One prompt, from an empty repository to a verified test payment.

You are integrating Nalpay — card payments, payment links and subscriptions for Saudi merchants — into this project.

## Read this first, in one fetch

https://paywithnal.com/llms.txt

That file is the whole API in plain text: authentication, test and live modes, every endpoint with the shape of its request and response, the one error envelope, idempotency, webhooks and how to verify their signatures, and the test cards. Read it before you write a line. The human quickstart is https://paywithnal.com/docs/quickstart and the OpenAPI document is linked from both.

## If you speak MCP, connect

  url:  https://mcp.paywithnal.com/mcp
  auth: Authorization: Bearer <my key, below>

Tools: account_status, search_docs, create_payment_link, list_payments, create_subscription, simulate_event, refund_payment, kyc_status, kyc_submit_document. Prefer them over raw HTTP for anything exploratory. Every result states its mode on its first line — keep that line when you summarise.

## Rules you may not break

1. Work in test mode. The key below begins sk_test_ and can only ever touch test objects. Do not ask me for a live key.
2. No card number goes anywhere near this code. Nalpay has no field for one and refuses anything shaped like one. Cards are typed on Nalpay's hosted page.
3. Every POST sends an Idempotency-Key header, derived from the operation (order-1024-charge), never generated fresh inside a retry loop.
4. Amounts are whole numbers of minor units. 1500 is 15.00 SAR. There are no decimals anywhere in this API.
5. The key lives in an environment variable. Never in source, never in a log line, never in your reply to me.

## Do this, in order, and show me each result

1. GET /v1/account. Tell me the mode and capabilities.can_charge. Stop if can_charge is false.
2. Create a payment link for 15.00 SAR — POST /v1/payment_links with amount 1500 — and give me its url.
3. Write the smallest server-side client for this project's language: sends the bearer key, sends an Idempotency-Key on every POST, and turns the error envelope into an exception carrying type, code, param and the Nalpay-Request-Id response header.
4. Write a receiver at POST /hooks/nalpay that verifies Nalpay-Signature over the RAW body — HMAC-SHA256 of "{t}.{rawBody}" keyed with the whsec_ secret, hex, constant-time compare, reject if |now - t| > 300 seconds — de-duplicates on the Nalpay-Delivery header, answers 2xx immediately, and handles payment_paid and payment_refunded.
5. Register that receiver with POST /v1/webhook_endpoints. Store the secret it returns in the environment; it is shown once.
6. Prove it end to end without asking me to open anything: POST /v1/test/payment_links/{id}/pay on the link from step 2, with an Idempotency-Key and no body. That records the payment through the same ledger a real one goes through, settles the link and sends a signed payment_paid to your receiver. Show me the receiver's log line for the verified event, and the payment's simulated, fee and net. Then send {"outcome":"failed"} on a second link and show me the failure path too.
7. Add a README section: the environment variables, how to run the receiver, and exactly what changes when we go live.

My key: NALPAY_KEY=sk_test_[paste yours here]

Put it in .env, add .env to .gitignore, and never print it back to me.