just arranging things.

src/main/scala/Generator.scala

@@ -0,0 +1,27 @@
+import cats.effect.*
+import cats.effect.syntax.all.*
+import cats.syntax.all.*
+import fs2.concurrent.*
+import fs2.dom.{Event => _, *}
+import io.circe.parser.*
+import calico.*
+import calico.html.io.{*, given}
+import calico.syntax.*
+import snow.*
+
+object Generator {
+  def apply(): Resource[IO, HtmlDivElement[IO]] =
+    SignallingRef[IO]
+      .of("")
+      .toResource
+      .flatMap { input =>
+        div(
+          cls := "my-3",
+          button(cls := buttonCls, "generate event"),
+          button(cls := buttonCls, "generate keypair")
+        )
+      }
+
+  val buttonCls =
+    "bg-blue-500 hover:bg-blue-700 text-white font-bold py-2 mx-2 px-4 rounded"
+}

src/main/scala/Input.scala

@@ -16,20 +16,34 @@ object Input {
       .toResource
       .flatMap { input =>
         div(
-          textArea.withSelf { self =>
-            (
-              cls := "w-2/3 min-h-fit max-h-96 p-3",
-              placeholder := "paste something nostric",
-              onInput --> (_.foreach(_ => self.value.get.flatMap(input.set))),
-              value <-- input
-            )
-          },
+          cls := "w-full",
           div(
+            cls := "w-full flex justify-center",
+            textArea.withSelf { self =>
+              (
+                cls := "w-2/3 max-h-96 p-3",
+                styleAttr := "min-height: 200px",
+                placeholder := "paste something nostric",
+                onInput --> (_.foreach(_ => self.value.get.flatMap(input.set))),
+                value <-- input
+              )
+            }
+          ),
+          div(
+            cls := "w-full flex justify-center",
             input.map(inp =>
-              decode[Event](inp) match {
-                case Left(err)    => err.toString
-                case Right(event) => event.toString
-              }
+              if inp.trim() == "" then ""
+              else
+                decode[Event](inp) match {
+                  case Right(event) => event.toString
+                  case Left(err: io.circe.DecodingFailure) =>
+                    err.pathToRootString match {
+                      case Some(path) => s"field $path is missing or wrong"
+                      case None       => s"decoding ${err.pathToRootString}"
+                    }
+                  case Left(err: io.circe.ParsingFailure) =>
+                    "not valid JSON"
+                }
             )
           )
         )

src/main/scala/Main.scala

@@ -8,6 +8,7 @@ object Main extends IOWebApp {
   def render: Resource[IO, HtmlDivElement[IO]] = div(
     cls := "flex w-full h-full flex-col items-center justify-center",
     h1(cls := "px-1 py-2 text-lg", "nostr army knife"),
-    Input()
+    Input(),
+    Generator()
   )
 }