feat(snap-networks-utils): add shareable keyring account helpers

packages/snap-networks-utils/CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- Add `ExtendedKeyringAccount`, `KeyringAccountExtension`, and `asStrictKeyringAccount` for snap keyring accounts that persist `entropySource`, `derivationPath`, and `index`. ([#300](https://github.com/MetaMask/internal-snaps/pull/300))
 - Add shared snap state helpers `IStateManager`, `State`, and `InMemoryState` (Tron-style write mutex plus blob/path locking). ([#288](https://github.com/MetaMask/internal-snaps/pull/288))
 - Add shared caching utilities for network snaps ([#287](https://github.com/MetaMask/internal-snaps/pull/287))
   - `ICache`, `CacheEntry`, and `TimestampMilliseconds` for describing a generic cache

packages/snap-networks-utils/package.json

@@ -72,6 +72,7 @@
   },
   "dependencies": {
     "@metamask/assets-controller": "^13.0.0",
+    "@metamask/keyring-api": "^24.1.0",
     "@metamask/remote-feature-flag-controller": "^5.0.0",
     "@metamask/snaps-sdk": "^12.0.1",
     "@metamask/superstruct": "^3.4.1",

packages/snap-networks-utils/src/index.ts

@@ -17,6 +17,11 @@ export {
 } from './utils/sanitize/sanitize';
 export { UrlStruct } from './utils/urlStruct/urlStruct';
 export { UuidStruct } from './utils/uuidStruct/uuidStruct';
+export { asStrictKeyringAccount } from './utils/keyringAccount/keyringAccount';
+export type {
+  ExtendedKeyringAccount,
+  KeyringAccountExtension,
+} from './utils/keyringAccount/keyringAccount';
 export {
   batchesAll,
   batchesAllSettled,

packages/snap-networks-utils/src/utils/keyringAccount/keyringAccount.test.ts

@@ -0,0 +1,42 @@
+import { asStrictKeyringAccount } from './keyringAccount';
+import type { ExtendedKeyringAccount } from './keyringAccount';
+
+describe('asStrictKeyringAccount', () => {
+  const account: ExtendedKeyringAccount = {
+    type: 'eip155:eoa',
+    id: '4b445722-6766-4f99-ade5-c2c9295f21d0',
+    address: 'TAddress0',
+    options: {
+      entropy: {
+        type: 'mnemonic',
+        id: 'entropy-source',
+        derivationPath: "m/44'/195'/0'/0/0",
+        groupIndex: 0,
+      },
+    },
+    methods: ['personal_sign'],
+    scopes: ['tron:mainnet'],
+    entropySource: 'entropy-source',
+    derivationPath: "m/44'/195'/0'/0/0",
+    index: 0,
+  };
+
+  it('returns only KeyringAccount fields', () => {
+    expect(asStrictKeyringAccount(account)).toStrictEqual({
+      type: account.type,
+      id: account.id,
+      address: account.address,
+      options: account.options,
+      methods: account.methods,
+      scopes: account.scopes,
+    });
+  });
+
+  it('does not include entropySource, derivationPath, or index', () => {
+    expect(asStrictKeyringAccount(account)).not.toHaveProperty('entropySource');
+    expect(asStrictKeyringAccount(account)).not.toHaveProperty(
+      'derivationPath',
+    );
+    expect(asStrictKeyringAccount(account)).not.toHaveProperty('index');
+  });
+});

packages/snap-networks-utils/src/utils/keyringAccount/keyringAccount.ts

@@ -0,0 +1,39 @@
+import type { EntropySourceId, KeyringAccount } from '@metamask/keyring-api';
+
+/**
+ * Keyring account fields snaps persist in addition to `@metamask/keyring-api`'s
+ * `KeyringAccount`. `index` is stored so an account can be restored at a
+ * previously used derivation index.
+ */
+export type KeyringAccountExtension = {
+  entropySource: EntropySourceId;
+  derivationPath: `m/${string}`;
+  index: number;
+};
+
+/**
+ * A `KeyringAccount` plus the derivation fields used by Solana, Tron, and Stellar.
+ *
+ * A snap may narrow `derivationPath` (for example Stellar's BIP-44 coin type).
+ */
+export type ExtendedKeyringAccount = KeyringAccount & KeyringAccountExtension;
+
+/**
+ * Converts an extended keyring account to the Keyring API shape (no extra fields).
+ *
+ * @param account - A keyring account, possibly with snap-specific fields.
+ * @returns A strict keyring account.
+ */
+export function asStrictKeyringAccount(
+  account: KeyringAccount,
+): KeyringAccount {
+  const { id, address, type, options, methods, scopes } = account;
+  return {
+    id,
+    address,
+    type,
+    options,
+    methods,
+    scopes,
+  };
+}

yarn.lock

@@ -3327,6 +3327,7 @@ __metadata:
   dependencies:
     "@metamask/assets-controller": "npm:^13.0.0"
     "@metamask/auto-changelog": "npm:^6.1.1"
+    "@metamask/keyring-api": "npm:^24.1.0"
     "@metamask/messenger": "npm:^2.0.0"
     "@metamask/remote-feature-flag-controller": "npm:^5.0.0"
     "@metamask/snaps-sdk": "npm:^12.0.1"