agents-u-cash (Python)

Zero-dependency Python client for the agents.u.cash API - the 402 Online Protocol for non-custodial agent payments. Works for both sides of the network: an agent selling (manage resources, watch settlements) and a buyer (fetch a 402 door, pay, and settle - automatically via on-chain detection, or instantly by submitting the tx hash). Supports ~40 native coins (Bitcoin + Lightning, Ethereum + 15 EVM L2s, Solana, Tron, XRP, USDT/USDC, USDC-on-Base gasless, UCASH) plus custom tokens on 20 chains (ERC-20 / TRC-20 / SPL / ...) - see agents.u.cash for the full live list.

Uses only the standard library (urllib). No dependencies. Python 3.7+.

Highlights

• Monetize AI agents pay-per-call: sell priced resources over HTTP 402; buyers pay direct to your own wallet.
• Non-custodial: the platform never holds funds. 40+ chains (BTC + Lightning, ETH + 15 EVM L2s, SOL, TRX, XRP, USDC-on-Base, UCASH, custom tokens).
• Zero-dependency Python client (3.7+, stdlib urllib) + a JavaScript SDK + an MCP server (77 tools).
• Scoped subagent (RBAC) keys, per-caller spend caps, HMAC-signed settlement webhooks with a built-in verifier.
• Two-sided: sell (resources, one-off payment links, shop, stores, landers, payout-info/OTC) and buy (402 door, UCP checkout sessions).

Docs: agents.u.cash · OpenAPI · llms.txt · CHANGELOG

Contents

• Install · Sell · Buy · UCP checkout sessions
• Manage your store · Subagents · Spend caps
• Verifying webhooks · Asset codes · Resource vs payment request
• API · Error handling

Install

pip install agents-u-cash

Or copy agents_u_cash.py - it has no dependencies.

Sell (as an agent)

from agents_u_cash import AgentsUCash

# Get an API key once (wallet-first; works at $0 immediately - verify email optionally for free credit):
# key = AgentsUCash().signup(email="me@agent.dev", password="longpass")["api_key"]

agent = AgentsUCash(api_key="...")
agent.set_wallet("btc", "bc1q…")
agent.set_webhook("https://my.bot/webhook")

res = agent.create_resource(amount=0.05)               # priced resource; res["checkout_url"] = pay.u.cash door
acc = agent.create_challenge(res["res_id"])             # what a buyer pays
# Share res["checkout_url"] - the pay.u.cash buyer door (/checkout/<enc>?cloud=<token>):
# a human opens the HTML checkout, an agent fetches it + "?agent=1" for the 402 manifest,
# an x402 client sends X-PAYMENT. (https://agents.u.cash/r/{res_id} is a back-compat alias.)
# Exact vs dust: save 3+ addresses per coin (agent.set_wallet("ucash", "0xaaa...,0xbbb...,0xccc..."))
# for exact-amount unique-address payments (500.00000000); one address adds sub-unit dust (500.00004180).

# One-off link instead of a persistent resource (closes when paid or after expiry):
req = agent.create_payment_request(amount=5, expiry="24h")   # -> {"url": "https://pay.u.cash/id/<enc>"}

settled = agent.get_settlements()                       # your earnings log

Buy (as a buyer)

from agents_u_cash import AgentsUCash

buyer = AgentsUCash()                                   # no key needed to buy
door = buyer.view_door(res_id)                          # the 402 door (JSON)
# 1. pick an entry, pay entry["payTo"] exactly entry["amount"] from your wallet (out of band)
# 2. the platform auto-detects the on-chain payment and settles it.
#    Optionally POST the tx hash to settle instantly instead:
result = buyer.verify(door["accepts"][0]["challengeId"], tx_hash)
# -> {"settled": True} | {"status": "pending", "confirmations": n, "required": m}

A human-friendly payable page is also available: buyer.view_door(res_id, html=True) returns the HTML.

UCP checkout sessions (buyer)

Multi-item, mixed-currency carts over the Universal Commerce Protocol. The merchant is resolved from the custom-domain base_url, or from a cloud merchant token on the shared host. No API key.

buyer = AgentsUCash()   # base_url = the merchant's domain (or the platform host + cloud)
cart = buyer.create_checkout(
    line_items=[{"item": {"id": res_id_a}, "quantity": 1}, {"item": {"id": res_id_b}, "quantity": 2}],
    currency="USD",            # optional: cart currency for mixed-currency carts
    cloud="<merchant-token>",  # only on the shared platform host
)
# -> {"id": ..., "status": "incomplete", "currency", "line_items", "totals", "ap2": {"merchant_authorization", "nonce"}}
ready = buyer.complete_checkout(cart["id"], cloud="<merchant-token>")
# -> ready_for_complete + payment_handlers[] (pay each challenge on-chain)
order = buyer.get_order(cart["id"], cloud="<merchant-token>")   # per-item fulfillment status

Optional AP2 (dev.ucp.shopping.ap2_mandate): pass complete_checkout(id, ap2={"checkout_mandate": ...}, cloud=...) with a buyer-signed SD-JWT-VC for holder-proof authorization. Responses are RFC 9421-signed (ES256) with the merchant key.

Manage your store (full merchant surface)

Beyond priced 402 resources, an agent is a first-class merchant over its own account: full transaction history + actions, multi-store, shop products, landers, payout-info/OTC, discount codes, checkout custom fields, and billing. All key-authenticated; tenant-scoped to the agent.

# Transactions: full history, CSV export, + actions
txs = agent.get_transactions(status="C", limit=50)
csv = agent.download_transactions(date_from="2026-01-01")     # raw CSV text
agent.refund_transaction(tx_id)        # self-guarding: only if you connected a refund-capable node/coinbase
agent.resend_webhook(tx_id)
agent.submit_hash(tx_id, "0xabc...")

# Stores (sub-merchants)
store = agent.create_store(label="Store B")  # api_key+cloud_token+webhook_secret returned once
agent.rotate_store_credential(store["store"]["id"], "cloud_token")

# Shop products, landers, payout-info/OTC
agent.create_shop_product(title="Ebook", price=9.99, currency="USD")
agent.create_lander(checkout_id=flag_id)
agent.create_payout_info(amount=50, currency="USD", email="payee@x.dev")  # emails the payee a link

# Discount codes (amount = price multiplier: 0.9 = 10% off) + checkout custom fields
agent.add_discount_code(code="LAUNCH", amount=0.9, checkout_ids="all")
agent.add_custom_field(type="select", label="Size", options=["S", "M", "L"])

# Billing: balances + capacity
bill = agent.get_billing()             # {credit_balance, ucash_points, lander_slots:{...}}
agent.buy_lander_pack(10)              # debits credit_balance, grows slots
agent.redeem_ucash(1000)               # UCASH points -> fee credit

Subagents (scoped RBAC keys)

Delegate a LIMITED credential to another automated principal. A subagent is a scoped sa_ API key with a staff role: it authenticates against your tenant, but the existing RBAC (uxc_can) enforces a limited capability set on every endpoint, so it can only do what the role allows. Owner-only (you create them; a subagent cannot create subagents). Reuses the merchant staff model + seat billing (a subagent with no free slot debits credit_balance).

# Built-in role: a clerk can create resources + read, but not edit settings, refund, or manage stores
sub = agent.create_subagent(role="clerk", display_name="Fulfillment bot")
# sub["api_key"] is the sa_ key, returned ONCE. The key works on every /v1/* endpoint; writes its role
# lacks return 403, and managing stores stays owner-only.

# Or a custom permission set (slugs: transactions.view, checkouts.edit, payment-links.create, ...).
# store_scope (store ids) restricts it to those stores (empty = all stores).
ro = agent.create_subagent(
    role="custom", permissions=["transactions.view", "checkouts.view"], store_scope=[store_id]
)

agent.get_subagents()                                  # list (never returns the api_key)
agent.update_subagent(sub["subagent"]["id"], role="manager", status="suspended")
fresh = agent.rotate_subagent_key(sub["subagent"]["id"])   # old key stops working; new key ONCE
agent.delete_subagent(sub["subagent"]["id"])           # key stops working; seat slot frees

Spend caps (per-caller limits)

Cap how much a single payer can spend on a resource in a rolling window. A payer whose settled spend in the window reaches amount is refused new authorization (x402 before-charge; on detect the platform refuses to credit an over-cap payment). Caller identity is the payer wallet (or, with by: 'ip', the buyer IP, enforced at the door before any charge). Optional; off by default.

res = agent.create_resource(amount=0.05, currency="USD", max_per_caller={"amount": 1.00, "window_hours": 24})
agent.set_resource_cap(res["res_id"], {"amount": 0.50, "window_hours": 6})  # change it
agent.set_resource_cap(res["res_id"], None)                                  # clear it
callers = agent.get_resource_callers(res["res_id"])                          # [{caller, spend, payments}]

Verifying webhooks

When a payment settles, agents.u.cash POSTs an HMAC-signed event to your webhook URL. Verify it with the static helper (it runs on your server; no instance or API key needed). The signature is HMAC-SHA256 of "<t>.<raw_body>" in the X-Webhook-Signature: t=<unix>,v1=<hex> header. Use the raw request body - re-encoding the JSON breaks the signature.

import json, os
from agents_u_cash import AgentsUCash

# Flask - use the RAW body (request.get_data()), NOT request.get_json():
@app.post("/webhook")
def webhook():
    valid = AgentsUCash.verify_webhook_signature(
        request.get_data(),                          # the EXACT raw bytes you received
        request.headers.get("X-Webhook-Signature"),  # t=<unix>,v1=<hex>
        os.environ["UXC_WEBHOOK_SECRET"],            # from set_webhook()/rotate_webhook_secret() - shown ONCE
    )
    if not valid:
        return "bad signature", 401
    event = json.loads(request.get_data())
    # Deduplicate by event["event_id"] (also in X-Webhook-Event-Id) - a settled txn may be delivered >1x.
    return "ok", 200

The 300-second replay window is on by default; pass tolerance=0 to skip the freshness check.

Asset codes

accepted_assets takes coin codes (omit it to accept all your configured wallets). Common built-in codes:

Plus any custom-token code you added via set_custom_token(). A misspelled code raises AgentsUCashError with .code = 'uxc_unknown_asset' ("Unsupported asset: X"). The live canonical list grows as chains are added - see agents.u.cash.

Resource vs payment request

Two ways to get paid - pick by use case:

A resource is a standing price buyers pay repeatedly; a payment request is a single invoice link.

API

All calls return the parsed response dict and raise AgentsUCashError on API errors (which carries .code and .status).

Error handling

All calls return the parsed response dict on success and raise AgentsUCashError on errors; the error carries .code and .status.

from agents_u_cash import AgentsUCash, AgentsUCashError

try:
    agent.create_resource(amount=0.05)
except AgentsUCashError as e:
    print(e.code, e.status, e)   # e.g. 'uxc_agent_not_activated' 402 ...

Status codes you will see:

verify(challenge_id, hash) returns {"settled": True} on success, {"status": "pending", "confirmations": n, "required": m} while the payment awaits on-chain confirmation, or {"status": "underpaid"}. An expired challenge raises with .code === 'uxc_challenge_expired' (HTTP 410 Gone) - catch on .code:

try:
    r = buyer.verify(challenge_id, tx_hash)
except AgentsUCashError as e:
    if e.code == "uxc_challenge_expired":
        ...  # re-fetch accepts[] and retry
    else:
        raise

Non-custodial: the platform never holds funds - every payTo is the seller's own wallet, and this client never sees your wallet keys.