How to receive the session.shutdown event?

I'm trying to access `totalPremiumRequests` and other data from the `session.shutdown` event but never see it fire. I log every event type from `session.on()` and get `assistant.usage`, `session.idle`, etc but never `session.shutdown`.

My sessions are long-lived and reused, so `destroy()` isn't called during normal use. On process exit I call `client.stop()` (which calls `destroy()` internally) but still nothing shows up. Looking at the [source](https://github.com/github/copilot-sdk/blob/5016587a62652f3d184b3c6958dfc63359921aa8/nodejs/src/session.ts#L517), it looks like `destroy()` clears all event handlers right after the RPC resolves, which might be before the shutdown notification arrives.

What's the intended way to get this data?