There's no docs atm for that particular use-case, but please check this thread where I answered something with a similar workflow that can be applicable here:
https://discord.com/channels/1108396290624213082/1133770315873398794/1134570342229233785
Note that the user ID would need to be defined by your frontend and passed to the bot in the auto-triggered message to the webchat (you'll also need access to the triggers beta, please check that link for more info).