# USDC Spend Template

> Documentation index: [llms.txt](https://namera.ai/llms.txt).

Source: https://namera.ai/docs/sdk/guides/templates/usdc-allowance

Give a session a fixed lifetime USDC budget on each selected network.

`usdcAllowanceTemplate.build(input, { now })` creates ERC-20 USDC transfer
permissions with a chosen expiry. Its registry ID is `usdc-lifetime-allowance`
and its definition version is `2`.

The budget applies independently to each selected network. Choosing two networks
with `allowance: "100"` grants 100 USDC on each, up to 200 USDC in total. It does
not reset daily or monthly. Transfers can go to any recipient.

## Usage [#usage]

This deterministic example grants 100 USDC on Arc testnet for one day. Its fixed
clock makes the output reproducible; use the current Unix time in your application.

```ts title="index.ts"
import { usdcAllowanceTemplate, type UsdcAllowanceInput } from "@namera-ai/templates";

const now = 1_800_000_000;
const input = {
  networks: ["eip155:5042002"],
  allowance: "100",
  expiresAt: new Date((now + 86_400) * 1000).toISOString(),
} satisfies UsdcAllowanceInput;

const permissions = usdcAllowanceTemplate.build(input, { now });
console.dir(permissions, { depth: null });
```

Pass `permissions` to the existing `sessionKeys.create()` method as shown in
[Templates Overview](https://namera.ai/docs/sdk/guides/templates). Building alone creates no
account, signer or session and submits no transaction.

## Returns [#returns]

Returns a `TemplateOutput` object containing `onchain` and `policies`.
`allowance` values in JavaScript are `bigint`; timestamps are Unix seconds.
The JSON representation below encodes bigint amounts as decimal strings:

<div className="docs-response">

```json
{
  "onchain": {
    "installations": [
      {
        "chainId": "eip155:5042002",
        "validAfter": 1800000000,
        "validUntil": 1800086400,
        "allowSignatures": false,
        "permissions": [
          {
            "type": "erc20-token-transfer",
            "address": "0x3600000000000000000000000000000000000000",
            "allowance": "100000000"
          }
        ]
      }
    ]
  },
  "policies": []
}
```

</div>

The builder grants no signatures, native transfers, approvals or unrestricted
contract calls. Expiry limits the installed session's lifetime; changing this
template in your application does not update sessions already created from it.

## Parameters [#parameters]

### input.networks [#inputnetworks]

Type: `readonly SupportedEvmChainId[]`. Required; no default for building.

Provide one or more unique CAIP-2 IDs. Numeric chain IDs and duplicate networks
are rejected. Every selected network receives the full allowance.

| Mainnet                      | Testnet                           |
| ---------------------------- | --------------------------------- |
| Ethereum: `eip155:1`         | Sepolia: `eip155:11155111`        |
| OP Mainnet: `eip155:10`      | OP Sepolia: `eip155:11155420`     |
| Base: `eip155:8453`          | Base Sepolia: `eip155:84532`      |
| Arbitrum One: `eip155:42161` | Arbitrum Sepolia: `eip155:421614` |
| Arc: `eip155:5042`           | Arc Testnet: `eip155:5042002`     |

Deployments are pinned to the package version. They use Circle-issued USDC,
not bridged USDC.e. Testnet tokens have no monetary value.

### input.allowance [#inputallowance]

Type: `string`. Required; no default for building.

A positive decimal USDC amount with up to six fractional digits. `"0.000001"`
is the smallest accepted amount. The converted integer must fit in `uint256`.
Zero, negative numbers, exponent notation and additional decimal places throw;
the builder does not round the user's amount.

On Arc, this permission uses the 6-decimal ERC-20 interface at
`0x3600000000000000000000000000000000000000`. Native gas uses 18-decimal USDC.
Those interfaces share a balance, but the template grants only the ERC-20 path.
Gas sponsorship and the workspace's billing allowance are separate.

### input.expiresAt [#inputexpiresat]

Type: `string`. Required; no default for building.

A valid UTC ISO timestamp ending in `Z`, with whole seconds or exactly three
millisecond digits, such as `2027-03-01T18:30:00.000Z`. It must be later than
`context.now` after conversion to whole Unix seconds. The builder rejects invalid
calendar dates, missing time zones and past or equal expiry instants.

### context.now [#contextnow]

Type: `number`. Required; no default.

The current Unix time in whole seconds, for example
`Math.floor(Date.now() / 1000)`. Supply an explicit clock so previews and tests
can reproduce the same permissions. It becomes every installation's `validAfter`.
An expiry less than one full second later cannot produce a valid installation.

## Validation and Discovery [#validation-and-discovery]

The builder validates inputs synchronously. Invalid inputs throw an Effect
`SchemaError`; an elapsed expiry throws an `Error`. Neither failure contacts
Namera. Use `try/catch` around a build when inputs come from a user, then handle
the SDK result separately.

`usdcAllowanceTemplate.inputSchema` exposes the Effect schema for form validation.
`display`, `metadata`, `fields` and `defaults` describe the template's presentation;
the empty defaults are form placeholders, not a valid permission request.
`getTemplate("usdc-lifetime-allowance")` resolves this same built-in definition.