budibase/packages/server/src/api/routes/static.js

const Router = require("@koa/router")
const controller = require("../controllers/static")
const { budibaseTempDir } = require("../../utilities/budibaseDir")

const router = Router()

router
  .param("file", async (file, ctx, next) => {
    ctx.file = file && file.includes(".") ? file : "index.html"

    // Serving the client library from your local dir in dev
    if (ctx.isDev && ctx.file.startsWith("budibase-client")) {
      ctx.devPath = budibaseTempDir()
    }

    await next()
  })
  .get("/_builder/:file*", controller.serveBuilder)
  .get("/:appId/componentlibrary", controller.serveComponentLibrary)
  .get("/:appId/:file*", controller.serveApp)

module.exports = router