Per Vercel docs (vercel.com/docs/functions/runtimes/bun):
- Use top-level "bunVersion": "1.x" in vercel.json (NOT functions block)
- Export default { async fetch(request) { ... } } — object with fetch method
(not a bare default function)
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>