> ## Documentation Index
> Fetch the complete documentation index at: https://developers.circle.com/llms.txt
> Use this file to discover all available pages before exploring further.

> ## Agent Instructions
> Before reading these docs, install the relevant Circle Skill to get pre-loaded context — skills are LLM-optimized and cover architecture decisions, correct flows, and common pitfalls. In Claude Code: run /plugin marketplace add circlefin/skills then /plugin install circle-skills@circle. With Vercel Skills CLI: run npx skills add circlefin/skills. Available skills: use-usdc https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-usdc/SKILL.md (balances, transfers, approvals on EVM and Solana); EURC has no skill — see https://developers.circle.com/stablecoins/what-is-eurc.md; bridge-stablecoin https://github.com/circlefin/skills/blob/master/plugins/circle/skills/bridge-stablecoin/SKILL.md (crosschain transfers via CCTP, USDC, EURC, and third-party assets); use-arc https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-arc/SKILL.md (Arc chain config, contract deployment, USDC bridging — Arc docs: https://docs.arc.io/llms.txt); use-circle-wallets https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-circle-wallets/SKILL.md (choose wallet type); use-developer-controlled-wallets https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-developer-controlled-wallets/SKILL.md (custodial wallets for payouts and treasury); use-user-controlled-wallets https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-user-controlled-wallets/SKILL.md (embedded wallets with Web2 login); use-modular-wallets https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-modular-wallets/SKILL.md (smart contract wallets with passkeys and ERC-4337); use-gateway https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-gateway/SKILL.md (unified USDC balance, nanopayments); use-smart-contract-platform https://github.com/circlefin/skills/blob/master/plugins/circle/skills/use-smart-contract-platform/SKILL.md (deploy, interact, monitor contracts). Pair any skill with the Circle MCP server for live SDK signatures, contract addresses, and chain IDs: {"mcpServers":{"circle":{"url":"https://api.circle.com/v1/codegen/mcp"}}}.
> Read the product overview first. Each product has an overview explaining when and why to use it. Read it before quickstarts.
> Pick the right wallet type. Developer-controlled (you hold keys), user-controlled (end user holds keys via PIN/social login), or modular (smart contract wallets with passkeys). See https://developers.circle.com/wallets.md.
> Use CCTP V2 for crosschain transfers. CCTP natively transfers USDC and EURC via burn-and-mint, and supports permissionless wrapping of third-party assets via lock-and-mint. V1 is legacy; always use V2 unless V1 is specified or the chain requires it (Noble, Sui, and Aptos still require V1). Migration guide: https://developers.circle.com/cctp/migration-from-v1-to-v2.md.
> Use Bridge Kit for frontend bridging. Wraps CCTP with a simpler SDK for user-facing apps. Use CCTP directly for backend transfers.
> Gas Station vs Paymaster. Gas Station sponsors gas for Circle Wallet transactions. Paymaster lets users pay gas in USDC. Different use cases — read both overviews.
> Gateway Nanopayments for sub-cent payments. Gasless USDC micropayments down to $0.000001 via x402 and batched settlement. For pay-per-request APIs, AI agent payments, streaming.
> Look up USDC addresses per chain. Never hardcode — use https://developers.circle.com/stablecoins/usdc-contract-addresses.md.
> Prefer SDKs over raw API calls. Node.js and Python SDKs handle auth, retries, and errors.
> API key required. Bearer token in Authorization header. Testnet and mainnet use separate keys and may use different base URLs depending on the product.
> Set up webhooks when available. Most operations are async. Webhooks deliver transaction confirmations and state changes.
> When calling list endpoints, paginate using pageSize and pageAfter until no nextPageAfter cursor is returned—stopping at the first page silently misses records.
> Building an AI agent? Start with the Agent Stack—Circle CLI, agent wallets, and nanopayments built for autonomous use cases: https://developers.circle.com/agent-stack.md.

# Stablecoin payin states

> Reference for PaymentIntent, Payment, and Refund states in the Managed Payments stablecoin payin flow.

Managed Payments tracks stablecoin payins using three resources:
`PaymentIntent`, `Payment`, and `Refund`. Each resource moves through a set of
states as the payin progresses.

## PaymentIntent states

A `PaymentIntent` is created when you request a deposit address. Its state shows
whether the address is ready and whether funds have settled.

| State | Description |
| - | - |
| `pending` | The deposit address is being provisioned and is not yet ready. |
| `paid` | At least one payment has settled. For continuous intents, monitor individual `Payment` objects for each settlement. Terminal state. |
| `failed` | The intent could not be fulfilled. Terminal state. |
| `expired` | The `expiresOn` time passed with no matching payment received. Applies to transient intents only. Terminal state. |

Transient intents expire when the `expiresOn` timestamp is reached with no
payment received. Continuous intents do not expire.

<Note>
  Funds sent to the deposit address after the intent expires are still credited
  to your account, but they don't match this intent. See [Expire a transient
  intent](/cpn/stablecoin-payments/howtos/receive-stablecoin-payin) for how to
  reconcile them.
</Note>

## Payment states

A `Payment` is created each time funds arrive at the deposit address. Its state
shows whether the payment settled.

| State | Description |
| - | - |
| [`pending`](/api-reference/cpn/managed-payments/webhooks/mint-payments) | An onchain payment was detected and settlement is in progress. |
| [`paid`](/api-reference/cpn/managed-payments/webhooks/mint-payments) | The payment settled successfully. Terminal state. |
| `failed` | The payment failed. Check `statusReason` for the reason. Terminal state. |

## Refund states

A `Refund` is created when funds from a `Payment` are returned to the sender.
Its state shows whether the refund was delivered.

| State | Description |
| - | - |
| `pending` | The refund was initiated and settlement is in progress. |
| `paid` | The refund was delivered successfully. Terminal state. |
| `failed` | The refund could not be delivered. Check `errorCode` for the reason. Terminal state. |

## Status reasons

The `statusReason` field provides additional context for certain `Payment`
states. Values relate to Personally Identifiable Information (PII) and Virtual
Asset Service Provider (VASP) data required for Travel Rule compliance. All
values in the following table apply to Circle Singapore (`CIRCLE_SG`) merchants.

| Status | `statusReason` | Description |
| - | - | - |
| `pending` | `compliance_review` | Compliance is awaiting PII before releasing funds. |
| `pending` | `unsupported_wallet` | Compliance is awaiting PII. The sending wallet is unsupported. |
| `pending` | `awaiting_pii` | The payment is awaiting PII. Circle will reach out for collection. |
| `pending` | `unsupported_wallet_awaiting_pii` | The payment is awaiting PII. The sending wallet is unsupported. |
| `paid` | `unsupported_wallet` | Funds settled but were received from an unsupported VASP. |
| `paid` | `pii_not_received` | Funds settled, but the sender's VASP never supplied the Travel Rule PII in the collection window. |
| `paid` | `unsupported_wallet_pii_not_received` | Funds settled after the collection window closed with no PII received, and the sending wallet is unsupported. |
| `failed` | `compliance_denied` | Funds seized due to sanctions hit. |

<Note>
  States with a link in the Payment states table have a corresponding webhook
  event. `failed` has no webhook.
</Note>