“The paid search never reached Exa”

I tested the Exa via Tempo MPP integration on July 17, 2026 with a realistic developer-research query: find current documentation and examples for the MPP payment protocol. The endpoint advertised a $0.005 web search.

POST https://exa.mpp.tempo.xyz/search
{"query":"Machine Payments Protocol MPP API documentation examples","numResults":5,"type":"auto"}

The request reached a valid payment challenge, but the sponsored transaction path failed before the search could run.

Sponsored transaction from this sender is already in flight.

No results, titles, URLs, snippets, request ID, debit, or provider output arrived. This review is explicitly about Exa's named Tempo MPP integration, not Exa's core API. A pay-per-search wrapper that cannot clear its own payment state provides nothing to evaluate beyond the failure.