MetaMask
diff --git a/‎packages/wallet-cli/CHANGELOG.md‎
Lines changed: 1 addition & 2 deletions b/‎packages/wallet-cli/CHANGELOG.md‎
Lines changed: 1 addition & 2 deletions
diff --git a/‎packages/wallet-cli/package.json‎
Lines changed: 2 additions & 0 deletions b/‎packages/wallet-cli/package.json‎
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diff --git a/‎packages/wallet-cli/src/daemon/daemon-client.test.ts‎
Lines changed: 368 additions & 0 deletions b/‎packages/wallet-cli/src/daemon/daemon-client.test.ts‎
Lines changed: 368 additions & 0 deletions
@@ -9,9 +9,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- Add a daemon transport layer: a JSON-RPC client and server over a Unix socket, plus daemon spawn/stop lifecycle helpers ([#9108](https://github.com/MetaMask/core/pull/9108))
 - Add SQLite-backed persistence for wallet controller state ([#9067](https://github.com/MetaMask/core/pull/9067))
-  - A `KeyValueStore` backed by `better-sqlite3` for synchronous reads and writes.
-  - `loadState` to rehydrate persist-flagged controller state from the store and `subscribeToChanges` to write persist-flagged controller state through to disk on every `stateChanged` event.
 - Initial package scaffold for `@metamask/wallet-cli`, an [oclif](https://oclif.io)-based `mm` CLI for `@metamask/wallet` ([#9065](https://github.com/MetaMask/core/pull/9065)).
 
 ### Changed
 
@@ -43,7 +43,9 @@
     "test:watch": "NODE_OPTIONS=--experimental-vm-modules jest --watch"
   },
   "dependencies": {
+    "@inquirer/confirm": "^6.0.11",
     "@metamask/base-controller": "^9.1.0",
+    "@metamask/rpc-errors": "^7.0.2",
     "@metamask/utils": "^11.11.0",
     "@metamask/wallet": "^4.0.0",
     "@oclif/core": "^4.10.5",
 
@@ -0,0 +1,368 @@
+import type { JsonRpcResponse } from '@metamask/utils';
+import { EventEmitter } from 'node:events';
+import { createConnection } from 'node:net';
+import type { Socket } from 'node:net';
+
+import { sendCommand, pingDaemon } from './daemon-client';
+import { readLine, writeLine } from './socket-line';
+
+jest.mock('node:net');
+jest.mock('./socket-line');
+
+const mockCreateConnection = jest.mocked(createConnection);
+const mockReadLine = jest.mocked(readLine);
+const mockWriteLine = jest.mocked(writeLine);
+
+/**
+ * Create a mock Socket and wire up createConnection to return it.
+ * The connection callback is deferred via process.nextTick to match
+ * real behavior (the `socket` const must be assigned before the callback
+ * references it).
+ *
+ * @returns The mock socket.
+ */
+function setupMockSocket(): Socket {
+  const emitter = new EventEmitter();
+  const socket = Object.assign(emitter, {
+    destroy: jest.fn(),
+    write: jest.fn(),
+    removeListener: emitter.removeListener.bind(emitter),
+  }) as unknown as Socket;
+
+  mockCreateConnection.mockImplementation(
+    (_path: unknown, callback: unknown) => {
+      process.nextTick(() => (callback as () => void)());
+      return socket;
+    },
+  );
+
+  return socket;
+}
+
+/**
+ * Build a JSON-RPC response that mirrors back the request id from the most
+ * recent `mockWriteLine` call. `sendCommand` now verifies id correlation, so
+ * static fixtures no longer work — the response must echo the generated id.
+ *
+ * @param overrides - Optional fields to override on the response.
+ * @returns A function suitable for `mockReadLine.mockImplementation`.
+ */
+function respondWithMatchingId(
+  overrides: Partial<JsonRpcResponse> = {},
+): () => Promise<string> {
+  return async () => {
+    const lastWrite = mockWriteLine.mock.calls.at(-1)?.[1];
+    const sentId =
+      typeof lastWrite === 'string'
+        ? (JSON.parse(lastWrite).id as string)
+        : 'test-id';
+    return JSON.stringify({
+      jsonrpc: '2.0',
+      id: sentId,
+      result: { status: 'ok' },
+      ...overrides,
+    });
+  };
+}
+
+describe('sendCommand', () => {
+  it('sends a JSON-RPC request and returns the response', async () => {
+    const socket = setupMockSocket();
+    mockWriteLine.mockResolvedValue(undefined);
+    mockReadLine.mockImplementation(respondWithMatchingId());
+
+    const response = await sendCommand({
+      socketPath: '/tmp/test.sock',
+      method: 'getStatus',
+    });
+
+    expect(mockCreateConnection).toHaveBeenCalledWith(
+      '/tmp/test.sock',
+      expect.any(Function),
+    );
+    expect(mockWriteLine).toHaveBeenCalledWith(
+      socket,
+      expect.stringContaining('"method":"getStatus"'),
+    );
+    expect(response.result).toStrictEqual({ status: 'ok' });
+    expect(socket.destroy).toHaveBeenCalled();
+  });
+
+  it('includes params when provided', async () => {
+    setupMockSocket();
+    mockWriteLine.mockResolvedValue(undefined);
+    mockReadLine.mockImplementation(respondWithMatchingId());
+
+    await sendCommand({
+      socketPath: '/tmp/test.sock',
+      method: 'test',
+      params: { key: 'value' },
+    });
+
+    const written = mockWriteLine.mock.calls[0][1];
+    expect(JSON.parse(written)).toHaveProperty('params', { key: 'value' });
+  });
+
+  it('omits params when undefined', async () => {
+    setupMockSocket();
+    mockWriteLine.mockResolvedValue(undefined);
+    mockReadLine.mockImplementation(respondWithMatchingId());
+
+    await sendCommand({
+      socketPath: '/tmp/test.sock',
+      method: 'test',
+    });
+
+    const written = mockWriteLine.mock.calls[0][1];
+    expect(JSON.parse(written)).not.toHaveProperty('params');
+  });
+
+  it('passes timeoutMs to readLine', async () => {
+    setupMockSocket();
+    mockWriteLine.mockResolvedValue(undefined);
+    mockReadLine.mockImplementation(respondWithMatchingId());
+
+    await sendCommand({
+      socketPath: '/tmp/test.sock',
+      method: 'test',
+      timeoutMs: 5000,
+    });
+
+    expect(mockReadLine).toHaveBeenCalledWith(expect.anything(), 5000);
+  });
+
+  it('throws when the response id does not match the request id', async () => {
+    setupMockSocket();
+    mockWriteLine.mockResolvedValue(undefined);
+    mockReadLine.mockResolvedValue(
+      JSON.stringify({
+        jsonrpc: '2.0',
+        id: 'unrelated-id',
+        result: { status: 'ok' },
+      }),
+    );
+
+    await expect(
+      sendCommand({ socketPath: '/tmp/test.sock', method: 'test' }),
+    ).rejects.toThrow(/does not match request id/u);
+  });
+
+  it('retries once on ECONNREFUSED', async () => {
+    const socket = setupMockSocket();
+    mockWriteLine.mockResolvedValue(undefined);
+    mockReadLine
+      .mockRejectedValueOnce(
+        Object.assign(new Error('refused'), { code: 'ECONNREFUSED' }),
+      )
+      .mockImplementationOnce(respondWithMatchingId());
+
+    const response = await sendCommand({
+      socketPath: '/tmp/test.sock',
+      method: 'test',
+    });
+
+    expect(response.result).toStrictEqual({ status: 'ok' });
+    expect(socket.destroy).toHaveBeenCalledTimes(2);
+  });
+
+  it('retries once on ECONNRESET', async () => {
+    setupMockSocket();
+    mockWriteLine.mockResolvedValue(undefined);
+    mockReadLine
+      .mockRejectedValueOnce(
+        Object.assign(new Error('reset'), { code: 'ECONNRESET' }),
+      )
+      .mockImplementationOnce(respondWithMatchingId());
+
+    const response = await sendCommand({
+      socketPath: '/tmp/test.sock',
+      method: 'test',
+    });
+
+    expect(response).toHaveProperty('result');
+  });
+
+  it('does not retry on other errors', async () => {
+    setupMockSocket();
+    mockWriteLine.mockResolvedValue(undefined);
+    mockReadLine.mockRejectedValue(new Error('parse error'));
+
+    await expect(
+      sendCommand({ socketPath: '/tmp/test.sock', method: 'test' }),
+    ).rejects.toThrow('parse error');
+
+    expect(mockReadLine).toHaveBeenCalledTimes(1);
+  });
+
+  it('destroys socket even when attempt throws', async () => {
+    const socket = setupMockSocket();
+    mockWriteLine.mockRejectedValue(new Error('write error'));
+
+    await expect(
+      sendCommand({ socketPath: '/tmp/test.sock', method: 'test' }),
+    ).rejects.toThrow('write error');
+
+    expect(socket.destroy).toHaveBeenCalled();
+  });
+
+  it('destroys each socket when the connection fails, including the retry', async () => {
+    const sockets: Socket[] = [];
+    mockCreateConnection.mockImplementation((_path: unknown) => {
+      const emitter = new EventEmitter();
+      const socket = Object.assign(emitter, {
+        destroy: jest.fn(),
+        write: jest.fn(),
+        removeListener: emitter.removeListener.bind(emitter),
+      }) as unknown as Socket;
+      sockets.push(socket);
+      process.nextTick(() =>
+        socket.emit(
+          'error',
+          Object.assign(new Error('refused'), { code: 'ECONNREFUSED' }),
+        ),
+      );
+      return socket;
+    });
+
+    await expect(
+      sendCommand({ socketPath: '/tmp/test.sock', method: 'test' }),
+    ).rejects.toThrow('refused');
+
+    expect(sockets).toHaveLength(2);
+    sockets.forEach((socket) => expect(socket.destroy).toHaveBeenCalled());
+  });
+});
+
+describe('pingDaemon', () => {
+  /**
+   * Configure `createConnection` to emit a connection error synchronously.
+   *
+   * @param code - The Node errno code (e.g. ENOENT, ECONNREFUSED) the mock
+   * socket should emit on the next attempt.
+   */
+  function mockConnectionError(code: string): void {
+    mockCreateConnection.mockImplementation((_path: unknown) => {
+      const emitter = new EventEmitter();
+      const socket = Object.assign(emitter, {
+        destroy: jest.fn(),
+        write: jest.fn(),
+        removeListener: emitter.removeListener.bind(emitter),
+      }) as unknown as Socket;
+      process.nextTick(() =>
+        socket.emit('error', Object.assign(new Error(code), { code })),
+      );
+      return socket;
+    });
+  }
+
+  it('returns responsive when daemon responds', async () => {
+    setupMockSocket();
+    mockWriteLine.mockResolvedValue(undefined);
+    mockReadLine.mockImplementation(respondWithMatchingId());
+
+    expect(await pingDaemon('/tmp/test.sock')).toStrictEqual({
+      status: 'responsive',
+    });
+  });
+
+  it('returns absent when the socket file does not exist', async () => {
+    mockConnectionError('ENOENT');
+
+    expect(await pingDaemon('/tmp/test.sock')).toStrictEqual({
+      status: 'absent',
+    });
+  });
+
+  it('returns unreachable with reason=refused when the socket refuses connection', async () => {
+    // ECONNREFUSED is retried once; both attempts will reject with the same
+    // mock implementation.
+    mockConnectionError('ECONNREFUSED');
+
+    const result = await pingDaemon('/tmp/test.sock');
+    expect(result).toStrictEqual({
+      status: 'unreachable',
+      reason: 'refused',
+      error: expect.any(Error),
+    });
+  });
+
+  it('returns unreachable with reason=permission on EACCES', async () => {
+    mockConnectionError('EACCES');
+
+    const result = await pingDaemon('/tmp/test.sock');
+    expect(result).toMatchObject({
+      status: 'unreachable',
+      reason: 'permission',
+    });
+  });
+
+  it('returns unreachable with reason=timeout when the socket read times out', async () => {
+    setupMockSocket();
+    mockWriteLine.mockResolvedValue(undefined);
+    mockReadLine.mockRejectedValue(new Error('Socket read timed out'));
+
+    const result = await pingDaemon('/tmp/test.sock');
+    expect(result).toMatchObject({
+      status: 'unreachable',
+      reason: 'timeout',
+    });
+  });
+
+  it('returns unreachable with reason=protocol on a JSON-RPC id mismatch', async () => {
+    setupMockSocket();
+    mockWriteLine.mockResolvedValue(undefined);
+    mockReadLine.mockResolvedValue(
+      JSON.stringify({
+        jsonrpc: '2.0',
+        id: 'unrelated-id',
+        result: { status: 'ok' },
+      }),
+    );
+
+    const result = await pingDaemon('/tmp/test.sock');
+    expect(result).toMatchObject({
+      status: 'unreachable',
+      reason: 'protocol',
+    });
+  });
+
+  it('returns unreachable with reason=protocol on a JSON parse error', async () => {
+    setupMockSocket();
+    mockWriteLine.mockResolvedValue(undefined);
+    mockReadLine.mockResolvedValue('not json');
+
+    const result = await pingDaemon('/tmp/test.sock');
+    expect(result).toMatchObject({
+      status: 'unreachable',
+      reason: 'protocol',
+    });
+  });
+
+  it('returns unreachable with reason=other for unclassified errors', async () => {
+    setupMockSocket();
+    mockWriteLine.mockResolvedValue(undefined);
+    mockReadLine.mockRejectedValue(new Error('something weird'));
+
+    const result = await pingDaemon('/tmp/test.sock');
+    expect(result).toMatchObject({
+      status: 'unreachable',
+      reason: 'other',
+    });
+  });
+
+  it('normalizes non-Error throws into an Error instance', async () => {
+    setupMockSocket();
+    mockWriteLine.mockResolvedValue(undefined);
+    // Simulate a non-Error throw; the producer must normalize it.
+    mockReadLine.mockImplementation(async () =>
+      Promise.reject('string-throw' as unknown as Error),
+    );
+
+    const result = await pingDaemon('/tmp/test.sock');
+    expect(result).toStrictEqual({
+      status: 'unreachable',
+      reason: 'other',
+      error: expect.objectContaining({ message: 'string-throw' }),
+    });
+  });
+});