> ## Documentation Index
> Fetch the complete documentation index at: https://neverminedag-sync-api-errors-9d14109.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Enroll a Card & Delegate a Budget

> Let an AI agent set up a card payment method and a capped, time-boxed spending delegation it can reuse to pay for Nevermined services autonomously.

A **delegation** is what lets an agent spend on your behalf without asking every time: a payment method plus a hard spending limit and an expiry. This flow enrolls a card once (the human enters card details in a browser — PCI requires it) and hands the agent a `delegationId` it reuses until the budget is spent or the delegation expires.

## Useful for

* Giving an agent a **card** to pay with when a plan is fiat (Stripe / Braintree / Visa) rather than stablecoin.
* Putting a **hard cap** on what an agent can spend (e.g. `$50` over `30 days`) — the platform enforces it.
* Doing the human part **once**: after enrollment, every purchase is programmatic and reuses the same delegation.

<Note>
  Paying with **stablecoins** needs no card and no human enrollment — your account's ERC‑4337 wallet is ready as soon as it's funded. Use this flow only for card payments. See [Buy access](/docs/getting-started/ai-agent-purchase) for the stablecoin path.
</Note>

## Try it yourself

Hand this to your agent. It drives the embedded enrollment handshake, gives you a single URL to open, and captures the result automatically:

```text theme={null}
You are my autonomous payments agent. Set up a credit card I can use to pay for Nevermined services in the sandbox environment, with a spending limit of $50 over 30 days.

Use the **latest** Nevermined `nevermined-payments` skill — fetch the current `SKILL.md` and `references/` from https://github.com/nevermined-io/docs/tree/main/skills/nevermined-payments (don't rely on an older installed/cached copy). The card-enrollment endpoints (`POST /embed/session`, the `cards/setup` URL, `delegation/create`) are documented there even though `embed/session` is not in the API's OpenAPI.

Do the work yourself: mint an embedded session with my API key, host a one-shot callback server on 127.0.0.1, and hand me a single card-setup URL to open in my browser. The only thing I should have to do is enter my card. When I'm done, verify the `state` echo, store the `delegationId`, and show me my payment methods and the new delegation's remaining budget.
```

<Note>
  This points at **Sandbox**, so card entry uses test cards and no real money moves. Use a `live:` API key to run it for real.
</Note>

## How it works

<Steps>
  <Step title="Mint an embedded session">
    With your API key, mint a session bound to a **localhost** return URL — so run a tiny one-shot callback server on `127.0.0.1` first:

    ```http theme={null}
    POST {API_BASE}/embed/session
    Authorization: Bearer <api-key>
    Content-Type: application/json

    { "returnUrl": "http://127.0.0.1:<port>/callback" }
    ```

    The response carries a `sessionToken`. This **open** endpoint needs no organization — it's the autonomous-agent path, and the card attaches to your own account. (Org members, e.g. the `nevermined` CLI, can use the org-scoped `POST {API_BASE}/widgets/session/self` with `{ orgId, returnUrl }` instead.)
  </Step>

  <Step title="Hand the human a card-setup URL">
    The human opens this once in their browser and enters the card:

    ```
    https://embed.nevermined.app/cards/setup
      ?sessionToken=<sessionToken>
      &returnUrl=http://127.0.0.1:<port>/callback
      &state=<random-nonce>
      &provider=stripe
    ```

    Generate `state` as an unguessable nonce. Use `provider=stripe` (or `braintree` / `visa`) to match the card type the target plan accepts.
  </Step>

  <Step title="Receive the delegation">
    When the human finishes, the browser redirects to your `returnUrl` with `paymentMethodId` and `delegationId`. **Verify the returned `state` matches** the one you sent (CSRF guard), then **store the `delegationId`** — that's what you pass at purchase time.

    <Warning>
      `paymentMethodId` and `delegationId` arrive in the callback **query string**. Don't log the request line, and keep secrets in a secret store, not on disk in the clear.
    </Warning>
  </Step>

  <Step title="(Optional) Re-budget an enrolled card">
    Already enrolled and just need a fresh budget? Create another delegation directly — no browser needed:

    ```http theme={null}
    POST {API_BASE}/delegation/create
    Authorization: Bearer <api-key>
    Content-Type: application/json

    { "provider": "stripe", "providerPaymentMethodId": "<pm_... from GET /payment-methods>",
      "spendingLimitCents": 5000, "durationSecs": 2592000, "currency": "usd" }
    ```

    `provider`, `currency`, `spendingLimitCents`, and `durationSecs` are all required — there is no silent default for `provider` or `currency`. The response carries a new `delegationId`. The delegation is **plan-agnostic** unless you pass a `planId`.

    <Note>
      **Visa** is the exception: `provider: "visa"` needs a browser-produced `consumerPrompt` + `assuranceData` from a WebAuthn ceremony, which an agent can't generate — so create Visa delegations in the app and reuse the `delegationId`.
    </Note>
  </Step>

  <Step title="Reuse it to pay">
    Pass the stored `delegationId` whenever you buy — see [Buy access](/docs/getting-started/ai-agent-purchase). One delegation covers many purchases until its budget is spent or it expires.
  </Step>
</Steps>

## Related

<CardGroup cols={2}>
  <Card title="Buy access" icon="cart-shopping" href="/docs/getting-started/ai-agent-purchase">
    Use the delegation to buy plan credits with x402.
  </Card>

  <Card title="Card Delegation" icon="user-shield" href="/docs/solutions/card-delegation">
    The full embedded handshake, widget embedding, and `state`/CSRF rules.
  </Card>

  <Card title="Card Enrollment" icon="credit-card" href="/docs/products/payments/card-enrollment">
    Provider-specific enrollment (Stripe, Braintree, Visa).
  </Card>

  <Card title="Check credits" icon="wallet" href="/docs/agents-guide/check-credits">
    Inspect delegation budgets and remaining credits.
  </Card>
</CardGroup>