Auto-submit /start when paying for premium.

Telegram/SourceFiles/settings/settings_premium.cpp

@@ -598,7 +598,12 @@ void StartPremiumPayment(
 		"premium_invoice_slug",
 		QString());
 	if (!username.isEmpty()) {
-		UrlClickHandler::Open("https://t.me/" + username + "?start=" + ref);
+		controller->showPeerByLink(Window::SessionNavigation::PeerByLinkInfo{
+			.usernameOrId = username,
+			.resolveType = Window::ResolveType::BotStart,
+			.startToken = ref,
+			.startAutoSubmit = true,
+		});
 	} else if (!slug.isEmpty()) {
 		UrlClickHandler::Open("https://t.me/$" + slug);
 	}

Telegram/SourceFiles/window/window_session_controller.cpp

@@ -346,6 +346,8 @@ void SessionNavigation::showPeerByLinkResolved(
 		// Show specific posts only in channels / supergroups.
 		const auto msgId = peer->isChannel()
 			? info.messageId
+			: info.startAutoSubmit
+			? ShowAndStartBotMsgId
 			: ShowAtUnreadMsgId;
 		const auto attachBotUsername = info.attachBotUsername;
 		if (bot && bot->botInfo->startToken != info.startToken) {

Telegram/SourceFiles/window/window_session_controller.h

@@ -193,6 +193,7 @@ public:
 		ResolveType resolveType = ResolveType::Default;
 		QString startToken;
 		ChatAdminRights startAdminRights;
+		bool startAutoSubmit = false;
 		QString attachBotUsername;
 		std::optional<QString> attachBotToggleCommand;
 		std::optional<QString> voicechatHash;