Support for akka style `Map[String, V]` path matchers

I'm currently migrating lot of endpoints from akka-http to tapir. And sometimes we used some really handy akka features in our code. My current struggle is the Map[String, V] handling;

Here are the official akka path matchers list: https://doc.akka.io/docs/akka-http/current/routing-dsl/path-matchers.html#basic-pathmatchers

My not tested but compiling code for the Maps;

  def pathFromMapWithDefault[K: PlainCodec, V](inMap: Map[K, V], default: V): EndpointInput[V] =
    EndpointInput
      .PathCapture(implicitly[PlainCodec[K]], None, EndpointIO.Info.empty)
      .map(k => inMap.getOrElse(k, default))(_ => inMap.keys.head)
  def pathFromMapWithDefault[K: PlainCodec, V](
      inMap: Map[K, V],
      default: V,
      name: String
  ): EndpointInput[V] =
    EndpointInput
      .PathCapture(implicitly[PlainCodec[K]], Some(name), EndpointIO.Info.empty)
      .map(k => inMap.getOrElse(k, default))(_ => inMap.keys.head)

  def stringMapValidator[V](inMap: Map[String, V]) = {
    Validator.Enum[String](inMap.keys.toList, Option(s => Some(s)))
  }

  def pathFromStringMap[V](inMap: Map[String, V]): EndpointInput[V] =
    EndpointInput
      .PathCapture(Codec.stringPlainCodecUtf8.validate(stringMapValidator(inMap)), None, EndpointIO.Info.empty)
      .map(inMap)(_ => inMap.keys.head)
  def pathFromStringMap[V](inMap: Map[String, V], name: String): EndpointInput[V] =
    EndpointInput
      .PathCapture(Codec.stringPlainCodecUtf8.validate(stringMapValidator(inMap)), Some(name), EndpointIO.Info.empty)
      .map(inMap)(_ => inMap.keys.head)

  def pathFromMap[K: PlainCodec, V](
      inMap: Map[K, V],
      encode: Option[Validator.EncodeToRaw[K]]
  ): EndpointInput[V] =
    EndpointInput
      .PathCapture(
        implicitly[PlainCodec[K]].validate(Validator.Enum[K](inMap.keys.toList, encode)),
        None,
        EndpointIO.Info.empty
      )
      .map(inMap)(_ => inMap.keys.head)
  def pathFromMap[K: PlainCodec, V](
      inMap: Map[K, V],
      encode: Option[Validator.EncodeToRaw[K]],
      name: String
  ): EndpointInput[V] =
    EndpointInput
      .PathCapture(
        implicitly[PlainCodec[K]].validate(Validator.Enum[K](inMap.keys.toList, encode)),
        Some(name),
        EndpointIO.Info.empty
      )
      .map(inMap)(_ => inMap.keys.head)

My main question is the .map(inMap)(_ => inMap.keys.head) line and how bad this idea is? (If we not count the Map.empty.head case.)

Also can we add this next to the official path[T]?

Start by locating the implementation of the official path[T] entry point and reviewing how EndpointInput.PathCapture, Validator.Enum, and map are used. Determine the intended Map[K, V] path-matcher semantics, including reverse mapping and empty maps, then confirm that the resulting API supports the requested Akka-style use case.