Improve type safety in RBF service by replacing any types with proper interfaces

package.json

@@ -101,7 +101,7 @@
   },
   "devDependencies": {
     "@expo/ngrok": "^4.1.3",
-    "@types/node": "^24.5.2",
+    "@types/node": "^24.10.7",
     "@types/react": "~19.1.0",
     "eas-cli-local-build-plugin": "^1.0.240",
     "eslint": "^9.35.0",

services/rbf-service.ts

@@ -29,7 +29,12 @@ const MIN_RBF_FEE_INCREASE_RATE = 0.1;
  * Validates the given ECC library by checking basic functionality.
  * Throws an error if validation fails.
  */
-function validateECCLibrary(ecc: any): void {
+interface ECCLibrary {
+  isPrivate(privKey: Uint8Array): boolean;
+  pointFromScalar(scalar: Uint8Array, compressed: boolean): Uint8Array | null;
+}
+
+function validateECCLibrary(ecc: ECCLibrary): void {
   const testPrivateKey = new Uint8Array(32);
   testPrivateKey[31] = 1; // Set to 1 to ensure it's a valid private key
 
@@ -45,9 +50,47 @@ function validateECCLibrary(ecc: any): void {
   }
 }
 
+export interface EsploraTransactionVin {
+  txid?: string;
+  vout?: number;
+  sequence?: number;
+  prevout?: {
+    value?: number;
+    scriptpubkey?: string;
+    scriptpubkey_address?: string;
+  } | null;
+  [key: string]: unknown;
+}
+
+export interface EsploraTransactionVout {
+  value?: number;
+  scriptpubkey?: string;
+  scriptpubkey_address?: string;
+  [key: string]: unknown;
+}
+
+/**
+ * Minimal representation of an Esplora transaction used by the RBF service.
+ * Additional fields returned by Esplora are allowed via the index signature.
+ */
+export interface EsploraTransaction {
+  txid: string;
+  version?: number;
+  locktime?: number;
+  vin: EsploraTransactionVin[];
+  vout: EsploraTransactionVout[];
+  status?: {
+    confirmed?: boolean;
+    block_height?: number;
+    block_hash?: string;
+    block_time?: number;
+  };
+  [key: string]: unknown;
+}
+
 export interface RBFTransaction {
   txid: string;
-  originalTx: any; // Raw Esplora transaction with vin/vout properties
+  originalTx: EsploraTransaction; // Raw Esplora transaction with vin/vout properties
   newFeeRate: number;
   newFee: number;
   replacementTx?: string; // hex transaction
@@ -59,7 +102,7 @@ export interface RBFValidationResult {
   isValid: boolean;
   canReplace: boolean;
   reason?: string;
-  originalTx?: any; // Raw Esplora transaction with vin/vout properties
+  originalTx?: EsploraTransaction; // Raw Esplora transaction with vin/vout properties
   utxos?: UTXO[];
 }
 
@@ -72,7 +115,7 @@ export interface RBFValidationResult {
  * causing incorrect RBF validation. This function now detects the format
  * and parses accordingly.
  */
-function parseSequenceNumber(sequence: any): number {
+function parseSequenceNumber(sequence: unknown): number {
   if (typeof sequence === 'number') {
     return sequence;
   }
@@ -415,6 +458,7 @@ export async function createReplacementTransaction(
     const bip32Instance = bip32.BIP32Factory(ecc);
 
     // Create transaction builder (replace TransactionBuilder with PSBT for modern bitcoinjs-lib)
+    // TransactionBuilder is deprecated in newer versions of bitcoinjs-lib. Consider migrating to PSBT (Partially Signed Bitcoin Transaction) for better compatibility and future-proofing.
     let txb = new bitcoin.TransactionBuilder(bitcoin.networks.bitcoin);
 
     // Get our inputs from the original transaction
@@ -433,7 +477,11 @@ export async function createReplacementTransaction(
     const inputMap = new Map<string, { input: any; utxo: UTXO; addressIndex: number; chain: number }>();
 
     for (const input of ourInputs) {
-      const address = input.prevout.scriptpubkey_address;
+      const address = input.prevout?.scriptpubkey_address;
+
+      if (!address) {
+        throw new Error(`Input missing address information: ${JSON.stringify(input)}`);
+      }
 
       // Derive the actual BIP32 address index and chain instead of using array index
       const { index: addressIndex, chain } = await deriveAddressIndexAndChainFromAddress(mnemonic, address);
@@ -490,7 +538,7 @@ export async function createReplacementTransaction(
       } else {
         throw new Error(`Unsupported output type: ${JSON.stringify(output)}`);
       }
-      totalOutputValue += output.value;
+      totalOutputValue += output.value ?? 0;
     }
 
     // Find the change output in the original transaction (if any)
@@ -502,7 +550,7 @@ export async function createReplacementTransaction(
       const output = originalTx.vout[i];
       if (output.scriptpubkey_address && walletAddressesSet.has(output.scriptpubkey_address)) {
         changeOutputIndex = i;
-        changeOutputValue = output.value;
+        changeOutputValue = output.value ?? 0;
         break;
       }
     }
@@ -947,6 +995,7 @@ async function createCancellationTransaction(
     const bip32Instance = bip32.BIP32Factory(ecc);
 
     // Create transaction builder (replace TransactionBuilder with PSBT for modern bitcoinjs-lib)
+    // TransactionBuilder is deprecated in newer versions of bitcoinjs-lib. Consider migrating to PSBT (Partially Signed Bitcoin Transaction) for better compatibility and future-proofing.
     let txb = new bitcoin.TransactionBuilder(bitcoin.networks.bitcoin);
 
     // Get our inputs from the original transaction

tsconfig.json

@@ -2,6 +2,8 @@
   "extends": "expo/tsconfig.base",
   "compilerOptions": {
     "strict": true,
+    "lib": ["ES2015", "ES2016", "ES2017", "ES2018", "ES2019", "ES2020", "DOM"],
+    "target": "ES2015",
     "paths": {
       "@/*": [
         "./*"