> ## Documentation Index
> Fetch the complete documentation index at: https://trust-link-tsn.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# How a TSN Payment Feels: One Action, Many Checks

> A TSN payment looks like one action to the user. Under the hood, TIN, GPRU, TSN, and TCAP cooperate. This page shows both views side by side.

**In plain English:** From the user's side, a TSN payment is one action: enter a 10-digit TIN, review the amount, and approve. The protocol then resolves the route, verifies the authorization, coordinates settlement, and records a private credit. Timing depends on wallet approval, service leases, Solana confirmation, and the current settlement path.

## What the user sees

```text theme={null}
1. Type a 10-digit TIN
2. Confirm amount
3. See a pending or confirmed status
```

That is the intended product surface. No wallet address to copy and no settlement network to choose. The wallet still authorizes the payment, and the app should distinguish a submitted payment from a confirmed one.

## What actually happens

```mermaid theme={null}
sequenceDiagram
    autonumber
    participant U as User
    participant TIN as TIN
    participant GPRU as GPRU
    participant TSN as TSN
    participant TCAP as TCAP

    U->>TIN: Resolve 10-digit TIN to a route
    TIN-->>U: Route commitment + policy
    U->>GPRU: Sign intent bound to route
    GPRU->>TSN: Sender authorization and route commitment
    TSN->>TSN: Node verifies and submits authorized work to Receiver
    TSN->>TSN: Cranker leases and submits the exact authorized transaction
    TSN->>TCAP: Advance opaque tip commitment (CPI)
    TCAP-->>U: Encrypted snapshot updated
    U-->>U: Pending or confirmed status
```

Each layer stays inside its boundary, so no layer needs to know more than it should.

## Layer-by-layer, in one line each

| Step           | Layer    | What it does                                                                  | What it never sees                                           |
| -------------- | -------- | ----------------------------------------------------------------------------- | ------------------------------------------------------------ |
| Look up        | **TIN**  | Resolves the 10-digit number to a route                                       | Sender's balance                                             |
| Authorize      | **GPRU** | Signs a scoped authorization                                                  | Custody of funds                                             |
| Move value     | **TSN**  | Coordinates authorized funding, acceptance, leases, and settlement submission | Recipient's private route material inside the tip transition |
| Update balance | **TCAP** | Advances the commitment tip and encrypted snapshot                            | Plaintext balance                                            |

Any single layer, on its own, is incomplete. Together, they form a payment path.

## Why the user does not see any of this

Because no layer needs the full picture, the user does not have to hand it out. The wallet approves the signed authorization, while the Node, Receiver, Cranker, TSN program, and TCAP program each perform only their assigned checks.

The product is a payment. The architecture is a set of enforced boundaries.

## Related

<CardGroup cols={2}>
  <Card title="Architecture" icon="diagram-project" href="/how-it-works/architecture">
    The current TIN, GPRU, TSN, and TCAP architecture.
  </Card>

  <Card title="FAQ" icon="circle-question" href="/get-started/faq">
    What is on-chain, what is private, and what operators can see.
  </Card>
</CardGroup>