Typed message schema contracts with version negotiation and backward-compatibility enforcement.

Sub-modules:

• PhoenixMicro.Schema.Field — field struct & type validation
• PhoenixMicro.Schema.Validator — validation engine
• PhoenixMicro.Schema.Migrator — version migration chains
• PhoenixMicro.Schema.Registry — ETS topic→module registry

Defining a schema

defmodule MyApp.Events.PaymentCreated do
  use PhoenixMicro.Schema

  schema_version 2
  topic "payments.created"

  field :payment_id,   :string,  required: true
  field :amount_cents, :integer, required: true
  field :currency,     :string,  required: true, default: "USD"
  field :metadata,     :map,     required: false

  compatible_with [1]

  def migrate(1, payload) do
    {amount, rest} = Map.pop(payload, "amount")
    Map.put(rest, "amount_cents", round(amount * 100))
  end
end

Publishing with schema validation

PhoenixMicro.Schema.publish(MyApp.Events.PaymentCreated, %{
  payment_id: "pay_123",
  amount_cents: 9999,
  currency: "USD"
})

Decoding in consumers

def handle(message, _ctx) do
  {:ok, event} =
    PhoenixMicro.Schema.decode(MyApp.Events.PaymentCreated,
      message.payload, message.headers)
  process(event)
  :ok
end