Even though you write both sides with Kotlin, those are still separated parts of your project.

hmmm... guess react is the router

This look okay?

fun main() {
    val root = "test"
    val useHash = false
    val hash = "#!"
    val router = Navigo(root, useHash, hash)
    router.on(
        mutableMapOf(
            "/testDemo" to demoWebEditor(),
            "/testProj" to demoTableAndProjection()
        )
    ).resolve()
    document.addEventListener("DOMContentLoaded", {
        stdNotifier()
        demoWebEditor()
    })
}

http://localhost:8080/test/testDemo doesnt seem to work

I think I got something partly working. Remaining issues: a) weird pathing behavior (http://localhost:8080/web/home works but add a "/" on the end and it still works but my image linked are broken. I wasted at least an hour on this, lol, a single slash. b) really would prefer a catch all/most in the backend, so that even http://localhost:8080/k/aj/sdf/lka/wjf8/90432u takes me somewhere, default page. Had to move stuff in the /static pathing and make that generic route (but doesn't work for anything, just web/ANYTHING till next start. Backend code next, seems the route has to be open in both for this to work, is there a better wildcard? I thought

**.*.*

worked somewhere but I think my brain is creating language salad now.

route("web") {
  route("*") {
      get {
          call.respondHtml {
              frontend()
          }
      }
  }
}
static("/static") {
    resources("web")
    defaultResource("web/index.html")
}

Frontend:

fun main() {
    document.addEventListener("DOMContentLoaded", {
        val router = Navigo(null, false)
        router
            .on("/web/home*", fun () {
                stdNotifier()
                demoWebEditor()
            }).on("/web/projection*", fun () {
                stdNotifier()
                demoTableAndProjection()
            })
            .resolve()
    })
}

Also a little concerned about security with front end routing... I mean I know the clients brain and they usually want to restrict access to pages as well as data, one giant JS file with front end routing makes that kinda pointless. But, I mean... there will be a user/group/role admin panel in this... so even user's will have that in the JS file they download? Granted there shouldn't be users, but just having access to the interface and calls and such saves a hacker much work. Or are we just being paranoid? Learning... trying to wrap my head around this... I feel like an old man trying to learn AOL in 1991, lol, or a grandmother learning to program her VCR in 1982, lol.

static("/static") {
            resources("web")
            defaultResource("web/index.html")
        }
        route("{...}") {
            get {
                call.respondHtml {
                    frontend()
                }
            }
        }

Seems to work great, fixes all the above except for the images... when I go to localhost:8080/web/home the page works great, but when I add /asdf/asdf/asdf the img src and css background img urls break. Kind of interesting.

There we go, life is grand.... front end mod fixes:

router
    .on("/web/home", fun () {
        demoWebEditor()
    }).on("/web/projection", fun () {
        demoTableAndProjection()
    }).on("/web/login", fun () {
        login()
    }).on("/web*", fun () {
        router.navigate("/web/login")
    }).resolve()