppVersion,
-		stream);
-	if (legacy) {
-		return ImageLocation(
-			DownloadLocation{ legacy->file() },
-			legacy->width(),
-			legacy->height());
-	}
-	auto serialized = QByteArray();
-	stream >> serialized;
-	return (stream.status() == QDataStream::Ok)
-		? ImageLocation::FromSerialized(serialized)
-		: std::nullopt;
-}
-
-uint32 peerSize(not_null<PeerData*> peer) {
-	uint32 result = sizeof(quint64)
-		+ sizeof(quint64)
-		+ imageLocationSize(peer->userpicLocation());
-	if (peer->isUser()) {
-		UserData *user = peer->asUser();
-
-		// first + last + phone + username + access
-		result += stringSize(user->firstName) + stringSize(user->lastName) + stringSize(user->phone()) + stringSize(user->username) + sizeof(quint64);
-
-		// flags
-		if (AppVersion >= 9012) {
-			result += sizeof(qint32);
-		}
-
-		// onlineTill + contact + botInfoVersion
-		result += sizeof(qint32) + sizeof(qint32) + sizeof(qint32);
-	} else if (peer->isChat()) {
-		ChatData *chat = peer->asChat();
-
-		// name + count + date + version + admin + old forbidden + left + inviteLink
-		result += stringSize(chat->name) + sizeof(qint32) + sizeof(qint32) + sizeof(qint32) + sizeof(qint32) + sizeof(qint32) + sizeof(quint32) + stringSize(chat->inviteLink());
-	} else if (peer->isChannel()) {
-		ChannelData *channel = peer->asChannel();
-
-		// name + access + date + version + old forbidden + flags + inviteLink
-		result += stringSize(channel->name) + sizeof(quint64) + sizeof(qint32) + sizeof(qint32) + sizeof(qint32) + sizeof(quint32) + stringSize(channel->inviteLink());
-	}
-	return result;
-}
-
-void writePeer(QDataStream &stream, PeerData *peer) {
-	stream << quint64(peer->id) << quint64(peer->userpicPhotoId());
-	writeImageLocation(stream, peer->userpicLocation());
-	if (const auto user = peer->asUser()) {
-		stream
-			<< user->firstName
-			<< user->lastName
-			<< user->phone()
-			<< user->username
-			<< quint64(user->accessHash());
-		if (AppVersion >= 9012) {
-			stream << qint32(user->flags());
-		}
-		if (AppVersion >= 9016) {
-			const auto botInlinePlaceholder = user->isBot()
-				? user->botInfo->inlinePlaceholder
-				: QString();
-			stream << botInlinePlaceholder;
-		}
-		stream
-			<< qint32(user->onlineTill)
-			<< qint32(user->isContact() ? 1 : 0)
-			<< qint32(user->isBot() ? user->botInfo->version : -1);
-	} else if (const auto chat = peer->asChat()) {
-		stream
-			<< chat->name
-			<< qint32(chat->count)
-			<< qint32(chat->date)
-			<< qint32(chat->version())
-			<< qint32(chat->creator)
-			<< qint32(0)
-			<< quint32(chat->flags())
-			<< chat->inviteLink();
-	} else if (const auto channel = peer->asChannel()) {
-		stream
-			<< channel->name
-			<< quint64(channel->access)
-			<< qint32(channel->date)
-			<< qint32(channel->version())
-			<< qint32(0)
-			<< quint32(channel->flags())
-			<< channel->inviteLink();
-	}
-}
-
-PeerData *readPeer(
-		not_null<Main::Session*> session,
-		int streamAppVersion,
-		QDataStream &stream) {
-	quint64 peerId = 0, photoId = 0;
-	stream >> peerId >> photoId;
-	if (!peerId) {
-		return nullptr;
-	}
-
-	const auto userpic = readImageLocation(streamAppVersion, stream);
-	auto userpicAccessHash = uint64(0);
-	if (!userpic) {
-		return nullptr;
-	}
-
-	const auto selfId = session->userPeerId();
-	const auto loaded = (peerId == selfId)
-		? session->user().get()
-		: session->data().peerLoaded(peerId);
-	const auto result = loaded ? loaded : session->data().peer(peerId).get();
-	if (!loaded) {
-		result->loadedStatus = PeerData::FullLoaded;
-	}
-	if (const auto user = result->asUser()) {
-		QString first, last, phone, username, inlinePlaceholder;
-		quint64 access;
-		qint32 flags = 0, onlineTill, contact, botInfoVersion;
-		stream >> first >> last >> phone >> username >> access;
-		if (streamAppVersion >= 9012) {
-			stream >> flags;
-		}
-		if (streamAppVersion >= 9016) {
-			stream >> inlinePlaceholder;
-		}
-		stream >> onlineTill >> contact >> botInfoVersion;
-
-		userpicAccessHash = access;
-
-		const auto showPhone = !user->isServiceUser()
-			&& (user->id != selfId)
-			&& (contact <= 0);
-		const auto pname = (showPhone && !phone.isEmpty())
-			? App::formatPhone(phone)
-			: QString();
-
-		if (!loaded) {
-			user->setPhone(phone);
-			user->setName(first, last, pname, username);
-
-			user->setFlags(MTPDuser::Flags::from_raw(flags));
-			user->setAccessHash(access);
-			user->onlineTill = onlineTill;
-			user->setIsContact(contact == 1);
-			user->setBotInfoVersion(botInfoVersion);
-			if (!inlinePlaceholder.isEmpty() && user->isBot()) {
-				user->botInfo->inlinePlaceholder = inlinePlaceholder;
-			}
-
-			if (user->id == selfId) {
-				user->input = MTP_inputPeerSelf();
-				user->inputUser = MTP_inputUserSelf();
-			} else {
-				user->input = MTP_inputPeerUser(MTP_int(peerToUser(user->id)), MTP_long(user->accessHash()));
-				user->inputUser = MTP_inputUser(MTP_int(peerToUser(user->id)), MTP_long(user->accessHash()));
-			}
-		}
-	} else if (const auto chat = result->asChat()) {
-		QString name, inviteLink;
-		qint32 count, date, version, creator, oldForbidden;
-		quint32 flagsData, flags;
-		stream >> name >> count >> date >> version >> creator >> oldForbidden >> flagsData >> inviteLink;
-
-		if (streamAppVersion >= 9012) {
-			flags = flagsData;
-		} else {
-			// flagsData was haveLeft
-			flags = (flagsData == 1)
-				? MTPDchat::Flags(MTPDchat::Flag::f_left)
-				: MTPDchat::Flags(0);
-		}
-		if (oldForbidden) {
-			flags |= quint32(MTPDchat_ClientFlag::f_forbidden);
-		}
-		if (!loaded) {
-			chat->setName(name);
-			chat->count = count;
-			chat->date = date;
-
-			// We don't save participants, admin status and banned rights.
-			// So we don't restore the version field, info is still unknown.
-			chat->setVersion(0);
-
-			chat->creator = creator;
-			chat->setFlags(MTPDchat::Flags::from_raw(flags));
-			chat->setInviteLink(inviteLink);
-
-			chat->input = MTP_inputPeerChat(MTP_int(peerToChat(chat->id)));
-			chat->inputChat = MTP_int(peerToChat(chat->id));
-		}
-	} else if (const auto channel = result->asChannel()) {
-		QString name, inviteLink;
-		quint64 access;
-		qint32 date, version, oldForbidden;
-		quint32 flags;
-		stream >> name >> access >> date >> version >> oldForbidden >> flags >> inviteLink;
-
-		userpicAccessHash = access;
-
-		if (oldForbidden) {
-			flags |= quint32(MTPDchannel_ClientFlag::f_forbidden);
-		}
-		if (!loaded) {
-			channel->setName(name, QString());
-			channel->access = access;
-			channel->date = date;
-
-			// We don't save participants, admin status and banned rights.
-			// So we don't restore the version field, info is still unknown.
-			channel->setVersion(0);
-
-			channel->setFlags(MTPDchannel::Flags::from_raw(flags));
-			channel->setInviteLink(inviteLink);
-
-			channel->input = MTP_inputPeerChannel(MTP_int(peerToChannel(channel->id)), MTP_long(access));
-			channel->inputChannel = MTP_inputChannel(MTP_int(peerToChannel(channel->id)), MTP_long(access));
-		}
-	}
-	if (!loaded) {
-		using LocationType = StorageFileLocation::Type;
-		const auto location = (userpic->valid() && userpic->isLegacy())
-			? userpic->convertToModern(
-				LocationType::PeerPhoto,
-				result->id,
-				userpicAccessHash)
-			: *userpic;
-		result->setUserpic(photoId, location);
-	}
-	return result;
-}
-
-QString peekUserPhone(int streamAppVersion, QDataStream &stream) {
-	quint64 peerId = 0, photoId = 0;
-	stream >> peerId >> photoId;
-	DEBUG_LOG(("peekUserPhone.id: %1").arg(peerId));
-	if (!peerId
-		|| !peerIsUser(peerId)
-		|| !readStorageImageLocation(streamAppVersion, stream)) {
-		return QString();
-	}
-
-	QString first, last, phone;
-	stream >> first >> last >> phone;
-	DEBUG_LOG(("peekUserPhone.data: %1 %2 %3"
-		).arg(first).arg(last).arg(phone));
-	return phone;
-}
-
 } // namespace Serialize
diff --git a/Telegram/SourceFiles/storage/serialize_common.h b/Telegram/SourceFiles/storage/serialize_common.h
index 6db828ecf..fcf017185 100644
--- a/Telegram/SourceFiles/storage/serialize_common.h
+++ b/Telegram/SourceFiles/storage/serialize_common.h
@@ -8,6 +8,9 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #pragma once
 
 #include "mtproto/mtproto_auth_key.h"
+#include "base/bytes.h"
+
+#include <QtCore/QDataStream>
 
 namespace Serialize {
 
@@ -91,26 +94,6 @@ inline int dateTimeSize() {
 	return (sizeof(qint64) + sizeof(quint32) + sizeof(qint8));
 }
 
-int storageImageLocationSize(const StorageImageLocation &location);
-void writeStorageImageLocation(
-	QDataStream &stream,
-	const StorageImageLocation &location);
-
-// NB! This method can return StorageFileLocation with Type::Generic!
-// The reader should discard it or convert to one of the valid modern types.
-std::optional<StorageImageLocation> readStorageImageLocation(
-	int streamAppVersion,
-	QDataStream &stream);
-
-int imageLocationSize(const ImageLocation &location);
-void writeImageLocation(QDataStream &stream, const ImageLocation &location);
-
-// NB! This method can return StorageFileLocation with Type::Generic!
-// The reader should discard it or convert to one of the valid modern types.
-std::optional<ImageLocation> readImageLocation(
-	int streamAppVersion,
-	QDataStream &stream);
-
 template <typename T>
 inline T read(QDataStream &stream) {
 	auto result = T();
@@ -125,12 +108,4 @@ inline MTP::AuthKey::Data read<MTP::AuthKey::Data>(QDataStream &stream) {
 	return result;
 }
 
-uint32 peerSize(not_null<PeerData*> peer);
-void writePeer(QDataStream &stream, PeerData *peer);
-PeerData *readPeer(
-	not_null<Main::Session*> session,
-	int streamAppVersion,
-	QDataStream &stream);
-QString peekUserPhone(int streamAppVersion, QDataStream &stream);
-
 } // namespace Serialize
diff --git a/Telegram/SourceFiles/storage/serialize_document.cpp b/Telegram/SourceFiles/storage/serialize_document.cpp
index e8fa97d61..34638982e 100644
--- a/Telegram/SourceFiles/storage/serialize_document.cpp
+++ b/Telegram/SourceFiles/storage/serialize_document.cpp
@@ -8,6 +8,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "storage/serialize_document.h"
 
 #include "storage/serialize_common.h"
+#include "storage/serialize_peer.h"
 #include "data/data_session.h"
 #include "data/stickers/data_stickers.h"
 #include "ui/image/image.h"
diff --git a/Telegram/SourceFiles/storage/serialize_peer.cpp b/Telegram/SourceFiles/storage/serialize_peer.cpp
new file mode 100644
index 000000000..e888b7cac
--- /dev/null
+++ b/Telegram/SourceFiles/storage/serialize_peer.cpp
@@ -0,0 +1,345 @@
+/*
+This file is part of Telegram Desktop,
+the official desktop application for the Telegram messaging service.
+
+For license and copyright information please follow this link:
+https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
+*/
+#include "storage/serialize_peer.h"
+
+#include "storage/serialize_common.h"
+#include "main/main_session.h"
+#include "data/data_channel.h"
+#include "data/data_chat.h"
+#include "data/data_user.h"
+#include "data/data_session.h"
+#include "ui/image/image.h"
+#include "app.h"
+
+namespace Serialize {
+namespace {
+
+constexpr auto kModernImageLocationTag = std::numeric_limits<qint32>::min();
+
+} // namespace
+
+std::optional<StorageImageLocation> readLegacyStorageImageLocationOrTag(
+		int streamAppVersion,
+		QDataStream &stream) {
+	qint32 width, height, dc, local;
+	quint64 volume, secret;
+	QByteArray fileReference;
+	stream >> width;
+	if (width == kModernImageLocationTag) {
+		return std::nullopt;
+	}
+	stream >> height >> dc >> volume >> local >> secret;
+	if (streamAppVersion >= 1003013) {
+		stream >> fileReference;
+	}
+	if (stream.status() != QDataStream::Ok) {
+		return std::nullopt;
+	}
+	return StorageImageLocation(
+		StorageFileLocation(
+			dc,
+			UserId(0),
+			MTP_inputFileLocation(
+				MTP_long(volume),
+				MTP_int(local),
+				MTP_long(secret),
+				MTP_bytes(fileReference))),
+		width,
+		height);
+}
+
+int storageImageLocationSize(const StorageImageLocation &location) {
+	// Modern image location tag + (size + content) of the serialization.
+	return sizeof(qint32) * 2 + location.serializeSize();
+}
+
+void writeStorageImageLocation(
+		QDataStream &stream,
+		const StorageImageLocation &location) {
+	stream << kModernImageLocationTag << location.serialize();
+}
+
+std::optional<StorageImageLocation> readStorageImageLocation(
+		int streamAppVersion,
+		QDataStream &stream) {
+	const auto legacy = readLegacyStorageImageLocationOrTag(
+		streamAppVersion,
+		stream);
+	if (legacy) {
+		return legacy;
+	}
+	auto serialized = QByteArray();
+	stream >> serialized;
+	return (stream.status() == QDataStream::Ok)
+		? StorageImageLocation::FromSerialized(serialized)
+		: std::nullopt;
+}
+
+int imageLocationSize(const ImageLocation &location) {
+	// Modern image location tag + (size + content) of the serialization.
+	return sizeof(qint32) * 2 + location.serializeSize();
+}
+
+void writeImageLocation(QDataStream &stream, const ImageLocation &location) {
+	stream << kModernImageLocationTag << location.serialize();
+}
+
+std::optional<ImageLocation> readImageLocation(
+		int streamAppVersion,
+		QDataStream &stream) {
+	const auto legacy = readLegacyStorageImageLocationOrTag(
+		streamAppVersion,
+		stream);
+	if (legacy) {
+		return ImageLocation(
+			DownloadLocation{ legacy->file() },
+			legacy->width(),
+			legacy->height());
+	}
+	auto serialized = QByteArray();
+	stream >> serialized;
+	return (stream.status() == QDataStream::Ok)
+		? ImageLocation::FromSerialized(serialized)
+		: std::nullopt;
+}
+
+uint32 peerSize(not_null<PeerData*> peer) {
+	uint32 result = sizeof(quint64)
+		+ sizeof(quint64)
+		+ imageLocationSize(peer->userpicLocation());
+	if (peer->isUser()) {
+		UserData *user = peer->asUser();
+
+		// first + last + phone + username + access
+		result += stringSize(user->firstName) + stringSize(user->lastName) + stringSize(user->phone()) + stringSize(user->username) + sizeof(quint64);
+
+		// flags
+		if (AppVersion >= 9012) {
+			result += sizeof(qint32);
+		}
+
+		// onlineTill + contact + botInfoVersion
+		result += sizeof(qint32) + sizeof(qint32) + sizeof(qint32);
+	} else if (peer->isChat()) {
+		ChatData *chat = peer->asChat();
+
+		// name + count + date + version + admin + old forbidden + left + inviteLink
+		result += stringSize(chat->name) + sizeof(qint32) + sizeof(qint32) + sizeof(qint32) + sizeof(qint32) + sizeof(qint32) + sizeof(quint32) + stringSize(chat->inviteLink());
+	} else if (peer->isChannel()) {
+		ChannelData *channel = peer->asChannel();
+
+		// name + access + date + version + old forbidden + flags + inviteLink
+		result += stringSize(channel->name) + sizeof(quint64) + sizeof(qint32) + sizeof(qint32) + sizeof(qint32) + sizeof(quint32) + stringSize(channel->inviteLink());
+	}
+	return result;
+}
+
+void writePeer(QDataStream &stream, PeerData *peer) {
+	stream << quint64(peer->id) << quint64(peer->userpicPhotoId());
+	writeImageLocation(stream, peer->userpicLocation());
+	if (const auto user = peer->asUser()) {
+		stream
+			<< user->firstName
+			<< user->lastName
+			<< user->phone()
+			<< user->username
+			<< quint64(user->accessHash());
+		if (AppVersion >= 9012) {
+			stream << qint32(user->flags());
+		}
+		if (AppVersion >= 9016) {
+			const auto botInlinePlaceholder = user->isBot()
+				? user->botInfo->inlinePlaceholder
+				: QString();
+			stream << botInlinePlaceholder;
+		}
+		stream
+			<< qint32(user->onlineTill)
+			<< qint32(user->isContact() ? 1 : 0)
+			<< qint32(user->isBot() ? user->botInfo->version : -1);
+	} else if (const auto chat = peer->asChat()) {
+		stream
+			<< chat->name
+			<< qint32(chat->count)
+			<< qint32(chat->date)
+			<< qint32(chat->version())
+			<< qint32(chat->creator)
+			<< qint32(0)
+			<< quint32(chat->flags())
+			<< chat->inviteLink();
+	} else if (const auto channel = peer->asChannel()) {
+		stream
+			<< channel->name
+			<< quint64(channel->access)
+			<< qint32(channel->date)
+			<< qint32(channel->version())
+			<< qint32(0)
+			<< quint32(channel->flags())
+			<< channel->inviteLink();
+	}
+}
+
+PeerData *readPeer(
+		not_null<Main::Session*> session,
+		int streamAppVersion,
+		QDataStream &stream) {
+	quint64 peerId = 0, photoId = 0;
+	stream >> peerId >> photoId;
+	if (!peerId) {
+		return nullptr;
+	}
+
+	const auto userpic = readImageLocation(streamAppVersion, stream);
+	auto userpicAccessHash = uint64(0);
+	if (!userpic) {
+		return nullptr;
+	}
+
+	const auto selfId = session->userPeerId();
+	const auto loaded = (peerId == selfId)
+		? session->user().get()
+		: session->data().peerLoaded(peerId);
+	const auto result = loaded ? loaded : session->data().peer(peerId).get();
+	if (!loaded) {
+		result->loadedStatus = PeerData::FullLoaded;
+	}
+	if (const auto user = result->asUser()) {
+		QString first, last, phone, username, inlinePlaceholder;
+		quint64 access;
+		qint32 flags = 0, onlineTill, contact, botInfoVersion;
+		stream >> first >> last >> phone >> username >> access;
+		if (streamAppVersion >= 9012) {
+			stream >> flags;
+		}
+		if (streamAppVersion >= 9016) {
+			stream >> inlinePlaceholder;
+		}
+		stream >> onlineTill >> contact >> botInfoVersion;
+
+		userpicAccessHash = access;
+
+		const auto showPhone = !user->isServiceUser()
+			&& (user->id != selfId)
+			&& (contact <= 0);
+		const auto pname = (showPhone && !phone.isEmpty())
+			? App::formatPhone(phone)
+			: QString();
+
+		if (!loaded) {
+			user->setPhone(phone);
+			user->setName(first, last, pname, username);
+
+			user->setFlags(MTPDuser::Flags::from_raw(flags));
+			user->setAccessHash(access);
+			user->onlineTill = onlineTill;
+			user->setIsContact(contact == 1);
+			user->setBotInfoVersion(botInfoVersion);
+			if (!inlinePlaceholder.isEmpty() && user->isBot()) {
+				user->botInfo->inlinePlaceholder = inlinePlaceholder;
+			}
+
+			if (user->id == selfId) {
+				user->input = MTP_inputPeerSelf();
+				user->inputUser = MTP_inputUserSelf();
+			} else {
+				user->input = MTP_inputPeerUser(MTP_int(peerToUser(user->id)), MTP_long(user->accessHash()));
+				user->inputUser = MTP_inputUser(MTP_int(peerToUser(user->id)), MTP_long(user->accessHash()));
+			}
+		}
+	} else if (const auto chat = result->asChat()) {
+		QString name, inviteLink;
+		qint32 count, date, version, creator, oldForbidden;
+		quint32 flagsData, flags;
+		stream >> name >> count >> date >> version >> creator >> oldForbidden >> flagsData >> inviteLink;
+
+		if (streamAppVersion >= 9012) {
+			flags = flagsData;
+		} else {
+			// flagsData was haveLeft
+			flags = (flagsData == 1)
+				? MTPDchat::Flags(MTPDchat::Flag::f_left)
+				: MTPDchat::Flags(0);
+		}
+		if (oldForbidden) {
+			flags |= quint32(MTPDchat_ClientFlag::f_forbidden);
+		}
+		if (!loaded) {
+			chat->setName(name);
+			chat->count = count;
+			chat->date = date;
+
+			// We don't save participants, admin status and banned rights.
+			// So we don't restore the version field, info is still unknown.
+			chat->setVersion(0);
+
+			chat->creator = creator;
+			chat->setFlags(MTPDchat::Flags::from_raw(flags));
+			chat->setInviteLink(inviteLink);
+
+			chat->input = MTP_inputPeerChat(MTP_int(peerToChat(chat->id)));
+			chat->inputChat = MTP_int(peerToChat(chat->id));
+		}
+	} else if (const auto channel = result->asChannel()) {
+		QString name, inviteLink;
+		quint64 access;
+		qint32 date, version, oldForbidden;
+		quint32 flags;
+		stream >> name >> access >> date >> version >> oldForbidden >> flags >> inviteLink;
+
+		userpicAccessHash = access;
+
+		if (oldForbidden) {
+			flags |= quint32(MTPDchannel_ClientFlag::f_forbidden);
+		}
+		if (!loaded) {
+			channel->setName(name, QString());
+			channel->access = access;
+			channel->date = date;
+
+			// We don't save participants, admin status and banned rights.
+			// So we don't restore the version field, info is still unknown.
+			channel->setVersion(0);
+
+			channel->setFlags(MTPDchannel::Flags::from_raw(flags));
+			channel->setInviteLink(inviteLink);
+
+			channel->input = MTP_inputPeerChannel(MTP_int(peerToChannel(channel->id)), MTP_long(access));
+			channel->inputChannel = MTP_inputChannel(MTP_int(peerToChannel(channel->id)), MTP_long(access));
+		}
+	}
+	if (!loaded) {
+		using LocationType = StorageFileLocation::Type;
+		const auto location = (userpic->valid() && userpic->isLegacy())
+			? userpic->convertToModern(
+				LocationType::PeerPhoto,
+				result->id,
+				userpicAccessHash)
+			: *userpic;
+		result->setUserpic(photoId, location);
+	}
+	return result;
+}
+
+QString peekUserPhone(int streamAppVersion, QDataStream &stream) {
+	quint64 peerId = 0, photoId = 0;
+	stream >> peerId >> photoId;
+	DEBUG_LOG(("peekUserPhone.id: %1").arg(peerId));
+	if (!peerId
+		|| !peerIsUser(peerId)
+		|| !readStorageImageLocation(streamAppVersion, stream)) {
+		return QString();
+	}
+
+	QString first, last, phone;
+	stream >> first >> last >> phone;
+	DEBUG_LOG(("peekUserPhone.data: %1 %2 %3"
+		).arg(first).arg(last).arg(phone));
+	return phone;
+}
+
+} // namespace Serialize
diff --git a/Telegram/SourceFiles/storage/serialize_peer.h b/Telegram/SourceFiles/storage/serialize_peer.h
new file mode 100644
index 000000000..a56175c76
--- /dev/null
+++ b/Telegram/SourceFiles/storage/serialize_peer.h
@@ -0,0 +1,40 @@
+/*
+This file is part of Telegram Desktop,
+the official desktop application for the Telegram messaging service.
+
+For license and copyright information please follow this link:
+https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
+*/
+#pragma once
+
+namespace Serialize {
+
+int storageImageLocationSize(const StorageImageLocation &location);
+void writeStorageImageLocation(
+	QDataStream &stream,
+	const StorageImageLocation &location);
+
+// NB! This method can return StorageFileLocation with Type::Generic!
+// The reader should discard it or convert to one of the valid modern types.
+std::optional<StorageImageLocation> readStorageImageLocation(
+	int streamAppVersion,
+	QDataStream &stream);
+
+int imageLocationSize(const ImageLocation &location);
+void writeImageLocation(QDataStream &stream, const ImageLocation &location);
+
+// NB! This method can return StorageFileLocation with Type::Generic!
+// The reader should discard it or convert to one of the valid modern types.
+std::optional<ImageLocation> readImageLocation(
+	int streamAppVersion,
+	QDataStream &stream);
+
+uint32 peerSize(not_null<PeerData*> peer);
+void writePeer(QDataStream &stream, PeerData *peer);
+PeerData *readPeer(
+	not_null<Main::Session*> session,
+	int streamAppVersion,
+	QDataStream &stream);
+QString peekUserPhone(int streamAppVersion, QDataStream &stream);
+
+} // namespace Serialize
diff --git a/Telegram/SourceFiles/storage/storage_account.cpp b/Telegram/SourceFiles/storage/storage_account.cpp
index 0f52c1e79..8daa289aa 100644
--- a/Telegram/SourceFiles/storage/storage_account.cpp
+++ b/Telegram/SourceFiles/storage/storage_account.cpp
@@ -15,10 +15,13 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "storage/details/storage_file_utilities.h"
 #include "storage/details/storage_settings_scheme.h"
 #include "storage/serialize_common.h"
+#include "storage/serialize_peer.h"
 #include "storage/serialize_document.h"
 #include "main/main_account.h"
 #include "main/main_session.h"
-#include "mtproto/dc_options.h"
+#include "mtproto/mtproto_config.h"
+#include "mtproto/mtproto_dc_options.h"
+#include "mtproto/mtp_instance.h"
 #include "history/history.h"
 #include "core/application.h"
 #include "data/stickers/data_stickers.h"
@@ -80,7 +83,9 @@ enum { // Local Storage Keys
 };
 
 [[nodiscard]] FileKey ComputeDataNameKey(const QString &dataName) {
-	const auto testAddition = (cTestMode() ? qsl(":/test/") : QString());
+	// We dropped old test authorizations when migrated to multi auth.
+	//const auto testAddition = (cTestMode() ? qsl(":/test/") : QString());
+	const auto testAddition = QString();
 	const auto dataNameUtf8 = (dataName + testAddition).toUtf8();
 	FileKey dataNameHash[2] = { 0 };
 	hashMd5(dataNameUtf8.constData(), dataNameUtf8.size(), dataNameHash);
@@ -94,7 +99,8 @@ enum { // Local Storage Keys
 [[nodiscard]] QString ComputeDatabasePath(const QString &dataName) {
 	return BaseGlobalPath()
 		+ "user_" + dataName
-		+ (cTestMode() ? "[test]" : "")
+		// We dropped old test authorizations when migrated to multi auth.
+		//+ (cTestMode() ? "[test]" : "")
 		+ '/';
 }
 
@@ -131,12 +137,13 @@ StartResult Account::legacyStart(const QByteArray &passcode) {
 	return StartResult::Success;
 }
 
-void Account::start(MTP::AuthKeyPtr localKey) {
+std::unique_ptr<MTP::Config> Account::start(MTP::AuthKeyPtr localKey) {
 	Expects(localKey != nullptr);
 
 	_localKey = std::move(localKey);
 	readMapWith(_localKey);
 	clearLegacyFiles();
+	return readMtpConfig();
 }
 
 void Account::startAdded(MTP::AuthKeyPtr localKey) {
@@ -173,7 +180,12 @@ base::flat_set<QString> Account::collectGoodNames() const {
 		_exportSettingsKey,
 		_trustedBotsKey,
 	};
-	auto result = base::flat_set<QString>{ "map0", "map1", "maps" };
+	auto result = base::flat_set<QString>{
+		"map0",
+		"map1",
+		"maps",
+		"configs",
+	};
 	const auto push = [&](FileKey key) {
 		if (!key) {
 			return;
@@ -549,7 +561,8 @@ void Account::reset() {
 		for (const auto &name : names) {
 			if (!name.endsWith(qstr("map0"))
 				&& !name.endsWith(qstr("map1"))
-				&& !name.endsWith(qstr("maps"))) {
+				&& !name.endsWith(qstr("maps"))
+				&& !name.endsWith(qstr("configs"))) {
 				QFile::remove(base + name);
 			}
 		}
@@ -878,7 +891,7 @@ std::unique_ptr<Main::Settings> Account::readSettings() {
 
 std::unique_ptr<Main::Settings> Account::applyReadContext(
 		ReadSettingsContext &&context) {
-	Core::App().dcOptions()->addFromOther(std::move(context.dcOptions));
+	ApplyReadFallbackConfig(context);
 
 	_cacheTotalSizeLimit = context.cacheTotalSizeLimit;
 	_cacheTotalTimeLimit = context.cacheTotalTimeLimit;
@@ -908,18 +921,14 @@ std::unique_ptr<Main::Settings> Account::applyReadContext(
 }
 
 void Account::writeMtpData() {
+	Expects(_localKey != nullptr);
+
+	const auto serialized = _owner->serializeMtpAuthorization();
+	const auto size = sizeof(quint32) + Serialize::bytearraySize(serialized);
+
 	FileWriteDescriptor mtp(ToFilePart(_dataNameKey), BaseGlobalPath());
-	if (!_localKey) {
-		LOG(("App Error: localkey not created in _writeMtpData()"));
-		return;
-	}
-
-	auto mtpAuthorizationSerialized = _owner->serializeMtpAuthorization();
-
-	quint32 size = sizeof(quint32) + Serialize::bytearraySize(mtpAuthorizationSerialized);
-
 	EncryptedDescriptor data(size);
-	data.stream << quint32(dbiMtpAuthorization) << mtpAuthorizationSerialized;
+	data.stream << quint32(dbiMtpAuthorization) << serialized;
 	mtp.writeEncrypted(data, _localKey);
 }
 
@@ -951,6 +960,35 @@ void Account::readMtpData() {
 	applyReadContext(std::move(context));
 }
 
+void Account::writeMtpConfig() {
+	Expects(_localKey != nullptr);
+
+	const auto serialized = _owner->mtp().config().serialize();
+	const auto size = Serialize::bytearraySize(serialized);
+
+	FileWriteDescriptor file(u"config"_q, _basePath);
+	EncryptedDescriptor data(size);
+	data.stream << serialized;
+	file.writeEncrypted(data, _localKey);
+}
+
+std::unique_ptr<MTP::Config> Account::readMtpConfig() {
+	Expects(_localKey != nullptr);
+
+	FileReadDescriptor file;
+	if (!ReadEncryptedFile(file, "config", _basePath, _localKey)) {
+		return nullptr;
+	}
+
+	LOG(("App Info: reading encrypted mtp config..."));
+	auto serialized = QByteArray();
+	file.stream >> serialized;
+	if (!CheckStreamStatus(file.stream)) {
+		return nullptr;
+	}
+	return MTP::Config::FromSerialized(serialized);
+}
+
 void Account::writeDrafts(not_null<History*> history) {
 	Storage::MessageDraft storedLocalDraft, storedEditDraft;
 	MessageCursor localCursor, editCursor;
@@ -1846,7 +1884,9 @@ void Account::importOldRecentStickers() {
 			custom->stickers.push_back(doc);
 			++custom->count;
 		}
-		if (recent.size() < Global::StickersRecentLimit() && qAbs(value) > 1) {
+		if (qAbs(value) > 1
+			&& (recent.size()
+				< _owner->session().serverConfig().stickersRecentLimit)) {
 			recent.push_back(qMakePair(doc, qAbs(value)));
 		}
 	}
diff --git a/Telegram/SourceFiles/storage/storage_account.h b/Telegram/SourceFiles/storage/storage_account.h
index 25bd282c3..dfe18aa56 100644
--- a/Telegram/SourceFiles/storage/storage_account.h
+++ b/Telegram/SourceFiles/storage/storage_account.h
@@ -28,6 +28,7 @@ class WallPaper;
 } // namespace Data
 
 namespace MTP {
+class Config;
 class AuthKey;
 using AuthKeyPtr = std::shared_ptr<AuthKey>;
 } // namespace MTP
@@ -55,7 +56,8 @@ public:
 	~Account();
 
 	[[nodiscard]] StartResult legacyStart(const QByteArray &passcode);
-	void start(MTP::AuthKeyPtr localKey);
+	[[nodiscartd]] std::unique_ptr<MTP::Config> start(
+		MTP::AuthKeyPtr localKey);
 	void startAdded(MTP::AuthKeyPtr localKey);
 	[[nodiscard]] int oldMapVersion() const {
 		return _oldMapVersion;
@@ -67,6 +69,7 @@ public:
 
 	void writeSettings();
 	void writeMtpData();
+	void writeMtpConfig();
 
 	void writeBackground(const Data::WallPaper &paper, const QImage &image);
 	bool readBackground();
@@ -172,6 +175,7 @@ private:
 	std::unique_ptr<Main::Settings> readSettings();
 	void writeSettings(Main::Settings *stored);
 
+	std::unique_ptr<MTP::Config> readMtpConfig();
 	void readMtpData();
 	std::unique_ptr<Main::Settings> applyReadContext(
 		details::ReadSettingsContext &&context);
diff --git a/Telegram/SourceFiles/storage/storage_accounts.cpp b/Telegram/SourceFiles/storage/storage_accounts.cpp
index a2daa9787..09e06bf91 100644
--- a/Telegram/SourceFiles/storage/storage_accounts.cpp
+++ b/Telegram/SourceFiles/storage/storage_accounts.cpp
@@ -9,6 +9,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 
 #include "storage/details/storage_file_utilities.h"
 #include "storage/serialize_common.h"
+#include "mtproto/mtproto_config.h"
 #include "main/main_accounts.h"
 #include "main/main_account.h"
 #include "facades.h"
@@ -25,11 +26,15 @@ constexpr auto kMaxAccounts = 3;
 }
 
 [[nodiscard]] QString ComputeKeyName(const QString &dataName) {
-	return "key_" + dataName + (cTestMode() ? "[test]" : "");
+	// We dropped old test authorizations when migrated to multi auth.
+	//return "key_" + dataName + (cTestMode() ? "[test]" : "");
+	return "key_" + dataName;
 }
 
 [[nodiscard]] QString ComputeInfoName(const QString &dataName) {
-	return "info_" + dataName + (cTestMode() ? "[test]" : "");
+	// We dropped old test authorizations when migrated to multi auth.
+	//return "info_" + dataName + (cTestMode() ? "[test]" : "");
+	return "info_" + dataName;
 }
 
 } // namespace
@@ -63,10 +68,12 @@ StartResult Accounts::start(const QByteArray &passcode) {
 	return result;
 }
 
-void Accounts::startAdded(not_null<Main::Account*> account) {
+void Accounts::startAdded(
+		not_null<Main::Account*> account,
+		std::unique_ptr<MTP::Config> config) {
 	Expects(_localKey != nullptr);
 
-	account->startAdded(_localKey);
+	account->startAdded(_localKey, std::move(config));
 }
 
 void Accounts::startWithSingleAccount(
diff --git a/Telegram/SourceFiles/storage/storage_accounts.h b/Telegram/SourceFiles/storage/storage_accounts.h
index 3926bfd46..9434f8a67 100644
--- a/Telegram/SourceFiles/storage/storage_accounts.h
+++ b/Telegram/SourceFiles/storage/storage_accounts.h
@@ -8,6 +8,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #pragma once
 
 namespace MTP {
+class Config;
 class AuthKey;
 using AuthKeyPtr = std::shared_ptr<AuthKey>;
 } // namespace MTP
@@ -30,7 +31,9 @@ public:
 	~Accounts();
 
 	[[nodiscard]] StartResult start(const QByteArray &passcode);
-	void startAdded(not_null<Main::Account*> account);
+	void startAdded(
+		not_null<Main::Account*> account,
+		std::unique_ptr<MTP::Config> config);
 	void writeAccounts();
 	void startFromScratch();
 
diff --git a/Telegram/SourceFiles/support/support_helper.cpp b/Telegram/SourceFiles/support/support_helper.cpp
index 174257a39..b86152ca3 100644
--- a/Telegram/SourceFiles/support/support_helper.cpp
+++ b/Telegram/SourceFiles/support/support_helper.cpp
@@ -289,7 +289,7 @@ TimeId OccupiedBySomeoneTill(History *history) {
 
 Helper::Helper(not_null<Main::Session*> session)
 : _session(session)
-, _api(_session->mtp())
+, _api(&_session->mtp())
 , _templates(_session)
 , _reoccupyTimer([=] { reoccupy(); })
 , _checkOccupiedTimer([=] { checkOccupiedChats(); }) {
diff --git a/Telegram/SourceFiles/ui/special_fields.cpp b/Telegram/SourceFiles/ui/special_fields.cpp
index c7973ca59..5631b426d 100644
--- a/Telegram/SourceFiles/ui/special_fields.cpp
+++ b/Telegram/SourceFiles/ui/special_fields.cpp
@@ -225,10 +225,9 @@ UsernameInput::UsernameInput(
 	const style::InputField &st,
 	rpl::producer<QString> placeholder,
 	const QString &val,
-	bool isLink)
+	const QString &linkPlaceholder)
 : MaskedInputField(parent, st, std::move(placeholder), val) {
-	setLinkPlaceholder(
-		isLink ? Core::App().createInternalLink(QString()) : QString());
+	setLinkPlaceholder(linkPlaceholder);
 }
 
 void UsernameInput::setLinkPlaceholder(const QString &placeholder) {
diff --git a/Telegram/SourceFiles/ui/special_fields.h b/Telegram/SourceFiles/ui/special_fields.h
index 2306c8606..77f7c2de6 100644
--- a/Telegram/SourceFiles/ui/special_fields.h
+++ b/Telegram/SourceFiles/ui/special_fields.h
@@ -73,7 +73,7 @@ public:
 		const style::InputField &st,
 		rpl::producer<QString> placeholder,
 		const QString &val,
-		bool isLink);
+		const QString &linkPlaceholder);
 
 	void setLinkPlaceholder(const QString &placeholder);
 
diff --git a/Telegram/SourceFiles/window/main_window.cpp b/Telegram/SourceFiles/window/main_window.cpp
index 65fe7b4ec..195c67e5c 100644
--- a/Telegram/SourceFiles/window/main_window.cpp
+++ b/Telegram/SourceFiles/window/main_window.cpp
@@ -158,8 +158,6 @@ MainWindow::MainWindow(not_null<Controller*> controller)
 			updateControlsGeometry();
 		}, _outdated->lifetime());
 	}
-
-	_isActiveTimer.setCallback([this] { updateIsActive(0); });
 }
 
 Main::Account &MainWindow::account() const {
@@ -267,7 +265,7 @@ bool MainWindow::hideNoQuit() {
 		}
 	} else if (Platform::IsMac()) {
 		closeWithoutDestroy();
-		updateIsActive(Global::OfflineBlurTimeout());
+		controller().updateIsActiveBlur();
 		updateGlobalMenu();
 		Ui::showChatsList();
 		return true;
@@ -280,10 +278,7 @@ void MainWindow::clearWidgets() {
 	updateGlobalMenu();
 }
 
-void MainWindow::updateIsActive(int timeout) {
-	if (timeout > 0) {
-		return _isActiveTimer.callOnce(timeout);
-	}
+void MainWindow::updateIsActive() {
 	_isActive = computeIsActive();
 	updateIsActiveHook();
 }
@@ -337,7 +332,11 @@ void MainWindow::init() {
 
 void MainWindow::handleStateChanged(Qt::WindowState state) {
 	stateChangedHook(state);
-	updateIsActive((state == Qt::WindowMinimized) ? Global::OfflineBlurTimeout() : Global::OnlineFocusTimeout());
+	if (state == Qt::WindowMinimized) {
+		controller().updateIsActiveBlur();
+	} else {
+		controller().updateIsActiveFocus();
+	}
 	Core::App().updateNonIdle();
 	if (state == Qt::WindowMinimized && Global::WorkMode().value() == dbiwmTrayOnly) {
 		minimizeToTray();
@@ -593,7 +592,7 @@ bool MainWindow::minimizeToTray() {
 	if (App::quitting() || !hasTrayIcon()) return false;
 
 	closeWithoutDestroy();
-	updateIsActive(Global::OfflineBlurTimeout());
+	controller().updateIsActiveBlur();
 	updateTrayMenu();
 	updateGlobalMenu();
 	showTrayTooltip();
diff --git a/Telegram/SourceFiles/window/main_window.h b/Telegram/SourceFiles/window/main_window.h
index 3392bd9a5..43e28f728 100644
--- a/Telegram/SourceFiles/window/main_window.h
+++ b/Telegram/SourceFiles/window/main_window.h
@@ -51,7 +51,9 @@ public:
 
 	void init();
 	HitTestResult hitTest(const QPoint &p) const;
-	void updateIsActive(int timeout);
+
+	void updateIsActive();
+
 	bool isActive() const {
 		return _isActive;
 	}
@@ -195,7 +197,6 @@ private:
 	QString _titleText;
 
 	bool _isActive = false;
-	base::Timer _isActiveTimer;
 
 	base::Observable<void> _dragFinished;
 	rpl::event_stream<> _leaveEvents;
diff --git a/Telegram/SourceFiles/window/notifications_manager.cpp b/Telegram/SourceFiles/window/notifications_manager.cpp
index c00167259..8902445b9 100644
--- a/Telegram/SourceFiles/window/notifications_manager.cpp
+++ b/Telegram/SourceFiles/window/notifications_manager.cpp
@@ -11,6 +11,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "window/notifications_manager_default.h"
 #include "media/audio/media_audio_track.h"
 #include "media/audio/media_audio.h"
+#include "mtproto/mtproto_config.h"
 #include "history/history.h"
 #include "history/history_item_components.h"
 //#include "history/feed/history_feed_section.h" // #feed
@@ -121,13 +122,14 @@ void System::schedule(not_null<HistoryItem*> item) {
 	const auto t = base::unixtime::now();
 	const auto ms = crl::now();
 	const auto &updates = history->session().updates();
+	const auto &config = history->session().serverConfig();
 	const bool isOnline = updates.lastWasOnline();
-	const auto otherNotOld = ((cOtherOnline() * 1000LL) + Global::OnlineCloudTimeout() > t * 1000LL);
+	const auto otherNotOld = ((cOtherOnline() * 1000LL) + config.onlineCloudTimeout > t * 1000LL);
 	const bool otherLaterThanMe = (cOtherOnline() * 1000LL + (ms - updates.lastSetOnline()) > t * 1000LL);
 	if (!isOnline && otherNotOld && otherLaterThanMe) {
-		delay = Global::NotifyCloudDelay();
+		delay = config.notifyCloudDelay;
 	} else if (cOtherOnline() >= t) {
-		delay = Global::NotifyDefaultDelay();
+		delay = config.notifyDefaultDelay;
 	}
 
 	auto when = ms + delay;
diff --git a/Telegram/SourceFiles/window/themes/window_theme_editor_box.cpp b/Telegram/SourceFiles/window/themes/window_theme_editor_box.cpp
index a28f14e59..71a8c09ce 100644
--- a/Telegram/SourceFiles/window/themes/window_theme_editor_box.cpp
+++ b/Telegram/SourceFiles/window/themes/window_theme_editor_box.cpp
@@ -843,7 +843,7 @@ void SaveThemeBox(
 		st::createThemeLink,
 		rpl::single(qsl("link")),
 		cloud.slug.isEmpty() ? GenerateSlug() : cloud.slug,
-		true);
+		window->account().session().createInternalLink(QString()));
 	linkWrap->widthValue(
 	) | rpl::start_with_next([=](int width) {
 		link->resize(width, link->height());
@@ -854,7 +854,7 @@ void SaveThemeBox(
 		linkWrap->resize(linkWrap->width(), height);
 	}, link->lifetime());
 	link->setLinkPlaceholder(
-		Core::App().createInternalLink(qsl("addtheme/")));
+		window->account().session().createInternalLink(qsl("addtheme/")));
 	link->setPlaceholderHidden(false);
 	link->setMaxLength(kMaxSlugSize);
 
diff --git a/Telegram/SourceFiles/window/themes/window_themes_cloud_list.cpp b/Telegram/SourceFiles/window/themes/window_themes_cloud_list.cpp
index a41fed61e..fa04fbd81 100644
--- a/Telegram/SourceFiles/window/themes/window_themes_cloud_list.cpp
+++ b/Telegram/SourceFiles/window/themes/window_themes_cloud_list.cpp
@@ -586,7 +586,7 @@ void CloudList::showMenu(Element &element) {
 	if (const auto slug = element.theme.slug; !slug.isEmpty()) {
 		_contextMenu->addAction(tr::lng_theme_share(tr::now), [=] {
 			QGuiApplication::clipboard()->setText(
-				Core::App().createInternalLinkFull("addtheme/" + slug));
+				_window->session().createInternalLinkFull("addtheme/" + slug));
 			Ui::Toast::Show(tr::lng_background_link_copied(tr::now));
 		});
 	}
diff --git a/Telegram/SourceFiles/window/window_connecting_widget.cpp b/Telegram/SourceFiles/window/window_connecting_widget.cpp
index a84b45df1..a735a9c3b 100644
--- a/Telegram/SourceFiles/window/window_connecting_widget.cpp
+++ b/Telegram/SourceFiles/window/window_connecting_widget.cpp
@@ -290,21 +290,19 @@ void ConnectionState::refreshState() {
 	const auto state = [&]() -> State {
 		const auto under = _widget && _widget->isOver();
 		const auto ready = (Checker().state() == Checker::State::Ready);
-		const auto mtp = _account->mtp()
-			? _account->mtp()->dcstate()
-			: MTP::DisconnectedState;
+		const auto state = _account->mtp().dcstate();
 		const auto proxy
 			= (Global::ProxySettings() == MTP::ProxyData::Settings::Enabled);
-		if (mtp == MTP::ConnectingState
-			|| mtp == MTP::DisconnectedState
-			|| (mtp < 0 && mtp > -600)) {
+		if (state == MTP::ConnectingState
+			|| state == MTP::DisconnectedState
+			|| (state < 0 && state > -600)) {
 			return { State::Type::Connecting, proxy, under, ready };
-		} else if (mtp < 0
-			&& mtp >= -kMinimalWaitingStateDuration
+		} else if (state < 0
+			&& state >= -kMinimalWaitingStateDuration
 			&& _state.type != State::Type::Waiting) {
 			return { State::Type::Connecting, proxy, under, ready };
-		} else if (mtp < 0) {
-			const auto wait = ((-mtp) / 1000) + 1;
+		} else if (state < 0) {
+			const auto wait = ((-state) / 1000) + 1;
 			return { State::Type::Waiting, proxy, under, ready, wait };
 		}
 		return { State::Type::Connected, proxy, under, ready };
@@ -617,9 +615,7 @@ void ConnectionState::Widget::refreshRetryLink(bool hasRetry) {
 			tr::lng_reconnecting_try_now(tr::now),
 			st::connectingRetryLink);
 		_retry->addClickHandler([=] {
-			if (const auto mtproto = _account->mtp()) {
-				mtproto->restart();
-			}
+			_account->mtp().restart();
 		});
 		updateRetryGeometry();
 	} else if (!hasRetry) {
diff --git a/Telegram/SourceFiles/window/window_controller.cpp b/Telegram/SourceFiles/window/window_controller.cpp
index 8b05d6983..b906131ff 100644
--- a/Telegram/SourceFiles/window/window_controller.cpp
+++ b/Telegram/SourceFiles/window/window_controller.cpp
@@ -11,6 +11,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "main/main_account.h"
 #include "main/main_accounts.h"
 #include "main/main_session.h"
+#include "mtproto/mtproto_config.h"
 #include "ui/layers/box_content.h"
 #include "ui/layers/layer_widget.h"
 #include "ui/toast/toast.h"
@@ -29,7 +30,8 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 namespace Window {
 
 Controller::Controller()
-: _widget(this) {
+: _widget(this)
+, _isActiveTimer([=] { updateIsActive(); }) {
 	_widget.init();
 }
 
@@ -143,8 +145,20 @@ void Controller::reActivate() {
 	_widget.reActivateWindow();
 }
 
-void Controller::updateIsActive(int timeout) {
-	_widget.updateIsActive(timeout);
+void Controller::updateIsActiveFocus() {
+	_isActiveTimer.callOnce(sessionController()
+		? sessionController()->session().serverConfig().onlineFocusTimeout
+		: crl::time(1000));
+}
+
+void Controller::updateIsActiveBlur() {
+	_isActiveTimer.callOnce(sessionController()
+		? sessionController()->session().serverConfig().offlineBlurTimeout
+		: crl::time(1000));
+}
+
+void Controller::updateIsActive() {
+	_widget.updateIsActive();
 }
 
 void Controller::minimize() {
diff --git a/Telegram/SourceFiles/window/window_controller.h b/Telegram/SourceFiles/window/window_controller.h
index ec7a5493a..32401d17b 100644
--- a/Telegram/SourceFiles/window/window_controller.h
+++ b/Telegram/SourceFiles/window/window_controller.h
@@ -63,7 +63,9 @@ public:
 
 	void activate();
 	void reActivate();
-	void updateIsActive(int timeout);
+	void updateIsActiveFocus();
+	void updateIsActiveBlur();
+	void updateIsActive();
 	void minimize();
 	void close();
 
@@ -81,6 +83,7 @@ private:
 	Main::Account *_account = nullptr;
 	::MainWindow _widget;
 	std::unique_ptr<SessionController> _sessionController;
+	base::Timer _isActiveTimer;
 
 	rpl::lifetime _accountLifetime;
 	rpl::lifetime _lifetime;
diff --git a/Telegram/SourceFiles/window/window_main_menu.cpp b/Telegram/SourceFiles/window/window_main_menu.cpp
index 1d8cbe634..e87232633 100644
--- a/Telegram/SourceFiles/window/window_main_menu.cpp
+++ b/Telegram/SourceFiles/window/window_main_menu.cpp
@@ -28,12 +28,12 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "lang/lang_keys.h"
 #include "core/click_handler_types.h"
 #include "main/main_session.h"
+#include "mtproto/mtproto_config.h"
 #include "data/data_folder.h"
 #include "data/data_session.h"
 #include "data/data_user.h"
 #include "data/data_changes.h"
 #include "mainwidget.h"
-#include "facades.h"
 #include "app.h"
 #include "styles/style_window.h"
 #include "styles/style_dialogs.h"
@@ -221,7 +221,11 @@ MainMenu::MainMenu(
 		updatePhone();
 	}, lifetime());
 
-	subscribe(Global::RefPhoneCallsEnabledChanged(), [this] { refreshMenu(); });
+	_controller->session().serverConfig().phoneCallsEnabled.changes(
+	) | rpl::start_with_next([=] {
+		refreshMenu();
+	}, lifetime());
+
 	subscribe(Window::Theme::Background(), [this](const Window::Theme::BackgroundUpdate &update) {
 		if (update.type == Window::Theme::BackgroundUpdate::Type::ApplyingTheme) {
 			refreshMenu();
@@ -261,7 +265,7 @@ void MainMenu::refreshMenu() {
 				box->addLeftButton(tr::lng_profile_add_contact(), [] { App::wnd()->onShowAddContact(); });
 			}));
 		}, &st::mainMenuContacts, &st::mainMenuContactsOver);
-		if (Global::PhoneCallsEnabled()) {
+		if (_controller->session().serverConfig().phoneCallsEnabled.current()) {
 			_menu->addAction(tr::lng_menu_calls(tr::now), [=] {
 				Ui::show(Box<PeerListBox>(std::make_unique<Calls::BoxController>(controller), [](not_null<PeerListBox*> box) {
 					box->addButton(tr::lng_close(), [=] {
diff --git a/Telegram/SourceFiles/window/window_peer_menu.cpp b/Telegram/SourceFiles/window/window_peer_menu.cpp
index f6c10bbc8..c6cf23534 100644
--- a/Telegram/SourceFiles/window/window_peer_menu.cpp
+++ b/Telegram/SourceFiles/window/window_peer_menu.cpp
@@ -26,6 +26,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "mainwindow.h"
 #include "api/api_common.h"
 #include "api/api_chat_filters.h"
+#include "mtproto/mtproto_config.h"
 #include "history/history.h"
 #include "history/history_item.h"
 #include "history/history_message.h" // GetErrorTextForSending.
@@ -49,7 +50,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "data/data_chat_filters.h"
 #include "dialogs/dialogs_key.h"
 #include "boxes/peers/edit_peer_info_box.h"
-#include "facades.h"
+#include "facades.h" // Adaptive::ThreeColumn
 #include "styles/style_layers.h"
 #include "styles/style_boxes.h"
 #include "styles/style_window.h" // st::windowMinWidth
@@ -1011,7 +1012,8 @@ void PeerMenuAddChannelMembers(
 		not_null<Window::SessionNavigation*> navigation,
 		not_null<ChannelData*> channel) {
 	if (!channel->isMegagroup()
-		&& channel->membersCount() >= Global::ChatSizeMax()) {
+		&& (channel->membersCount()
+			>= channel->session().serverConfig().chatSizeMax)) {
 		Ui::show(
 			Box<MaxInviteBox>(channel),
 			Ui::LayerOption::KeepOther);
diff --git a/Telegram/cmake/lib_mtproto.cmake b/Telegram/cmake/lib_mtproto.cmake
index 87a5f5f19..6ede5106f 100644
--- a/Telegram/cmake/lib_mtproto.cmake
+++ b/Telegram/cmake/lib_mtproto.cmake
@@ -39,6 +39,10 @@ PRIVATE
     mtproto/mtproto_auth_key.h
     mtproto/mtproto_concurrent_sender.cpp
     mtproto/mtproto_concurrent_sender.h
+    mtproto/mtproto_config.cpp
+    mtproto/mtproto_config.h
+    mtproto/mtproto_dc_options.cpp
+    mtproto/mtproto_dc_options.h
     mtproto/mtproto_dh_utils.cpp
     mtproto/mtproto_dh_utils.h
     mtproto/mtproto_proxy_data.cpp
diff --git a/Telegram/lib_rpl b/Telegram/lib_rpl
index 88ae67c59..6d6f69235 160000
--- a/Telegram/lib_rpl
+++ b/Telegram/lib_rpl
@@ -1 +1 @@
-Subproject commit 88ae67c59ab791084f43163d4484c9874003ac42
+Subproject commit 6d6f692354b1b1d7b3808a01cc3337175ea5213d