Day 146: The One Thing the Model Never Decides

The first durable piece of the Inbox Agent landed: the ledger that tracks which emails a workflow has already handled (PR #710), built on the background-jobs foundation from the org-timezone slice (PR #707). No poller, no dispatcher, no agent run yet, just the data layer, because there's no caller for the rest. The design decision worth writing down is what answers 'have we already processed this…