fix(expand): Enhance context handling in expandAllTasks function

- Added `tag` to context destructuring for better context management.
- Updated `readJSON` call to include `contextTag` for improved data integrity.
- Ensured the correct tag is passed during task expansion to prevent tag corruption.

scripts/modules/task-manager/expand-all-tasks.js

@@ -32,7 +32,12 @@ async function expandAllTasks(
 	context = {},
 	outputFormat = 'text' // Assume text default for CLI
 ) {
-	const { session, mcpLog, projectRoot: providedProjectRoot } = context;
+	const {
+		session,
+		mcpLog,
+		projectRoot: providedProjectRoot,
+		tag: contextTag
+	} = context;
 	const isMCPCall = !!mcpLog; // Determine if called from MCP
 
 	const projectRoot = providedProjectRoot || findProjectRoot();
@@ -74,7 +79,7 @@ async function expandAllTasks(
 
 	try {
 		logger.info(`Reading tasks from ${tasksPath}`);
-		const data = readJSON(tasksPath, projectRoot);
+		const data = readJSON(tasksPath, projectRoot, contextTag);
 		if (!data || !data.tasks) {
 			throw new Error(`Invalid tasks data in ${tasksPath}`);
 		}
@@ -124,7 +129,7 @@ async function expandAllTasks(
 					numSubtasks,
 					useResearch,
 					additionalContext,
-					{ ...context, projectRoot }, // Pass the whole context object with projectRoot
+					{ ...context, projectRoot, tag: data.tag || contextTag }, // Pass the whole context object with projectRoot and resolved tag
 					force
 				);
 				expandedCount++;

tests/integration/mcp-server/direct-functions.test.js

@@ -625,19 +625,38 @@ describe('MCP Server Direct Functions', () => {
 			// For successful cases, record that functions were called but don't make real calls
 			mockEnableSilentMode();
 
-			// Mock expandAllTasks
+			// Mock expandAllTasks - now returns a structured object instead of undefined
 			const mockExpandAll = jest.fn().mockImplementation(async () => {
-				// Just simulate success without any real operations
-				return undefined; // expandAllTasks doesn't return anything
+				// Return the new structured response that matches the actual implementation
+				return {
+					success: true,
+					expandedCount: 2,
+					failedCount: 0,
+					skippedCount: 1,
+					tasksToExpand: 3,
+					telemetryData: {
+						timestamp: new Date().toISOString(),
+						commandName: 'expand-all-tasks',
+						totalCost: 0.05,
+						totalTokens: 1000,
+						inputTokens: 600,
+						outputTokens: 400
+					}
+				};
 			});
 
-			// Call mock expandAllTasks
-			await mockExpandAll(
-				args.num,
-				args.research || false,
-				args.prompt || '',
-				args.force || false,
-				{ mcpLog: mockLogger, session: options.session }
+			// Call mock expandAllTasks with the correct signature
+			const result = await mockExpandAll(
+				args.file, // tasksPath
+				args.num, // numSubtasks
+				args.research || false, // useResearch
+				args.prompt || '', // additionalContext
+				args.force || false, // force
+				{
+					mcpLog: mockLogger,
+					session: options.session,
+					projectRoot: args.projectRoot
+				}
 			);
 
 			mockDisableSilentMode();
@@ -645,13 +664,14 @@ describe('MCP Server Direct Functions', () => {
 			return {
 				success: true,
 				data: {
-					message: 'Successfully expanded all pending tasks with subtasks',
+					message: `Expand all operation completed. Expanded: ${result.expandedCount}, Failed: ${result.failedCount}, Skipped: ${result.skippedCount}`,
 					details: {
-						numSubtasks: args.num,
-						research: args.research || false,
-						prompt: args.prompt || '',
-						force: args.force || false
-					}
+						expandedCount: result.expandedCount,
+						failedCount: result.failedCount,
+						skippedCount: result.skippedCount,
+						tasksToExpand: result.tasksToExpand
+					},
+					telemetryData: result.telemetryData
 				}
 			};
 		}
@@ -671,10 +691,13 @@ describe('MCP Server Direct Functions', () => {
 
 			// Assert
 			expect(result.success).toBe(true);
-			expect(result.data.message).toBe(
-				'Successfully expanded all pending tasks with subtasks'
-			);
-			expect(result.data.details.numSubtasks).toBe(3);
+			expect(result.data.message).toMatch(/Expand all operation completed/);
+			expect(result.data.details.expandedCount).toBe(2);
+			expect(result.data.details.failedCount).toBe(0);
+			expect(result.data.details.skippedCount).toBe(1);
+			expect(result.data.details.tasksToExpand).toBe(3);
+			expect(result.data.telemetryData).toBeDefined();
+			expect(result.data.telemetryData.commandName).toBe('expand-all-tasks');
 			expect(mockEnableSilentMode).toHaveBeenCalled();
 			expect(mockDisableSilentMode).toHaveBeenCalled();
 		});
@@ -695,7 +718,8 @@ describe('MCP Server Direct Functions', () => {
 
 			// Assert
 			expect(result.success).toBe(true);
-			expect(result.data.details.research).toBe(true);
+			expect(result.data.details.expandedCount).toBe(2);
+			expect(result.data.telemetryData).toBeDefined();
 			expect(mockEnableSilentMode).toHaveBeenCalled();
 			expect(mockDisableSilentMode).toHaveBeenCalled();
 		});
@@ -715,7 +739,8 @@ describe('MCP Server Direct Functions', () => {
 
 			// Assert
 			expect(result.success).toBe(true);
-			expect(result.data.details.force).toBe(true);
+			expect(result.data.details.expandedCount).toBe(2);
+			expect(result.data.telemetryData).toBeDefined();
 			expect(mockEnableSilentMode).toHaveBeenCalled();
 			expect(mockDisableSilentMode).toHaveBeenCalled();
 		});
@@ -735,11 +760,77 @@ describe('MCP Server Direct Functions', () => {
 
 			// Assert
 			expect(result.success).toBe(true);
-			expect(result.data.details.prompt).toBe(
-				'Additional context for subtasks'
-			);
+			expect(result.data.details.expandedCount).toBe(2);
+			expect(result.data.telemetryData).toBeDefined();
 			expect(mockEnableSilentMode).toHaveBeenCalled();
 			expect(mockDisableSilentMode).toHaveBeenCalled();
 		});
+
+		test('should handle case with no eligible tasks', async () => {
+			// Arrange
+			const args = {
+				projectRoot: testProjectRoot,
+				file: testTasksPath,
+				num: 3
+			};
+
+			// Act - Mock the scenario where no tasks are eligible for expansion
+			async function testNoEligibleTasks(args, mockLogger, options = {}) {
+				mockEnableSilentMode();
+
+				const mockExpandAll = jest.fn().mockImplementation(async () => {
+					return {
+						success: true,
+						expandedCount: 0,
+						failedCount: 0,
+						skippedCount: 0,
+						tasksToExpand: 0,
+						telemetryData: null,
+						message: 'No tasks eligible for expansion.'
+					};
+				});
+
+				const result = await mockExpandAll(
+					args.file,
+					args.num,
+					false,
+					'',
+					false,
+					{
+						mcpLog: mockLogger,
+						session: options.session,
+						projectRoot: args.projectRoot
+					},
+					'json'
+				);
+
+				mockDisableSilentMode();
+
+				return {
+					success: true,
+					data: {
+						message: result.message,
+						details: {
+							expandedCount: result.expandedCount,
+							failedCount: result.failedCount,
+							skippedCount: result.skippedCount,
+							tasksToExpand: result.tasksToExpand
+						},
+						telemetryData: result.telemetryData
+					}
+				};
+			}
+
+			const result = await testNoEligibleTasks(args, mockLogger, {
+				session: mockSession
+			});
+
+			// Assert
+			expect(result.success).toBe(true);
+			expect(result.data.message).toBe('No tasks eligible for expansion.');
+			expect(result.data.details.expandedCount).toBe(0);
+			expect(result.data.details.tasksToExpand).toBe(0);
+			expect(result.data.telemetryData).toBeNull();
+		});
 	});
 });

tests/unit/mcp/tools/expand-all.test.js

@@ -0,0 +1,324 @@
+/**
+ * Tests for the expand-all MCP tool
+ *
+ * Note: This test does NOT test the actual implementation. It tests that:
+ * 1. The tool is registered correctly with the correct parameters
+ * 2. Arguments are passed correctly to expandAllTasksDirect
+ * 3. Error handling works as expected
+ *
+ * We do NOT import the real implementation - everything is mocked
+ */
+
+import { jest } from '@jest/globals';
+
+// Mock EVERYTHING
+const mockExpandAllTasksDirect = jest.fn();
+jest.mock('../../../../mcp-server/src/core/task-master-core.js', () => ({
+	expandAllTasksDirect: mockExpandAllTasksDirect
+}));
+
+const mockHandleApiResult = jest.fn((result) => result);
+const mockGetProjectRootFromSession = jest.fn(() => '/mock/project/root');
+const mockCreateErrorResponse = jest.fn((msg) => ({
+	success: false,
+	error: { code: 'ERROR', message: msg }
+}));
+const mockWithNormalizedProjectRoot = jest.fn((fn) => fn);
+
+jest.mock('../../../../mcp-server/src/tools/utils.js', () => ({
+	getProjectRootFromSession: mockGetProjectRootFromSession,
+	handleApiResult: mockHandleApiResult,
+	createErrorResponse: mockCreateErrorResponse,
+	withNormalizedProjectRoot: mockWithNormalizedProjectRoot
+}));
+
+// Mock the z object from zod
+const mockZod = {
+	object: jest.fn(() => mockZod),
+	string: jest.fn(() => mockZod),
+	number: jest.fn(() => mockZod),
+	boolean: jest.fn(() => mockZod),
+	optional: jest.fn(() => mockZod),
+	describe: jest.fn(() => mockZod),
+	_def: {
+		shape: () => ({
+			num: {},
+			research: {},
+			prompt: {},
+			force: {},
+			tag: {},
+			projectRoot: {}
+		})
+	}
+};
+
+jest.mock('zod', () => ({
+	z: mockZod
+}));
+
+// DO NOT import the real module - create a fake implementation
+// This is the fake implementation of registerExpandAllTool
+const registerExpandAllTool = (server) => {
+	// Create simplified version of the tool config
+	const toolConfig = {
+		name: 'expand_all',
+		description: 'Use Taskmaster to expand all eligible pending tasks',
+		parameters: mockZod,
+
+		// Create a simplified mock of the execute function
+		execute: mockWithNormalizedProjectRoot(async (args, context) => {
+			const { log, session } = context;
+
+			try {
+				log.info &&
+					log.info(`Starting expand-all with args: ${JSON.stringify(args)}`);
+
+				// Call expandAllTasksDirect
+				const result = await mockExpandAllTasksDirect(args, log, { session });
+
+				// Handle result
+				return mockHandleApiResult(result, log);
+			} catch (error) {
+				log.error && log.error(`Error in expand-all tool: ${error.message}`);
+				return mockCreateErrorResponse(error.message);
+			}
+		})
+	};
+
+	// Register the tool with the server
+	server.addTool(toolConfig);
+};
+
+describe('MCP Tool: expand-all', () => {
+	// Create mock server
+	let mockServer;
+	let executeFunction;
+
+	// Create mock logger
+	const mockLogger = {
+		debug: jest.fn(),
+		info: jest.fn(),
+		warn: jest.fn(),
+		error: jest.fn()
+	};
+
+	// Test data
+	const validArgs = {
+		num: 3,
+		research: true,
+		prompt: 'additional context',
+		force: false,
+		tag: 'master',
+		projectRoot: '/test/project'
+	};
+
+	// Standard responses
+	const successResponse = {
+		success: true,
+		data: {
+			message:
+				'Expand all operation completed. Expanded: 2, Failed: 0, Skipped: 1',
+			details: {
+				expandedCount: 2,
+				failedCount: 0,
+				skippedCount: 1,
+				tasksToExpand: 3,
+				telemetryData: {
+					commandName: 'expand-all-tasks',
+					totalCost: 0.15,
+					totalTokens: 2500
+				}
+			}
+		}
+	};
+
+	const errorResponse = {
+		success: false,
+		error: {
+			code: 'EXPAND_ALL_ERROR',
+			message: 'Failed to expand tasks'
+		}
+	};
+
+	beforeEach(() => {
+		// Reset all mocks
+		jest.clearAllMocks();
+
+		// Create mock server
+		mockServer = {
+			addTool: jest.fn((config) => {
+				executeFunction = config.execute;
+			})
+		};
+
+		// Setup default successful response
+		mockExpandAllTasksDirect.mockResolvedValue(successResponse);
+
+		// Register the tool
+		registerExpandAllTool(mockServer);
+	});
+
+	test('should register the tool correctly', () => {
+		// Verify tool was registered
+		expect(mockServer.addTool).toHaveBeenCalledWith(
+			expect.objectContaining({
+				name: 'expand_all',
+				description: expect.stringContaining('expand all eligible pending'),
+				parameters: expect.any(Object),
+				execute: expect.any(Function)
+			})
+		);
+
+		// Verify the tool config was passed
+		const toolConfig = mockServer.addTool.mock.calls[0][0];
+		expect(toolConfig).toHaveProperty('parameters');
+		expect(toolConfig).toHaveProperty('execute');
+	});
+
+	test('should execute the tool with valid parameters', async () => {
+		// Setup context
+		const mockContext = {
+			log: mockLogger,
+			session: { workingDirectory: '/mock/dir' }
+		};
+
+		// Execute the function
+		const result = await executeFunction(validArgs, mockContext);
+
+		// Verify expandAllTasksDirect was called with correct arguments
+		expect(mockExpandAllTasksDirect).toHaveBeenCalledWith(
+			validArgs,
+			mockLogger,
+			{ session: mockContext.session }
+		);
+
+		// Verify handleApiResult was called
+		expect(mockHandleApiResult).toHaveBeenCalledWith(
+			successResponse,
+			mockLogger
+		);
+		expect(result).toEqual(successResponse);
+	});
+
+	test('should handle expand all with no eligible tasks', async () => {
+		// Arrange
+		const mockDirectResult = {
+			success: true,
+			data: {
+				message:
+					'Expand all operation completed. Expanded: 0, Failed: 0, Skipped: 0',
+				details: {
+					expandedCount: 0,
+					failedCount: 0,
+					skippedCount: 0,
+					tasksToExpand: 0,
+					telemetryData: null
+				}
+			}
+		};
+
+		mockExpandAllTasksDirect.mockResolvedValue(mockDirectResult);
+		mockHandleApiResult.mockReturnValue({
+			success: true,
+			data: mockDirectResult.data
+		});
+
+		// Act
+		const result = await executeFunction(validArgs, {
+			log: mockLogger,
+			session: { workingDirectory: '/test' }
+		});
+
+		// Assert
+		expect(result.success).toBe(true);
+		expect(result.data.details.expandedCount).toBe(0);
+		expect(result.data.details.tasksToExpand).toBe(0);
+	});
+
+	test('should handle expand all with mixed success/failure', async () => {
+		// Arrange
+		const mockDirectResult = {
+			success: true,
+			data: {
+				message:
+					'Expand all operation completed. Expanded: 2, Failed: 1, Skipped: 0',
+				details: {
+					expandedCount: 2,
+					failedCount: 1,
+					skippedCount: 0,
+					tasksToExpand: 3,
+					telemetryData: {
+						commandName: 'expand-all-tasks',
+						totalCost: 0.1,
+						totalTokens: 1500
+					}
+				}
+			}
+		};
+
+		mockExpandAllTasksDirect.mockResolvedValue(mockDirectResult);
+		mockHandleApiResult.mockReturnValue({
+			success: true,
+			data: mockDirectResult.data
+		});
+
+		// Act
+		const result = await executeFunction(validArgs, {
+			log: mockLogger,
+			session: { workingDirectory: '/test' }
+		});
+
+		// Assert
+		expect(result.success).toBe(true);
+		expect(result.data.details.expandedCount).toBe(2);
+		expect(result.data.details.failedCount).toBe(1);
+	});
+
+	test('should handle errors from expandAllTasksDirect', async () => {
+		// Arrange
+		mockExpandAllTasksDirect.mockRejectedValue(
+			new Error('Direct function error')
+		);
+
+		// Act
+		const result = await executeFunction(validArgs, {
+			log: mockLogger,
+			session: { workingDirectory: '/test' }
+		});
+
+		// Assert
+		expect(mockLogger.error).toHaveBeenCalledWith(
+			expect.stringContaining('Error in expand-all tool')
+		);
+		expect(mockCreateErrorResponse).toHaveBeenCalledWith(
+			'Direct function error'
+		);
+	});
+
+	test('should handle different argument combinations', async () => {
+		// Test with minimal args
+		const minimalArgs = {
+			projectRoot: '/test/project'
+		};
+
+		// Act
+		await executeFunction(minimalArgs, {
+			log: mockLogger,
+			session: { workingDirectory: '/test' }
+		});
+
+		// Assert
+		expect(mockExpandAllTasksDirect).toHaveBeenCalledWith(
+			minimalArgs,
+			mockLogger,
+			expect.any(Object)
+		);
+	});
+
+	test('should use withNormalizedProjectRoot wrapper correctly', () => {
+		// Verify that the execute function is wrapped with withNormalizedProjectRoot
+		expect(mockWithNormalizedProjectRoot).toHaveBeenCalledWith(
+			expect.any(Function)
+		);
+	});
+});

tests/unit/scripts/modules/task-manager/expand-all-tasks.test.js

@@ -0,0 +1,502 @@
+/**
+ * Tests for the expand-all-tasks.js module
+ */
+import { jest } from '@jest/globals';
+
+// Mock the dependencies before importing the module under test
+jest.unstable_mockModule(
+	'../../../../../scripts/modules/task-manager/expand-task.js',
+	() => ({
+		default: jest.fn()
+	})
+);
+
+jest.unstable_mockModule('../../../../../scripts/modules/utils.js', () => ({
+	readJSON: jest.fn(),
+	log: jest.fn(),
+	isSilentMode: jest.fn(() => false),
+	findProjectRoot: jest.fn(() => '/test/project'),
+	aggregateTelemetry: jest.fn()
+}));
+
+jest.unstable_mockModule(
+	'../../../../../scripts/modules/config-manager.js',
+	() => ({
+		getDebugFlag: jest.fn(() => false)
+	})
+);
+
+jest.unstable_mockModule('../../../../../scripts/modules/ui.js', () => ({
+	startLoadingIndicator: jest.fn(),
+	stopLoadingIndicator: jest.fn(),
+	displayAiUsageSummary: jest.fn()
+}));
+
+jest.unstable_mockModule('chalk', () => ({
+	default: {
+		white: { bold: jest.fn((text) => text) },
+		cyan: jest.fn((text) => text),
+		green: jest.fn((text) => text),
+		gray: jest.fn((text) => text),
+		red: jest.fn((text) => text),
+		bold: jest.fn((text) => text)
+	}
+}));
+
+jest.unstable_mockModule('boxen', () => ({
+	default: jest.fn((text) => text)
+}));
+
+// Import the mocked modules
+const { default: expandTask } = await import(
+	'../../../../../scripts/modules/task-manager/expand-task.js'
+);
+const { readJSON, aggregateTelemetry, findProjectRoot } = await import(
+	'../../../../../scripts/modules/utils.js'
+);
+
+// Import the module under test
+const { default: expandAllTasks } = await import(
+	'../../../../../scripts/modules/task-manager/expand-all-tasks.js'
+);
+
+const mockExpandTask = expandTask;
+const mockReadJSON = readJSON;
+const mockAggregateTelemetry = aggregateTelemetry;
+const mockFindProjectRoot = findProjectRoot;
+
+describe('expandAllTasks', () => {
+	const mockTasksPath = '/test/tasks.json';
+	const mockProjectRoot = '/test/project';
+	const mockSession = { userId: 'test-user' };
+	const mockMcpLog = {
+		info: jest.fn(),
+		warn: jest.fn(),
+		error: jest.fn(),
+		debug: jest.fn()
+	};
+
+	const sampleTasksData = {
+		tag: 'master',
+		tasks: [
+			{
+				id: 1,
+				title: 'Pending Task 1',
+				status: 'pending',
+				subtasks: []
+			},
+			{
+				id: 2,
+				title: 'In Progress Task',
+				status: 'in-progress',
+				subtasks: []
+			},
+			{
+				id: 3,
+				title: 'Done Task',
+				status: 'done',
+				subtasks: []
+			},
+			{
+				id: 4,
+				title: 'Task with Subtasks',
+				status: 'pending',
+				subtasks: [{ id: '4.1', title: 'Existing subtask' }]
+			}
+		]
+	};
+
+	beforeEach(() => {
+		jest.clearAllMocks();
+		mockReadJSON.mockReturnValue(sampleTasksData);
+		mockAggregateTelemetry.mockReturnValue({
+			timestamp: '2024-01-01T00:00:00.000Z',
+			commandName: 'expand-all-tasks',
+			totalCost: 0.1,
+			totalTokens: 2000,
+			inputTokens: 1200,
+			outputTokens: 800
+		});
+	});
+
+	describe('successful expansion', () => {
+		test('should expand all eligible pending tasks', async () => {
+			// Arrange
+			const mockTelemetryData = {
+				timestamp: '2024-01-01T00:00:00.000Z',
+				commandName: 'expand-task',
+				totalCost: 0.05,
+				totalTokens: 1000
+			};
+
+			mockExpandTask.mockResolvedValue({
+				telemetryData: mockTelemetryData
+			});
+
+			// Act
+			const result = await expandAllTasks(
+				mockTasksPath,
+				3, // numSubtasks
+				false, // useResearch
+				'test context', // additionalContext
+				false, // force
+				{
+					session: mockSession,
+					mcpLog: mockMcpLog,
+					projectRoot: mockProjectRoot,
+					tag: 'master'
+				},
+				'json' // outputFormat
+			);
+
+			// Assert
+			expect(result.success).toBe(true);
+			expect(result.expandedCount).toBe(2); // Tasks 1 and 2 (pending and in-progress)
+			expect(result.failedCount).toBe(0);
+			expect(result.skippedCount).toBe(0);
+			expect(result.tasksToExpand).toBe(2);
+			expect(result.telemetryData).toBeDefined();
+
+			// Verify readJSON was called correctly
+			expect(mockReadJSON).toHaveBeenCalledWith(
+				mockTasksPath,
+				mockProjectRoot,
+				'master'
+			);
+
+			// Verify expandTask was called for eligible tasks
+			expect(mockExpandTask).toHaveBeenCalledTimes(2);
+			expect(mockExpandTask).toHaveBeenCalledWith(
+				mockTasksPath,
+				1,
+				3,
+				false,
+				'test context',
+				expect.objectContaining({
+					session: mockSession,
+					mcpLog: mockMcpLog,
+					projectRoot: mockProjectRoot,
+					tag: 'master'
+				}),
+				false
+			);
+		});
+
+		test('should handle force flag to expand tasks with existing subtasks', async () => {
+			// Arrange
+			mockExpandTask.mockResolvedValue({
+				telemetryData: { commandName: 'expand-task', totalCost: 0.05 }
+			});
+
+			// Act
+			const result = await expandAllTasks(
+				mockTasksPath,
+				2,
+				false,
+				'',
+				true, // force = true
+				{
+					session: mockSession,
+					mcpLog: mockMcpLog,
+					projectRoot: mockProjectRoot
+				},
+				'json'
+			);
+
+			// Assert
+			expect(result.expandedCount).toBe(3); // Tasks 1, 2, and 4 (including task with existing subtasks)
+			expect(mockExpandTask).toHaveBeenCalledTimes(3);
+		});
+
+		test('should handle research flag', async () => {
+			// Arrange
+			mockExpandTask.mockResolvedValue({
+				telemetryData: { commandName: 'expand-task', totalCost: 0.08 }
+			});
+
+			// Act
+			const result = await expandAllTasks(
+				mockTasksPath,
+				undefined, // numSubtasks not specified
+				true, // useResearch = true
+				'research context',
+				false,
+				{
+					session: mockSession,
+					mcpLog: mockMcpLog,
+					projectRoot: mockProjectRoot
+				},
+				'json'
+			);
+
+			// Assert
+			expect(result.success).toBe(true);
+			expect(mockExpandTask).toHaveBeenCalledWith(
+				mockTasksPath,
+				expect.any(Number),
+				undefined,
+				true, // research flag passed correctly
+				'research context',
+				expect.any(Object),
+				false
+			);
+		});
+
+		test('should return success with message when no tasks are eligible', async () => {
+			// Arrange - Mock tasks data with no eligible tasks
+			const noEligibleTasksData = {
+				tag: 'master',
+				tasks: [
+					{ id: 1, status: 'done', subtasks: [] },
+					{
+						id: 2,
+						status: 'pending',
+						subtasks: [{ id: '2.1', title: 'existing' }]
+					}
+				]
+			};
+			mockReadJSON.mockReturnValue(noEligibleTasksData);
+
+			// Act
+			const result = await expandAllTasks(
+				mockTasksPath,
+				3,
+				false,
+				'',
+				false, // force = false, so task with subtasks won't be expanded
+				{
+					session: mockSession,
+					mcpLog: mockMcpLog,
+					projectRoot: mockProjectRoot
+				},
+				'json'
+			);
+
+			// Assert
+			expect(result.success).toBe(true);
+			expect(result.expandedCount).toBe(0);
+			expect(result.failedCount).toBe(0);
+			expect(result.skippedCount).toBe(0);
+			expect(result.tasksToExpand).toBe(0);
+			expect(result.message).toBe('No tasks eligible for expansion.');
+			expect(mockExpandTask).not.toHaveBeenCalled();
+		});
+	});
+
+	describe('error handling', () => {
+		test('should handle expandTask failures gracefully', async () => {
+			// Arrange
+			mockExpandTask
+				.mockResolvedValueOnce({ telemetryData: { totalCost: 0.05 } }) // First task succeeds
+				.mockRejectedValueOnce(new Error('AI service error')); // Second task fails
+
+			// Act
+			const result = await expandAllTasks(
+				mockTasksPath,
+				3,
+				false,
+				'',
+				false,
+				{
+					session: mockSession,
+					mcpLog: mockMcpLog,
+					projectRoot: mockProjectRoot
+				},
+				'json'
+			);
+
+			// Assert
+			expect(result.success).toBe(true);
+			expect(result.expandedCount).toBe(1);
+			expect(result.failedCount).toBe(1);
+		});
+
+		test('should throw error when tasks.json is invalid', async () => {
+			// Arrange
+			mockReadJSON.mockReturnValue(null);
+
+			// Act & Assert
+			await expect(
+				expandAllTasks(
+					mockTasksPath,
+					3,
+					false,
+					'',
+					false,
+					{
+						session: mockSession,
+						mcpLog: mockMcpLog,
+						projectRoot: mockProjectRoot
+					},
+					'json'
+				)
+			).rejects.toThrow('Invalid tasks data');
+		});
+
+		test('should throw error when project root cannot be determined', async () => {
+			// Arrange - Mock findProjectRoot to return null for this test
+			mockFindProjectRoot.mockReturnValueOnce(null);
+
+			// Act & Assert
+			await expect(
+				expandAllTasks(
+					mockTasksPath,
+					3,
+					false,
+					'',
+					false,
+					{
+						session: mockSession,
+						mcpLog: mockMcpLog
+						// No projectRoot provided, and findProjectRoot will return null
+					},
+					'json'
+				)
+			).rejects.toThrow('Could not determine project root directory');
+		});
+	});
+
+	describe('telemetry aggregation', () => {
+		test('should aggregate telemetry data from multiple expand operations', async () => {
+			// Arrange
+			const telemetryData1 = {
+				commandName: 'expand-task',
+				totalCost: 0.03,
+				totalTokens: 600
+			};
+			const telemetryData2 = {
+				commandName: 'expand-task',
+				totalCost: 0.04,
+				totalTokens: 800
+			};
+
+			mockExpandTask
+				.mockResolvedValueOnce({ telemetryData: telemetryData1 })
+				.mockResolvedValueOnce({ telemetryData: telemetryData2 });
+
+			// Act
+			const result = await expandAllTasks(
+				mockTasksPath,
+				3,
+				false,
+				'',
+				false,
+				{
+					session: mockSession,
+					mcpLog: mockMcpLog,
+					projectRoot: mockProjectRoot
+				},
+				'json'
+			);
+
+			// Assert
+			expect(mockAggregateTelemetry).toHaveBeenCalledWith(
+				[telemetryData1, telemetryData2],
+				'expand-all-tasks'
+			);
+			expect(result.telemetryData).toBeDefined();
+			expect(result.telemetryData.commandName).toBe('expand-all-tasks');
+		});
+
+		test('should handle missing telemetry data gracefully', async () => {
+			// Arrange
+			mockExpandTask.mockResolvedValue({}); // No telemetryData
+
+			// Act
+			const result = await expandAllTasks(
+				mockTasksPath,
+				3,
+				false,
+				'',
+				false,
+				{
+					session: mockSession,
+					mcpLog: mockMcpLog,
+					projectRoot: mockProjectRoot
+				},
+				'json'
+			);
+
+			// Assert
+			expect(result.success).toBe(true);
+			expect(mockAggregateTelemetry).toHaveBeenCalledWith(
+				[],
+				'expand-all-tasks'
+			);
+		});
+	});
+
+	describe('output format handling', () => {
+		test('should use text output format for CLI calls', async () => {
+			// Arrange
+			mockExpandTask.mockResolvedValue({
+				telemetryData: { commandName: 'expand-task', totalCost: 0.05 }
+			});
+
+			// Act
+			const result = await expandAllTasks(
+				mockTasksPath,
+				3,
+				false,
+				'',
+				false,
+				{
+					projectRoot: mockProjectRoot
+					// No mcpLog provided, should use CLI logger
+				},
+				'text' // CLI output format
+			);
+
+			// Assert
+			expect(result.success).toBe(true);
+			// In text mode, loading indicators and console output would be used
+			// This is harder to test directly but we can verify the result structure
+		});
+
+		test('should handle context tag properly', async () => {
+			// Arrange
+			const taggedTasksData = {
+				...sampleTasksData,
+				tag: 'feature-branch'
+			};
+			mockReadJSON.mockReturnValue(taggedTasksData);
+			mockExpandTask.mockResolvedValue({
+				telemetryData: { commandName: 'expand-task', totalCost: 0.05 }
+			});
+
+			// Act
+			const result = await expandAllTasks(
+				mockTasksPath,
+				3,
+				false,
+				'',
+				false,
+				{
+					session: mockSession,
+					mcpLog: mockMcpLog,
+					projectRoot: mockProjectRoot,
+					tag: 'feature-branch'
+				},
+				'json'
+			);
+
+			// Assert
+			expect(mockReadJSON).toHaveBeenCalledWith(
+				mockTasksPath,
+				mockProjectRoot,
+				'feature-branch'
+			);
+			expect(mockExpandTask).toHaveBeenCalledWith(
+				mockTasksPath,
+				expect.any(Number),
+				3,
+				false,
+				'',
+				expect.objectContaining({
+					tag: 'feature-branch'
+				}),
+				false
+			);
+		});
+	});
+});