feat(stellar-utils): add transaction hash validation utility

shared/stellar-utils/index.ts

@@ -34,6 +34,13 @@ export function formatAmount(amount: string, decimals: number = 7): string {
   }
 }
 
+/**
+ * Validate a Stellar transaction hash (64-character lowercase hex string)
+ */
+export function validateTransactionHash(hash: string): boolean {
+  return /^[0-9a-f]{64}$/.test(hash);
+}
+
 export function buildPaymentOperation(params: { source?: string; destination: string; asset: string; amount: string }){
   // Placeholder: return normalized operation object
   return {

shared/stellar-utils/package.json

@@ -11,6 +11,7 @@
   },
   "scripts": {
     "build": "tsc",
-    "type-check": "tsc --noEmit"
+    "type-check": "tsc --noEmit",
+    "test": "cross-env TS_NODE_TRANSPILE_ONLY=true node --loader ts-node/esm transaction-hash.test.ts"
   }
 }

shared/stellar-utils/transaction-hash.test.ts

@@ -0,0 +1,32 @@
+import test from 'node:test';
+import assert from 'node:assert';
+import { validateTransactionHash } from './index.js';
+
+test('validateTransactionHash returns true for a valid 64-char lowercase hex', () => {
+  const hash = 'abcdef0123456789abcdef0123456789abcdef0123456789abcdef0123456789';
+  assert.strictEqual(hash.length, 64);
+  assert.strictEqual(validateTransactionHash(hash), true);
+});
+
+test('validateTransactionHash returns false for hash with invalid length', () => {
+  assert.strictEqual(validateTransactionHash('a1b2c3d4'), false);
+  assert.strictEqual(validateTransactionHash(''), false);
+  assert.strictEqual(validateTransactionHash('a'.repeat(63)), false);
+  assert.strictEqual(validateTransactionHash('a'.repeat(65)), false);
+});
+
+test('validateTransactionHash returns false for uppercase hex', () => {
+  const hash = 'A1B2C3D4E5F6A7B8C9D0E1F2A3B4C5D6E7F8A9B0C1D2E3F4A5B6C7D8E9F0A1B';
+  assert.strictEqual(validateTransactionHash(hash), false);
+});
+
+test('validateTransactionHash returns false for non-hex characters', () => {
+  assert.strictEqual(validateTransactionHash('x'.repeat(64)), false);
+  assert.strictEqual(validateTransactionHash('g'.repeat(64)), false);
+  assert.strictEqual(validateTransactionHash('z1b2c3d4e5f6a7b8c9d0e1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f0a1b'), false);
+});
+
+test('validateTransactionHash returns false for non-string input', () => {
+  assert.strictEqual(validateTransactionHash(undefined as any), false);
+  assert.strictEqual(validateTransactionHash(null as any), false);
+});