feat: add optional createAccounts method based on KeyringV2 (#448)

Adding a new optional `createAccounts` method that we could already
leverage today without having the full implementation of `KeyringV2`.

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Medium Risk**
> Touches core account-creation pathways and introduces batch mutation
with rollback and locking, which could affect state consistency and Snap
interactions if edge cases are missed.
> 
> **Overview**
> Introduces an optional `Keyring.createAccounts` method plus a new
`keyring_createAccounts` RPC (`KeyringRpcMethod.CreateAccounts`) that
accepts typed v2 `CreateAccountOptions` and returns an array of
accounts.
> 
> Wires the new RPC end-to-end: `keyring-snap-sdk` dispatches
`keyring_createAccounts` (and errors when unimplemented),
`keyring-snap-client` adds `KeyringClient.createAccounts`, and
`SnapKeyring` implements batch creation by validating/adding returned
accounts to internal state (without per-account
`notify:accountCreated`), enforcing idempotency, rejecting
duplicates/unsupported generic accounts, rolling back Snap state via
`deleteAccount` on failure, and serializing concurrent calls via an
`async-mutex` lock.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
7ec3108. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: ccharly

packages/keyring-api/CHANGELOG.md

@@ -9,6 +9,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- Add `Keyring.createAccounts` optional method ([#448](https://github.com/MetaMask/accounts/pull/448))
+  - This method is part of the keyring v2 specification and set as optional for backwards compatibility.
+  - This method can be used to create one or more accounts using the new keyring v2 account creation typed options.
+  - Add RPC support for this method through `KeyringRpcMethod.CreateAccounts`.
 - Add support for account derivations using range of indices in `KeyringV2` ([#451](https://github.com/MetaMask/accounts/pull/451))
   - Add `bip44:derive-index-range` capability to `KeyringCapabilities`.
   - Add `AccountCreationType.Bip44DeriveIndexRange` and `CreateAccountBip44DeriveIndexRangeOptions`.

packages/keyring-api/src/api/keyring.ts

@@ -13,6 +13,7 @@ import type { Paginated, Pagination } from './pagination';
 import type { KeyringRequest } from './request';
 import type { KeyringResponse } from './response';
 import type { Transaction } from './transaction';
+import type { CreateAccountOptions } from './v2';
 
 /**
  * Keyring interface.
@@ -56,6 +57,19 @@ export type Keyring = {
     options?: Record<string, Json> & MetaMaskOptions,
   ): Promise<KeyringAccount>;
 
+  /**
+   * Creates one or more new accounts according to the provided options.
+   *
+   * Deterministic account creation MUST be idempotent, meaning that for
+   * deterministic algorithms, like BIP-44, calling this method with the same
+   * options should always return the same accounts, even if the accounts
+   * already exist in the keyring.
+   *
+   * @param options - Options describing how to create the account(s).
+   * @returns A promise that resolves to an array of the created account objects.
+   */
+  createAccounts?(options: CreateAccountOptions): Promise<KeyringAccount[]>;
+
   /**
    * Lists the assets of an account (fungibles and non-fungibles) represented
    * by their respective CAIP-19:

packages/keyring-api/src/rpc.ts

@@ -28,6 +28,7 @@ import {
   PaginationStruct,
   CaipAccountIdStruct,
   DiscoveredAccountStruct,
+  CreateAccountOptionsStruct,
 } from './api';
 
 /**
@@ -36,6 +37,7 @@ import {
 export enum KeyringRpcMethod {
   // Account management
   CreateAccount = 'keyring_createAccount',
+  CreateAccounts = 'keyring_createAccounts',
   DeleteAccount = 'keyring_deleteAccount',
   DiscoverAccounts = 'keyring_discoverAccounts',
   ExportAccount = 'keyring_exportAccount',
@@ -126,6 +128,23 @@ export const CreateAccountResponseStruct = KeyringAccountStruct;
 
 export type CreateAccountResponse = Infer<typeof CreateAccountResponseStruct>;
 
+// ----------------------------------------------------------------------------
+// Create accounts
+
+export const CreateAccountsRequestStruct = object({
+  ...CommonHeader,
+  method: literal('keyring_createAccounts'),
+  params: object({
+    options: CreateAccountOptionsStruct,
+  }),
+});
+
+export type CreateAccountsRequest = Infer<typeof CreateAccountsRequestStruct>;
+
+export const CreateAccountsResponseStruct = array(KeyringAccountStruct);
+
+export type CreateAccountsResponse = Infer<typeof CreateAccountsResponseStruct>;
+
 // ----------------------------------------------------------------------------
 // Set selected accounts
 

packages/keyring-snap-bridge/CHANGELOG.md

@@ -7,6 +7,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Add `SnapKeyring.createAccounts` method ([#448](https://github.com/MetaMask/accounts/pull/448))
+  - This method can be used to create one or more accounts using the new keyring v2 account creation typed options.
+  - Generic accounts will be filtered out if they are not allowed by the keyring configuration.
+
 ### Changed
 
 - Bump `@metamask/snaps-controllers` from `^14.0.1` to `^17.2.0` ([#422](https://github.com/MetaMask/accounts/pull/422))

packages/keyring-snap-bridge/package.json

@@ -48,6 +48,7 @@
     "@metamask/superstruct": "^3.1.0",
     "@metamask/utils": "^11.1.0",
     "@types/uuid": "^9.0.8",
+    "async-mutex": "^0.5.0",
     "uuid": "^9.0.1"
   },
   "devDependencies": {