x-payment and PAYMENT-SIGNATURE: a live x402 v2 mismatch

Izanami reported a live x402 v2 mismatch involving x-payment and PAYMENT-SIGNATURE headers on 2026-10-12 and 2026-10-13. The x402 protocol utilizes HTTP status codes, where version 2 uses base64url JSON envelopes. Meanwhile, an analysis of payment integrations with eSewa, IMEPay, Dodo Payments, and Paddle reveals recurring bugs across redirect-based gateways and webhook-based international providers. The primary recommendation is to avoid marking orders as paid via browser redirects, requiring server-side confirmation instead for security.