feat: add destination action for event emitter

api/_dexes/utils.ts

@@ -16,6 +16,12 @@ import {
   encodeWithdrawAllWethCalldata,
   getMultiCallHandlerAddress,
 } from "../_multicall-handler";
+import {
+  getEventEmitterAddress,
+  isEventEmitterDeployed,
+  encodeSwapMetadata,
+  encodeEmitDataCalldata,
+} from "../_event-emitter";
 import {
   CrossSwap,
   CrossSwapQuotes,
@@ -771,10 +777,31 @@ export function buildDestinationSwapCrossChainMessage({
           value: "0",
         };
 
+  // Build event emitter action if the contract is deployed on this chain
+  const eventEmitterActions: Action[] = [];
+  if (isEventEmitterDeployed(destinationSwapChainId) && !isIndicativeQuote) {
+    const eventEmitterAddress = getEventEmitterAddress(destinationSwapChainId)!;
+    const metadata = encodeSwapMetadata({
+      version: 1,
+      swapTokenAddress: crossSwap.outputToken.address,
+      swapTokenAmount: destinationSwapQuote.minAmountOut,
+      recipient: crossSwap.recipient,
+      appFeeRecipient: crossSwap.appFeeRecipient || constants.AddressZero,
+      swapProvider: destinationSwapQuote.swapProvider.name,
+    });
+    eventEmitterActions.push({
+      target: eventEmitterAddress,
+      callData: encodeEmitDataCalldata(metadata),
+      value: "0",
+    });
+  }
+
   return buildMulticallHandlerMessage({
     fallbackRecipient: getFallbackRecipient(crossSwap, destinationRecipient),
     actions: [
       routerTransferAction,
+      // emit destination swap metadata event
+      ...eventEmitterActions,
       // swap bridgeable output token -> cross swap output token
       ...swapActions,
       // unwrap weth if output token is native

api/_event-emitter.ts

@@ -0,0 +1,102 @@
+import { CHAIN_IDs } from "@across-protocol/constants";
+import { ethers } from "ethers";
+
+// AcrossEventEmitter contract addresses per chain
+export const ACROSS_EVENT_EMITTER_ADDRESS: Record<number, string> = {
+  [CHAIN_IDs.MAINNET]: "0xBF75133b48b0a42AB9374027902E83C5E2949034",
+  [CHAIN_IDs.OPTIMISM]: "0xBF75133b48b0a42AB9374027902E83C5E2949034",
+  [CHAIN_IDs.ARBITRUM]: "0xBF75133b48b0a42AB9374027902E83C5E2949034",
+  [CHAIN_IDs.BASE]: "0xBF75133b48b0a42AB9374027902E83C5E2949034",
+  [CHAIN_IDs.POLYGON]: "0xBF75133b48b0a42AB9374027902E83C5E2949034",
+  [CHAIN_IDs.LINEA]: "0xBF75133b48b0a42AB9374027902E83C5E2949034",
+  [CHAIN_IDs.MODE]: "0xBF75133b48b0a42AB9374027902E83C5E2949034",
+  [CHAIN_IDs.BLAST]: "0xBF75133b48b0a42AB9374027902E83C5E2949034",
+  [CHAIN_IDs.LISK]: "0xBF75133b48b0a42AB9374027902E83C5E2949034",
+  [CHAIN_IDs.REDSTONE]: "0xBF75133b48b0a42AB9374027902E83C5E2949034",
+  [CHAIN_IDs.SCROLL]: "0xBF75133b48b0a42AB9374027902E83C5E2949034",
+  [CHAIN_IDs.ZORA]: "0xBF75133b48b0a42AB9374027902E83C5E2949034",
+  [CHAIN_IDs.WORLD_CHAIN]: "0xBF75133b48b0a42AB9374027902E83C5E2949034",
+  [CHAIN_IDs.INK]: "0xBF75133b48b0a42AB9374027902E83C5E2949034",
+  [CHAIN_IDs.SONEIUM]: "0xBF75133b48b0a42AB9374027902E83C5E2949034",
+  [CHAIN_IDs.UNICHAIN]: "0xBF75133b48b0a42AB9374027902E83C5E2949034",
+  [CHAIN_IDs.BSC]: "0xBF75133b48b0a42AB9374027902E83C5E2949034",
+  [CHAIN_IDs.PLASMA]: "0xBF75133b48b0a42AB9374027902E83C5E2949034",
+  [CHAIN_IDs.ZK_SYNC]: "0x74a2966e23B61A360b1345eA359127aF325beC4C",
+  [CHAIN_IDs.LENS]: "0x6AA1d7390C0B9F36f08503207985fEAE6C6a13Dc",
+  [CHAIN_IDs.HYPEREVM]: "0xBF75133b48b0a42AB9374027902E83C5E2949034",
+};
+
+/**
+ * Get the AcrossEventEmitter contract address for a given chain
+ * @param chainId The chain ID
+ * @returns The contract address or undefined if not deployed on that chain
+ */
+export function getEventEmitterAddress(chainId: number): string | undefined {
+  return ACROSS_EVENT_EMITTER_ADDRESS[chainId];
+}
+
+/**
+ * Check if AcrossEventEmitter is deployed on a given chain
+ * @param chainId The chain ID
+ * @returns True if the contract is deployed (non-zero address), false otherwise
+ */
+export function isEventEmitterDeployed(chainId: number): boolean {
+  const address = getEventEmitterAddress(chainId);
+  return !!address && address !== ethers.constants.AddressZero;
+}
+
+/**
+ * Encodes metadata for destination swap events
+ * @param version Metadata version (1 byte)
+ * @param swapTokenAddress The token being swapped to (32 bytes)
+ * @param swapTokenAmount The amount being swapped (32 bytes)
+ * @param recipient The final recipient address (32 bytes)
+ * @param appFeeRecipient The app fee recipient address (32 bytes, zero address if no app fee)
+ * @param swapProvider The name of the swap provider (UTF-8 encoded, variable length)
+ * @returns Encoded bytes
+ */
+export function encodeSwapMetadata(params: {
+  version: number;
+  swapTokenAddress: string;
+  swapTokenAmount: ethers.BigNumberish;
+  recipient: string;
+  appFeeRecipient: string;
+  swapProvider: string;
+}): string {
+  const {
+    version,
+    swapTokenAddress,
+    swapTokenAmount,
+    recipient,
+    appFeeRecipient,
+    swapProvider,
+  } = params;
+
+  const abiCoder = ethers.utils.defaultAbiCoder;
+
+  // Encode the metadata as a packed bytes structure
+  const encoded = abiCoder.encode(
+    ["uint8", "address", "uint256", "address", "address", "string"],
+    [
+      version,
+      swapTokenAddress,
+      ethers.BigNumber.from(swapTokenAmount),
+      recipient,
+      appFeeRecipient,
+      swapProvider,
+    ]
+  );
+
+  return encoded;
+}
+
+/**
+ * Encodes calldata for calling AcrossEventEmitter.emitData
+ * @param data The bytes data to emit
+ * @returns Encoded calldata
+ */
+export function encodeEmitDataCalldata(data: string): string {
+  const emitDataFunction = "function emitData(bytes calldata data)";
+  const eventEmitterInterface = new ethers.utils.Interface([emitDataFunction]);
+  return eventEmitterInterface.encodeFunctionData("emitData", [data]);
+}