"It would be fairly easy to convert deleted songs into 'ignore'
database entries that will never show up anywhere, rather than
deleting them. Then you need to provide a way to convert them back,
such as explicitly adding them to the library again, and make sure
it's easy enough to figure out how to do it, and make sure it doesn't
happen accidentally."
Comment from the developer:
"It would be fairly easy to convert deleted songs into 'ignore'
database entries that will never show up anywhere, rather than
deleting them. Then you need to provide a way to convert them back,
such as explicitly adding them to the library again, and make sure
it's easy enough to figure out how to do it, and make sure it doesn't
happen accidentally."