How Do I Pay for a SaaS Review With Crypto (x402) in Python?

curl -X POST https://saasreview.ai/api/x402/reviews \
  -H 'Content-Type: application/json' \
  -d '{"product_url":"https://your-app.com","tier":"ai","contact_email":"founder@your-app.com"}'

# -> { "submission_id": "...", "price_usd": 5.0,
#      "payment": { "type": "x402", "pay_url": "/api/x402/reviews/<id>/pay" },
#      "poll_url": "/api/agent/reviews/<id>" }

GET https://saasreview.ai/api/x402/reviews/<id>/pay   ->   HTTP 402

{
  "x402Version": 1,
  "error": "X-PAYMENT header required",
  "accepts": [
    {
      "scheme": "exact",
      "network": "base",
      "maxAmountRequired": "50000",          // 50000 base units = $0.05 USDC
      "payTo": "0x...deposit-address...",      // send USDC here
      "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",  // USDC on Base
      "resource": "https://saasreview.ai/api/x402/reviews/<id>/pay"
    }
  ]
}

import os, time, httpx
from eth_account import Account              # pip install eth-account
from x402.clients.httpx import x402_payment_hooks  # pip install x402 ; name varies by version, see x402.org

BASE = "https://saasreview.ai"

# A funded wallet holding USDC on Base. Read the key from the environment, never hardcode it.
account = Account.from_key(os.environ["AGENT_WALLET_PRIVATE_KEY"])

# An httpx client that auto-pays any HTTP 402 it receives, from the wallet above.
client = httpx.Client(base_url=BASE, event_hooks=x402_payment_hooks(account))

# 1. Order the review (no payment yet).
order = client.post("/api/x402/reviews", json={
    "product_url": "https://your-app.com",
    "tier": "ai",                      # ai $5, human $15, human_plus_plan $25, pentest $30
    "contact_email": "founder@your-app.com",
}).json()

# 2. Pay: GET the pay_url. The hook sees the 402, sends the exact USDC on Base,
#    and retries with the X-PAYMENT header. You get back {paid: true, poll_url}.
paid = client.get(order["payment"]["pay_url"]).json()
print("paid:", paid["paid"])

# 3. Poll until the review is published (a real person checks every published one).
while True:
    r = httpx.get(f"{BASE}/api/agent/reviews/{order['submission_id']}").json()
    if r.get("status") == "rejected":
        print("not published")
        break
    review = r.get("review")
    if review and review.get("published"):
        print(review["composite_score"], "-", review["verdict"])
        print(review["url"])
        break
    time.sleep(15)

You are an autonomous agent with a funded crypto wallet (USDC on Base). Write and run a
Python script that orders a paid SaaS review from saasreview and pays for it with x402,
then prints the finished review. Follow this contract exactly:

1. Read https://saasreview.ai/api/agent/catalog for the live tiers and prices.
2. POST https://saasreview.ai/api/x402/reviews
   body: {"product_url": "<URL to review>", "tier": "ai", "contact_email": "<email>"}
   -> returns {"submission_id": ..., "payment": {"pay_url": "/api/x402/reviews/<id>/pay"}}
3. GET https://saasreview.ai<pay_url> with no payment to read the HTTP 402 challenge.
   accepts[0] = {scheme:"exact", network, maxAmountRequired (USDC base units),
   payTo (deposit address), asset (USDC contract)}.
   Use an x402 client from https://x402.org and the wallet key in env AGENT_WALLET_PRIVATE_KEY
   to send the exact USDC on Base and retry the GET with an X-PAYMENT header.
   A 200 {"paid": true, "poll_url": ...} means it worked.
4. Poll https://saasreview.ai/api/agent/reviews/<submission_id> every 15 seconds until
   review.published is true (a real person checks every published one; the status ends published or rejected),
   then print review.composite_score, review.verdict, review.url.

Rules: keep the wallet key only in the environment, never in code. Print the amount from
the 402 challenge and confirm it is what you expect before paying. Stop after one review.