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Add Relay bridge guide, create Bridging sidebar section, fix USDC naming (#225)
- Add bridge-usdc-relay.mdx with full Relay integration guide (quote, execute, status) - Create 'Bridging' sidebar section nesting Stargate and Relay guides - Rename USDC references to 'Bridged USDC' / 'USDC.e' on Tempo side (Circle C&D) - Replace em dashes with hyphens across both guides Amp-Thread-ID: https://ampcode.com/threads/T-019d4fbd-7519-75b6-960e-3c3326e6a3da Co-authored-by: Amp <amp@ampcode.com>
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src/pages/guide/bridge-usdc-stargate.mdx renamed to src/pages/guide/bridge-layerzero.mdx

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---
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title: Bridge USDC via Stargate
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description: Bridge USDC to and from Tempo using Stargate and LayerZero. Includes source chain addresses, cast commands, and TypeScript examples with viem.
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title: Bridge via LayerZero
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description: Bridge tokens to and from Tempo using LayerZero. Covers Stargate pools and standard OFT adapters with cast commands and TypeScript examples.
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---
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import { Tabs, Tab } from 'vocs'
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# Bridge via LayerZero
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# Bridge USDC via Stargate
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[LayerZero](https://layerzero.network) is the omnichain messaging protocol that powers token bridging on Tempo. Tokens are bridged using the [OFT (Omnichain Fungible Token)](https://docs.layerzero.network/v2/developers/evm/oft/quickstart) standard - the source chain locks or burns tokens and the destination chain mints the bridged equivalent.
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[Stargate](https://stargate.finance/) uses [LayerZero](https://layerzero.network) to enable 1&#58;1 USDC bridging between Tempo and other chains. Stargate locks USDC on the source chain and mints **USDC.e** (Bridged USDC) on Tempo, typically in under a minute.
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There are two flavors of OFT on Tempo:
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## Contracts on Tempo
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- **Stargate** - an application built on LayerZero that manages liquidity pools. Tokens like USDC.e and EURC.e use Stargate's `sendToken()` interface.
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- **Standard OFT** - token issuers (e.g. Tether for USDT0) deploy their own OFT adapters using LayerZero's `send()` interface directly.
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Both use the same underlying LayerZero endpoint on Tempo.
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## Bridged tokens on Tempo
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| Token | Address | Bridge |
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|-------|---------|--------|
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| **USDC.e** (Bridged USDC) | [`0x20C000000000000000000000b9537d11c60E8b50`](https://explore.tempo.xyz/address/0x20C000000000000000000000b9537d11c60E8b50) | Stargate |
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| **EURC.e** (Bridged EURC) | [`0x20c0000000000000000000001621e21F71CF12fb`](https://explore.tempo.xyz/address/0x20c0000000000000000000001621e21F71CF12fb) | Stargate |
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| **USDT0** | [`0x20c00000000000000000000014f22ca97301eb73`](https://explore.tempo.xyz/address/0x20c00000000000000000000014f22ca97301eb73) | OFT |
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| **frxUSD** | [`0x20c0000000000000000000003554d28269e0f3c2`](https://explore.tempo.xyz/address/0x20c0000000000000000000003554d28269e0f3c2) | OFT |
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| **cUSD** | [`0x20c0000000000000000000000520792dcccccccc`](https://explore.tempo.xyz/address/0x20c0000000000000000000000520792dcccccccc) | OFT |
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| **stcUSD** | [`0x20c0000000000000000000008ee4fcff88888888`](https://explore.tempo.xyz/address/0x20c0000000000000000000008ee4fcff88888888) | OFT |
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| **GUSD** | [`0x20c0000000000000000000005c0bac7cef389a11`](https://explore.tempo.xyz/address/0x20c0000000000000000000005c0bac7cef389a11) | OFT |
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| **rUSD** | [`0x20c0000000000000000000007f7ba549dd0251b9`](https://explore.tempo.xyz/address/0x20c0000000000000000000007f7ba549dd0251b9) | OFT |
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| **wsrUSD** | [`0x20c000000000000000000000aeed2ec36a54d0e5`](https://explore.tempo.xyz/address/0x20c000000000000000000000aeed2ec36a54d0e5) | OFT |
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See the full token list at [tokenlist.tempo.xyz](https://tokenlist.tempo.xyz/list/4217).
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## LayerZero contracts on Tempo
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| Contract | Address |
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|----------|---------|
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| **USDC.e** (Bridged USDC) | [`0x20C000000000000000000000b9537d11c60E8b50`](https://explore.tempo.xyz/address/0x20C000000000000000000000b9537d11c60E8b50) |
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| **StargateOFTUSDC** | [`0x8c76e2F6C5ceDA9AA7772e7efF30280226c44392`](https://explore.tempo.xyz/address/0x8c76e2F6C5ceDA9AA7772e7efF30280226c44392) |
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| **EndpointV2** | [`0x20Bb7C2E2f4e5ca2B4c57060d1aE2615245dCc9C`](https://explore.tempo.xyz/address/0x20Bb7C2E2f4e5ca2B4c57060d1aE2615245dCc9C) |
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| **LZEndpointDollar** | [`0x0cEb237E109eE22374a567c6b09F373C73FA4cBb`](https://explore.tempo.xyz/address/0x0cEb237E109eE22374a567c6b09F373C73FA4cBb) |
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Tempo's LayerZero Endpoint ID is **`30410`**.
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## Source chain contracts
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## Stargate tokens
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[Stargate](https://stargate.finance/) manages liquidity pools for USDC.e and EURC.e. Use the Stargate `sendToken()` interface for these tokens.
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### Stargate contracts on Tempo
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| Token | Stargate OFT Contract |
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|-------|----------------------|
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| **USDC.e** | [`0x8c76e2F6C5ceDA9AA7772e7efF30280226c44392`](https://explore.tempo.xyz/address/0x8c76e2F6C5ceDA9AA7772e7efF30280226c44392) |
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| **EURC.e** | [`0x7753Dc8d4bd48Db599Da21E08b1Ab1D6FDFfdC71`](https://explore.tempo.xyz/address/0x7753Dc8d4bd48Db599Da21E08b1Ab1D6FDFfdC71) |
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Use the Stargate pool contract on the source chain to bridge USDC to Tempo, and the StargateOFTUSDC contract on Tempo to bridge back.
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### Source chain Stargate pools
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| Chain | LZ Endpoint ID | Stargate USDC Pool |
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|-------|---------------:|--------------------|
@@ -33,23 +61,20 @@ Use the Stargate pool contract on the source chain to bridge USDC to Tempo, and
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| Polygon | `30109` | [`0x9Aa02D4Fae7F58b8E8f34c66E756cC734DAc7fe4`](https://polygonscan.com/address/0x9Aa02D4Fae7F58b8E8f34c66E756cC734DAc7fe4) |
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| Avalanche | `30106` | [`0x5634c4a5FEd09819E3c46D86A965Dd9447d86e47`](https://snowtrace.io/address/0x5634c4a5FEd09819E3c46D86A965Dd9447d86e47) |
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## Bridge to Tempo
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### Bridge to Tempo via Stargate
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### Using the Stargate app
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#### Using the Stargate app
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1. Go to [stargate.finance](https://stargate.finance/)
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2. Select your source chain (e.g. Ethereum) and USDC
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2. Select your source chain and token (USDC or EURC)
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3. Set **Tempo** as the destination chain
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4. Enter the amount, approve, and send
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### Using cast (Foundry)
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#### Using cast (Foundry)
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Bridge USDC from Base to Tempo using `cast`. This calls `sendToken` on the Stargate pool on the source chain. This example uses [taxi mode](#bus-vs-taxi-mode) for immediate delivery.
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This example bridges USDC from Base to Tempo. Replace addresses for other tokens or source chains.
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#### Step 1 — Get a quote fee estimate from Stargate router
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Use the same parameters you will pass to `sendToken`. Returns `(nativeFee, lzTokenFee)`.
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Take the first returned number as `<NATIVE_FEE>`.
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##### Step 1 - Get a quote
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```bash
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cast call 0x27a16dc786820B16E5c9028b75B99F6f604b5d26 \
@@ -59,9 +84,9 @@ cast call 0x27a16dc786820B16E5c9028b75B99F6f604b5d26 \
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--rpc-url https://mainnet.base.org
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```
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#### Step 2 — Approve USDC on Base
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Take the first returned number as `<NATIVE_FEE>`.
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Approve the Stargate router to spend USDC.
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##### Step 2 - Approve token on source chain
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```bash
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cast send 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 \
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--private-key $PRIVATE_KEY
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```
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#### Step 3 — Send bridge transaction
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##### Step 3 - Send bridge transaction
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```bash
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cast send 0x27a16dc786820B16E5c9028b75B99F6f604b5d26 \
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'sendToken((uint32,bytes32,uint256,uint256,bytes,bytes,bytes),(uint256,uint256),address)' \
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"(30410,$(cast abi-encode 'f(address)' <TEMPO_WALLET_ADDRESS>),<AMOUNT>,<MIN_AMOUNT>,0x,0x,0x)" \
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"(<NATIVE_FEE>,0)" \
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<SOURCE_BASE_ADDRESS> \
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<SOURCE_ADDRESS> \
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--value <NATIVE_FEE> \
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--rpc-url https://mainnet.base.org \
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--private-key $PRIVATE_KEY
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```
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#### Step 4 — Verify transaction status
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Track the bridge with the transaction hash returned by `sendToken`:
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##### Step 4 - Verify transaction status
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```text
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https://scan.layerzero-api.com/v1/messages/tx/<SOURCE_TX_HASH>
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```
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Once delivered, view the destination transaction on Tempo:
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```text
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https://explore.tempo.xyz/tx/<DESTINATION_TX_HASH>
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```
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### Using TypeScript (viem)
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#### Using TypeScript (viem)
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```typescript
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import { createWalletClient, createPublicClient, http, parseUnits, pad } from 'viem'
@@ -219,7 +236,7 @@ const msgFee = await publicClient.readContract({
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args: [sendParam, false],
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})
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// 2. Approve USDC
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// 2. Approve token
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await walletClient.writeContract({
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address: usdc,
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abi: erc20Abi,
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})
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```
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## Bridge from Tempo
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To bridge USDC.e from Tempo back to another chain, call `sendToken` on the **StargateOFTUSDC** contract on Tempo. The process is the same — quote, approve, send — but the source contract and destination EID are swapped.
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### Bridge from Tempo via Stargate
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### Using cast (Foundry)
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To bridge from Tempo back to another chain, call `sendToken` on the Stargate OFT contract on Tempo. The process is the same - quote, approve, send - but the source contract and destination EID are swapped.
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Bridge USDC.e from Tempo to Base using `cast`. This calls `sendToken` on the **StargateOFTUSDC** contract on Tempo. This example uses [taxi mode](#bus-vs-taxi-mode) for immediate delivery.
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#### Using cast (Foundry)
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#### Step 1 — Quote the fee
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This example bridges USDC.e from Tempo to Base.
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Use the same parameters you will pass to `sendToken`. Returns `(nativeFee, lzTokenFee)`.
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Take the first returned number as `<NATIVE_FEE>` (in stablecoin units, not ETH).
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##### Step 1 - Quote the fee
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```bash
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cast call 0x8c76e2F6C5ceDA9AA7772e7efF30280226c44392 \
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--rpc-url https://rpc.tempo.xyz
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```
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#### Step 2 — Approve USDC.e on Tempo
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Take the first returned number as `<NATIVE_FEE>` (in stablecoin units, not ETH).
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Approve the StargateOFTUSDC contract to spend USDC.e.
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##### Step 2 - Approve token on Tempo
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```bash
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cast send 0x20C000000000000000000000b9537d11c60E8b50 \
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--private-key $PRIVATE_KEY
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```
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#### Step 3 — Send bridge transaction
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##### Step 3 - Send bridge transaction
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No `--value` is needed on Tempo — the messaging fee is paid in a TIP-20 stablecoin via [EndpointDollar](#endpointdollar).
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No `--value` is needed on Tempo - the messaging fee is paid in a TIP-20 stablecoin via [EndpointDollar](#endpointdollar).
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```bash
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cast send 0x8c76e2F6C5ceDA9AA7772e7efF30280226c44392 \
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--private-key $PRIVATE_KEY
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```
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#### Step 4 — Verify transaction status
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Track the bridge with the transaction hash returned by `sendToken`:
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##### Step 4 - Verify transaction status
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```text
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https://scan.layerzero-api.com/v1/messages/tx/<SOURCE_TX_HASH>
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Once delivered, view the destination transaction on the destination chain explorer.
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### Using TypeScript (viem)
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#### Using TypeScript (viem)
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```typescript
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import { createWalletClient, createPublicClient, http, parseUnits, pad } from 'viem'
@@ -310,7 +320,7 @@ const walletClient = createWalletClient({
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transport: http(),
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// StargateOFTUSDC on Tempo
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// Stargate OFT for USDC.e on Tempo
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const stargateOFT = '0x8c76e2F6C5ceDA9AA7772e7efF30280226c44392' as const
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// USDC.e on Tempo
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const usdce = '0x20C000000000000000000000b9537d11c60E8b50' as const
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args: [sendParam, false],
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})
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// 2. Approve USDC.e
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// 2. Approve token
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await walletClient.writeContract({
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address: usdce,
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abi: erc20Abi,
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functionName: 'approve',
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args: [stargateOFT, amount],
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})
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// 3. Send the bridge transaction (no value — fee handled via EndpointDollar)
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// 3. Send the bridge transaction (no value - fee handled via EndpointDollar)
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await walletClient.writeContract({
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address: stargateOFT,
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abi: stargateAbi,
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```
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## EndpointDollar
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Tempo has no native gas token, so there is no `msg.value`. Standard LayerZero endpoints require `msg.value` to pay messaging fees, which doesn't work on Tempo.
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**LZEndpointDollar** ([`0x0cEb237E109eE22374a567c6b09F373C73FA4cBb`](https://explore.tempo.xyz/address/0x0cEb237E109eE22374a567c6b09F373C73FA4cBb)) is an adapter contract that routes LayerZero messaging fees through a TIP-20 stablecoin instead of `msg.value`. It wraps the standard `EndpointV2` so that Stargate's OFT contracts can function on Tempo without modification.
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This is transparent for end users:
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- **Bridging to Tempo** — fees are paid in native gas on the source chain (ETH, MATIC, AVAX, etc.) as normal.
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- **Bridging from Tempo** — `LZEndpointDollar` automatically deducts the messaging fee from a TIP-20 stablecoin. No `msg.value` is needed.
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- **Developers** don't need to interact with `LZEndpointDollar` directly. The StargateOFTUSDC contract handles it internally.
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## Bus vs. Taxi mode
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### Bus vs. Taxi mode
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Stargate offers two delivery modes:
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| Mode | `oftCmd` | Delivery | Cost |
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|------|----------|----------|------|
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| **Taxi** | `0x` (empty) | Immediate — message sent right away | Higher gas cost |
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| **Bus** | `0x00` (1 byte) | Batched — waits for other passengers | Lower gas cost |
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| **Taxi** | `0x` (empty) | Immediate - message sent right away | Higher gas cost |
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| **Bus** | `0x00` (1 byte) | Batched - waits for other passengers | Lower gas cost |
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All examples above use taxi mode for immediate delivery. To use bus mode, set `oftCmd` to `0x00`:
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All examples above use taxi mode. To use bus mode, set `oftCmd` to `0x00`:
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```bash
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# cast — bus mode
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# cast - bus mode
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oftCmd=0x00
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```
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```typescript
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// viem — bus mode
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// viem - bus mode
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const sendParam = {
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// ...
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oftCmd: '0x00' as const, // bus mode
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395393
Bus mode is not available on all routes. If a bus route is not configured for your source/destination pair, the transaction will revert. Use taxi mode (`0x`) for guaranteed delivery.
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:::
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## Standard OFT tokens
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Tokens like USDT0, frxUSD, cUSD, and others are bridged using the standard LayerZero OFT `send()` interface. Each token issuer deploys their own OFT adapter contract. The `send()` interface uses the same `SendParam` struct as Stargate but calls `send()` instead of `sendToken()`.
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To bridge a standard OFT token, you need the OFT adapter contract address on the source chain. Refer to the token issuer's documentation for their deployment addresses:
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- **USDT0** - [Tether](https://tether.io)
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- **frxUSD** - [Frax](https://docs.frax.com)
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- **cUSD** - [Coinbase](https://docs.cdp.coinbase.com)
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The flow is the same as Stargate - quote, approve, send - but you call `send()` on the OFT adapter instead of `sendToken()` on a Stargate pool:
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```bash
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# Quote
410+
cast call <OFT_ADAPTER> \
411+
'quoteSend((uint32,bytes32,uint256,uint256,bytes,bytes,bytes),bool)((uint256,uint256))' \
412+
"(30410,$(cast abi-encode 'f(address)' <TEMPO_ADDRESS>),<AMOUNT>,<MIN_AMOUNT>,0x,0x,0x)" \
413+
false \
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--rpc-url <SOURCE_RPC>
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# Approve
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cast send <TOKEN_ADDRESS> \
418+
'approve(address,uint256)' \
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<OFT_ADAPTER> \
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<AMOUNT> \
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--rpc-url <SOURCE_RPC> \
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--private-key $PRIVATE_KEY
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# Send
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cast send <OFT_ADAPTER> \
426+
'send((uint32,bytes32,uint256,uint256,bytes,bytes,bytes),(uint256,uint256),address)' \
427+
"(30410,$(cast abi-encode 'f(address)' <TEMPO_ADDRESS>),<AMOUNT>,<MIN_AMOUNT>,0x,0x,0x)" \
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"(<NATIVE_FEE>,0)" \
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<REFUND_ADDRESS> \
430+
--value <NATIVE_FEE> \
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--rpc-url <SOURCE_RPC> \
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--private-key $PRIVATE_KEY
433+
```
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## EndpointDollar
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Tempo has no native gas token, so there is no `msg.value`. Standard LayerZero endpoints require `msg.value` to pay messaging fees, which doesn't work on Tempo.
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**LZEndpointDollar** ([`0x0cEb237E109eE22374a567c6b09F373C73FA4cBb`](https://explore.tempo.xyz/address/0x0cEb237E109eE22374a567c6b09F373C73FA4cBb)) is an adapter contract that routes LayerZero messaging fees through a TIP-20 stablecoin instead of `msg.value`. It wraps the standard `EndpointV2` so that OFT contracts can function on Tempo without modification.
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This is transparent for end users:
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- **Bridging to Tempo** - fees are paid in native gas on the source chain (ETH, MATIC, AVAX, etc.) as normal.
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- **Bridging from Tempo** - `LZEndpointDollar` automatically deducts the messaging fee from a TIP-20 stablecoin. No `msg.value` is needed.
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- **Developers** don't need to interact with `LZEndpointDollar` directly. The OFT contracts on Tempo handle it internally.
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## Further reading
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- [Stargate documentation](https://stargateprotocol.gitbook.io/stargate/v2-developer-docs)
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- [LayerZero V2 documentation](https://docs.layerzero.network/v2)
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- [Stargate documentation](https://stargateprotocol.gitbook.io/stargate/v2-developer-docs)
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- [Bridges & Exchanges on Tempo](/ecosystem/bridges)
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- [Getting Funds on Tempo](/guide/getting-funds)

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