Question re:generating images by GPT actions

I have a custom GPT (formerly plugin) where some custom actions generate illustrations: maps, timeline diagrams, image collages, plots etc.
These are images hosted on a cloud and the action returns the URL to these images. The GPT nicely picks these up and displays the images inline.

My question is: How long should these generated images persist before they are purged?
My GPTs serve learning. Ideally I would like the learner to be able to “Share link to Chat” and include it as a citation in their bibliography.
Today it is not yet supported…

…but eventually I hope it will.
It will be a great thing for schools; it will make it clear that genAI was used for legit research and not plagiarism.

Maybe an endpoint we can periodically query, to see which OpenAI-Conversation-Id have been deleted by the user

Or maybe for inline content, OpenAI could cache a copy of the img themselves?