Declarative workflow contract for Squid Mesh workflow modules.

Example

defmodule Billing.InvoiceReminder do
  use SquidMesh.Workflow

  workflow do
    trigger :invoice_delivery do
      manual()

      payload do
        field :account_id, :string
        field :invoice_id, :string
      end
    end

    step :load_invoice, Billing.Steps.LoadInvoice
    step :send_email, Billing.Steps.SendReminderEmail, retry: [max_attempts: 3]

    transition :load_invoice, on: :ok, to: :send_email
  end
end

The contract defined here captures workflow structure. Validation and runtime execution behavior are added in subsequent slices.