Relay Bridging

Playbook for bridging, swapping, and bridge+calling via Relay through OpenFinance.

Three operations, one API

Operation	What it is
Swap	Same-chain token swap (origin = destination chain)
Bridge	Move tokens across chains (USDC on Polygon → USDC on Base)
Bridge+call	Bridge + execute a destination-chain tx after the bridge lands — pass the tx(s) in `txs`

Relay picks the route automatically; you just provide the inputs.

Endpoints

All three require

x-api-key: open_…

. Relay aggregates liquidity across 40+ chains — you pass the chain IDs directly; the backend picks the route.

POST /agent/relay/quote

— quote only

Fetches a Relay quote for a swap, bridge, or bridge+call. Does NOT submit any transactions. Use for preview UIs, fee estimation, or to show the user the route before they confirm.

Request body:

json

{
  "originChainId": 137,
  "destinationChainId": 8453,
  "originCurrency": "0x2791Bca1f2de4661ED88A30C99A7a9449Aa84174",
  "destinationCurrency": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
  "amount": "10000000",
  "tradeType": "EXACT_INPUT",
  "recipient": "...",               // optional; defaults to user's dest-chain addr
  "slippageTolerance": "50",        // basis points, optional
  "topupGas": true,                 // optional; forced false for Solana routes
  "topupGasAmount": "100000",       // USD micro-units, optional
  "usePermit": false,               // EIP-3009 permit for supported tokens
  "txs": [{"to", "data", "value"}], // optional; for bridge+call
  "appFees": [{"recipient", "fee"}] // optional
}

user

is server-injected from the caller's wallet based on

originChainId

— do NOT pass it. The backend selects EVM or Solana address automatically.

Returns the full response:

{steps, fees, feeSponsorship}

steps

is an array of signable/submittable actions (transactions or signatures) with embedded

check

endpoints for status polling.

POST /agent/relay/execute

— quote + sign + submit + poll

End-to-end flow. Same body as

/quote

. The backend:

Fetches the quote
Walks every
```
step
```
:
- EVM transaction step → sends via viem
```
walletClient.sendTransaction
```
  on the correct chain, waits for 1 confirmation
- Solana transaction step → compiles
```
instructions
```
  + ALTs into a VersionedTransaction, has Privy sign it (
```
signTransaction
```
  ), broadcasts via our RPC with
```
skipPreflight: true
```
  , confirms with the original blockhash/lastValidBlockHeight
- EIP-712 signature step → signs with the user's EVM account and POSTs the signature to the step's
```
check.endpoint
```
Polls
```
GET /intents/status/v3
```
with exponential backoff (1s → 10s, 5-min cap) until terminal status

Returns

{requestId, quote, txHashes, finalStatus}

Use when the user confirms the quote or directly asks to bridge / swap / execute. Solana-origin requires the user's Solana wallet to be delegated (see

openfin-setup

step 2).

GET /agent/relay/status?requestId=<id>

— manual status lookup

Get the current status of a Relay intent by its

requestId

. Use for manual polling from the frontend when

/execute

wasn't awaited, or for audit lookups.

Status values:

```
waiting
```
— awaiting deposit confirmation
```
depositing
```
— origin deposit confirmed, pending fill
```
pending
```
— deposit confirmed, awaiting destination submission
```
submitted
```
— destination transaction submitted
```
delayed
```
— destination fill still processing
success
— successful fill on destination (terminal)
refunded
— successfully refunded (terminal)
failure
— unsuccessful fill (terminal)

Response also includes

details

(free-form text),

inTxHashes

txHashes

updatedAt

(ms),

originChainId

destinationChainId

Required inputs

Field	Type	Notes
`originChainId`	number	Source chain
`destinationChainId`	number	Destination chain
`originCurrency`	string	Token contract on origin (or `0x0…0` for EVM native)
`destinationCurrency`	string	Token contract on destination
`amount`	string	Smallest unit as a STRING (wei for 18-dec, `10000000` = 10 USDC)
`tradeType`	string	`EXACT_INPUT` \| `EXACT_OUTPUT` \| `EXPECTED_OUTPUT`

user
is server-injected based on

originChainId

— pass the right wallet for the origin. Solana origin → Solana address; EVM origin → EVM address. Do not pass it yourself.

recipient
defaults to the user's address on the destination chain. Override explicitly if bridging to a different address.

Chain ID cheatsheet

Chain	ID
Ethereum	`1`
Polygon	`137`
Base	`8453`
Optimism	`10`
Arbitrum	`42161`
BSC	`56`
Linea	`59144`
Blast	`81457`
Scroll	`534352`
zkSync Era	`324`
Hyperliquid	`1337`
Solana	`792703809`
Bitcoin	`8253038`
Tron	`728126428`

Live list:

GET https://api.relay.link/chains

. Treat that endpoint as source of truth for supported origin chains.

Native-token sentinel

Use

0x0000000000000000000000000000000000000000

for the EVM native token on any EVM chain (ETH / MATIC / BNB / etc.).

For Solana, use

So11111111111111111111111111111111111111112

for wrapped SOL, or the SPL mint address for tokens (e.g.

EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v

for USDC).

Trade types

Type	Meaning	Example
`EXACT_INPUT`	Send exactly `amount` , receive variable	"Bridge 10 USDC"
`EXACT_OUTPUT`	Send variable, receive exactly `amount`	"Get me exactly 1 ETH on Base"
`EXPECTED_OUTPUT`	Alternate routing	Rarely needed

Most prompts are

EXACT_INPUT

. If user says "I want to receive X", use

EXACT_OUTPUT

Gas topup defaults

Backend behavior:

EVM ↔ EVM:
```
topupGas: true
```
default,
```
topupGasAmount: "100000"
```
($0.10). Relay only applies it if the recipient needs gas.
Any route with Solana (chainId
792703809
):
```
topupGas
```
forced
```
false
```
.
Ethereum L1 destination: bump
```
topupGasAmount
```
to
```
"500000"
```
($0.50).

Override per-call via body fields

topupGas

and

topupGasAmount

Solana-origin example

Bridge the user's USDC from Solana back to USDC.e on Polygon:

json

{
  "originChainId": 792703809,
  "destinationChainId": 137,
  "originCurrency": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
  "destinationCurrency": "0x2791Bca1f2de4661ED88A30C99A7a9449Aa84174",
  "amount": "1000000",
  "tradeType": "EXACT_INPUT"
}

user

auto-fills as the user's Solana address;

recipient

auto-fills as their EVM address. Requires Solana wallet delegation (see

openfin-setup

). Without it, execute fails with 412.

Bridge+call example

Bridge USDC.e Polygon → USDC Base, then call a contract on Base:

json

{
  "originChainId": 137,
  "destinationChainId": 8453,
  "originCurrency": "0x2791Bca1f2de4661ED88A30C99A7a9449Aa84174",
  "destinationCurrency": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
  "amount": "10000000",
  "tradeType": "EXACT_INPUT",
  "txs": [
    { "to": "0x…target…", "data": "0x…calldata…", "value": "0" }
  ]
}

Status values

Terminal success:
```
success
```
,
```
refunded
```
Terminal failure:
```
failure
```

In-flight:

waiting

depositing

pending

submitted

delayed

/execute

returns non-terminal

finalStatus

, keep polling

/status

with the

requestId

Don't

Don't use human-readable amounts.
```
"1000000"
```
= 1 USDC, not
```
"1"
```
.
Don't pass
```
user
```
or
```
userId
```
— server injects.
Don't retry a
```
failure
```
without checking
```
details
```
— refund may be automatic (
```
status: refunded
```
will follow), or the route may be unsupported.
Don't assume Solana delegation carries over from EVM. Each chain type delegates separately in Privy.

MCP note

Tool names match:

relay_get_quote

relay_execute

relay_get_status

openfin-relay

NPX Install

Tags

SKILL.md Content

Relay Bridging

Three operations, one API

Endpoints

`POST /agent/relay/quote`
— quote only

`POST /agent/relay/execute`
— quote + sign + submit + poll

`GET /agent/relay/status?requestId=<id>`
— manual status lookup

Required inputs

Chain ID cheatsheet

Native-token sentinel

Trade types

Gas topup defaults

Solana-origin example

Bridge+call example

Status values

Don't

MCP note