Creating an issue in case people have the same question.

I am not fully happy with the namespace system we have. Not enough for easy invalidation. So I would love to have tags and it's planned, but it's quite a tricky thing to nail down, especially in bentocache, where we have a lot of different features

I've been doing quite a bit of research on the topic and should try an implementation when I have some time. The API will be super simple:

await bento.getOrSet({
  key: 'foo',
  factory: getFromDb(),
  tags: ['tag-1', 'tag-2']
});

await bento.set({ 
  key: 'foo',
  tags: ['tag-1']
});

Then, we could delete all entries tagged with tag-1 using:

await bento.delete({ tag: 'tag-1' });

This would remove all entries that have the tag-1 tag.

It's likely that this tagging system will deprecate the current namespace system we have. I think they would become useless once we have tags. We would keep namespaces until v2, but they would be marked as deprecated via JSDoc