I am working on an telegram bot, and looking for the exact URL schema to popup the "Share / Select Group / Send to" dialogue in the telegram client.
I have seen this link in @pollbot, for which I took following screenshots.

A bit more details:
tg protocol url: tg://resolve?domain=PollBot&startgroup=5148bed5f90678b93246464b3e132052. So I tried to resend this url via bot.sendMessage. But it turned out Telegram api server won't parse the tg://resolve url. The link there works with deeplinking, please read about it here: https://core.telegram.org/bots#deep-linking
the url has the following scheme:
https://telegram.me/<YourBotUsername>?startgroup=<Payload>
the startgroup part (parameter) of the url tells telegram to open the 'add to group' dialog.
when you choose a group there (and you can add bot's to it) the bot will be added to the group and /start PAYLOAD will be send to that group.
The Payload is what you defined as value of the startgroup parameter, so your bot can assosiate it with something and send the matching reply.
please mind, that the Payload can only contain certain characters and don't mind that the telegram clients might internaly convert that link to an tg:// url.
you can also use start instead of startgroup to open a private chat.
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