Coinbase cbBTC$77,486.93+1.0% pushed three updates to its x402 facilitator on Solana on September 17, shipping them to both the open-source SDK and the CDP Facilitator. The changes address billing flexibility, verification speed, and settlement reliability for AI agents making per-request USDC payments on Solana.
The 'Upto' Scheme: Flexible Billing After Work Is Done
The most structurally significant update is the live availability of the upto payment scheme. Under the older exact scheme, a buyer must authorize a precise dollar amount before the service delivers anything. With upto, the buyer authorizes a ceiling, and the seller settles the actual amount once the work is complete, always at or below the authorized maximum.
For AI agents running token-metered tasks like text generation, web scraping, compute jobs, or dynamic data queries, the final cost is only determinable after execution. The upto scheme fits that model. On Solana, it uses a payment-channels program with escrowed deposits and signed vouchers; a facilitator can handle settlement signing after authentication, or the server can manage it self-hosted.
The scheme is now live in the open-source x402 SDKs and the CDP Facilitator.
x402 Verify at 75ms, Settle at 900ms on Solana
Both core facilitator operations are faster in the September 17 update:
Verification runs on every request before the server releases any content or data. At 75ms (down from 220ms), agents running high-frequency queries against x402-protected endpoints spend materially less time waiting on payment confirmation. Settlement at 900ms (down from 1,150ms) closes each transaction roughly 250ms faster.
Automatic Retry for Pending Settlements
The third update closes a reliability gap. When the facilitator returns a settlement_pending status on a transaction, the canonical x402 SDKs now automatically retry rather than surfacing an error to the calling agent. Previously, agents had to implement their own retry logic or handle pending-settlement errors in application code. The canonical SDKs absorb that work automatically.
x402 on Solana: 75.41M Transactions and $24.24M Volume in 30 Days
x402.org shows 75.41M transactions and $24.24M in volume over the past 30 days, across 94,000 active buyers and 22,000 sellers. Solana is the protocol's most active chain by transaction count, a position it reached in August when AI agents settled $3.3M in USDC in a single week. These three facilitator updates improve the infrastructure that volume depends on.
