Supervision tree and repo ownership — the otp: section.

supervisor is derived, not a free choice: an Ecto repo is a supervised process, so repo: true forces it. Svelixir.Config.Otp applies that implication; nothing here does, because a section cannot see its siblings.

This is the one section whose module name differs from its config key, hence the :as override — a user who mistypes a key under otp: should be told about otp, not about supervision.