var, target-typed new, and init

Three small conveniences you'll read constantly. var infers the type on the left from the right, like TS const without an annotation; the team uses it freely where the type is obvious from the initializer. Target-typed new goes the other way: when the type is already stated, you can write new() and let the compiler fill it in. And init accessors make a property settable only during object construction, which is how you get immutability without a giant constructor.

// var: type inferred from the right
var rows = await query.ToListAsync();      // List<FlightDisruptionCostCalc>

// target-typed new: type stated on the left, so new() is enough
private readonly List<EjError> _errors = new();

// init-only property: set at construction, immutable after
public record DecidedSnapshot
{
    public string FlightNumber { get; init; }
}