Cross-retailer product price comparison via Google Shopping, Amazon, Walmart, and eBay. Built for agent deal-hunting against spend-cap mandates.
https://backend-payment-proxy-servers-qa.up.railway.app/api/price-shopping/{CREATOR_UID}Amazon product detail by ASIN. Returns title, price, availability, ratings, key features. Required: asin. Optional: amazon_domain.
Search Amazon. Required: k (keyword). Optional: amazon_domain (default amazon.com), s (sort), rh (refinements), page.
eBay listing detail. Returns title, current bid/price, shipping, seller. Required: _nkw or item_id (listing identifier). Optional: _sacat, ebay_domain.
Cross-retailer Google Shopping search. Returns prices and links across all major US retailers in one call. Required: q (product query). Optional: location, gl (country), hl (language), tbs (filters), num.
Walmart product detail. Returns title, price, availability, ratings. Required: product_id (Walmart item id).
Copy this prompt and paste it into your AI agent (like Claude, GPT-4, etc.) to enable automatic X-402 payment handling.
** Your task ** Call the API at: https://backend-payment-proxy-servers-qa.up.railway.app/api/price-shopping/{CREATOR_UID}
Follow the steps below in order.
** Step 1 - Install FluxA Wallet CLI **
npm install -g @fluxa-pay/fluxa-wallet
Or use without installing: npx fluxa-wallet <command>
** Step 2 - Register agent **
fluxa-wallet init --name "<YOUR_AGENT_NAME>" --client "<YOUR_CLIENT>"
The response may include an authorization URL. Present the user with options: [Yes, open the link] [No, don't open]. If YES: run 'open "<URL>"' to open in their browser.
Verify: fluxa-wallet status
** Step 3 - Discover endpoints **
curl https://backend-payment-proxy-servers-qa.up.railway.app/api/price-shopping/{CREATOR_UID}
Returns JSON with: name, description, endpoints (paths, methods, descriptions, prices), paymentRequired, and networks.
** Step 4 - Choose payment method **
Ask the user: [On-chain USDC (Base)] or [FluxA Monetize Credits]
If USDC:
- --currency USDC
- --amount in atomic units (6 decimals, e.g., 100000 = 0.10 USDC)
If Credits (1 credit = 1 USDC):
- --currency FLUXA_MONETIZE_CREDITS
- --amount in 2-decimal units (e.g., 10 = 0.10 credits, 100 = 1.00 credits)
** Step 5 - Create an intent mandate **
x402 v3 uses intent mandates: the user pre-approves a spending plan (budget + time window), then the agent makes autonomous payments within those limits.
fluxa-wallet mandate-create \
--desc "Spend up to <BUDGET> for <DESCRIPTION> valid for <DURATION>" \
--amount <BUDGET_IN_UNITS> \
--seconds <DURATION_IN_SECONDS> \
--currency <USDC or FLUXA_MONETIZE_CREDITS>
Options:
- --desc (required): Human-readable spending plan description
- --amount (required): Budget in units for the chosen currency (see Step 4)
- --seconds (optional, default 28800 = 8h): Duration in seconds
- --currency (optional, default USDC): USDC or FLUXA_MONETIZE_CREDITS
** Step 6 - Get user to sign the mandate **
The response from Step 5 includes mandateId and authorizationUrl (TTL: 10 minutes).
Present the user with options: [Yes, open the link] [No, don't open]. If YES: run 'open "<authorizationUrl>"' to open in their browser.
** Step 7 - Wait for mandate to be signed **
fluxa-wallet mandate-status --id <MANDATE_ID>
Poll until mandate.status is "signed". The response also includes remainingAmount.
Important: Use --id, not --mandate.
** Step 8 - Call the API **
curl https://backend-payment-proxy-servers-qa.up.railway.app/api/price-shopping/{CREATOR_UID}
Optionally add the X-Agent-ID header for agent attribution (its value is the agent_id from 'fluxa-wallet status'): curl -H "X-Agent-ID: <YOUR_AGENT_ID>" https://backend-payment-proxy-servers-qa.up.railway.app/api/price-shopping/{CREATOR_UID}
If it returns HTTP 402, continue to Step 9.
** Step 9 - Pay via x402 v3 **
Pass the complete HTTP 402 response body as --payload:
fluxa-wallet x402-v3 \
--mandate <MANDATE_ID> \
--payload '$PAYLOAD_402'
The payload must contain an accepts array. Do NOT extract individual fields - pass the entire 402 response JSON.
The response includes xPaymentB64 (the payment token).
** Step 10 - Retry with payment token **
Retry the same request with the X-Payment header (optionally add X-Agent-ID for attribution):
curl -H "X-Payment: <xPaymentB64>" <ORIGINAL_API_URL>
Return the raw API response to the user without post-processing.
** Opening links for user **
Whenever you need to open a URL (authorization, approval, or any external link):
1. Present the user with a choice using your interactive options/menu capability (e.g., AskUserQuestion tool)
2. Options: [Yes, open the link] [No, don't open]
3. If YES: run 'open "<URL>"' to open in their default browser
4. If NO: ask how they would like to proceed
** Error handling **
- mandate_not_signed: User hasn't signed yet - ask them to open authorizationUrl
- mandate_expired: Time window passed - create a new mandate
- mandate_budget_exceeded: Budget too low - create a new mandate with a higher limit
- agent_not_registered: No Agent ID - run 'fluxa-wallet init' first
- Invalid payload: missing accepts array: Pass the full 402 response JSON