Pattern for per-session tool collection lifetimes?

[derrickaccountnumbertwo]

Hi, I'm trying to figure out the intended way to combine ListChanged notifications with per-session tool collections. Specifically, I don't know how I can become aware that a session has ended.

I'll describe my use case in more detail, so that you can check my assumptions and correct me if I'm wrong:

1. I'm implementing an MCP server. My Tools are inheriting from Microsoft.Extensions.AI.AIFunction. During tool invocation, I need to know which user/session this is, and therefore each tool must carry the user/session state it needs, and therefore I need to create a separate tool collection per user/session. Does any of that sound wrong so far?
2. On my MCP server program I have a way for tools to be enabled/disabled, which should send a list changed notification to clients. I have a collection of tool collections (one per session) which I can iterate over and update in order to automatically send those notifications.
3. But here is the problem: Now a client disconnects. How can I be aware of this, so that I can forget that tool collection, and stop keeping it in memory and trying to update it?

I'm fairly inexperienced at this, so I don't know whether I should be considering things like "stateless" or whether it would help or what the tradeoffs would be.
Any advice would be appreciated, thank you.