Ideally, we can unsubscribe from any child comment ... that way we can unsubscribe from just the tangent.

I've given this some thought... I think a general solution would easily become prohibitively expensive. I think we need to restrict this feature for example by saying all unsubscriptions will take precedence (meaning you can't arbitrarily nest unsubscriptions and subscriptions). Your thoughts?

(EDIT: Let me clarify what I mean by unsubscriptions in this case: a record in the database indicating that a particular post has been positively unsubscribed, not just that it has no subscription. Probably indicated by a new flag in the existing ThreatSubscription table.)

a record in the database indicating that a particular post has been positively unsubscribed, not just that it has no subscription.

You're right! I had the same thought yesterday. It'll be so much easier to be able to assume all children threads are subscribed to and let stackers selectively unsubscribe.