ReScript RPC like?

Which solution comes to mind to when you control the client and the server.
You want to share types between front-end and back-end.

Right now I have a Hono server and I call this from my client using fetch.
And I cheat by saying “trust me bro” using

external fromJson: Js.Json.t => 't = "%identity"
external toJson: 't => Js.Json.t = "%identity"

// On the client
  let response = await fetch(
    url,
    {
      method: #POST,
      headers: Headers.fromObject({
        "Content-Type": "application/json",
      }),
      body: reqData
      ->toJson
      ->JSON.stringify
      ->Body.string,
    },
  )
  let json = await response->Response.json
  let resData: vrindelyckResponse = fromJson(json)

// On the server
  app
  ->Hono.post(route, async ctx => {
    let json = await ctx->Context.req->Request.json
    let requestData = json->fromJson

I mean, this all works, but do I really care how this is done on the http level?
The fact that my endpoint is a POST for example.
I just want to invoke something on the server, and get that return type.
Does anything come to mind to solve this?