further simplications...

build.sbt

@@ -5,10 +5,8 @@ inThisBuild(
 lazy val api = project.in(file("modules/api"))
   .settings(
     libraryDependencies ++= Seq(
-      "org.typelevel" %% "cats-core" % "2.10.0",
       "com.softwaremill.sttp.tapir" %% "tapir-core" % "1.8.5",
       "com.softwaremill.sttp.tapir" %% "tapir-iron" % "1.8.5",
       "io.github.iltotore" %% "iron" % "2.3.0",
-      "io.github.iltotore" %% "iron-cats" % "2.3.0",
     )
   )

modules/api/src/main/scala/types.scala

@@ -1,14 +1,11 @@
-import cats.Show
-import cats.syntax.all.*
 import io.github.iltotore.iron.*
 import io.github.iltotore.iron.constraint.all.*
-import sttp.tapir
 import sttp.tapir.Codec.PlainCodec
+import sttp.tapir.DecodeResult
 import sttp.tapir.codec.iron.TapirCodecIron
-import sttp.tapir.{CodecFormat, DecodeResult, Codec as TapirCodec, Schema as TapirSchema}
 
 private type VersionConstraints = DescribedAs[GreaterEqual[0], "Version must be positive"]
 opaque type Version = Int :| VersionConstraints
 
 object Version extends RefinedTypeOps[Int, VersionConstraints, Version] with TapirCodecIron:
-  given PlainCodec[Version] = summon[PlainCodec[Int]].mapDecode(s => DecodeResult.fromEitherString(s.show, either(s)))(_.value)
+  given PlainCodec[Version] = summon[PlainCodec[Int]].mapDecode(s => DecodeResult.fromEitherString(s.toString, either(s)))(_.value)