List delivery attempts for an endpoint
Authentication: Supports API key and bearer token authentication.
Authentication: Supports API key and bearer token authentication.
Bearer authentication of the form Bearer <token>, where token is your auth token.
Per-attempt delivery state.
SENDING is the transient state that prevents double-sends: the
delivery task atomically flips PENDING → SENDING (compare-and-set
on the row) before doing the outbound POST, so any other worker that
picks up the same row from the sweeper backs off cleanly. Always a
terminal status (SUCCEEDED/FAILED/DEAD) by the time the task returns.