Best way to display chat messages with Headless Mode SDK

We are currently using the Genesys Web Chat Widget v2.0, but are in the process of scoping the migration to Web Messenger. We need to rebuild the frontend experience using Messenger’s Headless SDK functions to show as an embedded chat window on a webpage. We only want customers to be able to access the chat functionality after they have completed a support request form in our Customer Success Hub. Once they end this chat, we do not want to give them the option to resume the conversation at a later time; the next time they file a chat support request, the interaction should be a completely new one with no visible history.

In terms of the best way to display message history in the chat window during the same session: Does the Messenger JavaScript SDK keep track of inbound and outbound messages in the current conversation as they are posted? Does the fetchHistory call need to be used within the same session to ensure that not only the most recent message posted is displayed, but also the previous messages are displayed to the customer?