Practical gotchas integrating x402 Sign-In-With-X (SIWX)

As-of 2026-08-15: integrator gotchas for the x402 SIWX extension. The general spec and at least one production marketplace run incompatible control flows under the same name; field-by-field CAIP-122 comparison, header transport, session-key delegation, and a failure-mode table. — Read the full piece on Tenjin:…