@kage/x402-zcash

x402 v1 over Zcash shielded payments for TypeScript, matching Kage's Rust server and facilitator. No runtime dependencies; Node >= 22.18 runs the .ts sources directly (type stripping).

Client:

import { parsePaymentRequired, zip321Uri, fetchWithPayment } from '@kage/x402-zcash';
const r = await fetch('http://127.0.0.1:4020/api/quote');            // 402
const c = parsePaymentRequired(await r.json());                       // the zcash-shielded / zcash-testnet option
const uri = zip321Uri(c.payTo, c.amountZat, c.memoNonce);             // any Zcash wallet can pay this
// ...pay it, then present the txid (repeat while settlement.errorReason === 'settlement_pending'):
const out = await fetchWithPayment(c.resource, { txid, memoNonce: c.memoNonce });

Server (Express or plain node:http): paywall({facilitatorUrl, facilitatorToken, receiptPubkeyHex, payTo, amountZat}) answers 402 with a fresh challenge, settles X-PAYMENT through the Kage facilitator's /settle (bearer X402Z_FACILITATOR_TOKEN), accepts only an ed25519 receipt from X402Z_RECEIPT_PUBKEY for that nonce, txid, payTo and amount, burns the nonce once and calls next() with X-PAYMENT-RESPONSE set. Like x402z-server it limits 402s and X-PAYMENT attempts to ratePerMin (30) per client (429 + Retry-After; pass clientKey behind a proxy), gives up on the facilitator after facilitatorTimeoutMs (90 s, a 502 that burns nothing), and answers the same X-PAYMENT again for resendWindowSecs (600) after it settled, so a lost 200 is not a refusal. Challenges live in memory by default (memoryStore(): one process, lost on restart, pruned once their redeem window is over, at most maxEntries = 100,000, then 503). Pass a durable store for production.

Not done: the x402 v2 header names (PAYMENT-REQUIRED / PAYMENT-SIGNATURE) and the Kage Tab scheme; the Rust agent (x402z-agent, x402z-mcp) is still the paying client.

Tests (npm test, 11): 9 without a chain (pure functions, the config check, and the paywall's limits over in-process HTTP: bounded store, 503 when full, rate limit, facilitator timeout), plus 2 live against the real x402z-server and x402z-facilitator binaries (published demo UIVK, throwaway receipt key) and Zcash testnet: a real mined payment presented for another nonce is refused by the server, and the middleware settles real tx ccb4214c…0ed3 for its own nonce once, serves it again inside the resend window without burning anything new, and refuses it after. Build the binaries first: cargo build -p x402z-server -p x402z-facilitator --bins --examples.