vite.config.ts

import { type Plugin, defineConfig } from 'vite'

// REPRO=patch  -> drop one bundled-dev-update (issue 2: lost patch is undetectable)
// REPRO=reload -> drop one full-reload reply  (issue 1: reloadPending is sticky)
const mode = process.env.REPRO ?? 'patch'

export default defineConfig({
  experimental: { bundledDev: true },
  plugins: [dropOneMessage(mode === 'reload' ? 'full-reload' : 'bundled-dev-update')],
})

/**
 * Drops the first WS message of `type` sent to each client, then passes everything through.
 *
 * Stands in for a message lost in transit. In our production setup the equivalent loss happens
 * inside Vite itself: `bundledDev.ts` returns without replying when `this.clients.getId(client)`
 * misses, which it can right after a server restart.
 */
function dropOneMessage(type: string): Plugin {
  return {
    name: 'repro-drop-one-message',
    apply: 'serve',
    configureServer(server) {
      let dropped = false
      server.ws.on('vite:client:connect', (_data, client) => {
        const send = client.send.bind(client)
        client.send = (payload: unknown) => {
          const p = payload as { type?: string; url?: string }
          if (!dropped && p?.type === type) {
            dropped = true
            console.log(`\n[repro] DROPPED ${type}${p.url ? ` (${p.url})` : ''}\n`)
            return
          }
          send(payload)
        }
      })
    },
  }
}