feat: build transaction to update pool Fee

package.json

@@ -18,18 +18,21 @@
   "packageManager": "pnpm@10.18.1",
   "devDependencies": {
     "@eslint/js": "^9.39.1",
+    "@types/json-bigint": "^1.0.4",
     "@types/node": "^24.10.1",
     "eslint": "^9.39.1",
+    "json-bigint": "^1.0.0",
     "prettier": "^3.6.2",
     "tsup": "^8.5.1",
+    "tsx": "^4.20.6",
     "typescript": "^5.9.3",
     "typescript-eslint": "^8.48.0",
     "vitest": "^4.0.13"
   },
   "dependencies": {
     "@anastasia-labs/cardano-multiplatform-lib-nodejs": "6.0.2-3",
-    "dotenv": "^17.2.3",
     "@lucid-evolution/lucid": "^0.4.29",
+    "dotenv": "^17.2.3",
     "winston": "^3.18.3"
   }
 }

src/example.ts

@@ -0,0 +1,40 @@
+import { Blockfrost, Lucid } from '@lucid-evolution/lucid';
+import { updatePoolFeeTx } from './tx';
+
+async function main() {
+  const blockfrostProjectId = '<>YOUR_BLOCKFROST_PROJECT_ID<>';
+  const blockfrostUrl = 'https://cardano-preprod.blockfrost.io/api/v0';
+
+  // Example wallet: It has been granted permissions to manage the pool
+  const seed =
+    'mouse carpet zebra giant just pizza very song simple state rebel lunar above naive bundle accuse buffalo hurry mango scorpion country silly layer average';
+  const walletAddr =
+    'addr_test1qz280luwccrquk3lk4ykjjsexl840ppsy2u6vtq4wflwa2c279l7xk8kwpt4zc27c4dsngvpyuqn700m3s8e0k6fw9nsdudnqx';
+  // The LP asset for the pool we want to update fees for
+  const poolLPAsset = {
+    policyId: 'd6aae2059baee188f74917493cf7637e679cd219bdfbbf4dcbeb1d0b',
+    tokenName:
+      '0c9dfded2857d530ce2cc536d4517a6e4c54e280f5e89b4f315fe0d81cabbcf5',
+  };
+
+  const lucid = await Lucid(
+    new Blockfrost(blockfrostUrl, blockfrostProjectId),
+    'Preprod',
+  );
+
+  lucid.selectWallet.fromSeed(seed);
+
+  const tx = updatePoolFeeTx(lucid, {
+    managerAddress: walletAddr,
+    poolLPAsset: poolLPAsset,
+    newFeeA: 0.9,
+    newFeeB: 0.3,
+  });
+
+  const txComplete = await tx.complete();
+  const signedTx = await txComplete.sign.withWallet().complete();
+  const txHash = await signedTx.submit();
+  console.log('Transaction submitted successfully: ', txHash);
+}
+
+void main();

src/tx.ts

@@ -0,0 +1,110 @@
+import { getAddressDetails, LucidEvolution, TxBuilder } from "@lucid-evolution/lucid";
+import JSONBig from "json-bigint"
+
+const MIN_TRADING_FEE: bigint = 5n; // 0.05%
+const MAX_TRADING_FEE: bigint = 2000n; // 20%
+
+const LP_POLICY_ID_CFG = {
+  ["Mainnet"]: "f5808c2c990d86da54bfc97d89cee6efa20cd8461616359478d96b4c",
+  ["Preprod"]: "d6aae2059baee188f74917493cf7637e679cd219bdfbbf4dcbeb1d0b",
+}
+
+function assetToDottedString(asset: { policyId: string; tokenName: string }): string {
+  if (asset.policyId === "" && asset.tokenName === "") {
+    return "lovelace"
+  }
+  if (asset.tokenName === "") {
+    return asset.policyId;
+  }
+  return `${asset.policyId}.${asset.tokenName}`;
+}
+
+/**
+ * Request to update the trading fees for a liquidity pool.
+ * @property managerAddress - The address of the pool manager authorized to update fees
+ * @property poolLPAsset - The LP token asset identifying the pool
+ * @property newFeeA - The new fee for trading direction A as a percentage (0.05% - 20%)
+ * @property newFeeB - The new fee for trading direction B as a percentage (0.05% - 20%)
+ * @property version - Protocol version for the fee request format
+ */
+export type PoolFeeRequest = {
+  managerAddress: string;
+  poolLPAsset: {
+    policyId: string,
+    tokenName: string
+  };
+  newFeeA: number;
+  newFeeB: number;
+  version: "1";
+};
+
+export type RequestPoolFeeOptions = {
+  request: Omit<PoolFeeRequest, "version">;
+};
+
+/**
+ * Creates a transaction to update the trading fees for a liquidity pool.
+ * This method builds a transaction with metadata that requests fee changes for a pool.
+ * The transaction must be signed by the pool manager address.
+ */
+export function updatePoolFeeTx(
+  lucid: LucidEvolution,
+  options: Omit<PoolFeeRequest, "version">
+): TxBuilder {
+  const { managerAddress, poolLPAsset, newFeeA, newFeeB } = options;
+  const newFeeABps = BigInt(Math.floor(newFeeA * 100));
+  const newFeeBBps = BigInt(Math.floor(newFeeB * 100));
+
+  if (newFeeABps < MIN_TRADING_FEE || newFeeABps > MAX_TRADING_FEE) {
+    throw new Error(
+      `Liquidity Pool Fee A must be in 0.05% - 20%, actual: ${newFeeA}%`
+    );
+  }
+  if (newFeeBBps < MIN_TRADING_FEE || newFeeBBps > MAX_TRADING_FEE) {
+    throw new Error(
+      `Liquidity Pool Fee B must be in 0.05% - 20%, actual: ${newFeeB}%`
+    );
+  }
+
+  const network = lucid.config().network;
+  if (network !== "Mainnet" && network !== "Preprod") {
+    throw new Error(`Unsupported network: ${network}`);
+  }
+
+  if (poolLPAsset.policyId != LP_POLICY_ID_CFG[network]) {
+    throw new Error(
+      `Invalid LP Policy ID for network ${network}: ${poolLPAsset.policyId}`
+    );
+  }
+
+  const feeRequestJSON = JSONBig.stringify({
+    managerAddress: managerAddress,
+    poolLPAsset: assetToDottedString(poolLPAsset),
+    newFeeA: newFeeABps.toString(),
+    newFeeB: newFeeBBps.toString(),
+    version: "1",
+  }).match(/.{1,64}/g);
+
+  if (!feeRequestJSON) {
+    throw new Error("Failed to create fee request JSON metadata");
+  }
+  const addressDetails = getAddressDetails(managerAddress);
+  if (addressDetails.type != "Base" && addressDetails.type != "Enterprise") {
+    throw new Error("Manager address must be a Base or Enterprise address");
+  }
+  const paymentCred = addressDetails.paymentCredential;
+  if (!paymentCred) {
+    throw new Error("Manager address must have a payment credential");
+  }
+  if (paymentCred.type !== "Key") {
+    throw new Error("Manager address must be a key address");
+  }
+
+  return lucid
+    .newTx()
+    .addSigner(managerAddress)
+    .attachMetadata(674, {
+      ["msg"]: ["Minswap: Request of Pool Fee Manager"],
+      ["extraData"]: feeRequestJSON,
+    });
+}