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

# Overview

> How Prism is built: one orchestration layer that speaks every commerce protocol, settling on-chain through Spectrum.

Prism is designed as **two layers with a clean separation of concerns**: an off-chain **orchestration layer** (Prism) that speaks the agent-commerce protocols and handles everything a merchant integrates against, and an on-chain **settlement layer** (Spectrum) that moves the money. You build against Prism; Spectrum settles underneath, and you never touch a smart contract directly.

```mermaid theme={"theme":{"light":"github-light","dark":"one-dark-pro"}}
flowchart TB
    subgraph prism["Prism — Orchestration (off-chain)"]
        direction TB
        P1["Protocol implementations · x402 · UCP · ACP"]
        P2["Merchant management & onboarding"]
        P3["Charge creation & transaction routing"]
        P4["Webhooks & analytics"]
        P5["API: prism-gw.fd.xyz · Console: apps.fd.xyz/prism/"]
    end
    subgraph spectrum["Spectrum — Settlement (on-chain)"]
        direction TB
        S1["Smart-contract execution · ERC-3009"]
        S2["Stablecoin transfer · FDUSD · USDC"]
        S3["Multi-chain · Base · Arbitrum · BSC · Ethereum"]
        S4["Verification & finality"]
    end
    prism -->|"payment credential"| spectrum
    spectrum -->|"on-chain confirmation"| prism
```

## Prism — the orchestration layer

Prism is everything the merchant interacts with. It is protocol-aware, off-chain, and stateless with respect to funds — it never holds money. Prism handles:

* **Protocol implementations** — a single integration that speaks x402, UCP, and ACP. Prism translates each protocol's checkout and payment semantics into one internal settlement model, so you're covered whichever protocol a buyer's agent uses.
* **Merchant management** — Project Identify Tokens, accepted chains and tokens, settlement address, onboarding.
* **Charge creation & routing** — turning an order into concrete on-chain payment requirements (amount, token, chain, recipient).
* **Webhooks & analytics** — delivering settlement events and transaction history to your systems.

When you call the Prism Gateway API or drop in a Prism SDK, you're talking to this layer.

## Spectrum — the settlement layer

**Spectrum** is Finance District's on-chain settlement layer — the part that actually moves stablecoins. It's the piece the rest of the docs reference whenever a payment is "settled on-chain."

* **Executes the transfer.** The buyer's wallet signs a payment off-chain using [ERC-3009](https://eips.ethereum.org/EIPS/eip-3009) (`transferWithAuthorization`). Spectrum submits that signed authorization on-chain, moving stablecoins **directly from the buyer's wallet to the merchant's wallet**. No intermediary custodies the funds at any point.
* **Verifies and finalizes.** Spectrum confirms the on-chain transfer — correct amount, token, recipient, and a valid signature — and returns the transaction hash. Once confirmed on-chain, the payment is final: no chargebacks, no clawbacks.
* **Runs multi-chain.** Spectrum settles on EVM-compatible chains — Base, Arbitrum, BSC, and Ethereum today — in the stablecoins merchants enable (FDUSD, USDC). See [Network Support](/prism/production/network-support) for the current matrix.

Because the `payTo` address in every x402 payment requirement is a Spectrum settlement contract, the buyer's signed credential is bound to the on-chain settlement path from the moment it's created.

## One integration, every protocol

The reason the layers are split this way: **protocols evolve, settlement shouldn't.** Prism can add a new commerce protocol or change its merchant-facing business logic without touching the on-chain settlement infrastructure — and Spectrum can stay minimal, auditable, and stable. A merchant integrates once and inherits every protocol Prism supports.

<CardGroup cols={3}>
  <Card title="UCP Implementation" icon="diagram-project" href="/prism/integrations/ucp">
    How Prism implements the Universal Commerce Protocol as a payment handler.
  </Card>

  <Card title="x402 Implementation" icon="diagram-project" href="/prism/integrations/x402">
    How Prism acts as the x402 facilitator — enforce, verify, settle.
  </Card>

  <Card title="ACP Implementation" icon="diagram-project" href="/prism/integrations/acp">
    How Prism plugs into the Agentic Commerce Protocol for settlement.
  </Card>
</CardGroup>

<CardGroup cols={2}>
  <Card title="Transaction lifecycle" icon="timeline" href="/prism/concepts/how-it-works">
    The step-by-step behavior of a single payment, request to settlement.
  </Card>

  <Card title="Stablecoin settlement" icon="coins" href="/prism/concepts/settlement">
    Why settlement is on-chain, and what that gives you: finality, no chargebacks.
  </Card>
</CardGroup>