x402 Preflight

Inspect and validate an unfamiliar x402 endpoint before an autonomous agent spends USDC.

x402 Preflight performs bounded, read-only HTTPS probes. It observes the live payment challenge, price, network, asset, receiver, Bazaar discovery metadata, CORS, redirects, cache behavior, and other operational signals. It never connects a buyer wallet, forwards payment credentials, signs a payload, or spends funds.

A report is time-bound evidence, not an endorsement. It cannot prove seller identity or intent, contract safety, future availability, successful settlement, or delivery of a business outcome.

Canonical Capabilities

For HTTP clients that cannot submit a JSON body during discovery, the paid audit also has a compatibility alias at GET /api/x402/preflight/audit. It requires resource_url in the query string and accepts optional method=GET|HEAD, expected_network, and max_price_usd parameters. The alias uses the same price, x402 payment, and audit report as the canonical POST, but is not a fourth capability and never audits a POST target.

Canonical remediation requires a healthy ORDER_DATABASE_URL. If durable storage is unavailable, HTTP and MCP calls fail with REMEDIATION_UNAVAILABLE before a payment challenge is served.

These are the only primary operations in OpenAPI, MCP, llms.txt, the manifest, and agent metadata. Existing wallet, market, weather, repository, marketplace, and helper routes remain available under the manifest's labs section.

Fixed-Price Service Routes

The public inspector also generates direct GET intakes for buyers who want a human readback after payment settles. They are ordinary x402 resources, not additional MCP tools:

Each route requires repository_or_url and goal query parameters before it serves an x402 challenge. Optional contact, constraints, callback_url, response_format, and language parameters can travel with the paid intake.

Example payable URLs:

https://x402.chikocorp.com/api/x402/services/quick-review?repository_or_url=https%3A%2F%2Fgithub.com%2Fexample%2Fproject&goal=Verify%20the%20x402%20payment%20challenge%20and%20identify%20the%20next%20patch&response_format=both

https://x402.chikocorp.com/api/x402/services/integration-triage?repository_or_url=https%3A%2F%2Fgithub.com%2Fexample%2Fproject&goal=Make%20the%20x402%20Base%20USDC%20endpoint%20browser-agent%20readable&response_format=both

Bitcoin Lightning / L402 Seller

The service also contains a gateway-only repository opportunity scanner for coding agents:

GET or POST https://l402.chikocorp.com/api/l402/repo-opportunity-scan

Lightning Labs Aperture presents the public L402 challenge and then forwards a private gateway credential to this backend. Direct backend requests fail closed when the credential is absent, so the public Node/Vercel route cannot bypass the Lightning paywall. The deterministic report ranks public GitHub issues, detects open-PR competition and hardware risk, and treats payout words as unverified until an authorized payer and amount are explicit.

Free machine-readable discovery lives at:

https://l402.chikocorp.com/.well-known/l402.json

Production setup, invoice-only LND permissions, and no-payment verification are documented in deploy/l402/README.md. Wallet seeds, passwords, admin macaroons, and backend tokens must remain outside Git.

Local Development

Requires Node.js 20 or newer.

npm install
npm start

The API listens on http://localhost:4021 by default. The service does not auto-load .env; export variables through your process manager or shell.

Useful checks:

npm run check
npm test
npm run validate:bazaar
npm run verify:discovery
npm run metrics:summary

HTTP and OpenAPI

Free inspection:

curl -sS http://localhost:4021/api/preflight/inspect \
  -H 'content-type: application/json' \
  --data '{
    "resource_url": "https://example.com/api/resource",
    "method": "GET",
    "expected_network": "eip155:8453",
    "max_price_usd": 1
  }'

The same input sent to the paid audit returns HTTP 402 until a client supplies a valid x402 payment:

curl -i http://localhost:4021/api/x402/preflight/audit \
  -H 'content-type: application/json' \
  --data '{
    "resource_url": "https://example.com/api/resource",
    "method": "GET",
    "expected_network": "eip155:8453",
    "max_price_usd": 1
  }'

An entirely empty unauthenticated POST to the paid audit also returns its 402 challenge for method probes. A request that includes a payment attempt still requires the complete input before payment processing.

The compatibility GET alias requires its target before payment and returns 400 without a challenge when resource_url is missing or query parameters are unknown, repeated, empty, non-scalar, unsafe, or invalid:

curl -i 'http://localhost:4021/api/x402/preflight/audit?resource_url=https%3A%2F%2Fexample.com%2Fapi%2Fresource&method=GET&expected_network=eip155%3A8453&max_price_usd=1'

The runtime 402 response is authoritative for amount, network, asset, payTo, and Bazaar extensions. The static contract is available at /openapi.json. Errors use one strict envelope with a machine code, retryability, optional delay, and request ID.

Remote MCP

The stateless Streamable HTTP endpoint is:

https://x402.chikocorp.com/mcp

The previous Vercel origin remains an allowlisted compatibility alias, so clients that still call https://x402-wallet-readiness-service.vercel.app/mcp continue to receive challenges that name that Vercel resource.

Discover tools without payment:

curl -sS http://localhost:4021/mcp \
  -H 'content-type: application/json' \
  -H 'accept: application/json, text/event-stream' \
  --data '{"jsonrpc":"2.0","id":1,"method":"tools/list","params":{}}'

tools/list returns exactly the three canonical tools and strict input/output schemas. A paid tools/call receives an x402 challenge before tool execution. The buyer's MCP client remains responsible for explicit payment authorization; the server never signs or spends automatically.

This service does not implement A2A. /.well-known/agent-card.json returns a clear A2A_NOT_IMPLEMENTED response and points clients to MCP, OpenAPI, and x402 metadata.

Registry-ready remote-server metadata lives in server.json. It is intentionally not published automatically.

Discovery and Bazaar

Primary discovery surfaces:

GET /manifest
GET /openapi.json
GET /llms.txt
GET /.well-known/agent.json
GET /.well-known/x402.json
POST /mcp  (initialize, tools/list, tools/call)

The x402 resource server registers the Bazaar extension and publishes strict HTTP and MCP declarations for audit and remediation, including schemas and examples. The POST audit declaration uses a JSON body; the compatibility GET declaration publishes compact Bazaar queryParams and summary-output contracts so the payment challenge remains safely below common header limits. OpenAPI documents the alias's full response schema, which is identical to the canonical audit.

Use CDP Facilitator in production:

X402_USE_CDP_FACILITATOR=true
CDP_API_KEY_ID=<configured outside git>
CDP_API_KEY_SECRET=<configured outside git>

To keep a non-CDP facilitator, leave X402_USE_CDP_FACILITATOR=false and set X402_FACILITATOR_URL. npm run validate:bazaar validates local Bazaar declarations. When PUBLIC_URL is exported, it also inspects the public unpaid challenge and queries CDP's read-only merchant catalog for the configured receiver. Bazaar catalog indexing still requires a successful settlement through CDP; validation alone does not publish a listing.

URL Safety

Inspection accepts public HTTPS URLs only. It rejects credentials and sensitive query parameters, localhost, private/link-local/reserved addresses, metadata hosts, nonstandard ports, and unsafe redirects before a paid challenge is created. DNS is checked on the target and every redirect. Requests have bounded timeouts, response bytes, and redirect counts; JavaScript and target code are never executed.

Do not submit private keys, seed phrases, access tokens, authorization headers, cookies, payment signatures, or confidential repository URLs.

Runtime and Metrics

GET /health reports the public service version, commit, deployment time, network, facilitator mode, database availability, worker heartbeat, and settlement reconciler status. GET /ping returns the same non-secret payload for deployment health checks that require that route. Neither endpoint exposes wallets, orders, transaction hashes, URLs, secrets, or filesystem paths. Every response includes:

X-Service-Version
X-Commit-SHA
X-Request-ID

Telemetry is allowlisted, structured JSON and fail-open. Buyer addresses are recorded only as SHA-256 hashes when TELEMETRY_BUYER_PEPPER is configured. Apply 002_preflight_telemetry.sql to an existing PostgreSQL installation, then use npm run metrics:summary for 7-day and 30-day aggregates.

Deployment stamping, public smoke checks, database migration, CDP activation, and MCP Registry preparation are documented in docs/OPERATIONS.md.

Labs and Compatibility

Legacy routes have not been deleted and their existing prices remain unchanged. Representative surfaces include:

• /api/preview, /api/readiness, and /api/agent-commerce-receipt
• /api/market/*, /api/x402/market/*, and /api/weather/current
• /api/dev/repo-snapshot and /api/x402/dev/repo-snapshot
• /api/x402/services/quick-review and /api/x402/services/integration-triage
• marketplace webhooks, /wallet-sign, and /open-frame

No sunset date is announced. The historical custom metadata documents remain at /labs/legacy-agent.json and /labs/legacy-agent-card.json with a Deprecation: true response header.