Implement contracts

.gitignore

@@ -1,5 +1,7 @@
 .devenv
 .direnv
 out
+.bsp
 .bloop
 .metals
+mill.*

api/src/lu/foyer/App.scala

@@ -1,6 +1,7 @@
 package lu.foyer
 
 import lu.foyer.clients.*
+import lu.foyer.contracts.*
 import zio.*
 import zio.Console.*
 import zio.http.*
@@ -10,17 +11,26 @@ import zio.http.endpoint.*
 import zio.http.endpoint.openapi.OpenAPIGen
 import zio.http.endpoint.openapi.SwaggerUI
 import zio.schema.*
+import zio.http.Middleware.cors
+import zio.http.Middleware.CorsConfig
+import zio.http.Header.AccessControlAllowOrigin
 
 import java.net.URI
 import java.time.LocalDate
 import java.util.UUID
 
 object HttpServer:
+
+  val corsConfig = CorsConfig(_ => Some(AccessControlAllowOrigin.All))
+
   def routes =
     for
       client   <- ZIO.service[ClientController]
-      openAPI = OpenAPIGen.fromEndpoints(client.endpoints)
-    yield client.routes @@ Middleware.debug ++ SwaggerUI.routes("docs" / "openapi", openAPI)
+      contract <- ZIO.service[ContractController]
+      openAPI = OpenAPIGen.fromEndpoints(client.endpoints ++ contract.endpoints)
+    yield (client.routes ++ contract.routes)
+      @@ cors(corsConfig) @@ Middleware.debug
+      ++ SwaggerUI.routes("docs" / "openapi", openAPI)
 
 object App extends ZIOAppDefault:
   val app =
@@ -31,9 +41,17 @@ object App extends ZIOAppDefault:
 
   override def run = app.provide(
     CommandEngine.layer[ClientCommand, ClientEvent, ClientState],
+    CommandEngine.layer[ContractCommand, ContractEvent, ContractState],
     ClientHandlers.layer,
+    ContractHandlers.layer,
     ClientReducer.layer,
+    ContractReducer.layer,
     ClientEventRepositoryInMemory.layer,
+    ContractEventRepositoryInMemory.layer,
     ClientStateRepositoryInMemory.layer,
-    ClientController.layer
+    ContractStateRepositoryInMemory.layer,
+    ClientController.layer,
+    ContractController.layer,
+    PremiumServiceImpl.layer,
+    EmployeeServiceImpl.layer
   )

api/src/lu/foyer/CommandEngineController.scala

@@ -1,5 +1,6 @@
 package lu.foyer
 
+import lu.foyer.JsonApiResponse.One
 import zio.*
 import zio.Console.*
 import zio.http.*
@@ -11,34 +12,27 @@ import zio.schema.*
 import java.net.URI
 import java.time.LocalDate
 import java.util.UUID
-import lu.foyer.JsonApiResponse.One
 
-trait CommandEngineController[Command: Schema, Event: Schema, State: Schema](
-  domain: String,
-  entityName: String)
+trait CommandEngineController[Command: Schema, Event: Schema, State: Schema]
     extends JsonApiController:
 
   def commandEngine: CommandEngine[Command, Event, State]
 
-  val onthology = s"$domain:$entityName"
-
-  private val fetchMany =
+  private lazy val fetchMany =
     Endpoint(Method.GET / entityName)
-      .query(HttpCodec.query[Page])
+      // .query(HttpCodec.query[Page])
       .jsonApiMany[State]
 
-  private val fetchOne =
+  private lazy val fetchOne =
     Endpoint(Method.GET / entityName / uuid("entityId"))
       .jsonApiOne[State]
 
-  private val fetchEventsMany =
+  private lazy val fetchEventsMany =
     Endpoint(Method.GET / entityName / uuid("entityId") / "events")
-      .query(HttpCodec.query[Page])
+      // .query(HttpCodec.query[Page])
       .jsonApiMany[Event]
 
-  private val fetchEventsOne: Endpoint[(UUID, UUID), (UUID, UUID), JsonApiResponse.Error, One[
-    Event
-  ], zio.http.endpoint.AuthType.None.type] =
+  private lazy val fetchEventsOne =
     Endpoint(Method.GET / entityName / uuid("entityId") / "events" / uuid("eventId"))
       .jsonApiOne[Event]
 
@@ -51,7 +45,7 @@ trait CommandEngineController[Command: Schema, Event: Schema, State: Schema](
     given Schema[Command] = handler.commandSchema.asInstanceOf[Schema[Command]]
     val endpoint = Endpoint(Method.POST / entityName / "commands" / handler.name)
       .in[Command]
-      .jsonApiOne[Event]
+      .jsonApiOneWithStatus[Event](Status.Created)
     val route = endpoint.implementJsonApiOneEvent(command =>
       for
         entityId <- Random.nextUUID
@@ -73,32 +67,36 @@ trait CommandEngineController[Command: Schema, Event: Schema, State: Schema](
     )
     (endpoint, route)
 
-  private val (commands, commandsRoutes) = generateCommands.unzip
+  private lazy val (commands, commandsRoutes) = generateCommands.unzip
 
-  private val fetchManyRoute =
-    fetchMany.implementJsonApiManyEntity(commandEngine.stateRepo.fetchMany)
+  private lazy val fetchManyRoute =
+    fetchMany.implementJsonApiManyEntity(_ =>
+      commandEngine.stateRepo.fetchMany(Page(None, None, totals = Some(true)))
+    )
 
-  private val fetchOneRoute =
+  private lazy val fetchOneRoute =
     fetchOne.implementJsonApiOneEntity(commandEngine.stateRepo.fetchOne)
 
-  private val fetchEventsManyRoute =
-    fetchEventsMany.implementJsonApiManyEvent(commandEngine.eventRepo.fetchMany(_, _))
+  private lazy val fetchEventsManyRoute =
+    fetchEventsMany.implementJsonApiManyEvent(entityId =>
+      commandEngine.eventRepo.fetchMany(entityId, Page(None, None, totals = Some(true)))
+    )
 
-  private val fetchEventsOneRoute =
+  private lazy val fetchEventsOneRoute =
     fetchEventsOne.implementJsonApiOneEvent(commandEngine.eventRepo.fetchOne(_, _))
 
-  val endpoints = List(
+  lazy val endpoints = List(
     fetchMany,
     fetchOne,
     fetchEventsMany,
     fetchEventsOne
   ) ++ commands
 
-  val routes = Routes(
+  lazy val routes = (Routes(
     fetchManyRoute,
     fetchOneRoute,
     fetchEventsManyRoute,
     fetchEventsOneRoute
-  ) ++ Routes.fromIterable(commandsRoutes)
+  ) ++ Routes.fromIterable(commandsRoutes)) @@ proxyHeadersAspect
 
 end CommandEngineController

api/src/lu/foyer/JsonApiController.scala

@@ -1,41 +1,45 @@
 package lu.foyer
 
+import lu.foyer.JsonApiResponse.Many
+import lu.foyer.JsonApiResponse.One
 import zio.*
-import zio.schema.*
 import zio.http.*
+import zio.http.Header.Forwarded
 import zio.http.codec.*
 import zio.http.codec.PathCodec.path
 import zio.http.endpoint.*
-import lu.foyer.JsonApiResponse.Many
-import lu.foyer.JsonApiResponse.One
+import zio.schema.*
+import zio.schema.annotation.discriminatorName
+import zio.schema.annotation.fieldName
+
 import java.util.UUID
 import scala.annotation.targetName
-import zio.schema.annotation.discriminatorName
 
 object JsonApiResponse:
 
-  case class One[T](
-    data: Entity[T],
-    links: Links)
+  case class One[T](data: Entity[T]) derives Schema
+
+  case class Many[T](data: List[Entity[T]], links: Map[String, String], meta: Meta) derives Schema
+
+  case class Meta(totalRecords: Option[Long], totalPages: Option[Long], page: Page) derives Schema
+  case class Page(number: Int, size: Int) derives Schema
+
+  case class Entity[T](
+    `type`: String,
+    id: UUID,
+    attributes: T,
+    relationships: Option[Relationships] = None,
+    links: Map[String, String])
       derives Schema
 
-  case class Many[T](
-    data: List[Entity[T]],
-    links: Links,
-    meta: Meta)
-      derives Schema
-
-  case class Links(
-    self: String,
-    first: Option[String] = None,
-    prev: Option[String] = None,
-    next: Option[String] = None,
-    last: Option[String] = None)
-      derives Schema
-
-  case class Meta(totalRecords: Option[Long], totalPages: Option[Long]) derives Schema
-
-  case class Entity[T](id: UUID, `type`: String, attributes: T) derives Schema
+  case class Relationships(_entity: RelationshipsEntity) derives Schema
+  object Relationships:
+    def apply(id: UUID, `type`: String, entityUrl: String): Relationships = Relationships(
+      RelationshipsEntity(RelationshipsData(id, `type`), RelationshipsLinks(entityUrl))
+    )
+  case class RelationshipsEntity(data: RelationshipsData, links: RelationshipsLinks) derives Schema
+  case class RelationshipsData(id: UUID, `type`: String) derives Schema
+  case class RelationshipsLinks(related: String) derives Schema
 
   @discriminatorName("errorType")
   enum Error(title: String) derives Schema:
@@ -46,16 +50,47 @@ object JsonApiResponse:
     given Schema[Error.InternalServerError] = DeriveSchema.gen
 end JsonApiResponse
 
-trait JsonApiController:
+final case class ProxyHeaders(
+  protocol: Option[String],
+  host: Option[String],
+  prefix: Option[String])
+    derives Schema:
+  def rootUrl =
+    (for
+      proto  <- protocol
+      host   <- host
+      prefix <- prefix
+    yield s"$proto://$host$prefix")
+      .getOrElse("")
 
+trait JsonApiController:
   def onthology: String
+  def entityName: String
+  def allEntities: List[String]
+
+  val proxyHeadersAspect = HandlerAspect.interceptIncomingHandler(
+    Handler.fromFunction[Request](request =>
+      (
+        request,
+        ProxyHeaders(
+          protocol = request.headers.get("X-Forwarded-Proto"),
+          host = request.headers.get("X-Forwarded-Host"),
+          prefix = request.headers.get("X-Forwarded-Prefix")
+        )
+      )
+    )
+  )
 
   extension [PathInput, Input, Auth <: AuthType](
     endpoint: Endpoint[PathInput, Input, ZNothing, ZNothing, AuthType.None]
   )
-    def jsonApiOne[Output: Schema] =
+    inline def jsonApiOne[Output: Schema]
+      : Endpoint[PathInput, Input, JsonApiResponse.Error, One[Output], AuthType.None.type] =
+      jsonApiOneWithStatus(Status.Ok)
+
+    def jsonApiOneWithStatus[Output: Schema](status: Status) =
       endpoint
-        .out[JsonApiResponse.One[Output]]
+        .out[JsonApiResponse.One[Output]](status)
         .outErrors[JsonApiResponse.Error](
           HttpCodec.error[JsonApiResponse.Error.NotFound](Status.NotFound),
           HttpCodec.error[JsonApiResponse.Error.InternalServerError](Status.InternalServerError)
@@ -71,21 +106,31 @@ trait JsonApiController:
     def implementJsonApiOne[Env, A](
       f: Input => RIO[Env, Option[A]],
       getId: A => UUID,
-      getEntity: A => Output
+      getEntity: A => Output,
+      onthology: String = this.onthology,
+      links: (A, ProxyHeaders) => Map[String, String] = (_: A, _: ProxyHeaders) => Map.empty,
+      relationships: (A, ProxyHeaders) => Option[JsonApiResponse.Relationships] = (
+        _: A,
+        _: ProxyHeaders
+      ) => None
     )(implicit trace: Trace
-    ): Route[Env, Nothing] =
+    ): Route[Env & ProxyHeaders, Nothing] =
       endpoint.implement(input =>
-        f(input)
+        for
+          item <- f(input)
                     .mapError(e => JsonApiResponse.Error.InternalServerError(e.getMessage))
-          .someOrFail(JsonApiResponse.Error.NotFound(input.toString))
-          .map(item =>
-            JsonApiResponse.One(
+                    .flatMap {
+                      case Some(paged) => ZIO.succeed(paged)
+                      case None        => ZIO.fail(JsonApiResponse.Error.NotFound(input.toString))
+                    }
+          headers <- ZIO.service[ProxyHeaders]
+        yield JsonApiResponse.One(
           JsonApiResponse.Entity(
             id = getId(item),
             `type` = onthology,
-                attributes = getEntity(item)
-              ),
-              JsonApiResponse.Links("https://api.example.org") // TODO
+            attributes = getEntity(item),
+            relationships = relationships(item, headers),
+            links = links(item, headers)
           )
         )
       )
@@ -93,14 +138,38 @@ trait JsonApiController:
     def implementJsonApiOneEntity[Env](
       f: Input => RIO[Env, Option[Entity[Output]]]
     )(implicit trace: Trace
-    ): Route[Env, Nothing] =
-      implementJsonApiOne(f, _.entityId, _.data)
+    ): Route[Env & ProxyHeaders, Nothing] =
+      implementJsonApiOne(
+        f,
+        _.entityId,
+        _.data,
+        links = (e, headers) =>
+          Map(
+            "self"   -> s"${headers.rootUrl}/$entityName/${e.entityId}",
+            "events" -> s"${headers.rootUrl}/$entityName/${e.entityId}/events"
+          )
+      )
 
     def implementJsonApiOneEvent[Env](
       f: Input => RIO[Env, Option[Event[Output]]]
     )(implicit trace: Trace
-    ): Route[Env, Nothing] =
-      implementJsonApiOne(f, _.eventId, _.data)
+    ): Route[Env & ProxyHeaders, Nothing] =
+      implementJsonApiOne(
+        f,
+        _.eventId,
+        _.data,
+        onthology + ":event",
+        links = (e, headers) =>
+          Map("self" -> s"${headers.rootUrl}/$entityName/${e.entityId}/events/${e.eventId}"),
+        relationships = (e, headers) =>
+          Some(
+            JsonApiResponse.Relationships(
+              e.entityId,
+              onthology,
+              s"${headers.rootUrl}/$entityName/${e.entityId}"
+            )
+          )
+      )
   end extension
 
   extension [PathInput, Input, Output, Auth <: AuthType](
@@ -109,33 +178,60 @@ trait JsonApiController:
     def implementJsonApiMany[Env, A](
       f: Input => RIO[Env, Paged[A]],
       getId: A => UUID,
-      getEntity: A => Output
+      getEntity: A => Output,
+      links: (A, ProxyHeaders) => Map[String, String] = (_: A, _: ProxyHeaders) => Map.empty
     )(implicit trace: Trace
-    ): Route[Env, Nothing] =
-      endpoint.implement(
-        f(_)
-          .map(paged =>
-            JsonApiResponse.Many(
+    ): Route[Env & ProxyHeaders, Nothing] =
+      endpoint.implement(input =>
+        (for
+          paged   <- f(input)
+          headers <- ZIO.service[ProxyHeaders]
+        yield JsonApiResponse.Many(
           paged.items.map(item =>
-                JsonApiResponse.Entity(id = getId(item), `type` = onthology, getEntity(item))
+            JsonApiResponse.Entity(
+              id = getId(item),
+              `type` = onthology,
+              attributes = getEntity(item),
+              links = links(item, headers)
+            )
           ),
-              JsonApiResponse.Links("https://api.example.org"),
-              meta = JsonApiResponse.Meta(paged.totals, None) // TODO
+          links = Map( // TODO compute proper pagination
+            "self"  -> s"${headers.rootUrl}/$entityName",
+            "prev"  -> s"${headers.rootUrl}/$entityName?page[number]=0&page[size]=10",
+            "first" -> s"${headers.rootUrl}/$entityName?page[number]=0&page[size]=10",
+            "next"  -> s"${headers.rootUrl}/$entityName?page[number]=0&page[size]=10",
+            "last"  -> s"${headers.rootUrl}/$entityName?page[number]=0&page[size]=10"
           )
+            ++ allEntities.map(e => e -> s"${headers.rootUrl}/$e"),
+          meta = JsonApiResponse
+            .Meta(
+              totalRecords = paged.totals,
+              totalPages = Some(1),
+              page = JsonApiResponse.Page(number = 0, size = 10)
             )
+        ))
           .mapError(e => JsonApiResponse.Error.InternalServerError(e.getMessage))
       )
 
     inline def implementJsonApiManyEntity[Env](
       f: Input => RIO[Env, Paged[Entity[Output]]]
     )(implicit trace: Trace
-    ): Route[Env, Nothing] =
-      implementJsonApiMany(f, _.entityId, _.data)
+    ): Route[Env & ProxyHeaders, Nothing] =
+      implementJsonApiMany(
+        f,
+        _.entityId,
+        _.data,
+        links = (e, headers) =>
+          Map(
+            "self"   -> s"${headers.rootUrl}/$entityName/${e.entityId}",
+            "events" -> s"${headers.rootUrl}/$entityName/${e.entityId}/events"
+          )
+      )
 
     inline def implementJsonApiManyEvent[Env](
       f: Input => RIO[Env, Paged[Event[Output]]]
     )(implicit trace: Trace
-    ): Route[Env, Nothing] =
+    ): Route[Env & ProxyHeaders, Nothing] =
       implementJsonApiMany(f, _.eventId, _.data)
 
   end extension

api/src/lu/foyer/clients/ClientController.scala

@@ -13,12 +13,11 @@ import java.net.URI
 import java.time.LocalDate
 import java.util.UUID
 
-class ClientController(
-  override val commandEngine: CommandEngine[ClientCommand, ClientEvent, ClientState])
-    extends CommandEngineController[ClientCommand, ClientEvent, ClientState](
-      "api:example:insurance",
-      "client"
-    )
+class ClientController(val commandEngine: CommandEngine[ClientCommand, ClientEvent, ClientState])
+    extends CommandEngineController[ClientCommand, ClientEvent, ClientState]:
+  override val onthology   = "org:example:insurance:client"
+  override val entityName  = "clients"
+  override val allEntities = List("clients", "contracts")
 
 object ClientController:
   val layer = ZLayer.fromFunction(ClientController.apply)

api/src/lu/foyer/contracts/ContractController.scala

@@ -0,0 +1,24 @@
+package lu.foyer
+package contracts
+
+import zio.*
+import zio.Console.*
+import zio.http.*
+import zio.http.codec.*
+import zio.http.codec.PathCodec.path
+import zio.http.endpoint.*
+import zio.schema.*
+
+import java.net.URI
+import java.time.LocalDate
+import java.util.UUID
+
+class ContractController(
+  val commandEngine: CommandEngine[ContractCommand, ContractEvent, ContractState])
+    extends CommandEngineController[ContractCommand, ContractEvent, ContractState]:
+  override val onthology   = "org:example:insurance:contract"
+  override val entityName  = "contracts"
+  override val allEntities = List("clients", "contracts")
+
+object ContractController:
+  val layer = ZLayer.fromFunction(ContractController.apply)

api/src/lu/foyer/contracts/ContractEventRepositoryInMemory.scala

@@ -0,0 +1,23 @@
+package lu.foyer
+package contracts
+
+import java.util.UUID
+import zio.*
+
+class ContractEventRepositoryInMemory(events: Ref[Map[UUID, Event[ContractEvent]]])
+    extends EventRepository[ContractEvent]
+    with InMemoryRepository[Event[ContractEvent]](events):
+  def fetchOne(entityId: UUID, eventId: UUID): Task[Option[Event[ContractEvent]]] =
+    events.get.map(_.get(eventId))
+  def fetchMany(entityId: UUID, page: Page): Task[Paged[Event[ContractEvent]]] =
+    events.get
+      .map(entities =>
+        val items = entities.values
+          .filter(_.entityId == entityId)
+          .drop(page.number.getOrElse(0) * page.size.getOrElse(50))
+          .take(page.size.getOrElse(50))
+        Paged(items.toList, if page.totals.getOrElse(false) then Some(entities.size) else None)
+      )
+
+object ContractEventRepositoryInMemory:
+  val layer = ZLayer.fromZIO(Ref.make(Map.empty).map(ContractEventRepositoryInMemory(_)))

api/src/lu/foyer/contracts/ContractStateRepositoryInMemory.scala

@@ -0,0 +1,12 @@
+package lu.foyer
+package contracts
+
+import java.util.UUID
+import zio.*
+
+class ContractStateRepositoryInMemory(clients: Ref[Map[UUID, Entity[ContractState]]])
+    extends StateRepository[ContractState]
+    with InMemoryRepository[Entity[ContractState]](clients)
+
+object ContractStateRepositoryInMemory:
+  val layer = ZLayer.fromZIO(Ref.make(Map.empty).map(ContractStateRepositoryInMemory(_)))

api/src/lu/foyer/contracts/EmployeeServiceImpl.scala

@@ -0,0 +1,24 @@
+package lu.foyer
+package contracts
+
+import java.util.UUID
+import zio.*
+import lu.foyer.clients.Address
+import scala.math.BigDecimal.RoundingMode
+import java.util.Currency
+import lu.foyer.clients.Country
+
+object EmployeeServiceImpl extends EmployeeService:
+
+  def fetchOne(subject: String): Either[String, Employee] =
+    if subject == "usr:top" then
+      Right(
+        Employee(
+          subject,
+          EmployeeDisplayName.assume("MEIER Christoph"),
+          Email.assume("top@foyer.lu")
+        )
+      )
+    else Left("Invalid Employee")
+
+  val layer = ZLayer.succeed(EmployeeServiceImpl)

api/src/lu/foyer/contracts/PremiumServiceImpl.scala

@@ -0,0 +1,53 @@
+package lu.foyer
+package contracts
+
+import java.util.UUID
+import zio.*
+import lu.foyer.clients.Address
+import scala.math.BigDecimal.RoundingMode
+import java.util.Currency
+import lu.foyer.clients.Country
+
+object PremiumServiceImpl extends PremiumService:
+  private val EUR = Currency.getInstance("EUR")
+
+  private val brands =
+    Map(
+      "renault"    -> BigDecimal(0.5),
+      "fiat"       -> BigDecimal(0.6),
+      "ford"       -> BigDecimal(0.7),
+      "nissan"     -> BigDecimal(0.75),
+      "peugeot"    -> BigDecimal(0.8),
+      "volkswagen" -> BigDecimal(1.1),
+      "audi"       -> BigDecimal(1.25),
+      "bmw"        -> BigDecimal(1.25),
+      "mercedes"   -> BigDecimal(1.25),
+      "ferrari"    -> BigDecimal(2.3),
+      "bugatti"    -> BigDecimal(2.6),
+      "tesla"      -> BigDecimal(5.0)
+    )
+
+  private val countries =
+    Map(Country.CH -> BigDecimal(0.8), Country.LU -> BigDecimal(1.2))
+
+  private def computeAmountEUR(base: BigDecimal, brand: VehicleBrand, country: Country)
+    : BigDecimal =
+    val brandMultiplier   = brands.getOrElse(brand.toLowerCase, BigDecimal(1))
+    val countryMultiplier = countries.getOrElse(country, BigDecimal(1))
+    val amount            = base * brandMultiplier * countryMultiplier
+    amount.setScale(EUR.getDefaultFractionDigits, RoundingMode.HALF_UP).rounded
+
+  override def computePremium(formula: FormulaType, vehicle: Vehicle, residentialAddress: Address)
+    : Either[String, Amount] =
+    if vehicle.insuredValue.value > formula.maxCoverage then
+      Left(s"The $formula formula only covers amounts up to ${formula.maxCoverage} EUR")
+    else
+      Right(
+        Amount(
+          computeAmountEUR(formula.basePremium, vehicle.brand, residentialAddress.country),
+          EUR
+        )
+      )
+
+  val layer = ZLayer.succeed(PremiumServiceImpl)
+end PremiumServiceImpl

build.sc

@@ -11,7 +11,7 @@ object Versions {
   val zio        = "2.1.15"
   val zioJson    = "0.7.33"
   val zioSchema  = "1.6.3"
-  val zioHttp    = "3.0.1+97-29d12531-SNAPSHOT"
+  val zioHttp    = "3.1.0"
   val zioPrelude = "1.0.0-RC39"
 }
 
@@ -19,6 +19,8 @@ trait CommonModule extends ScalaModule {
   def scalaVersion = "3.6.3"
   def ivyDeps = Agg(
     ivy"dev.zio::zio:${Versions.zio}",
+    ivy"dev.zio::zio-json:${Versions.zioJson}",
+    ivy"dev.zio::zio-schema-json:${Versions.zioSchema}",
     ivy"dev.zio::zio-schema:${Versions.zioSchema}",
     ivy"dev.zio::zio-schema-derivation:${Versions.zioSchema}",
     ivy"dev.zio::zio-prelude:${Versions.zioPrelude}"
@@ -38,8 +40,6 @@ object api extends CommonModule {
   def moduleDeps = Seq(core)
   def ivyDeps = Agg(
     ivy"dev.zio::zio:${Versions.zio}",
-    ivy"dev.zio::zio-http:${Versions.zioHttp}",
-    ivy"dev.zio::zio-json:${Versions.zioJson}",
-    ivy"dev.zio::zio-schema-json:${Versions.zioSchema}"
+    ivy"dev.zio::zio-http:${Versions.zioHttp}"
   )
 }

core/src/lu/foyer/EventSourcing.scala

@@ -1,9 +1,10 @@
 package lu.foyer
 
 import zio.*
-import java.util.UUID
 import zio.schema.Schema
 
+import java.util.UUID
+
 final case class Entity[T](entityId: UUID, data: T, version: Long)
 final case class Event[T](entityId: UUID, data: T, eventId: UUID)
 

core/src/lu/foyer/Repository.scala

@@ -2,9 +2,17 @@ package lu.foyer
 
 import zio.*
 import zio.schema.*
+import zio.schema.annotation.fieldName
+
 import java.util.UUID
 
-final case class Page(number: Option[Int], size: Option[Int], totals: Option[Boolean])
+final case class Page(
+  @fieldName("page[number]")
+  number: Option[Int],
+  @fieldName("page[size]")
+  size: Option[Int],
+  @fieldName("page[totals]")
+  totals: Option[Boolean])
     derives Schema
 final case class Paged[T](items: List[T], totals: Option[Long])
 

core/src/lu/foyer/clients/ClientEvent.scala

@@ -2,13 +2,17 @@ package lu.foyer
 package clients
 
 import zio.schema.*
-
-import java.time.LocalDate
+import zio.schema.annotation.caseName
 import zio.schema.annotation.discriminatorName
 
+import java.time.LocalDate
+
 @discriminatorName("eventType")
-enum ClientEvent derives Schema:
-  case Created(
+sealed trait ClientEvent derives Schema
+object ClientEvent:
+
+  @caseName("created")
+  final case class Created(
     lastName: ClientLastName,
     firstName: ClientFirstName,
     birthDate: ClientBirthDate,
@@ -16,7 +20,10 @@ enum ClientEvent derives Schema:
     phoneNumber: Option[PhoneNumberInput],
     email: Option[Email],
     address: Option[Address])
-  case Updated(
+      extends ClientEvent derives Schema
+
+  @caseName("updated")
+  final case class Updated(
     lastName: Option[ClientLastName],
     firstName: Option[ClientFirstName],
     birthDate: Option[ClientBirthDate],
@@ -24,9 +31,7 @@ enum ClientEvent derives Schema:
     phoneNumber: Option[PhoneNumberInput],
     email: Option[Email],
     address: Option[Address])
-  case Disabled(reason: ClientDisabledReason)
+      extends ClientEvent derives Schema
 
-object ClientEvent:
-  given Schema[ClientEvent.Created]  = DeriveSchema.gen
-  given Schema[ClientEvent.Updated]  = DeriveSchema.gen
-  given Schema[ClientEvent.Disabled] = DeriveSchema.gen
+  @caseName("disabled")
+  final case class Disabled(reason: ClientDisabledReason) extends ClientEvent derives Schema

core/src/lu/foyer/clients/ClientState.scala

@@ -2,30 +2,59 @@ package lu.foyer
 package clients
 
 import zio.schema.*
+import zio.schema.annotation.caseName
 import zio.schema.annotation.discriminatorName
 
 import java.time.LocalDate
 
 @discriminatorName("statusType")
-enum ClientState derives Schema:
-  case Actif(
-    lastName: ClientLastName,
-    firstName: ClientFirstName,
-    birthDate: ClientBirthDate,
-    drivingLicenseDate: Option[ClientDrivingLicenseDate],
-    phoneNumber: Option[PhoneNumberInput],
-    email: Option[Email],
-    address: Option[Address])
-  case Inactif(
-    lastName: ClientLastName,
-    firstName: ClientFirstName,
-    birthDate: ClientBirthDate,
-    drivingLicenseDate: Option[ClientDrivingLicenseDate],
-    phoneNumber: Option[PhoneNumberInput],
-    email: Option[Email],
-    address: Option[Address])
-
+sealed trait ClientState derives Schema
 object ClientState:
+
+  @caseName("actif")
+  final case class Actif(
+    lastName: ClientLastName,
+    firstName: ClientFirstName,
+    birthDate: ClientBirthDate,
+    drivingLicenseDate: Option[ClientDrivingLicenseDate],
+    phoneNumber: Option[PhoneNumberInput],
+    email: Option[Email],
+    address: Option[Address])
+      extends ClientState derives Schema:
+
+    def update(e: ClientEvent.Updated) =
+      ClientState.Actif(
+        e.lastName.getOrElse(lastName),
+        e.firstName.getOrElse(firstName),
+        e.birthDate.getOrElse(birthDate),
+        e.drivingLicenseDate.orElse(drivingLicenseDate),
+        e.phoneNumber.orElse(phoneNumber),
+        e.email.orElse(email),
+        e.address.orElse(address)
+      )
+    def disable(e: ClientEvent.Disabled) =
+      ClientState.Inactif(
+        lastName,
+        firstName,
+        birthDate,
+        drivingLicenseDate,
+        phoneNumber,
+        email,
+        address
+      )
+  end Actif
+
+  @caseName("inactif")
+  final case class Inactif(
+    lastName: ClientLastName,
+    firstName: ClientFirstName,
+    birthDate: ClientBirthDate,
+    drivingLicenseDate: Option[ClientDrivingLicenseDate],
+    phoneNumber: Option[PhoneNumberInput],
+    email: Option[Email],
+    address: Option[Address])
+      extends ClientState derives Schema
+
   def create(event: ClientEvent.Created) =
     ClientState.Actif(
       event.lastName,
@@ -36,25 +65,4 @@ object ClientState:
       event.email,
       event.address
     )
-
-extension (s: ClientState.Actif)
-  def update(e: ClientEvent.Updated) =
-    ClientState.Actif(
-      e.lastName.getOrElse(s.lastName),
-      e.firstName.getOrElse(s.firstName),
-      e.birthDate.getOrElse(s.birthDate),
-      e.drivingLicenseDate.orElse(s.drivingLicenseDate),
-      e.phoneNumber.orElse(s.phoneNumber),
-      e.email.orElse(s.email),
-      e.address.orElse(s.address)
-    )
-  def disable(e: ClientEvent.Disabled) =
-    ClientState.Inactif(
-      s.lastName,
-      s.firstName,
-      s.birthDate,
-      s.drivingLicenseDate,
-      s.phoneNumber,
-      s.email,
-      s.address
-    )
+end ClientState

core/src/lu/foyer/contracts/ContractCommand.scala

@@ -0,0 +1,28 @@
+package lu.foyer
+package contracts
+
+import zio.schema.*
+
+import java.time.LocalDate
+import java.util.UUID
+
+enum ContractCommand derives Schema:
+  case Subscribe(
+    product: ProductType,
+    holder: ClientEntityId,
+    vehicle: Vehicle,
+    formula: FormulaType)
+  case Amend(
+    product: Option[ProductType],
+    vehicle: Option[Vehicle],
+    formula: Option[FormulaType])
+  case Approve()
+  case Reject(comment: String)
+  case Terminate(reason: TerminationReasonType)
+
+object ContractCommand:
+  given Schema[ContractCommand.Subscribe] = DeriveSchema.gen
+  given Schema[ContractCommand.Amend]     = DeriveSchema.gen
+  given Schema[ContractCommand.Approve]   = DeriveSchema.gen
+  given Schema[ContractCommand.Reject]    = DeriveSchema.gen
+  given Schema[ContractCommand.Terminate] = DeriveSchema.gen

core/src/lu/foyer/contracts/ContractEvent.scala

@@ -0,0 +1,39 @@
+package lu.foyer
+package contracts
+
+import zio.schema.*
+import zio.schema.annotation.caseName
+import zio.schema.annotation.discriminatorName
+
+import java.time.LocalDate
+
+@discriminatorName("eventType")
+sealed trait ContractEvent derives Schema
+object ContractEvent:
+
+  @caseName("created")
+  final case class Subscribed(
+    product: ProductType,
+    holder: ClientEntityId,
+    vehicle: Vehicle,
+    formula: FormulaType,
+    premium: Amount)
+      extends ContractEvent derives Schema
+
+  @caseName("amended")
+  final case class Amended(
+    product: ProductType,
+    vehicle: Vehicle,
+    formula: FormulaType,
+    premium: Amount)
+      extends ContractEvent derives Schema
+
+  @caseName("approved")
+  final case class Approved(approvedBy: Employee) extends ContractEvent derives Schema
+
+  @caseName("rejected")
+  final case class Rejected(rejectedBy: Employee, comment: String) extends ContractEvent
+      derives Schema
+
+  @caseName("terminated")
+  final case class Terminated(reason: TerminationReasonType) extends ContractEvent derives Schema

core/src/lu/foyer/contracts/ContractHandlers.scala

@@ -0,0 +1,137 @@
+package lu.foyer
+package contracts
+
+import lu.foyer.clients.*
+import zio.*
+import java.util.UUID
+
+object ContractHandlers:
+  val layer =
+    ZLayer.fromFunction(
+      (
+        clientStateRepo: StateRepository[ClientState],
+        premiumService: PremiumService,
+        employeeService: EmployeeService
+      ) =>
+        List(
+          SubscribeHandler(clientStateRepo, premiumService),
+          AmendHandler(clientStateRepo, premiumService),
+          ApproveHandler(employeeService),
+          RejectHandler(employeeService),
+          TerminateHandler()
+        )
+    )
+
+class SubscribeHandler(
+  clientStateRepo: StateRepository[ClientState],
+  premiumService: PremiumService)
+    extends CommandHandlerCreate[ContractCommand.Subscribe, ContractEvent.Subscribed]:
+
+  val name = "create"
+
+  def onCommand(entityId: UUID, command: ContractCommand.Subscribe)
+    : Task[ContractEvent.Subscribed] =
+    for
+      holder <- clientStateRepo.fetchOne(command.holder).someOrFailException
+      residentialAddress <-
+        holder.data match
+          case ClientState.Actif(_, _, _, _, _, _, Some(address)) =>
+            ZIO.succeed(address)
+          case _ =>
+            ZIO.fail(new IllegalArgumentException(s"No active holder found for ${command.holder}"))
+      premium = premiumService.computePremium(command.formula, command.vehicle, residentialAddress)
+      premium <-
+        ZIO
+          .fromEither(
+            premiumService.computePremium(command.formula, command.vehicle, residentialAddress)
+          )
+          .mapError(new IllegalArgumentException(_))
+    yield ContractEvent.Subscribed(
+      command.product,
+      command.holder,
+      command.vehicle,
+      command.formula,
+      premium
+    )
+end SubscribeHandler
+
+class AmendHandler(clientStateRepo: StateRepository[ClientState], premiumService: PremiumService)
+    extends CommandHandlerUpdate[ContractCommand.Amend, ContractEvent.Amended, ContractState]:
+
+  val name = "amend"
+
+  def onCommand(entityId: UUID, state: ContractState, command: ContractCommand.Amend)
+    : Task[ContractEvent.Amended] =
+    for
+      holder <- clientStateRepo.fetchOne(state.holder).someOrFailException
+      residentialAddress <-
+        holder.data match
+          case ClientState.Actif(_, _, _, _, _, _, Some(address)) =>
+            ZIO.succeed(address)
+          case _ =>
+            ZIO.fail(new IllegalArgumentException(s"No active holder found for ${state.holder}"))
+      premium <- ZIO
+                   .fromEither(
+                     premiumService.computePremium(
+                       command.formula.getOrElse(state.formula),
+                       command.vehicle.getOrElse(state.vehicle),
+                       residentialAddress
+                     )
+                   )
+                   .mapError(new IllegalArgumentException(_))
+    yield ContractEvent.Amended(
+      command.product.getOrElse(state.product),
+      command.vehicle.getOrElse(state.vehicle),
+      command.formula.getOrElse(state.formula),
+      premium
+    )
+end AmendHandler
+
+class ApproveHandler(employeeService: EmployeeService)
+    extends CommandHandlerUpdate[
+      ContractCommand.Approve,
+      ContractEvent.Approved,
+      ContractState.Pending
+    ]:
+
+  val name = "approve"
+
+  def onCommand(entityId: UUID, state: ContractState.Pending, command: ContractCommand.Approve)
+    : Task[ContractEvent.Approved] =
+    for
+      user <- ZIO.succeed("") // TODO current user
+      employee <- ZIO
+                    .fromEither(employeeService.fetchOne(user))
+                    .mapError(new IllegalArgumentException(_))
+    yield ContractEvent.Approved(employee)
+
+class RejectHandler(employeeService: EmployeeService)
+    extends CommandHandlerUpdate[
+      ContractCommand.Reject,
+      ContractEvent.Rejected,
+      ContractState.Pending
+    ]:
+
+  val name = "reject"
+
+  def onCommand(entityId: UUID, state: ContractState.Pending, command: ContractCommand.Reject)
+    : Task[ContractEvent.Rejected] =
+    for
+      user <- ZIO.succeed("") // TODO current user
+      employee <- ZIO
+                    .fromEither(employeeService.fetchOne(user))
+                    .mapError(new IllegalArgumentException(_))
+    yield ContractEvent.Rejected(employee, command.comment)
+
+class TerminateHandler()
+    extends CommandHandlerUpdate[
+      ContractCommand.Terminate,
+      ContractEvent.Terminated,
+      ContractState
+    ]:
+
+  val name = "reject"
+
+  def onCommand(entityId: UUID, state: ContractState, command: ContractCommand.Terminate)
+    : Task[ContractEvent.Terminated] =
+    ZIO.succeed(ContractEvent.Terminated(command.reason))

core/src/lu/foyer/contracts/ContractReducer.scala

@@ -0,0 +1,26 @@
+package lu.foyer
+package contracts
+
+import zio.*
+
+class ContractReducer() extends Reducer[ContractEvent, ContractState]:
+
+  override val fromEmpty =
+    case e: ContractEvent.Subscribed => ContractState.subscribe(e)
+
+  override val fromState =
+    case (s: ContractState.Actif, e: ContractEvent.Amended)    => s.amend(e)
+    case (s: ContractState.Actif, e: ContractEvent.Terminated) => s.terminate(e)
+
+    case (s: ContractState.PendingSubscription, e: ContractEvent.Amended)    => s.amend(e)
+    case (s: ContractState.PendingSubscription, e: ContractEvent.Approved)   => s.approve(e)
+    case (s: ContractState.PendingSubscription, e: ContractEvent.Rejected)   => s.reject(e)
+    case (s: ContractState.PendingSubscription, e: ContractEvent.Terminated) => s.terminate(e)
+
+    case (s: ContractState.PendingAmendment, e: ContractEvent.Amended)    => s.amend(e)
+    case (s: ContractState.PendingAmendment, e: ContractEvent.Approved)   => s.approve(e)
+    case (s: ContractState.PendingAmendment, e: ContractEvent.Rejected)   => s.reject(e)
+    case (s: ContractState.PendingAmendment, e: ContractEvent.Terminated) => s.terminate(e)
+
+object ContractReducer:
+  val layer: ULayer[Reducer[ContractEvent, ContractState]] = ZLayer.succeed(ContractReducer())

core/src/lu/foyer/contracts/ContractState.scala

@@ -0,0 +1,106 @@
+package lu.foyer
+package contracts
+
+import zio.schema.*
+import zio.schema.annotation.caseName
+import zio.schema.annotation.discriminatorName
+
+import java.time.LocalDate
+
+@discriminatorName("statusType")
+sealed trait ContractState derives Schema:
+  def product: ProductType
+  def holder: ClientEntityId
+  def vehicle: Vehicle
+  def formula: FormulaType
+  def premium: Amount
+
+object ContractState:
+
+  def subscribe(e: ContractEvent.Subscribed) =
+    PendingSubscription(e.product, e.holder, e.vehicle, e.formula, e.premium)
+
+  @caseName("actif")
+  final case class Actif(
+    product: ProductType,
+    holder: ClientEntityId,
+    vehicle: Vehicle,
+    formula: FormulaType,
+    premium: Amount)
+      extends ContractState derives Schema:
+
+    def amend(e: ContractEvent.Amended) =
+      Actif(e.product, holder, e.vehicle, e.formula, e.premium)
+
+    def terminate(e: ContractEvent.Terminated) =
+      Terminated(product, holder, vehicle, formula, premium)
+
+  @discriminatorName("statusType")
+  sealed trait Pending extends ContractState
+
+  @caseName("pending-subscription")
+  final case class PendingSubscription(
+    product: ProductType,
+    holder: ClientEntityId,
+    vehicle: Vehicle,
+    formula: FormulaType,
+    premium: Amount)
+      extends Pending derives Schema:
+
+    def amend(e: ContractEvent.Amended) =
+      PendingSubscription(e.product, holder, e.vehicle, e.formula, e.premium)
+
+    def approve(e: ContractEvent.Approved) =
+      Actif(product, holder, vehicle, formula, premium)
+
+    def reject(e: ContractEvent.Rejected) =
+      Terminated(product, holder, vehicle, formula, premium)
+
+    def terminate(e: ContractEvent.Terminated) =
+      Terminated(product, holder, vehicle, formula, premium)
+
+  final case class PendingChanges(
+    product: ProductType,
+    vehicle: Vehicle,
+    formula: FormulaType,
+    premium: Amount)
+      derives Schema
+
+  @caseName("pending-amendment")
+  final case class PendingAmendment(
+    product: ProductType,
+    holder: ClientEntityId,
+    vehicle: Vehicle,
+    formula: FormulaType,
+    premium: Amount,
+    pendingChanges: PendingChanges)
+      extends Pending derives Schema:
+
+    def amend(e: ContractEvent.Amended) =
+      copy(pendingChanges = PendingChanges(e.product, e.vehicle, e.formula, e.premium))
+
+    def approve(e: ContractEvent.Approved) =
+      Actif(
+        pendingChanges.product,
+        holder,
+        pendingChanges.vehicle,
+        pendingChanges.formula,
+        pendingChanges.premium
+      )
+
+    def reject(e: ContractEvent.Rejected) =
+      Actif(product, holder, vehicle, formula, premium)
+
+    def terminate(e: ContractEvent.Terminated) =
+      ContractState.Terminated(product, holder, vehicle, formula, premium)
+
+  @caseName("terminated")
+  final case class Terminated(
+    product: ProductType,
+    holder: ClientEntityId,
+    vehicle: Vehicle,
+    formula: FormulaType,
+    premium: Amount)
+      extends ContractState derives Schema
+
+end ContractState

core/src/lu/foyer/contracts/EmployeeService.scala

@@ -0,0 +1,7 @@
+package lu.foyer
+package contracts
+
+import lu.foyer.clients.Address
+
+trait EmployeeService:
+  def fetchOne(subject: String): Either[String, Employee]

core/src/lu/foyer/contracts/PremiumService.scala

@@ -0,0 +1,8 @@
+package lu.foyer
+package contracts
+
+import lu.foyer.clients.Address
+
+trait PremiumService:
+  def computePremium(formula: FormulaType, vehicle: Vehicle, residentialAddress: Address)
+    : Either[String, Amount]

flake.lock

@@ -39,11 +39,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1740460834,
-        "narHash": "sha256-RUL1r8zH5wG5L1YipNj1bmt0Oi8L9qwzXsf/ww8WxBc=",
+        "lastModified": 1742480343,
+        "narHash": "sha256-AN6X0t0pX0GLDh6CMG474aNffJUKPQtSEJ9aCZed474=",
         "owner": "cachix",
         "repo": "devenv",
-        "rev": "9e4003b2702483bd962dac3d4ff43e8dafb93cda",
+        "rev": "56fe80518d1c949520a2cea8e9c2a83ec3f9bdc5",
         "type": "github"
       },
       "original": {
@@ -102,11 +102,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1737465171,
-        "narHash": "sha256-R10v2hoJRLq8jcL4syVFag7nIGE7m13qO48wRIukWNg=",
+        "lastModified": 1740849354,
+        "narHash": "sha256-oy33+t09FraucSZ2rZ6qnD1Y1c8azKKmQuCvF2ytUko=",
         "owner": "cachix",
         "repo": "git-hooks.nix",
-        "rev": "9364dc02281ce2d37a1f55b6e51f7c0f65a75f17",
+        "rev": "4a709a8ce9f8c08fa7ddb86761fe488ff7858a07",
         "type": "github"
       },
       "original": {
@@ -172,11 +172,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1734114420,
-        "narHash": "sha256-n52PUzub5jZWc8nI/sR7UICOheU8rNA+YZ73YaHeCBg=",
+        "lastModified": 1741798497,
+        "narHash": "sha256-E3j+3MoY8Y96mG1dUIiLFm2tZmNbRvSiyN7CrSKuAVg=",
         "owner": "domenkozar",
         "repo": "nix",
-        "rev": "bde6a1a0d1f2af86caa4d20d23eca019f3d57eee",
+        "rev": "f3f44b2baaf6c4c6e179de8cbb1cc6db031083cd",
         "type": "github"
       },
       "original": {

model/src/lu/foyer/AppError.scala

@@ -0,0 +1,7 @@
+package lu.foyer
+
+import zio.schema.*
+
+enum AppError(description: String) extends Throwable:
+  case NotFound(desc: String)   extends AppError(desc)
+  case Unexpected(desc: String) extends AppError(desc)

model/src/lu/foyer/CommonTypes.scala

@@ -0,0 +1,10 @@
+package lu.foyer
+
+import zio.schema.*
+import java.util.UUID
+
+opaque type ClientEntityId <: UUID = UUID
+object ClientEntityId extends RefinedUUID[ClientEntityId]
+
+opaque type Email <: String = String
+object Email extends NonBlankString[Email]

model/src/lu/foyer/RefinedType.scala

@@ -4,6 +4,7 @@ import zio.prelude.*
 import zio.schema.Schema
 
 import java.time.LocalDate
+import java.util.UUID
 
 trait RefinedType[Base, New]:
   inline def assume(value: Base): New = value.asInstanceOf[New]
@@ -15,6 +16,15 @@ trait RefinedString[New <: String] extends RefinedType[String, New]:
     Right(_)
   )
 
+trait RefinedUUID[New <: UUID] extends RefinedType[UUID, New]:
+  def apply(value: UUID): New = assume(value)
+  override def validation(value: UUID): Validation[String, New] =
+    Validation.succeed(assume(value))
+  given Schema[New] = Schema[UUID].transformOrFail(
+    validation(_).toEither.left.map(_.toList.mkString(", ")),
+    Right(_)
+  )
+
 trait RefinedLocalDate[New <: LocalDate] extends RefinedType[LocalDate, New]:
   def apply(value: LocalDate): New = assume(value)
   override def validation(value: LocalDate): Validation[String, New] =

model/src/lu/foyer/clients/Client.scala

@@ -18,21 +18,9 @@ object ClientBirthDate extends RefinedLocalDate[ClientBirthDate]
 opaque type ClientDrivingLicenseDate <: LocalDate = LocalDate
 object ClientDrivingLicenseDate extends RefinedLocalDate[ClientDrivingLicenseDate]
 
-opaque type Email <: String = String
-object Email extends NonBlankString[Email]
-
 opaque type NationalNumber <: String = String
 object NationalNumber extends NonBlankString[NationalNumber]
 
-case class Client(
-  lastName: ClientFirstName,
-  firstName: ClientLastName,
-  drivingLicenseDate: ClientDrivingLicenseDate,
-  phoneNumber: PhoneNumber,
-  email: Email,
-  address: Address)
-    derives Schema
-
 case class PhoneNumber(
   country: Country,
   nationalNumber: NationalNumber,
@@ -45,4 +33,4 @@ case class PhoneNumberInput(
     derives Schema
 
 enum ClientDisabledReason derives Schema:
-  case GDPR, Death
+  case gdpr, death

model/src/lu/foyer/clients/Country.scala

@@ -4,4 +4,4 @@ package clients
 import zio.schema.*
 
 enum Country derives Schema:
-  case LU, FR, BE
+  case LU, FR, BE, CH

model/src/lu/foyer/contracts/Employee.scala

@@ -0,0 +1,11 @@
+package lu.foyer
+package contracts
+
+import zio.schema.*
+import java.util.Currency
+
+opaque type EmployeeDisplayName <: String = String
+object EmployeeDisplayName extends NonBlankString[EmployeeDisplayName]
+
+final case class Employee(uid: String, displayName: EmployeeDisplayName, email: Email)
+    derives Schema

model/src/lu/foyer/contracts/FormulaType.scala

@@ -0,0 +1,27 @@
+package lu.foyer
+package contracts
+
+import zio.schema.*
+
+enum FormulaType(val maxCoverage: Long, val basePremium: BigDecimal):
+  case Bronze extends FormulaType(10_000, 600)
+  case Silver extends FormulaType(25_000, 900)
+  case Gold   extends FormulaType(250_000, 1500)
+
+object FormulaType:
+  enum Json:
+    case bronze, silver, gold
+
+  given Schema[FormulaType] = DeriveSchema
+    .gen[Json].transform(
+      {
+        case Json.bronze => FormulaType.Bronze
+        case Json.silver => FormulaType.Silver
+        case Json.gold   => FormulaType.Gold
+      },
+      {
+        case FormulaType.Bronze => Json.bronze
+        case FormulaType.Silver => Json.silver
+        case FormulaType.Gold   => Json.gold
+      }
+    )

model/src/lu/foyer/contracts/ProductType.scala

@@ -0,0 +1,8 @@
+package lu.foyer
+package contracts
+
+import zio.schema.*
+import zio.schema.annotation.caseName
+
+enum ProductType derives Schema:
+  @caseName("car") case Car

model/src/lu/foyer/contracts/TerminationReasonType.scala

@@ -0,0 +1,7 @@
+package lu.foyer
+package contracts
+
+import zio.schema.*
+
+enum TerminationReasonType derives Schema:
+  case Rejected, HolderDeceased, TerminatedByClient

model/src/lu/foyer/contracts/Vehicle.scala

@@ -0,0 +1,16 @@
+package lu.foyer
+package contracts
+
+import zio.schema.*
+import java.util.Currency
+
+opaque type VehiclePlate <: String = String
+object VehiclePlate extends NonBlankString[VehiclePlate]
+
+opaque type VehicleBrand <: String = String
+object VehicleBrand extends NonBlankString[VehicleBrand]
+
+final case class Amount(value: BigDecimal, currency: Currency) derives Schema
+
+final case class Vehicle(plate: VehiclePlate, brand: VehicleBrand, insuredValue: Amount)
+    derives Schema