Support OFTs and OApps on Tempo

Does my existing OFT/OApp work on Tempo?

What changes on Tempo

• OFT/OApp contracts are replaced by their Alt variants: OFTAlt, OFTAdapterAlt, OFTBurnSelfMintAlt, or OAppAlt depending on your use case
• Fees are paid in LZD instead of msg.value (this is because Tempo has no native gas token). You must wrap a stablecoin into LZD and approve the OFT before calling send{value: 0}()
• Native drop is not supported (addExecutorNativeDropOption reverts)
• Gas costs are higher on Tempo for certain operations (state creation, new accounts). Set custom enforcedOptions with higher gas limits for lzReceive when Tempo is the destination. See TIP-1010 for the full gas schedule

Sending from other chains to Tempo

• Pay fees in the source chain’s native token (ETH, MATIC, etc.) as usual
• No LZD is needed on the source chain
• The receiver on Tempo does not pay anything to receive the message

Sending from Tempo to other chains

Direct flow (1 view call + 5 transactions)

// 1. Quote the fee (view call)
MessagingFee memory fee = oft.quoteSend(sendParam, false);

// 2. Approve the asset token to the OFT (bridge amount)
IERC20(usdce).approve(address(oft), sendParam.amountLD);

// 3. Approve the fee token to LZD (fee amount)
IERC20(usdce).approve(address(lzd), fee.nativeFee);

// 4. Wrap stablecoin into LZD (token must be whitelisted by LZD)
lzd.wrap(usdce, msg.sender, fee.nativeFee);

// 5. Approve LZD to the OFT (fee amount)
IERC20(lzd).approve(address(oft), fee.nativeFee);

// 6. Send with msg.value = 0
oft.send{value: 0}(sendParam, fee, refundAddress);

Wrapper flow (1 view call + 2 transactions)

// 1. Quote the fee
MessagingFee memory fee = oft.quoteSend(sendParam, false);

// 2. Approve the fee token to the wrapper (bridge amount + messaging fee)
IERC20(usdce).approve(address(wrapper), sendParam.amountLD + fee.nativeFee);

// 3. Call sendOFT: wrapper handles wrap, approve, and send atomically
wrapper.sendOFT(
    address(oft),       // OFT contract
    usdce,              // fee token (whitelisted stablecoin)
    sendParam,          // standard send parameters
    fee.nativeFee       // max acceptable fee (reverts if re-quote exceeds this)
);

1. Pulls tokens from the caller:
   • Same token (e.g., USDC.e for both bridging and fees): pulls amountLD + nativeFee in a single transfer
   • Different tokens (e.g., bridging EURC.e, fees in USDC.e): pulls amountLD and nativeFee separately, requiring two approvals
2. Wraps the fee portion into LZD
3. Approves LZD to the OFT
4. Calls oft.send() with the correct fee
5. Reverts the entire transaction if the re-quoted fee exceeds maxNativeFee

With the Value Transfer API (Stargate frontend)

Common pitfalls

• LZD is not available on DEXes. LZD is an ERC-20, not a TIP-20 token, so it cannot be traded on the Tempo DEX. Always use LZD.wrap() to obtain fee tokens.
• Wrapper becomes msg.sender. When using the TempoOFTWrapper, the wrapper is the sender for the OFT call. Do not use it for compose messages where the composer refunds the original sender. The refund goes to the wrapper, not the user, and the funds will be permanently lost.
• Fee token must be a whitelisted stablecoin, not LZD. The feeToken passed to the wrapper must be a 6-decimal stablecoin whitelisted by LZD (pathUSD, USDC.e, or USDT0). Passing LZD itself reverts.