Behaviour contract for channel-specific render validation.

Every channel render validator — built-in or host-defined — must implement this behaviour. Declaring use Chimeway.Rendering.Channel injects @behaviour Chimeway.Rendering.Channel so the Elixir compiler issues warnings for typo'd or missing validate/1 implementations.

Usage

defmodule MyApp.Channels.Slack do
  use Chimeway.Rendering.Channel

  @impl Chimeway.Rendering.Channel
  def validate(attrs) when is_map(attrs) do
    # Ecto.Changeset validation producing a stringified map
    {:ok, attrs}
  end

  def validate(_other) do
    {:error, :invalid}
  end
end

Contract

validate/1 receives the raw render attrs map from the notifier's rendering/2 callback and must return {:ok, stringified_map} on success or {:error, %Ecto.Changeset{}} on validation failure.

The returned map MUST have string keys (produced by Atom.to_string/1) so it survives JSONB round-trips and Oban serialization without key-type drift.