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

# Solvers

> The execution providers that compete to fill Reiy intents and settle on-chain.

# Solvers

Solvers are the execution providers of Reiy. They compete to fill user <Tooltip tip="An on-chain order that escrows your sell tokens and records your terms.">intents</Tooltip> and, when they win, settle the result on-chain. A solver can use any routing strategy as long as the final settlement satisfies the signed <Tooltip tip="The signed authorization that lets the winning solver settle on-chain.">certificate</Tooltip> and the Move contract checks.

## What a solver does

* **Registers on-chain** with a <Tooltip tip="A deposit a solver keeps to stay eligible to compete.">stake</Tooltip> and stays active while that stake is held.
* **Runs a service** that <Tooltip tip="The off-chain coordinator that runs solver competition and signs certificates; it holds no funds.">Fisherman</Tooltip> calls to request quotes and <Tooltip tip="A solver's proposed fills and payouts for a round, plus a score.">solutions</Tooltip>.
* **Returns solutions**: proposed fills, payouts, and a <Tooltip tip="The number Fisherman ranks solutions by; the highest valid score wins.">score</Tooltip> for the intents in a round.
* **Settles on a win**: takes the escrowed funds, sources liquidity, and delivers the payout, all in one Sui transaction.

## Where solvers source liquidity

* CoW matching across intents in the same batch
* Internal inventory
* External Sui venues such as DeepBook
* Aggregators or other execution infrastructure

## What constrains a solver

A solver is never trusted by the protocol. Every claim is re-checked on-chain at settlement: the payout must exactly match the certificate, must clear the user's protected minimum (which survives the volume fee), and the intent's epoch and fill rules must hold. Any violation aborts the whole transaction, so a solver that cannot deliver simply fails to settle, and escrow never moves.

<CardGroup cols={2}>
  <Card title="Fisherman" href="/reiy-protocol/concepts/introduction/fisherman">
    The coordinator that runs solver competition.
  </Card>

  <Card title="Solver integration" href="/reiy-protocol/integrate/solver-integration">
    Implement a solver service end to end.
  </Card>
</CardGroup>


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