ascent

History

ascent-history is an optional URL session bound to Squawk. The current location (path, query, hash) is a value-over-time; push / replace are effects; Back writes the Squawk. The already-mounted tree patches at reactive boundaries. This is not a router: no path matcher, nested layouts, or data loaders. Matching is hist.location.map(parse) plus when. A later ascent.router may sit on this primitive; it must not remount AscentApp.

Memory backend

History.memory is the backend for tests, Chekhov / JSEnv, VS Code webviews, and SSR (seed from the request URL). push of the current URL still records a stack entry; Eq[Location] is what stops observers firing.

for
  hist <- History.memory()
  _    <- hist.push("/a")
  _    <- hist.push("/b")
  _    <- hist.back
  here <- hist.location.get
yield here.href
/a

Derive an ADT

Hash-mode apps can use a real <a href="#/active"> and let hashchange update the Squawk. Path-mode apps call hist.push("/session/id") from handlers. There is no window-level click capture (a later Link helper would call History; it must not hijack every <a>).

for hist <- History.memory()
yield
  val here = hist.location.map(_.href)
  E.div(
    E.span(here),
    E.button(Events.onClick(_ => hist.push("/next")), "go"),
  )
/

Browser backend

On Scala.js, History.browser binds window.history plus popstate / hashchange. Construction is URIO[Scope, History]; Scope close removes the listeners. ZIOAppDefault.run already has a Scope.