Finding the current Sanity API version for preview setup

_const_ client = _await_ getClient({ apiVersion: '2023-01-01' })

import Iframe from 'sanity-plugin-iframe-pane'

// list of schema types supporting preview
const previewSchemaTypes = ['homePage', 'project', 'post', 'page']

// Default document node:
// Add preview view if part of list
export const defaultDocumentNode = (S, { schemaType }) => {
  const frontendUrl = '<http://localhost:3000>'

  if (previewSchemaTypes.includes(schemaType)) {
    return S.document().views([
      S.view.form(),
      S.view
        .component(Iframe)
        .title('Preview')
        .options({
          url: (doc) => resolveProductionUrl({ doc, context: S.context, frontendUrl }),
          defaultSize: 'desktop',
          reload: {
            button: true
          },
          attributes: {
            allow: 'fullscreen'
          }
        })
    ])
  }
}

// Resolve production url
export const resolveProductionUrl = async ({ doc, context, frontendUrl }) => {
  const { getClient } = context

  if (!doc) {
    doc = context.document
  }

  if (previewSchemaTypes.includes(doc._type)) {
    const client = await getClient({ apiVersion: '2023-01-01' })
    const slug = await client.fetch(`*[_id == $id][0].slug.current`, { id: doc._id })

    // Build preview url
    const url = new URL(frontendUrl)

    // Switch for resolving doc type urls
    switch (doc._type) {
      case 'homePage':
        url.pathname = `/`
        break
      case 'page':
        url.pathname = `/${slug}`
        break
      case 'project':
        url.pathname = `/projects/${slug}`
        break
      case 'post':
        url.pathname = `/posts/${slug}`
        break
      default:
        break
    }

    // Add preview url params
    url.searchParams.set('preview', 'true')

    return url.toString()
  }

  return ''
}

// Previews
import { defaultDocumentNode } from './config/content-preview'
import { resolveProductionUrl } from './config/content-preview'

export default defineConfig({
  ... // client stuff

  plugins: [
    deskTool({
      structure,
      defaultDocumentNode
    })
  ],

  document: {
    productionUrl: async (prev, context) =>
      resolveProductionUrl({
        context,
        frontendUrl: '<http://localhost:3000>'
      })
  }
})