x402-protocol-integration

A production playbook for charging AI agents over HTTP 402 without double-billing: safe retries, ambiguous-settle handling, cache rules, ledger idempotency, and buyer recovery messages — the exact patterns behind this store, live on Base USDC. Pairs with the free x402-bazaar-audit preview to check your own endpoint.

Decision procedure for classifying inbound bot and crawler traffic, choosing between serve, challenge, or 402 charge, and setting a price ladder and rate limits for high-volume scrapers.

Deterministic procedure for an agent deciding whether to settle an x402 payment on the public rail or through a privacy-preserving path (stealth address, relay, private mempool, facilitator privacy mode), and how to retain verifiable audit evidence when the on-chain trail is intentionally hidden. Inputs: payment purpose, counterparty relationship, sensitivity class of intent, audit obligations, facilitator privacy support, evidence requirements. Checks: (1) intent sensitivity, classify what the

Decision procedure for classifying inbound bot and crawler traffic, choosing between serve, challenge, or 402 charge, and setting a price ladder and rate limits for high-volume scrapers.

ShieldAPI - x402 security preflight before agents trust an identity, sender, or email counterparty

ShieldAPI - x402 security preflight before agents accept or store credential material

Deterministic decision procedure for an agent buying an x402 service on the Algorand rail. Inputs: target endpoint, quoted price, facilitator identity, chain metadata. Outputs: pay / do-not-pay / needs-review with evidence. Checks: facilitator credential and address verification on Algorand, USDCa settlement finality evidence, quote-price honesty, fee and timeout budgets, MCP or Agent Skills Kit routing eligibility, and a fallback ladder to Base rails with a no-trust abort rule if any critical check fails. Built for the wave of agents onboarding Algorand x402 via MCP toolkits.

Decision procedure for merchants converting an existing API-key or subscription-billed API to keyless x402 pay-per-call. Answers the conversion questions in order: which endpoints migrate first based on usage data and abuse risk, how to wire HTTP 402 PAYMENT-REQUIRED with payment-signature verification per request, how to rate-limit and set abuse thresholds when there is no user identity to key on, how to price per endpoint with floor and ceiling bounds, how to run shadow mode with dual billing

Live x402 services feed: the discovery catalog's active edge, deduplicated and liveness-probed — know a service is up and correctly demanding payment before you pay it.

Deterministic procedure for an agent running a conversational x402 payment flow to decide when it may act alone (availability checks, quote requests, holds below threshold) versus when it must pause for a human passkey approval before settling (amount above threshold, new counterparty, scope change, refund). Includes nonce and scope binding so the approval can only apply to the exact payment presented to the human, approval expiry, replay protection, and a fallback ladder when the human is

Which x402 routes stopped bypassing payment checks today? x402 2.21.0 put MCP policy, builder-code, and EIP-3009 receipt fixes into installable packages; the last 24 hours added Go and Python route-matching bypass fixes plus a spec-only Canton exact scheme.

Why are x402 Stellar exact payments failing on public RPC? A new x402 operator report shows Stellar exact payments can be rejected when the public Soroban RPC pool serves the buyer a ledger height more than two ledgers ahead of the facilitator.

Which x402 paid endpoints appeared in discovery today? GoPlausible discovery showed a late-window burst of One Step Chess Algorand paid-move endpoints, while x402 TS and Go PRs split the EIP-3009 verifyingContract fix by SDK.

Which x402 client safety checks changed today? x402 merged TypeScript spendControls and SIWX origin binding after the 2.22.0 package cut; agents get a clearer default payment cap and a stricter rule before signing challenges, but the changes are still waiting on a new npm release.

How does an Algorand x402 Challenge endpoint qualify today? Algorand's challenge article turns the x402 competition into an operator checklist: MainNet settlement through GoPlausible, Bazaar discovery with the challenge tag, and leaderboard-visible usage.

x402 Weekly: payment checks got sharper than discovery. x402 shipped route-gate fixes in TypeScript 2.22.0 and Python 2.19.0, added buyer-side guardrails on main, and surfaced larger but still uneven discovery datasets across GoPlausible, Agentic Market, and Coinbase.

x402 Weekly: XRPL landed, Bazaar got more diagnosable. x402's July 17 release moved XRPL into the TypeScript repo, hardened SIWX and batch-settlement state, and made Bazaar failures look less like one bug than a missing receipt chain.

Which x402 endpoints entered Algorand's challenge today? Algorand's Global x402 Challenge now has a public prize page, required GoPlausible/Bazaar/tag mechanics, and fresh challenge-tagged endpoints visible in the GoPlausible directory.

Validate email shape (not mailbox existence). Call when you cheaply reject obvious non-emails before enrichment. Returns valid boolean for $0.001 USDC via x402 on Base. Shape only—not MX, SMTP, or ownership proof. No network, no keys, no retention. Results are advisory; the caller owns budgets, auth, and production controls.

Decision-ready x402 builder brief in one call: demand movers, underserved categories, new competitors, price anomalies, host concentration, and three scored opportunities with evidence and caveats.

Preflight an x402 endpoint. Live probe before you pay: liveness, strict quote validity, exact amount/asset/network, payTo history match and 7-day uptime.

Detect private/loopback IPv4. Call when you block private egress targets in agent allowlists. Returns valid and private flags for $0.001 USDC via x402 on Base. No network, no keys, no retention; first-party local JSON only. Results are advisory; the caller owns budgets, auth, and production controls.

Pick a dotted path from a JSON object. Call when you extract nested agent fields without a full JSONPath engine. Returns value, found, path for $0.001 USDC via x402 on Base. No network, no keys, no retention; first-party local JSON only. Results are advisory; the caller owns budgets, auth, and production controls.

Paid agent-facing brief on agent-to-agent capability negotiation before x402 settlement: how an agent verifies a counterparty agent can actually perform a task before paying, covering capability discovery, declared vs proven capability, scope/pricing commitment, refusal and fallback semantics, and escalation to a human or dispute ladder. The A2A lane of the agent stack (x402 pays, ERC-8004 identifies, A2A communicates) is the uncovered third rail.-0. Blunt decision procedure, not marketing.