Delivers one notification to one external channel (Telegram, …), off the hot path. Enqueued transactionally from the notification creation choke point — one job per {source, channel} — so a slow bot API call never blocks the business action that logged the activity.

Job args

%{"channel" => "telegram",
  "recipient_uuid" => "<uuid>",
  "type_key" => "posts.likes",
  # exactly ONE source:
  "activity_uuid" => "<uuid>"    # activity-driven (renders from the Entry)
  # or
  "notification_uuid" => "<uuid>"}  # standalone (renders from the row)

Retry / failure policy

The channel returns a permanent/transient verdict:

• :ok — done.
• {:error, {:transient, _}} / {:error, {:transient, _}, retry_ms} — Oban retries (with a snooze on retry_ms), up to max_attempts.
• {:error, {:permanent, reason}} — soft-disable the channel in the user's config (enabled: false, status, disabled_reason) and stop. A bot the user blocked shouldn't retry-storm.

A channel/user/source that's gone by run time is discarded (:ok), not retried. The channel resolves its own credentials owner-scoped to the recipient, so this worker never handles a token.