Inbox zero as a scheduled task. The browser drives Gmail itself: files every thread into its client folder, archives everything, restores only the threads that still need action, and prunes anything stale, leaving an inbox that holds nothing but live conversations awaiting a response.
Numbered workflow labels say what state a thread is in; client and topic folders say what it’s about. Before anything is archived, threads that belong to a client folder get filed there, reading the live sidebar each run, since the folder set grows as clients are added.
The whole inbox is bulk-archived, then the two keeper labels, 1: to respond and 6: awaiting reply, are searched and moved back in. The skill waits out Gmail’s async bulk processing before restoring, so no keeper gets stranded.
Keeper threads older than 40 days get archived using the inbox’s own activity ordering (Gmail’s date search can’t express “last activity”), automation-test forwards don’t count as activity, and a final search verifies zero stragglers before the run reports its counts.