Write a "notmuch tag" command to add/remove tags from messages matching a search query. Rename notmuch_thread_results_t and notmuch_message_results_t to notmuch_threads_t and notmuch_messages_t respectively. Add a talloc context as the first argument to each command in notmuch.c. Write a "notmuch show" that displays a single thread. Fix to use the *last* Message-ID header if multiple such headers are encountered, (I noticed this is one thing that kept me from seeing the same message-ID values as sup). Audit everything for dealing with out-of-memory (and drop xutil.c). Write a test suite. Achieve 100% test coverage with the test suite. Think about this race condition: A client executes "notmuch search" Then executes "notmuch show" on a thread While user is reading, new mail is added to database for the thread Client asks for the thread to be archived. The bug here is that email that was never read will be archived. That's bad. The fix for the above is for the client to archive the individual messages already retrieved and shown, not the thread. (And in fact, we don't even have functions for removing tags on threads.) But this one is harder to fix: A client executes "notmuch search" While user is reading, new mail is added to database for the thread Client asks for a thread to be archived. To support this operation, (archiving a thread without even seeing the individual messages), we might need to provide a command to archive a thread as a whole. The problem is actually easy to fix for a persistent client. It can onto the originally retrieved thread objects which can hold onto the originally retrieved messages. So archiving those thread objects, (and not newly created thread objects), will be safe. It's harder to fix the non-persistent "notmuch" client. One approach is to simply tell the user to not run "notmuch new" between reading the results of "notmuch search" and executing "notmuch archive-thread" (or whatever we name it).