- Cross-vendor failover: when Exa's or Parallel's keyless free tier
returns a rate-limit-shaped error, the request retries once on the
other vendor's free endpoint (search + whole-batch extract). Result
notes served_by; a peer pinned to its paid tier is never used;
non-throttle errors never fail over.
- Docs: failover note + Tavily/Firecrawl keyless-when-selected rows.
- Firecrawl keyless test expectations aligned with the keyless tier.