opencode/packages/app/src/utils/server-switch.tsx

import { createSignal } from "solid-js"

// Global flag used to paint a full-window splash overlay while a server
// swap is in progress. ServerKey's keyed <Show> remount is a big
// synchronous cascade (dispose + remount of the entire app subtree) that
// can freeze the UI for several seconds; setting this true before the
// swap and false after lets us render an overlay above the ServerKey
// boundary so the freeze has visual feedback instead of looking stuck.
export const [serverSwitching, setServerSwitching] = createSignal(false)

let run = 0

const nextPaint = () =>
  new Promise<void>((resolve) => {
    if (typeof requestAnimationFrame === "function") {
      requestAnimationFrame(() => resolve())
      return
    }
    setTimeout(resolve, 0)
  })

export async function withServerSwitchOverlay(action: () => void | Promise<void>) {
  const token = ++run
  setServerSwitching(true)
  await nextPaint()
  try {
    await action()
  } finally {
    await nextPaint()
    if (run === token) setServerSwitching(false)
  }
}