Primary constructor parameters are not automatically properties
A primary constructor parameter stays a parameter. Declare a property or field when the value should be an explicit member of the type.
Code-Quality
Use TimeProvider instead of DateTime.UtcNow in testable code
Inject TimeProvider when business logic depends on the current time, then control that time in tests.
Use ValueTask only when you know why
Prefer Task unless you have a measured allocation reason and a simple consumption contract.
Nullable warnings are design feedback, not noise
Treat nullable warnings as pressure to make object state and API contracts clearer.