Currently, Coauthor messages do not thread well, because their subject lines are customized.
[ ] We can fix by adding In-Reply-To and/or References headers that refer to previous messages (by Message-ID) from Coauthor. I imagine one thread per group (if splitting by group is turned on). We can generate the Message-IDs from the last diff ID reported. I'm not quite sure how to keep track of that for replies, though; might need a new database. Actually, it might be possible to have all messages just have a References: <userId@coauthor> or References: <userId-groupId@coauthor> so they all reference a common non-existing parent.
For mail clients following the gold standard of mail threading (which includes Mutt and K-9, for example), adding a References header is enough.
Sadly, Pine/Alpine respects References but won't cluster into a thread if the parent doesn't exist. (See mail_thread_references) This is arguably a bug, and probably very few people use Pine, so maybe not worth fixing...
[ ] The fix would be to include recent previous messages in References as well.
[ ] Might users want the option to thread by day of update, or week of update, etc.? This would be easy to do by customizing the References header.
[ ] Perhaps add a settings toggle for "identical subjects for Gmail threading". Combined with threading by day or week, we could still have interesting subjects like "[Coauthor] Updates during 2021-06-12" or [Coauthor] Updates during week of 2021-06-13" or somesuch. Otherwise just "[Coauthor] Updates" or "[Coauthor/Group] Updates"?
[ ] Or have a toggle for "wrap subject in brackets for Gmail threading", so we get "[Coauthor: 7 updates in ...". But Gmail won't be showing these subjects generally anyway, so this might be less good (unless you use multiple email clients).
Currently, Coauthor messages do not thread well, because their subject lines are customized.
In-Reply-Toand/orReferencesheaders that refer to previous messages (byMessage-ID) from Coauthor. I imagine one thread per group (if splitting by group is turned on).We can generate theActually, it might be possible to have all messages just have aMessage-IDs from the last diff ID reported. I'm not quite sure how to keep track of that for replies, though; might need a new database.References: <userId@coauthor>orReferences: <userId-groupId@coauthor>so they all reference a common non-existing parent.Referencesheader is enough.Referencesbut won't cluster into a thread if the parent doesn't exist. (Seemail_thread_references) This is arguably a bug, and probably very few people use Pine, so maybe not worth fixing...Referencesas well.Referencesheader.Referencesheaders. (I tested this experimentally a fair amount, and it seems to be true.) Gmail does ignore stuff in leading square brackets though (for mailing list names), so could put all details there — but looks ugly.(Requested by Mati)