The test MongoClient_should_create_activities_when_tracing_enabled was failing for me occasionally when running locally. I thought this was a flaky test, but I had Junie (with Opus 4.6) investigate and it found this:

`_shouldTrace` in `CommandEventHelper` was set *once* at connection construction time via `MongoTelemetry.ActivitySource.HasListeners()`. Since connections are pooled and reused, if a connection was created before an `ActivityListener` was registered (or by a test with tracing disabled), `_shouldTrace` remained `false` permanently for that connection — command activities were never created even when a listener was later active.