fix: enforce privateKey format precondition on createEvmServerWallet

Author: fernandomg

src/sdk/core/evm/server-wallet.test.ts

@@ -1,4 +1,5 @@
 import type { WalletClient } from 'viem'
+import { mainnet } from 'viem/chains'
 import { beforeEach, describe, expect, it, type Mock, vi } from 'vitest'
 
 import { CapabilityNotSupportedError } from '../errors'
@@ -126,4 +127,23 @@ describe('createEvmServerWallet', () => {
     })
     expect(bundle.Provider).toBeUndefined()
   })
+
+  it('throws when privateKey is not 0x-prefixed', () => {
+    expect(() =>
+      createEvmServerWallet({
+        privateKey:
+          'abcd1234abcd1234abcd1234abcd1234abcd1234abcd1234abcd1234abcd1234' as `0x${string}`,
+        chain: mainnet,
+      }),
+    ).toThrow('privateKey must be a 0x-prefixed 66-character hex string')
+  })
+
+  it('throws when privateKey is wrong length', () => {
+    expect(() =>
+      createEvmServerWallet({
+        privateKey: '0xabcd' as `0x${string}`,
+        chain: mainnet,
+      }),
+    ).toThrow('privateKey must be a 0x-prefixed 66-character hex string')
+  })
 })

src/sdk/core/evm/server-wallet.ts

@@ -41,6 +41,11 @@ export interface EvmServerWalletConfig {
  * @invariant getStatus().connected === true (always connected)
  */
 export function createEvmServerWallet(config: EvmServerWalletConfig): WalletAdapterBundle {
+  if (!config.privateKey.startsWith('0x') || config.privateKey.length !== 66) {
+    throw new Error(
+      'createEvmServerWallet: privateKey must be a 0x-prefixed 66-character hex string.',
+    )
+  }
   const account = privateKeyToAccount(config.privateKey)
   const walletClient = createWalletClient({
     account,