Decides what to do with a dead-lettered event.

defmodule MyApp.DeadLetterPolicy do
  @behaviour DDD.Outbox.DeadLetterPolicy

  @impl true
  def handle(%{event_type: "MyApp.Events.OrderPlaced"}), do: :replay
  def handle(_dead_letter), do: :keep
end

handle/1 receives a map with :id, :event_type, :aggregate_type, :aggregate_id, :payload, :attempts, :last_error, :failed_at and :replays, and returns:

• :keep - acknowledge it and leave it dead-lettered
• :replay - make the poller retry it from scratch
• :discard - resolve it as discarded
• :later - decide on a later sweep (it stays unresolved)

A policy that raises is logged and treated as :later, so it can never crash the handler.