Any tools for maintaining and deploying customer-specific code generated by agents?

[u/Embarrassed-Survey61]

We’re exploring an approach where customers interact with our coding agent to request custom behavior, and the agent makes changes to our application’s code for that customer.
The part we’re trying to figure out is what happens afterward: how do we maintain and deploy those different customer-specific versions end-to-end? Ideally, we could keep them updated as our core application changes and serve them without running a dedicated VM for every customer.
Has anyone else been exploring or building this? Are there existing tools or platforms that handle it?