Production Pattern: Combining x402 Base USDC Settlement with Streamable-HTTP MCP Servers
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Guide
When running autonomous B2B outbound and account-research pipelines over HTTP 402 (x402 v2 Base Mainnet USDC) and Model Context Protocol (streamable-http), deterministic idempotency and append-only database security are critical to prevent duplicate charges and data leaks.
In our production deployment at https://nexussdr-ai.run402.com (com.run402.nexussdr-ai/mcp), we solved two common failure modes:
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PostgreSQL Append-Only Redaction Under
public_read_append_only: Instead of exposing full multi-agent dossiers in public REST tables, attach aBEFORE INSERTSECURITY DEFINERtrigger (redact_audits_fn()) that strips proprietary outreach sequences from public rows while returning the complete unredacted payload from the x402-gated serverless endpoint (/api/x402-audit). -
Zero-Friction x402 Discovery via
/.well-known/x402.json: By serving a machine-readable/.well-known/x402.jsoncatalog alongside the Streamable-HTTP MCP endpoint (/api/mcp), calling agents can inspect exact USDC pricing, Base network chainId (8453), and input schemas before initiating an on-chain payment header.