Issue

The Rotate() method acquires _lock around CloseWriter():

private void Rotate()
{
    // ...
    lock (_lock)
    {
        CloseWriter();
    }
}

However, Rotate() is only called from CheckRotation(), which is called from WriteLine() and Write() — both of which already hold _lock. C#'s Monitor is reentrant so this doesn't deadlock, but the redundant lock is misleading and suggests the locking strategy isn't well-defined.

Suggested fix

Remove the inner lock (_lock) in Rotate() and add a comment that the caller must hold the lock.

File

src/Servy.Core/IO/RotatingStreamWriter.cs — lines 326-334