feat: allow custom filename for context files (#654)

Co-authored-by: N. Taylor Mullen <[email protected]>

12 files changed, 1000 insertions, 97 deletions

diff --git a/packages/cli/src/config/config.ts b/packages/cli/src/config/config.ts
index 04347427..44057fad 100644
--- a/packages/cli/src/config/config.ts
+++ b/packages/cli/src/config/config.ts
@@ -13,6 +13,8 @@ import {
   createServerConfig,
   loadServerHierarchicalMemory,
   ConfigParameters,
+  setGeminiMdFilename as setServerGeminiMdFilename,
+  getCurrentGeminiMdFilename,
 } from '@gemini-code/core';
 import { Settings } from './settings.js';
 import { readPackageUp } from 'read-package-up';
@@ -132,6 +134,17 @@ export async function loadCliConfig(settings: Settings): Promise<Config> {
   const argv = await parseArguments();
   const debugMode = argv.debug || false;
 
+  // Set the context filename in the server's memoryTool module BEFORE loading memory
+  // TODO(b/343434939): This is a bit of a hack. The contextFileName should ideally be passed
+  // directly to the Config constructor in core, and have core handle setGeminiMdFilename.
+  // However, loadHierarchicalGeminiMemory is called *before* createServerConfig.
+  if (settings.contextFileName) {
+    setServerGeminiMdFilename(settings.contextFileName);
+  } else {
+    // Reset to default if not provided in settings.
+    setServerGeminiMdFilename(getCurrentGeminiMdFilename());
+  }
+
   // Call the (now wrapper) loadHierarchicalGeminiMemory which calls the server's version
   const { memoryContent, fileCount } = await loadHierarchicalGeminiMemory(
     process.cwd(),
@@ -159,7 +172,8 @@ export async function loadCliConfig(settings: Settings): Promise<Config> {
     userMemory: memoryContent,
     geminiMdFileCount: fileCount,
     vertexai: useVertexAI,
-    showMemoryUsage: argv.show_memory_usage || false,
+    showMemoryUsage:
+      argv.show_memory_usage || settings.showMemoryUsage || false,
   };
 
   return createServerConfig(configParams);
diff --git a/packages/cli/src/config/settings.test.ts b/packages/cli/src/config/settings.test.ts
new file mode 100644
index 00000000..4d61ed8b
--- /dev/null
+++ b/packages/cli/src/config/settings.test.ts
@@ -0,0 +1,309 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/// <reference types="vitest/globals" />
+
+const MOCK_HOME_DIR = '/mock/home/user'; // MUST BE FIRST
+
+// Mock 'os' first. Its factory uses MOCK_HOME_DIR.
+import * as osActual from 'os'; // Import for type info for the mock factory
+vi.mock('os', async (importOriginal) => {
+  const actualOs = await importOriginal<typeof osActual>();
+  return {
+    ...actualOs,
+    homedir: vi.fn(() => MOCK_HOME_DIR),
+  };
+});
+
+// Mock './settings.js' to ensure it uses the mocked 'os.homedir()' for its internal constants.
+vi.mock('./settings.js', async (importActual) => {
+  const originalModule = await importActual<typeof import('./settings.js')>();
+  return {
+    __esModule: true, // Ensure correct module shape
+    ...originalModule, // Re-export all original members
+    // We are relying on originalModule's USER_SETTINGS_PATH being constructed with mocked os.homedir()
+  };
+});
+
+// NOW import everything else, including the (now effectively re-exported) settings.js
+import * as pathActual from 'path'; // Restored for MOCK_WORKSPACE_SETTINGS_PATH
+import {
+  describe,
+  it,
+  expect,
+  vi,
+  beforeEach,
+  afterEach,
+  type Mocked,
+  type Mock,
+} from 'vitest';
+import * as fs from 'fs'; // fs will be mocked separately
+import stripJsonComments from 'strip-json-comments'; // Will be mocked separately
+
+// These imports will get the versions from the vi.mock('./settings.js', ...) factory.
+import {
+  LoadedSettings,
+  loadSettings,
+  USER_SETTINGS_PATH, // This IS the mocked path.
+  SETTINGS_DIRECTORY_NAME, // This is from the original module, but used by the mock.
+  SettingScope,
+} from './settings.js';
+
+const MOCK_WORKSPACE_DIR = '/mock/workspace';
+// Use the (mocked) SETTINGS_DIRECTORY_NAME for consistency
+const MOCK_WORKSPACE_SETTINGS_PATH = pathActual.join(
+  MOCK_WORKSPACE_DIR,
+  SETTINGS_DIRECTORY_NAME,
+  'settings.json',
+);
+
+vi.mock('fs');
+vi.mock('strip-json-comments', () => ({
+  default: vi.fn((content) => content),
+}));
+
+describe('Settings Loading and Merging', () => {
+  let mockFsExistsSync: Mocked<typeof fs.existsSync>;
+  let mockStripJsonComments: Mocked<typeof stripJsonComments>;
+  let mockFsMkdirSync: Mocked<typeof fs.mkdirSync>;
+
+  beforeEach(() => {
+    vi.resetAllMocks();
+
+    mockFsExistsSync = vi.mocked(fs.existsSync);
+    mockFsMkdirSync = vi.mocked(fs.mkdirSync);
+    mockStripJsonComments = vi.mocked(stripJsonComments);
+
+    vi.mocked(osActual.homedir).mockReturnValue(MOCK_HOME_DIR);
+    (mockStripJsonComments as unknown as Mock).mockImplementation(
+      (jsonString: string) => jsonString,
+    );
+    (mockFsExistsSync as Mock).mockReturnValue(false);
+    (fs.readFileSync as Mock).mockReturnValue('{}'); // Return valid empty JSON
+    (mockFsMkdirSync as Mock).mockImplementation(() => undefined);
+  });
+
+  afterEach(() => {
+    vi.restoreAllMocks();
+  });
+
+  describe('loadSettings', () => {
+    it('should load empty settings if no files exist', () => {
+      const settings = loadSettings(MOCK_WORKSPACE_DIR);
+      expect(settings.user.settings).toEqual({});
+      expect(settings.workspace.settings).toEqual({});
+      expect(settings.merged).toEqual({});
+    });
+
+    it('should load user settings if only user file exists', () => {
+      const expectedUserSettingsPath = USER_SETTINGS_PATH; // Use the path actually resolved by the (mocked) module
+
+      (mockFsExistsSync as Mock).mockImplementation(
+        (p: fs.PathLike) => p === expectedUserSettingsPath,
+      );
+      const userSettingsContent = {
+        theme: 'dark',
+        contextFileName: 'USER_CONTEXT.md',
+      };
+      (fs.readFileSync as Mock).mockImplementation(
+        (p: fs.PathOrFileDescriptor) => {
+          if (p === expectedUserSettingsPath)
+            return JSON.stringify(userSettingsContent);
+          return '{}';
+        },
+      );
+
+      const settings = loadSettings(MOCK_WORKSPACE_DIR);
+
+      expect(fs.readFileSync).toHaveBeenCalledWith(
+        expectedUserSettingsPath,
+        'utf-8',
+      );
+      expect(settings.user.settings).toEqual(userSettingsContent);
+      expect(settings.workspace.settings).toEqual({});
+      expect(settings.merged).toEqual(userSettingsContent);
+    });
+
+    it('should load workspace settings if only workspace file exists', () => {
+      (mockFsExistsSync as Mock).mockImplementation(
+        (p: fs.PathLike) => p === MOCK_WORKSPACE_SETTINGS_PATH,
+      );
+      const workspaceSettingsContent = {
+        sandbox: true,
+        contextFileName: 'WORKSPACE_CONTEXT.md',
+      };
+      (fs.readFileSync as Mock).mockImplementation(
+        (p: fs.PathOrFileDescriptor) => {
+          if (p === MOCK_WORKSPACE_SETTINGS_PATH)
+            return JSON.stringify(workspaceSettingsContent);
+          return '';
+        },
+      );
+
+      const settings = loadSettings(MOCK_WORKSPACE_DIR);
+
+      expect(fs.readFileSync).toHaveBeenCalledWith(
+        MOCK_WORKSPACE_SETTINGS_PATH,
+        'utf-8',
+      );
+      expect(settings.user.settings).toEqual({});
+      expect(settings.workspace.settings).toEqual(workspaceSettingsContent);
+      expect(settings.merged).toEqual(workspaceSettingsContent);
+    });
+
+    it('should merge user and workspace settings, with workspace taking precedence', () => {
+      (mockFsExistsSync as Mock).mockReturnValue(true);
+      const userSettingsContent = {
+        theme: 'dark',
+        sandbox: false,
+        contextFileName: 'USER_CONTEXT.md',
+      };
+      const workspaceSettingsContent = {
+        sandbox: true,
+        coreTools: ['tool1'],
+        contextFileName: 'WORKSPACE_CONTEXT.md',
+      };
+
+      (fs.readFileSync as Mock).mockImplementation(
+        (p: fs.PathOrFileDescriptor) => {
+          if (p === USER_SETTINGS_PATH)
+            return JSON.stringify(userSettingsContent);
+          if (p === MOCK_WORKSPACE_SETTINGS_PATH)
+            return JSON.stringify(workspaceSettingsContent);
+          return '';
+        },
+      );
+
+      const settings = loadSettings(MOCK_WORKSPACE_DIR);
+
+      expect(settings.user.settings).toEqual(userSettingsContent);
+      expect(settings.workspace.settings).toEqual(workspaceSettingsContent);
+      expect(settings.merged).toEqual({
+        theme: 'dark',
+        sandbox: true,
+        coreTools: ['tool1'],
+        contextFileName: 'WORKSPACE_CONTEXT.md',
+      });
+    });
+
+    it('should handle contextFileName correctly when only in user settings', () => {
+      (mockFsExistsSync as Mock).mockImplementation(
+        (p: fs.PathLike) => p === USER_SETTINGS_PATH,
+      );
+      const userSettingsContent = { contextFileName: 'CUSTOM.md' };
+      (fs.readFileSync as Mock).mockImplementation(
+        (p: fs.PathOrFileDescriptor) => {
+          if (p === USER_SETTINGS_PATH)
+            return JSON.stringify(userSettingsContent);
+          return '';
+        },
+      );
+
+      const settings = loadSettings(MOCK_WORKSPACE_DIR);
+      expect(settings.merged.contextFileName).toBe('CUSTOM.md');
+    });
+
+    it('should handle contextFileName correctly when only in workspace settings', () => {
+      (mockFsExistsSync as Mock).mockImplementation(
+        (p: fs.PathLike) => p === MOCK_WORKSPACE_SETTINGS_PATH,
+      );
+      const workspaceSettingsContent = {
+        contextFileName: 'PROJECT_SPECIFIC.md',
+      };
+      (fs.readFileSync as Mock).mockImplementation(
+        (p: fs.PathOrFileDescriptor) => {
+          if (p === MOCK_WORKSPACE_SETTINGS_PATH)
+            return JSON.stringify(workspaceSettingsContent);
+          return '';
+        },
+      );
+
+      const settings = loadSettings(MOCK_WORKSPACE_DIR);
+      expect(settings.merged.contextFileName).toBe('PROJECT_SPECIFIC.md');
+    });
+
+    it('should default contextFileName to undefined if not in any settings file', () => {
+      (mockFsExistsSync as Mock).mockReturnValue(true);
+      const userSettingsContent = { theme: 'dark' };
+      const workspaceSettingsContent = { sandbox: true };
+      (fs.readFileSync as Mock).mockImplementation(
+        (p: fs.PathOrFileDescriptor) => {
+          if (p === USER_SETTINGS_PATH)
+            return JSON.stringify(userSettingsContent);
+          if (p === MOCK_WORKSPACE_SETTINGS_PATH)
+            return JSON.stringify(workspaceSettingsContent);
+          return '';
+        },
+      );
+
+      const settings = loadSettings(MOCK_WORKSPACE_DIR);
+      expect(settings.merged.contextFileName).toBeUndefined();
+    });
+
+    it('should handle JSON parsing errors gracefully', () => {
+      (mockFsExistsSync as Mock).mockReturnValue(true);
+      (fs.readFileSync as Mock).mockImplementation(
+        (p: fs.PathOrFileDescriptor) => {
+          // Make it return invalid json for the paths it will try to read
+          if (p === USER_SETTINGS_PATH || p === MOCK_WORKSPACE_SETTINGS_PATH)
+            return 'invalid json';
+          return '';
+        },
+      );
+      const consoleErrorSpy = vi
+        .spyOn(console, 'error')
+        .mockImplementation(() => {});
+
+      const settings = loadSettings(MOCK_WORKSPACE_DIR);
+
+      expect(settings.user.settings).toEqual({});
+      expect(settings.workspace.settings).toEqual({});
+      expect(settings.merged).toEqual({});
+      expect(consoleErrorSpy).toHaveBeenCalledTimes(2);
+
+      consoleErrorSpy.mockRestore();
+    });
+  });
+
+  describe('LoadedSettings class', () => {
+    it('setValue should update the correct scope and recompute merged settings', () => {
+      (mockFsExistsSync as Mock).mockReturnValue(false);
+      const loadedSettings = loadSettings(MOCK_WORKSPACE_DIR) as LoadedSettings;
+
+      vi.mocked(fs.writeFileSync).mockImplementation(() => {});
+      // mkdirSync is mocked in beforeEach to return undefined, which is fine for void usage
+
+      loadedSettings.setValue(SettingScope.User, 'theme', 'matrix');
+      expect(loadedSettings.user.settings.theme).toBe('matrix');
+      expect(loadedSettings.merged.theme).toBe('matrix');
+      expect(fs.writeFileSync).toHaveBeenCalledWith(
+        USER_SETTINGS_PATH,
+        JSON.stringify({ theme: 'matrix' }, null, 2),
+        'utf-8',
+      );
+
+      loadedSettings.setValue(
+        SettingScope.Workspace,
+        'contextFileName',
+        'MY_AGENTS.md',
+      );
+      expect(loadedSettings.workspace.settings.contextFileName).toBe(
+        'MY_AGENTS.md',
+      );
+      expect(loadedSettings.merged.contextFileName).toBe('MY_AGENTS.md');
+      expect(loadedSettings.merged.theme).toBe('matrix');
+      expect(fs.writeFileSync).toHaveBeenCalledWith(
+        MOCK_WORKSPACE_SETTINGS_PATH,
+        JSON.stringify({ contextFileName: 'MY_AGENTS.md' }, null, 2),
+        'utf-8',
+      );
+
+      loadedSettings.setValue(SettingScope.Workspace, 'theme', 'ocean');
+      expect(loadedSettings.workspace.settings.theme).toBe('ocean');
+      expect(loadedSettings.merged.theme).toBe('ocean');
+    });
+  });
+});
diff --git a/packages/cli/src/config/settings.ts b/packages/cli/src/config/settings.ts
index 1aabc127..5d51ba15 100644
--- a/packages/cli/src/config/settings.ts
+++ b/packages/cli/src/config/settings.ts
@@ -30,6 +30,7 @@ export interface Settings {
   mcpServerCommand?: string;
   mcpServers?: Record<string, MCPServerConfig>;
   showMemoryUsage?: boolean;
+  contextFileName?: string;
   // Add other settings here.
 }
 
diff --git a/packages/cli/src/ui/App.test.tsx b/packages/cli/src/ui/App.test.tsx
new file mode 100644
index 00000000..a7811f6a
--- /dev/null
+++ b/packages/cli/src/ui/App.test.tsx
@@ -0,0 +1,289 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, it, expect, vi, beforeEach, afterEach, Mock } from 'vitest';
+import { render } from 'ink-testing-library';
+import { App } from './App.js';
+import { Config as ServerConfig, MCPServerConfig } from '@gemini-code/core';
+import type { ToolRegistry } from '@gemini-code/core';
+import { LoadedSettings, SettingsFile, Settings } from '../config/settings.js';
+
+// Define a more complete mock server config based on actual Config
+interface MockServerConfig {
+  apiKey: string;
+  model: string;
+  sandbox: boolean | string;
+  targetDir: string;
+  debugMode: boolean;
+  question?: string;
+  fullContext: boolean;
+  coreTools?: string[];
+  toolDiscoveryCommand?: string;
+  toolCallCommand?: string;
+  mcpServerCommand?: string;
+  mcpServers?: Record<string, MCPServerConfig>; // Use imported MCPServerConfig
+  userAgent: string;
+  userMemory: string;
+  geminiMdFileCount: number;
+  alwaysSkipModificationConfirmation: boolean;
+  vertexai?: boolean;
+  showMemoryUsage?: boolean;
+
+  getApiKey: Mock<() => string>;
+  getModel: Mock<() => string>;
+  getSandbox: Mock<() => boolean | string>;
+  getTargetDir: Mock<() => string>;
+  getToolRegistry: Mock<() => ToolRegistry>; // Use imported ToolRegistry type
+  getDebugMode: Mock<() => boolean>;
+  getQuestion: Mock<() => string | undefined>;
+  getFullContext: Mock<() => boolean>;
+  getCoreTools: Mock<() => string[] | undefined>;
+  getToolDiscoveryCommand: Mock<() => string | undefined>;
+  getToolCallCommand: Mock<() => string | undefined>;
+  getMcpServerCommand: Mock<() => string | undefined>;
+  getMcpServers: Mock<() => Record<string, MCPServerConfig> | undefined>;
+  getUserAgent: Mock<() => string>;
+  getUserMemory: Mock<() => string>;
+  setUserMemory: Mock<(newUserMemory: string) => void>;
+  getGeminiMdFileCount: Mock<() => number>;
+  setGeminiMdFileCount: Mock<(count: number) => void>;
+  getAlwaysSkipModificationConfirmation: Mock<() => boolean>;
+  setAlwaysSkipModificationConfirmation: Mock<(skip: boolean) => void>;
+  getVertexAI: Mock<() => boolean | undefined>;
+  getShowMemoryUsage: Mock<() => boolean>;
+}
+
+// Mock @gemini-code/core and its Config class
+vi.mock('@gemini-code/core', async (importOriginal) => {
+  const actualCore = await importOriginal<typeof import('@gemini-code/core')>();
+  const ConfigClassMock = vi
+    .fn()
+    .mockImplementation((optionsPassedToConstructor) => {
+      const opts = { ...optionsPassedToConstructor }; // Clone
+      // Basic mock structure, will be extended by the instance in tests
+      return {
+        apiKey: opts.apiKey || 'test-key',
+        model: opts.model || 'test-model-in-mock-factory',
+        sandbox: typeof opts.sandbox === 'boolean' ? opts.sandbox : false,
+        targetDir: opts.targetDir || '/test/dir',
+        debugMode: opts.debugMode || false,
+        question: opts.question,
+        fullContext: opts.fullContext ?? false,
+        coreTools: opts.coreTools,
+        toolDiscoveryCommand: opts.toolDiscoveryCommand,
+        toolCallCommand: opts.toolCallCommand,
+        mcpServerCommand: opts.mcpServerCommand,
+        mcpServers: opts.mcpServers,
+        userAgent: opts.userAgent || 'test-agent',
+        userMemory: opts.userMemory || '',
+        geminiMdFileCount: opts.geminiMdFileCount || 0,
+        alwaysSkipModificationConfirmation:
+          opts.alwaysSkipModificationConfirmation ?? false,
+        vertexai: opts.vertexai,
+        showMemoryUsage: opts.showMemoryUsage ?? false,
+
+        getApiKey: vi.fn(() => opts.apiKey || 'test-key'),
+        getModel: vi.fn(() => opts.model || 'test-model-in-mock-factory'),
+        getSandbox: vi.fn(() =>
+          typeof opts.sandbox === 'boolean' ? opts.sandbox : false,
+        ),
+        getTargetDir: vi.fn(() => opts.targetDir || '/test/dir'),
+        getToolRegistry: vi.fn(() => ({}) as ToolRegistry), // Simple mock
+        getDebugMode: vi.fn(() => opts.debugMode || false),
+        getQuestion: vi.fn(() => opts.question),
+        getFullContext: vi.fn(() => opts.fullContext ?? false),
+        getCoreTools: vi.fn(() => opts.coreTools),
+        getToolDiscoveryCommand: vi.fn(() => opts.toolDiscoveryCommand),
+        getToolCallCommand: vi.fn(() => opts.toolCallCommand),
+        getMcpServerCommand: vi.fn(() => opts.mcpServerCommand),
+        getMcpServers: vi.fn(() => opts.mcpServers),
+        getUserAgent: vi.fn(() => opts.userAgent || 'test-agent'),
+        getUserMemory: vi.fn(() => opts.userMemory || ''),
+        setUserMemory: vi.fn(),
+        getGeminiMdFileCount: vi.fn(() => opts.geminiMdFileCount || 0),
+        setGeminiMdFileCount: vi.fn(),
+        getAlwaysSkipModificationConfirmation: vi.fn(
+          () => opts.alwaysSkipModificationConfirmation ?? false,
+        ),
+        setAlwaysSkipModificationConfirmation: vi.fn(),
+        getVertexAI: vi.fn(() => opts.vertexai),
+        getShowMemoryUsage: vi.fn(() => opts.showMemoryUsage ?? false),
+      };
+    });
+  return {
+    ...actualCore,
+    Config: ConfigClassMock,
+    MCPServerConfig: actualCore.MCPServerConfig,
+  };
+});
+
+// Mock heavy dependencies or those with side effects
+vi.mock('./hooks/useGeminiStream', () => ({
+  useGeminiStream: vi.fn(() => ({
+    streamingState: 'Idle',
+    submitQuery: vi.fn(),
+    initError: null,
+    pendingHistoryItems: [],
+  })),
+}));
+
+vi.mock('./hooks/useLogger', () => ({
+  useLogger: vi.fn(() => ({
+    getPreviousUserMessages: vi.fn().mockResolvedValue([]),
+  })),
+}));
+
+vi.mock('../config/config.js', async (importOriginal) => {
+  const actual = await importOriginal();
+  return {
+    // @ts-expect-error - this is fine
+    ...actual,
+    loadHierarchicalGeminiMemory: vi
+      .fn()
+      .mockResolvedValue({ memoryContent: '', fileCount: 0 }),
+  };
+});
+
+describe('App UI', () => {
+  let mockConfig: MockServerConfig;
+  let mockSettings: LoadedSettings;
+  let currentUnmount: (() => void) | undefined;
+
+  const createMockSettings = (
+    settings: Partial<Settings> = {},
+  ): LoadedSettings => {
+    const userSettingsFile: SettingsFile = {
+      path: '/user/settings.json',
+      settings: {},
+    };
+    const workspaceSettingsFile: SettingsFile = {
+      path: '/workspace/.gemini/settings.json',
+      settings,
+    };
+    return new LoadedSettings(userSettingsFile, workspaceSettingsFile);
+  };
+
+  beforeEach(() => {
+    const ServerConfigMocked = vi.mocked(ServerConfig, true);
+    mockConfig = new ServerConfigMocked({
+      apiKey: 'test-key',
+      model: 'test-model-in-options',
+      sandbox: false,
+      targetDir: '/test/dir',
+      debugMode: false,
+      userAgent: 'test-agent',
+      userMemory: '',
+      geminiMdFileCount: 0,
+      showMemoryUsage: false,
+      // Provide other required fields for ConfigParameters if necessary
+    }) as unknown as MockServerConfig;
+
+    // Ensure the getShowMemoryUsage mock function is specifically set up if not covered by constructor mock
+    if (!mockConfig.getShowMemoryUsage) {
+      mockConfig.getShowMemoryUsage = vi.fn(() => false);
+    }
+    mockConfig.getShowMemoryUsage.mockReturnValue(false); // Default for most tests
+
+    mockSettings = createMockSettings();
+  });
+
+  afterEach(() => {
+    if (currentUnmount) {
+      currentUnmount();
+      currentUnmount = undefined;
+    }
+    vi.clearAllMocks(); // Clear mocks after each test
+  });
+
+  it('should display default "GEMINI.md" in footer when contextFileName is not set and count is 1', async () => {
+    mockConfig.getGeminiMdFileCount.mockReturnValue(1);
+    // For this test, ensure showMemoryUsage is false or debugMode is false if it relies on that
+    mockConfig.getDebugMode.mockReturnValue(false);
+    mockConfig.getShowMemoryUsage.mockReturnValue(false);
+
+    const { lastFrame, unmount } = render(
+      <App
+        config={mockConfig as unknown as ServerConfig}
+        settings={mockSettings}
+        cliVersion="1.0.0"
+      />,
+    );
+    currentUnmount = unmount;
+    await Promise.resolve(); // Wait for any async updates
+    expect(lastFrame()).toContain('Using 1 GEMINI.md file');
+  });
+
+  it('should display default "GEMINI.md" with plural when contextFileName is not set and count is > 1', async () => {
+    mockConfig.getGeminiMdFileCount.mockReturnValue(2);
+    mockConfig.getDebugMode.mockReturnValue(false);
+    mockConfig.getShowMemoryUsage.mockReturnValue(false);
+
+    const { lastFrame, unmount } = render(
+      <App
+        config={mockConfig as unknown as ServerConfig}
+        settings={mockSettings}
+        cliVersion="1.0.0"
+      />,
+    );
+    currentUnmount = unmount;
+    await Promise.resolve();
+    expect(lastFrame()).toContain('Using 2 GEMINI.md files');
+  });
+
+  it('should display custom contextFileName in footer when set and count is 1', async () => {
+    mockSettings = createMockSettings({ contextFileName: 'AGENTS.MD' });
+    mockConfig.getGeminiMdFileCount.mockReturnValue(1);
+    mockConfig.getDebugMode.mockReturnValue(false);
+    mockConfig.getShowMemoryUsage.mockReturnValue(false);
+
+    const { lastFrame, unmount } = render(
+      <App
+        config={mockConfig as unknown as ServerConfig}
+        settings={mockSettings}
+        cliVersion="1.0.0"
+      />,
+    );
+    currentUnmount = unmount;
+    await Promise.resolve();
+    expect(lastFrame()).toContain('Using 1 AGENTS.MD file');
+  });
+
+  it('should display custom contextFileName with plural when set and count is > 1', async () => {
+    mockSettings = createMockSettings({ contextFileName: 'MY_NOTES.TXT' });
+    mockConfig.getGeminiMdFileCount.mockReturnValue(3);
+    mockConfig.getDebugMode.mockReturnValue(false);
+    mockConfig.getShowMemoryUsage.mockReturnValue(false);
+
+    const { lastFrame, unmount } = render(
+      <App
+        config={mockConfig as unknown as ServerConfig}
+        settings={mockSettings}
+        cliVersion="1.0.0"
+      />,
+    );
+    currentUnmount = unmount;
+    await Promise.resolve();
+    expect(lastFrame()).toContain('Using 3 MY_NOTES.TXT files');
+  });
+
+  it('should not display context file message if count is 0, even if contextFileName is set', async () => {
+    mockSettings = createMockSettings({ contextFileName: 'ANY_FILE.MD' });
+    mockConfig.getGeminiMdFileCount.mockReturnValue(0);
+    mockConfig.getDebugMode.mockReturnValue(false);
+    mockConfig.getShowMemoryUsage.mockReturnValue(false);
+
+    const { lastFrame, unmount } = render(
+      <App
+        config={mockConfig as unknown as ServerConfig}
+        settings={mockSettings}
+        cliVersion="1.0.0"
+      />,
+    );
+    currentUnmount = unmount;
+    await Promise.resolve();
+    expect(lastFrame()).not.toContain('ANY_FILE.MD');
+  });
+});
diff --git a/packages/cli/src/ui/App.tsx b/packages/cli/src/ui/App.tsx
index e1657984..2f216db7 100644
--- a/packages/cli/src/ui/App.tsx
+++ b/packages/cli/src/ui/App.tsx
@@ -39,7 +39,11 @@ import { DetailedMessagesDisplay } from './components/DetailedMessagesDisplay.js
 import { HistoryItemDisplay } from './components/HistoryItemDisplay.js';
 import { useHistory } from './hooks/useHistoryManager.js';
 import process from 'node:process';
-import { getErrorMessage, type Config } from '@gemini-code/core';
+import {
+  getErrorMessage,
+  type Config,
+  getCurrentGeminiMdFilename,
+} from '@gemini-code/core';
 import { useLogger } from './hooks/useLogger.js';
 import { StreamingContext } from './contexts/StreamingContext.js';
 import { useGitBranchName } from './hooks/useGitBranchName.js';
@@ -398,7 +402,10 @@ export const App = ({
                     </Text>
                   ) : geminiMdFileCount > 0 ? (
                     <Text color={Colors.SubtleComment}>
-                      Using {geminiMdFileCount} GEMINI.md file
+                      Using {geminiMdFileCount}{' '}
+                      {settings.merged.contextFileName ||
+                        getCurrentGeminiMdFilename()}{' '}
+                      file
                       {geminiMdFileCount > 1 ? 's' : ''}
                     </Text>
                   ) : (
diff --git a/packages/core/src/config/config.test.ts b/packages/core/src/config/config.test.ts
index f84ad746..c3c46659 100644
--- a/packages/core/src/config/config.test.ts
+++ b/packages/core/src/config/config.test.ts
@@ -4,10 +4,10 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import { describe, it, expect, vi, beforeEach /*, afterEach */ } from 'vitest'; // afterEach removed as it was unused
-import { Config, createServerConfig, ConfigParameters } from './config.js'; // Adjust import path
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+import { Config, createServerConfig, ConfigParameters } from './config.js';
 import * as path from 'path';
-// import { ToolRegistry } from '../tools/tool-registry'; // ToolRegistry removed as it was unused
+import { setGeminiMdFilename as mockSetGeminiMdFilename } from '../tools/memoryTool.js';
 
 // Mock dependencies that might be called during Config construction or createServerConfig
 vi.mock('../tools/tool-registry', () => {
@@ -30,6 +30,12 @@ vi.mock('../tools/shell');
 vi.mock('../tools/write-file');
 vi.mock('../tools/web-fetch');
 vi.mock('../tools/read-many-files');
+vi.mock('../tools/memoryTool', () => ({
+  MemoryTool: vi.fn(),
+  setGeminiMdFilename: vi.fn(),
+  getCurrentGeminiMdFilename: vi.fn(() => 'GEMINI.md'), // Mock the original filename
+  DEFAULT_CONTEXT_FILENAME: 'GEMINI.md',
+}));
 
 describe('Server Config (config.ts)', () => {
   const API_KEY = 'server-api-key';
@@ -106,4 +112,34 @@ describe('Server Config (config.ts)', () => {
     const config = createServerConfig(paramsWithRelativeDir);
     expect(config.getTargetDir()).toBe(expectedResolvedDir);
   });
+
+  it('createServerConfig should call setGeminiMdFilename with contextFileName if provided', () => {
+    const contextFileName = 'CUSTOM_AGENTS.md';
+    const paramsWithContextFile: ConfigParameters = {
+      ...baseParams,
+      contextFileName,
+    };
+    createServerConfig(paramsWithContextFile);
+    expect(mockSetGeminiMdFilename).toHaveBeenCalledWith(contextFileName);
+  });
+
+  it('createServerConfig should not call setGeminiMdFilename if contextFileName is not provided', () => {
+    createServerConfig(baseParams); // baseParams does not have contextFileName
+    expect(mockSetGeminiMdFilename).not.toHaveBeenCalled();
+  });
+
+  it('Config constructor should call setGeminiMdFilename with contextFileName if provided', () => {
+    const contextFileName = 'CUSTOM_AGENTS.md';
+    const paramsWithContextFile: ConfigParameters = {
+      ...baseParams,
+      contextFileName,
+    };
+    new Config(paramsWithContextFile);
+    expect(mockSetGeminiMdFilename).toHaveBeenCalledWith(contextFileName);
+  });
+
+  it('Config constructor should not call setGeminiMdFilename if contextFileName is not provided', () => {
+    new Config(baseParams); // baseParams does not have contextFileName
+    expect(mockSetGeminiMdFilename).not.toHaveBeenCalled();
+  });
 });
diff --git a/packages/core/src/config/config.ts b/packages/core/src/config/config.ts
index 0cd7a4fa..d918de04 100644
--- a/packages/core/src/config/config.ts
+++ b/packages/core/src/config/config.ts
@@ -19,7 +19,7 @@ import { ShellTool } from '../tools/shell.js';
 import { WriteFileTool } from '../tools/write-file.js';
 import { WebFetchTool } from '../tools/web-fetch.js';
 import { ReadManyFilesTool } from '../tools/read-many-files.js';
-import { MemoryTool } from '../tools/memoryTool.js';
+import { MemoryTool, setGeminiMdFilename } from '../tools/memoryTool.js';
 import { WebSearchTool } from '../tools/web-search.js';
 
 export class MCPServerConfig {
@@ -56,6 +56,7 @@ export interface ConfigParameters {
   alwaysSkipModificationConfirmation?: boolean;
   vertexai?: boolean;
   showMemoryUsage?: boolean;
+  contextFileName?: string;
 }
 
 export class Config {
@@ -100,6 +101,10 @@ export class Config {
     this.vertexai = params.vertexai;
     this.showMemoryUsage = params.showMemoryUsage ?? false;
 
+    if (params.contextFileName) {
+      setGeminiMdFilename(params.contextFileName);
+    }
+
     this.toolRegistry = createToolRegistry(this);
   }
 
diff --git a/packages/core/src/tools/memoryTool.test.ts b/packages/core/src/tools/memoryTool.test.ts
index 42b1329d..612a08dc 100644
--- a/packages/core/src/tools/memoryTool.test.ts
+++ b/packages/core/src/tools/memoryTool.test.ts
@@ -5,7 +5,12 @@
  */
 
 import { vi, describe, it, expect, beforeEach, afterEach, Mock } from 'vitest';
-import { MemoryTool } from './memoryTool.js';
+import {
+  MemoryTool,
+  setGeminiMdFilename,
+  getCurrentGeminiMdFilename,
+  DEFAULT_CONTEXT_FILENAME,
+} from './memoryTool.js';
 import * as fs from 'fs/promises';
 import * as path from 'path';
 import * as os from 'os';
@@ -50,10 +55,33 @@ describe('MemoryTool', () => {
 
   afterEach(() => {
     vi.restoreAllMocks();
+    // Reset GEMINI_MD_FILENAME to its original value after each test
+    setGeminiMdFilename(DEFAULT_CONTEXT_FILENAME);
+  });
+
+  describe('setGeminiMdFilename', () => {
+    it('should update currentGeminiMdFilename when a valid new name is provided', () => {
+      const newName = 'CUSTOM_CONTEXT.md';
+      setGeminiMdFilename(newName);
+      expect(getCurrentGeminiMdFilename()).toBe(newName);
+    });
+
+    it('should not update currentGeminiMdFilename if the new name is empty or whitespace', () => {
+      const initialName = getCurrentGeminiMdFilename(); // Get current before trying to change
+      setGeminiMdFilename('  ');
+      expect(getCurrentGeminiMdFilename()).toBe(initialName);
+
+      setGeminiMdFilename('');
+      expect(getCurrentGeminiMdFilename()).toBe(initialName);
+    });
   });
 
   describe('performAddMemoryEntry (static method)', () => {
-    const testFilePath = path.join('/mock/home', '.gemini', 'GEMINI.md');
+    const testFilePath = path.join(
+      '/mock/home',
+      '.gemini',
+      DEFAULT_CONTEXT_FILENAME, // Use the default for basic tests
+    );
 
     it('should create section and save a fact if file does not exist', async () => {
       mockFsAdapter.readFile.mockRejectedValue({ code: 'ENOENT' }); // Simulate file not found
@@ -168,7 +196,12 @@ describe('MemoryTool', () => {
     it('should call performAddMemoryEntry with correct parameters and return success', async () => {
       const params = { fact: 'The sky is blue' };
       const result = await memoryTool.execute(params, mockAbortSignal);
-      const expectedFilePath = path.join('/mock/home', '.gemini', 'GEMINI.md');
+      // Use getCurrentGeminiMdFilename for the default expectation before any setGeminiMdFilename calls in a test
+      const expectedFilePath = path.join(
+        '/mock/home',
+        '.gemini',
+        getCurrentGeminiMdFilename(), // This will be DEFAULT_CONTEXT_FILENAME unless changed by a test
+      );
 
       // For this test, we expect the actual fs methods to be passed
       const expectedFsArgument = {
diff --git a/packages/core/src/tools/memoryTool.ts b/packages/core/src/tools/memoryTool.ts
index 49dce59d..a0c62eae 100644
--- a/packages/core/src/tools/memoryTool.ts
+++ b/packages/core/src/tools/memoryTool.ts
@@ -46,15 +46,29 @@ Do NOT use this tool:
 `;
 
 export const GEMINI_CONFIG_DIR = '.gemini';
-export const GEMINI_MD_FILENAME = 'GEMINI.md';
+export const DEFAULT_CONTEXT_FILENAME = 'GEMINI.md';
 export const MEMORY_SECTION_HEADER = '## Gemini Added Memories';
 
+// This variable will hold the currently configured filename for GEMINI.md context files.
+// It defaults to DEFAULT_CONTEXT_FILENAME but can be overridden by setGeminiMdFilename.
+let currentGeminiMdFilename = DEFAULT_CONTEXT_FILENAME;
+
+export function setGeminiMdFilename(newFilename: string): void {
+  if (newFilename && newFilename.trim() !== '') {
+    currentGeminiMdFilename = newFilename.trim();
+  }
+}
+
+export function getCurrentGeminiMdFilename(): string {
+  return currentGeminiMdFilename;
+}
+
 interface SaveMemoryParams {
   fact: string;
 }
 
 function getGlobalMemoryFilePath(): string {
-  return path.join(homedir(), GEMINI_CONFIG_DIR, GEMINI_MD_FILENAME);
+  return path.join(homedir(), GEMINI_CONFIG_DIR, getCurrentGeminiMdFilename());
 }
 
 /**
diff --git a/packages/core/src/tools/read-many-files.ts b/packages/core/src/tools/read-many-files.ts
index d826c9ba..4ba09ef0 100644
--- a/packages/core/src/tools/read-many-files.ts
+++ b/packages/core/src/tools/read-many-files.ts
@@ -9,7 +9,7 @@ import { SchemaValidator } from '../utils/schemaValidator.js';
 import { getErrorMessage } from '../utils/errors.js';
 import * as path from 'path';
 import fg from 'fast-glob';
-import { GEMINI_MD_FILENAME } from './memoryTool.js';
+import { getCurrentGeminiMdFilename } from './memoryTool.js';
 import {
   detectFileType,
   processSingleFileContent,
@@ -98,7 +98,7 @@ const DEFAULT_EXCLUDES: string[] = [
   '**/*.odp',
   '**/*.DS_Store',
   '**/.env',
-  `**/${GEMINI_MD_FILENAME}`,
+  `**/${getCurrentGeminiMdFilename()}`,
 ];
 
 const DEFAULT_OUTPUT_SEPARATOR_FORMAT = '--- {filePath} ---';
diff --git a/packages/core/src/utils/memoryDiscovery.test.ts b/packages/core/src/utils/memoryDiscovery.test.ts
index 229f51e5..db0ffd1d 100644
--- a/packages/core/src/utils/memoryDiscovery.test.ts
+++ b/packages/core/src/utils/memoryDiscovery.test.ts
@@ -4,22 +4,21 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import {
-  vi,
-  describe,
-  it,
-  expect,
-  beforeEach,
-  // afterEach, // Removed unused import
-  Mocked,
-} from 'vitest';
+import { vi, describe, it, expect, beforeEach, Mocked } from 'vitest';
 import * as fsPromises from 'fs/promises';
-import * as fsSync from 'fs'; // For constants
-import { Stats, Dirent } from 'fs'; // Import types directly from 'fs'
+import * as fsSync from 'fs';
+import { Stats, Dirent } from 'fs';
 import * as os from 'os';
 import * as path from 'path';
 import { loadServerHierarchicalMemory } from './memoryDiscovery.js';
-import { GEMINI_CONFIG_DIR, GEMINI_MD_FILENAME } from '../tools/memoryTool.js';
+import {
+  GEMINI_CONFIG_DIR,
+  setGeminiMdFilename,
+  getCurrentGeminiMdFilename,
+  DEFAULT_CONTEXT_FILENAME,
+} from '../tools/memoryTool.js';
+
+const ORIGINAL_GEMINI_MD_FILENAME_CONST_FOR_TEST = DEFAULT_CONTEXT_FILENAME;
 
 // Mock the entire fs/promises module
 vi.mock('fs/promises');
@@ -29,8 +28,6 @@ vi.mock('fs', async (importOriginal) => {
   return {
     ...actual, // Spread actual to get all exports, including Stats and Dirent if they are classes/constructors
     constants: { ...actual.constants }, // Preserve constants
-    // Mock other fsSync functions if directly used by memoryDiscovery, e.g., existsSync
-    // existsSync: vi.fn(),
   };
 });
 vi.mock('os');
@@ -42,20 +39,29 @@ describe('loadServerHierarchicalMemory', () => {
   const CWD = '/test/project/src';
   const PROJECT_ROOT = '/test/project';
   const USER_HOME = '/test/userhome';
-  const GLOBAL_GEMINI_DIR = path.join(USER_HOME, GEMINI_CONFIG_DIR);
-  const GLOBAL_GEMINI_FILE = path.join(GLOBAL_GEMINI_DIR, GEMINI_MD_FILENAME);
+
+  let GLOBAL_GEMINI_DIR: string;
+  let GLOBAL_GEMINI_FILE: string; // Defined in beforeEach
 
   beforeEach(() => {
     vi.resetAllMocks();
-
+    setGeminiMdFilename(DEFAULT_CONTEXT_FILENAME); // Use defined const
     mockOs.homedir.mockReturnValue(USER_HOME);
+
+    // Define these here to use potentially reset/updated values from imports
+    GLOBAL_GEMINI_DIR = path.join(USER_HOME, GEMINI_CONFIG_DIR);
+    GLOBAL_GEMINI_FILE = path.join(
+      GLOBAL_GEMINI_DIR,
+      getCurrentGeminiMdFilename(), // Use current filename
+    );
+
     mockFs.stat.mockRejectedValue(new Error('File not found'));
     mockFs.readdir.mockResolvedValue([]);
     mockFs.readFile.mockRejectedValue(new Error('File not found'));
     mockFs.access.mockRejectedValue(new Error('File not found'));
   });
 
-  it('should return empty memory and count if no GEMINI.md files are found', async () => {
+  it('should return empty memory and count if no context files are found', async () => {
     const { memoryContent, fileCount } = await loadServerHierarchicalMemory(
       CWD,
       false,
@@ -64,15 +70,19 @@ describe('loadServerHierarchicalMemory', () => {
     expect(fileCount).toBe(0);
   });
 
-  it('should load only the global GEMINI.md if present and others are not', async () => {
+  it('should load only the global context file if present and others are not (default filename)', async () => {
+    const globalDefaultFile = path.join(
+      GLOBAL_GEMINI_DIR,
+      DEFAULT_CONTEXT_FILENAME,
+    );
     mockFs.access.mockImplementation(async (p) => {
-      if (p === GLOBAL_GEMINI_FILE) {
+      if (p === globalDefaultFile) {
         return undefined;
       }
       throw new Error('File not found');
     });
     mockFs.readFile.mockImplementation(async (p) => {
-      if (p === GLOBAL_GEMINI_FILE) {
+      if (p === globalDefaultFile) {
         return 'Global memory content';
       }
       throw new Error('File not found');
@@ -84,15 +94,157 @@ describe('loadServerHierarchicalMemory', () => {
     );
 
     expect(memoryContent).toBe(
-      `--- Context from: ${path.relative(CWD, GLOBAL_GEMINI_FILE)} ---\nGlobal memory content\n--- End of Context from: ${path.relative(CWD, GLOBAL_GEMINI_FILE)} ---`,
+      `--- Context from: ${path.relative(CWD, globalDefaultFile)} ---\nGlobal memory content\n--- End of Context from: ${path.relative(CWD, globalDefaultFile)} ---`,
+    );
+    expect(fileCount).toBe(1);
+    expect(mockFs.readFile).toHaveBeenCalledWith(globalDefaultFile, 'utf-8');
+  });
+
+  it('should load only the global custom context file if present and filename is changed', async () => {
+    const customFilename = 'CUSTOM_AGENTS.md';
+    setGeminiMdFilename(customFilename);
+    const globalCustomFile = path.join(GLOBAL_GEMINI_DIR, customFilename);
+
+    mockFs.access.mockImplementation(async (p) => {
+      if (p === globalCustomFile) {
+        return undefined;
+      }
+      throw new Error('File not found');
+    });
+    mockFs.readFile.mockImplementation(async (p) => {
+      if (p === globalCustomFile) {
+        return 'Global custom memory';
+      }
+      throw new Error('File not found');
+    });
+
+    const { memoryContent, fileCount } = await loadServerHierarchicalMemory(
+      CWD,
+      false,
+    );
+
+    expect(memoryContent).toBe(
+      `--- Context from: ${path.relative(CWD, globalCustomFile)} ---\nGlobal custom memory\n--- End of Context from: ${path.relative(CWD, globalCustomFile)} ---`,
     );
     expect(fileCount).toBe(1);
-    expect(mockFs.readFile).toHaveBeenCalledWith(GLOBAL_GEMINI_FILE, 'utf-8');
+    expect(mockFs.readFile).toHaveBeenCalledWith(globalCustomFile, 'utf-8');
+  });
+
+  it('should load context files by upward traversal with custom filename', async () => {
+    const customFilename = 'PROJECT_CONTEXT.md';
+    setGeminiMdFilename(customFilename);
+    const projectRootCustomFile = path.join(PROJECT_ROOT, customFilename);
+    const srcCustomFile = path.join(CWD, customFilename);
+
+    mockFs.stat.mockImplementation(async (p) => {
+      if (p === path.join(PROJECT_ROOT, '.git')) {
+        return { isDirectory: () => true } as Stats;
+      }
+      throw new Error('File not found');
+    });
+
+    mockFs.access.mockImplementation(async (p) => {
+      if (p === projectRootCustomFile || p === srcCustomFile) {
+        return undefined;
+      }
+      throw new Error('File not found');
+    });
+
+    mockFs.readFile.mockImplementation(async (p) => {
+      if (p === projectRootCustomFile) {
+        return 'Project root custom memory';
+      }
+      if (p === srcCustomFile) {
+        return 'Src directory custom memory';
+      }
+      throw new Error('File not found');
+    });
+
+    const { memoryContent, fileCount } = await loadServerHierarchicalMemory(
+      CWD,
+      false,
+    );
+    const expectedContent =
+      `--- Context from: ${path.relative(CWD, projectRootCustomFile)} ---\nProject root custom memory\n--- End of Context from: ${path.relative(CWD, projectRootCustomFile)} ---\n\n` +
+      `--- Context from: ${customFilename} ---\nSrc directory custom memory\n--- End of Context from: ${customFilename} ---`;
+
+    expect(memoryContent).toBe(expectedContent);
+    expect(fileCount).toBe(2);
+    expect(mockFs.readFile).toHaveBeenCalledWith(
+      projectRootCustomFile,
+      'utf-8',
+    );
+    expect(mockFs.readFile).toHaveBeenCalledWith(srcCustomFile, 'utf-8');
+  });
+
+  it('should load context files by downward traversal with custom filename', async () => {
+    const customFilename = 'LOCAL_CONTEXT.md';
+    setGeminiMdFilename(customFilename);
+    const subDir = path.join(CWD, 'subdir');
+    const subDirCustomFile = path.join(subDir, customFilename);
+    const cwdCustomFile = path.join(CWD, customFilename);
+
+    mockFs.access.mockImplementation(async (p) => {
+      if (p === cwdCustomFile || p === subDirCustomFile) return undefined;
+      throw new Error('File not found');
+    });
+
+    mockFs.readFile.mockImplementation(async (p) => {
+      if (p === cwdCustomFile) return 'CWD custom memory';
+      if (p === subDirCustomFile) return 'Subdir custom memory';
+      throw new Error('File not found');
+    });
+
+    mockFs.readdir.mockImplementation((async (
+      p: fsSync.PathLike,
+    ): Promise<Dirent[]> => {
+      if (p === CWD) {
+        return [
+          {
+            name: customFilename,
+            isFile: () => true,
+            isDirectory: () => false,
+          } as Dirent,
+          {
+            name: 'subdir',
+            isFile: () => false,
+            isDirectory: () => true,
+          } as Dirent,
+        ] as Dirent[];
+      }
+      if (p === subDir) {
+        return [
+          {
+            name: customFilename,
+            isFile: () => true,
+            isDirectory: () => false,
+          } as Dirent,
+        ] as Dirent[];
+      }
+      return [] as Dirent[];
+    }) as unknown as typeof fsPromises.readdir);
+
+    const { memoryContent, fileCount } = await loadServerHierarchicalMemory(
+      CWD,
+      false,
+    );
+    const expectedContent =
+      `--- Context from: ${customFilename} ---\nCWD custom memory\n--- End of Context from: ${customFilename} ---\n\n` +
+      `--- Context from: ${path.join('subdir', customFilename)} ---\nSubdir custom memory\n--- End of Context from: ${path.join('subdir', customFilename)} ---`;
+
+    expect(memoryContent).toBe(expectedContent);
+    expect(fileCount).toBe(2);
   });
 
-  it('should load GEMINI.md files by upward traversal from CWD to project root', async () => {
-    const projectRootGeminiFile = path.join(PROJECT_ROOT, GEMINI_MD_FILENAME);
-    const srcGeminiFile = path.join(CWD, GEMINI_MD_FILENAME);
+  it('should load ORIGINAL_GEMINI_MD_FILENAME files by upward traversal from CWD to project root', async () => {
+    const projectRootGeminiFile = path.join(
+      PROJECT_ROOT,
+      ORIGINAL_GEMINI_MD_FILENAME_CONST_FOR_TEST,
+    );
+    const srcGeminiFile = path.join(
+      CWD,
+      ORIGINAL_GEMINI_MD_FILENAME_CONST_FOR_TEST,
+    );
 
     mockFs.stat.mockImplementation(async (p) => {
       if (p === path.join(PROJECT_ROOT, '.git')) {
@@ -124,7 +276,7 @@ describe('loadServerHierarchicalMemory', () => {
     );
     const expectedContent =
       `--- Context from: ${path.relative(CWD, projectRootGeminiFile)} ---\nProject root memory\n--- End of Context from: ${path.relative(CWD, projectRootGeminiFile)} ---\n\n` +
-      `--- Context from: ${GEMINI_MD_FILENAME} ---\nSrc directory memory\n--- End of Context from: ${GEMINI_MD_FILENAME} ---`;
+      `--- Context from: ${ORIGINAL_GEMINI_MD_FILENAME_CONST_FOR_TEST} ---\nSrc directory memory\n--- End of Context from: ${ORIGINAL_GEMINI_MD_FILENAME_CONST_FOR_TEST} ---`;
 
     expect(memoryContent).toBe(expectedContent);
     expect(fileCount).toBe(2);
@@ -135,10 +287,16 @@ describe('loadServerHierarchicalMemory', () => {
     expect(mockFs.readFile).toHaveBeenCalledWith(srcGeminiFile, 'utf-8');
   });
 
-  it('should load GEMINI.md files by downward traversal from CWD', async () => {
+  it('should load ORIGINAL_GEMINI_MD_FILENAME files by downward traversal from CWD', async () => {
     const subDir = path.join(CWD, 'subdir');
-    const subDirGeminiFile = path.join(subDir, GEMINI_MD_FILENAME);
-    const cwdGeminiFile = path.join(CWD, GEMINI_MD_FILENAME);
+    const subDirGeminiFile = path.join(
+      subDir,
+      ORIGINAL_GEMINI_MD_FILENAME_CONST_FOR_TEST,
+    );
+    const cwdGeminiFile = path.join(
+      CWD,
+      ORIGINAL_GEMINI_MD_FILENAME_CONST_FOR_TEST,
+    );
 
     mockFs.access.mockImplementation(async (p) => {
       if (p === cwdGeminiFile || p === subDirGeminiFile) return undefined;
@@ -157,59 +315,79 @@ describe('loadServerHierarchicalMemory', () => {
       if (p === CWD) {
         return [
           {
-            name: GEMINI_MD_FILENAME,
+            name: ORIGINAL_GEMINI_MD_FILENAME_CONST_FOR_TEST,
             isFile: () => true,
             isDirectory: () => false,
-          },
-          { name: 'subdir', isFile: () => false, isDirectory: () => true },
+          } as Dirent,
+          {
+            name: 'subdir',
+            isFile: () => false,
+            isDirectory: () => true,
+          } as Dirent,
         ] as Dirent[];
       }
       if (p === subDir) {
         return [
           {
-            name: GEMINI_MD_FILENAME,
+            name: ORIGINAL_GEMINI_MD_FILENAME_CONST_FOR_TEST,
             isFile: () => true,
             isDirectory: () => false,
-          },
+          } as Dirent,
         ] as Dirent[];
       }
       return [] as Dirent[];
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-    }) as any);
+    }) as unknown as typeof fsPromises.readdir);
 
     const { memoryContent, fileCount } = await loadServerHierarchicalMemory(
       CWD,
       false,
     );
     const expectedContent =
-      `--- Context from: ${GEMINI_MD_FILENAME} ---\nCWD memory\n--- End of Context from: ${GEMINI_MD_FILENAME} ---\n\n` +
-      `--- Context from: ${path.join('subdir', GEMINI_MD_FILENAME)} ---\nSubdir memory\n--- End of Context from: ${path.join('subdir', GEMINI_MD_FILENAME)} ---`;
+      `--- Context from: ${ORIGINAL_GEMINI_MD_FILENAME_CONST_FOR_TEST} ---\nCWD memory\n--- End of Context from: ${ORIGINAL_GEMINI_MD_FILENAME_CONST_FOR_TEST} ---\n\n` +
+      `--- Context from: ${path.join('subdir', ORIGINAL_GEMINI_MD_FILENAME_CONST_FOR_TEST)} ---\nSubdir memory\n--- End of Context from: ${path.join('subdir', ORIGINAL_GEMINI_MD_FILENAME_CONST_FOR_TEST)} ---`;
 
     expect(memoryContent).toBe(expectedContent);
     expect(fileCount).toBe(2);
   });
 
-  it('should load and correctly order global, upward, and downward GEMINI.md files', async () => {
+  it('should load and correctly order global, upward, and downward ORIGINAL_GEMINI_MD_FILENAME files', async () => {
+    setGeminiMdFilename(ORIGINAL_GEMINI_MD_FILENAME_CONST_FOR_TEST); // Explicitly set for this test
+
+    const globalFileToUse = path.join(
+      GLOBAL_GEMINI_DIR,
+      ORIGINAL_GEMINI_MD_FILENAME_CONST_FOR_TEST,
+    );
     const projectParentDir = path.dirname(PROJECT_ROOT);
     const projectParentGeminiFile = path.join(
       projectParentDir,
-      GEMINI_MD_FILENAME,
+      ORIGINAL_GEMINI_MD_FILENAME_CONST_FOR_TEST,
+    );
+    const projectRootGeminiFile = path.join(
+      PROJECT_ROOT,
+      ORIGINAL_GEMINI_MD_FILENAME_CONST_FOR_TEST,
+    );
+    const cwdGeminiFile = path.join(
+      CWD,
+      ORIGINAL_GEMINI_MD_FILENAME_CONST_FOR_TEST,
     );
-    const projectRootGeminiFile = path.join(PROJECT_ROOT, GEMINI_MD_FILENAME);
-    const cwdGeminiFile = path.join(CWD, GEMINI_MD_FILENAME);
     const subDir = path.join(CWD, 'sub');
-    const subDirGeminiFile = path.join(subDir, GEMINI_MD_FILENAME);
+    const subDirGeminiFile = path.join(
+      subDir,
+      ORIGINAL_GEMINI_MD_FILENAME_CONST_FOR_TEST,
+    );
 
     mockFs.stat.mockImplementation(async (p) => {
       if (p === path.join(PROJECT_ROOT, '.git')) {
         return { isDirectory: () => true } as Stats;
+      } else if (p === path.join(PROJECT_ROOT, '.gemini')) {
+        return { isDirectory: () => true } as Stats;
       }
       throw new Error('File not found');
     });
 
     mockFs.access.mockImplementation(async (p) => {
       if (
-        p === GLOBAL_GEMINI_FILE ||
+        p === globalFileToUse || // Use the dynamically set global file path
         p === projectParentGeminiFile ||
         p === projectRootGeminiFile ||
         p === cwdGeminiFile ||
@@ -221,7 +399,7 @@ describe('loadServerHierarchicalMemory', () => {
     });
 
     mockFs.readFile.mockImplementation(async (p) => {
-      if (p === GLOBAL_GEMINI_FILE) return 'Global memory';
+      if (p === globalFileToUse) return 'Global memory'; // Use the dynamically set global file path
       if (p === projectParentGeminiFile) return 'Project parent memory';
       if (p === projectRootGeminiFile) return 'Project root memory';
       if (p === cwdGeminiFile) return 'CWD memory';
@@ -234,21 +412,24 @@ describe('loadServerHierarchicalMemory', () => {
     ): Promise<Dirent[]> => {
       if (p === CWD) {
         return [
-          { name: 'sub', isFile: () => false, isDirectory: () => true },
+          {
+            name: 'sub',
+            isFile: () => false,
+            isDirectory: () => true,
+          } as Dirent,
         ] as Dirent[];
       }
       if (p === subDir) {
         return [
           {
-            name: GEMINI_MD_FILENAME,
+            name: ORIGINAL_GEMINI_MD_FILENAME_CONST_FOR_TEST,
             isFile: () => true,
             isDirectory: () => false,
-          },
+          } as Dirent,
         ] as Dirent[];
       }
       return [] as Dirent[];
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-    }) as any);
+    }) as unknown as typeof fsPromises.readdir);
 
     const { memoryContent, fileCount } = await loadServerHierarchicalMemory(
       CWD,
@@ -258,8 +439,11 @@ describe('loadServerHierarchicalMemory', () => {
     const relPathGlobal = path.relative(CWD, GLOBAL_GEMINI_FILE);
     const relPathProjectParent = path.relative(CWD, projectParentGeminiFile);
     const relPathProjectRoot = path.relative(CWD, projectRootGeminiFile);
-    const relPathCwd = GEMINI_MD_FILENAME;
-    const relPathSubDir = path.join('sub', GEMINI_MD_FILENAME);
+    const relPathCwd = ORIGINAL_GEMINI_MD_FILENAME_CONST_FOR_TEST;
+    const relPathSubDir = path.join(
+      'sub',
+      ORIGINAL_GEMINI_MD_FILENAME_CONST_FOR_TEST,
+    );
 
     const expectedContent = [
       `--- Context from: ${relPathGlobal} ---\nGlobal memory\n--- End of Context from: ${relPathGlobal} ---`,
@@ -275,11 +459,14 @@ describe('loadServerHierarchicalMemory', () => {
 
   it('should ignore specified directories during downward scan', async () => {
     const ignoredDir = path.join(CWD, 'node_modules');
-    const ignoredDirGeminiFile = path.join(ignoredDir, GEMINI_MD_FILENAME);
+    const ignoredDirGeminiFile = path.join(
+      ignoredDir,
+      ORIGINAL_GEMINI_MD_FILENAME_CONST_FOR_TEST,
+    ); // Corrected
     const regularSubDir = path.join(CWD, 'my_code');
     const regularSubDirGeminiFile = path.join(
       regularSubDir,
-      GEMINI_MD_FILENAME,
+      ORIGINAL_GEMINI_MD_FILENAME_CONST_FOR_TEST,
     );
 
     mockFs.access.mockImplementation(async (p) => {
@@ -303,38 +490,41 @@ describe('loadServerHierarchicalMemory', () => {
             name: 'node_modules',
             isFile: () => false,
             isDirectory: () => true,
-          },
-          { name: 'my_code', isFile: () => false, isDirectory: () => true },
+          } as Dirent,
+          {
+            name: 'my_code',
+            isFile: () => false,
+            isDirectory: () => true,
+          } as Dirent,
         ] as Dirent[];
       }
       if (p === regularSubDir) {
         return [
           {
-            name: GEMINI_MD_FILENAME,
+            name: ORIGINAL_GEMINI_MD_FILENAME_CONST_FOR_TEST,
             isFile: () => true,
             isDirectory: () => false,
-          },
+          } as Dirent,
         ] as Dirent[];
       }
       if (p === ignoredDir) {
         return [
           {
-            name: GEMINI_MD_FILENAME,
+            name: ORIGINAL_GEMINI_MD_FILENAME_CONST_FOR_TEST,
             isFile: () => true,
             isDirectory: () => false,
-          },
+          } as Dirent,
         ] as Dirent[];
       }
       return [] as Dirent[];
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-    }) as any);
+    }) as unknown as typeof fsPromises.readdir);
 
     const { memoryContent, fileCount } = await loadServerHierarchicalMemory(
       CWD,
       false,
     );
 
-    const expectedContent = `--- Context from: ${path.join('my_code', GEMINI_MD_FILENAME)} ---\nMy code memory\n--- End of Context from: ${path.join('my_code', GEMINI_MD_FILENAME)} ---`;
+    const expectedContent = `--- Context from: ${path.join('my_code', ORIGINAL_GEMINI_MD_FILENAME_CONST_FOR_TEST)} ---\nMy code memory\n--- End of Context from: ${path.join('my_code', ORIGINAL_GEMINI_MD_FILENAME_CONST_FOR_TEST)} ---`;
 
     expect(memoryContent).toBe(expectedContent);
     expect(fileCount).toBe(1);
@@ -365,8 +555,7 @@ describe('loadServerHierarchicalMemory', () => {
       if (p.toString().startsWith(path.join(CWD, 'deep_dir_')))
         return [] as Dirent[];
       return [] as Dirent[];
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any
-    }) as any);
+    }) as unknown as typeof fsPromises.readdir);
     mockFs.access.mockRejectedValue(new Error('not found'));
 
     await loadServerHierarchicalMemory(CWD, true);
diff --git a/packages/core/src/utils/memoryDiscovery.ts b/packages/core/src/utils/memoryDiscovery.ts
index 362134d8..2e6ce9fc 100644
--- a/packages/core/src/utils/memoryDiscovery.ts
+++ b/packages/core/src/utils/memoryDiscovery.ts
@@ -8,7 +8,10 @@ import * as fs from 'fs/promises';
 import * as fsSync from 'fs';
 import * as path from 'path';
 import { homedir } from 'os';
-import { GEMINI_CONFIG_DIR, GEMINI_MD_FILENAME } from '../tools/memoryTool.js';
+import {
+  GEMINI_CONFIG_DIR,
+  getCurrentGeminiMdFilename,
+} from '../tools/memoryTool.js';
 
 // Simple console logger, similar to the one previously in CLI's config.ts
 // TODO: Integrate with a more robust server-side logger if available/appropriate.
@@ -92,7 +95,7 @@ async function collectDownwardGeminiFiles(
 
   if (debugMode)
     logger.debug(
-      `Scanning downward for ${GEMINI_MD_FILENAME} files in: ${directory} (scanned: ${scannedDirCount.count}/${maxScanDirs})`,
+      `Scanning downward for ${getCurrentGeminiMdFilename()} files in: ${directory} (scanned: ${scannedDirCount.count}/${maxScanDirs})`,
     );
   const collectedPaths: string[] = [];
   try {
@@ -113,18 +116,21 @@ async function collectDownwardGeminiFiles(
           maxScanDirs,
         );
         collectedPaths.push(...subDirPaths);
-      } else if (entry.isFile() && entry.name === GEMINI_MD_FILENAME) {
+      } else if (
+        entry.isFile() &&
+        entry.name === getCurrentGeminiMdFilename()
+      ) {
         try {
           await fs.access(fullPath, fsSync.constants.R_OK);
           collectedPaths.push(fullPath);
           if (debugMode)
             logger.debug(
-              `Found readable downward ${GEMINI_MD_FILENAME}: ${fullPath}`,
+              `Found readable downward ${getCurrentGeminiMdFilename()}: ${fullPath}`,
             );
         } catch {
           if (debugMode)
             logger.debug(
-              `Downward ${GEMINI_MD_FILENAME} not readable, skipping: ${fullPath}`,
+              `Downward ${getCurrentGeminiMdFilename()} not readable, skipping: ${fullPath}`,
             );
         }
       }
@@ -139,7 +145,7 @@ async function collectDownwardGeminiFiles(
 
 async function getGeminiMdFilePathsInternal(
   currentWorkingDirectory: string,
-  userHomePath: string, // Keep userHomePath as a parameter for clarity
+  userHomePath: string,
   debugMode: boolean,
 ): Promise<string[]> {
   const resolvedCwd = path.resolve(currentWorkingDirectory);
@@ -147,13 +153,13 @@ async function getGeminiMdFilePathsInternal(
   const globalMemoryPath = path.join(
     resolvedHome,
     GEMINI_CONFIG_DIR,
-    GEMINI_MD_FILENAME,
+    getCurrentGeminiMdFilename(),
   );
   const paths: string[] = [];
 
   if (debugMode)
     logger.debug(
-      `Searching for ${GEMINI_MD_FILENAME} starting from CWD: ${resolvedCwd}`,
+      `Searching for ${getCurrentGeminiMdFilename()} starting from CWD: ${resolvedCwd}`,
     );
   if (debugMode) logger.debug(`User home directory: ${resolvedHome}`);
 
@@ -162,12 +168,12 @@ async function getGeminiMdFilePathsInternal(
     paths.push(globalMemoryPath);
     if (debugMode)
       logger.debug(
-        `Found readable global ${GEMINI_MD_FILENAME}: ${globalMemoryPath}`,
+        `Found readable global ${getCurrentGeminiMdFilename()}: ${globalMemoryPath}`,
       );
   } catch {
     if (debugMode)
       logger.debug(
-        `Global ${GEMINI_MD_FILENAME} not found or not readable: ${globalMemoryPath}`,
+        `Global ${getCurrentGeminiMdFilename()} not found or not readable: ${globalMemoryPath}`,
       );
   }
 
@@ -186,7 +192,7 @@ async function getGeminiMdFilePathsInternal(
     // Loop until filesystem root or currentDir is empty
     if (debugMode) {
       logger.debug(
-        `Checking for ${GEMINI_MD_FILENAME} in (upward scan): ${currentDir}`,
+        `Checking for ${getCurrentGeminiMdFilename()} in (upward scan): ${currentDir}`,
       );
     }
 
@@ -201,7 +207,7 @@ async function getGeminiMdFilePathsInternal(
       break;
     }
 
-    const potentialPath = path.join(currentDir, GEMINI_MD_FILENAME);
+    const potentialPath = path.join(currentDir, getCurrentGeminiMdFilename());
     try {
       await fs.access(potentialPath, fsSync.constants.R_OK);
       // Add to upwardPaths only if it's not the already added globalMemoryPath
@@ -209,14 +215,14 @@ async function getGeminiMdFilePathsInternal(
         upwardPaths.unshift(potentialPath);
         if (debugMode) {
           logger.debug(
-            `Found readable upward ${GEMINI_MD_FILENAME}: ${potentialPath}`,
+            `Found readable upward ${getCurrentGeminiMdFilename()}: ${potentialPath}`,
           );
         }
       }
     } catch {
       if (debugMode) {
         logger.debug(
-          `Upward ${GEMINI_MD_FILENAME} not found or not readable in: ${currentDir}`,
+          `Upward ${getCurrentGeminiMdFilename()} not found or not readable in: ${currentDir}`,
         );
       }
     }
@@ -247,7 +253,7 @@ async function getGeminiMdFilePathsInternal(
   downwardPaths.sort(); // Sort for consistent ordering, though hierarchy might be more complex
   if (debugMode && downwardPaths.length > 0)
     logger.debug(
-      `Found downward ${GEMINI_MD_FILENAME} files (sorted): ${JSON.stringify(downwardPaths)}`,
+      `Found downward ${getCurrentGeminiMdFilename()} files (sorted): ${JSON.stringify(downwardPaths)}`,
     );
   // Add downward paths only if they haven't been included already (e.g. from upward scan)
   for (const dPath of downwardPaths) {
@@ -258,7 +264,7 @@ async function getGeminiMdFilePathsInternal(
 
   if (debugMode)
     logger.debug(
-      `Final ordered ${GEMINI_MD_FILENAME} paths to read: ${JSON.stringify(paths)}`,
+      `Final ordered ${getCurrentGeminiMdFilename()} paths to read: ${JSON.stringify(paths)}`,
     );
   return paths;
 }
@@ -279,7 +285,7 @@ async function readGeminiMdFiles(
     } catch (error: unknown) {
       const message = error instanceof Error ? error.message : String(error);
       logger.warn(
-        `Warning: Could not read ${GEMINI_MD_FILENAME} file at ${filePath}. Error: ${message}`,
+        `Warning: Could not read ${getCurrentGeminiMdFilename()} file at ${filePath}. Error: ${message}`,
       );
       results.push({ filePath, content: null }); // Still include it with null content
       if (debugMode) logger.debug(`Failed to read: ${filePath}`);