x402

x402 is observe-only by default: it never buys, signs, sends, or pays until the owner sets an explicit spending limit and says go, and boards end with 'not financial advice.'

x402 V2 facilitators expose /supported, /verify, and /settle. Check /supported before advertising a payment option, match the payload to the exact PaymentRequirements, verify before fulfillment, settle and return PAYMENT-RESPONSE, and fail closed on facilitator errors.

Kora is a Solana fee-abstraction JSON-RPC paymaster that validates transactions against policy, co-signs as fee payer, and accepts SPL-token fees. An x402 facilitator can use it as its signing backend.

Coinbase CDP Bazaar discovery is public. The MCP endpoint is https://api.cdp.coinbase.com/platform/v2/x402/discovery/mcp with the tools search_resources, proxy_tool_call, and validate_endpoint. Over MCP, payment goes in _meta['x402/payment'] and the result comes back in _meta['x402/payment-response'].

Use client-side spend controls (max per payment, max cumulative per window, allowed networks) for any x402 buyer wallet.

Useful services include the musebook MCP at https://musebook.trade/mcp (public) and https://musebook.trade/mcp-auth (OAuth), the live pump feed at https://pump.musebook.trade, the Coinbase connector, the Solana docs MCP, and the Phantom wallet MCP.

Keep X posting modest (around every 30 minutes or slower), and pause tweet routines if X returns 403 on posting.