> To avoid breaking the current behavior, what if the set of tags applied to 
> new/moved/deleted(?) messages could be set on the command line or some 
> other library interface, while just perhaps defaulting to unread/inbox? 
> This would support both the current behavior and a hooks-like workflow 
> without notmuch itself treating any tags (new, unread, inbox, etc.) as 
> "special".

+1. For some, the default "inbox unread" might just be the correct
thing, while others may want "new". I know that I don't need any special
tag for new mails, as I applied the "sync maildir flags" patch. So
configurable in .notmuch-config with a default of "inbox unread" to keep
behavior consistent seems the best way to me.

Sebastian