> ## 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.

# Transfer Settlement Network: Private Stablecoin Settlement

> The Transfer Settlement Network (TSN) by TrustLink Labs is private stablecoin settlement infrastructure on Solana. Currently live on Devnet.

**In plain English:** The Transfer Settlement Network (TSN) is settlement and authorization coordination infrastructure built by TrustLink Labs. It moves stablecoins on Solana without publishing a payment ID, sender, or recipient TIN on-chain. Funding goes into an epoch treasury. Settlement runs through an opaque, keyed slot authorized by a Mother-rooted DNA permit. There is no per-payment PDA. TSN is currently live on Solana Devnet.

## The four layers

TSN is not one program. It is four cooperating layers, each with a strict boundary.

| Layer    | Role                                                                       | Custody                                         |
| -------- | -------------------------------------------------------------------------- | ----------------------------------------------- |
| **TIN**  | Payment identity and route discovery                                       | None                                            |
| **GPRU** | Non-custodial authorization and routing                                    | Never holds funds                               |
| **TSN**  | Settlement coordination, epoch treasury, Mother-rooted permits             | Program-owned epoch treasury and cranker vaults |
| **TCAP** | Private balance accounting through commitment tips and encrypted snapshots | Governed reserves and vaults, per-asset         |

The layers are separated on purpose. A GPRU signature alone cannot move custody. A cranker cannot rewrite an authorization. TCAP owns the tip and sequence, not payment intent. TIN never holds a key.

## What is deployed today

* **Solana Devnet.** All four programs (TSN, TCAP, TIN Registrar, Stable TCAP Faucet) are live.
* **Privacy-safe credit path.** The TCAP credit instruction uses opaque commitments, sequence checks, and nullifiers. There is no per-transfer PDA and no receipt joining funding to credit.
* **Debit and exit.** Proof-gated and disabled. Live confidential debit and exit return `ProofSystemNotEnabled` until an audited proof verifier and the surrounding invariants are enabled.

## Protocol layers

Each layer has its own page detailing every operation and its status.

<CardGroup cols={2}>
  <Card title="TSN" icon="network-wired" href="/layers/tsn">
    Settlement coordination, epoch treasury, Mother-rooted DNA permits.
  </Card>

  <Card title="TIN" icon="id-card" href="/layers/tin">
    10-digit payment identity and route discovery.
  </Card>

  <Card title="GPRU" icon="route" href="/layers/gpru">
    Non-custodial authorization and routing.
  </Card>

  <Card title="TCAP" icon="lock" href="/layers/tcap">
    Confidential balances: credit (live), debit and exit (in development).
  </Card>
</CardGroup>

## Where to go next

<CardGroup cols={2}>
  <Card title="How It Works" icon="hand-pointer" href="/how-it-works/how-a-payment-feels">
    What the user sees versus what happens under the hood.
  </Card>

  <Card title="Current Architecture" icon="diagram-project" href="/how-it-works/architecture">
    The canonical TIN → GPRU → TSN → TCAP model with the end-to-end sequence
    diagram.
  </Card>

  <Card title="FAQ" icon="circle-question" href="/get-started/faq">
    Answers about privacy boundaries, deployment status, and the debit gate.
  </Card>

  <Card title="Run a Cranker" icon="gears" href="/operators/tsn-cranker">
    Operator process that leases work and pays Solana fees.
  </Card>
</CardGroup>

## About TrustLink Labs

TrustLink Labs is the team building TSN. Everything on this site describes the Transfer Settlement Network protocol itself, not any hosted product.

<CardGroup cols={2}>
  <Card title="GitHub Organization" icon="github" href="https://github.com/Trustlink-Labs">
    All open-source repositories from TrustLink Labs.
  </Card>

  <Card title="Follow on X" icon="x-twitter" href="https://x.com/TrustLinkLabs">
    Protocol announcements and Devnet updates.
  </Card>

  <Card title="Blog" icon="rss" href="https://tsn-protocol.blogspot.com">
    Engineering notes and protocol write-ups.
  </Card>

  <Card title="Protocol Source" icon="code" href="https://github.com/bigdreamsweb3/trustlink-pay">
    TSN, TCAP, TIN Registrar, and Faucet program source.
  </Card>

  <Card title="Docs Source" icon="book" href="https://github.com/bigdreamsweb3/tsn-docs">
    This documentation site.
  </Card>
</CardGroup>