Still having a hard time deciding how much effort to spend rebuilding threads.
Old way: just use context. This is fast and simple, but misses posts when people don't set it.
New way: grab the thread, then check replies for missing parents, and go back to the database to load them. This works in many cases, particularly when coming in at the bottom of a thread, we get everything previous. But it still misses mismatched replies. We don't know what we're missing below us.
The usual fix is a CTE query. But they don't work well if posts are actually missing from the DB. Or deleted. The whole idea behind using context is that it's resilient against broken threads.
I guess the ultimate fix would be search for the context, do a CTE query for all the results, then do more context queries for any contexts seen, then iterate endlessly until we suck it all in.