feat(tags): Implement tagged task lists migration system (Part 1/2)

This commit introduces the foundational infrastructure for tagged task lists,
enabling multi-context task management without remote storage to prevent merge conflicts.

CORE ARCHITECTURE:
• Silent migration system transforms tasks.json from old format { "tasks": [...] }
  to new tagged format { "master": { "tasks": [...] } }
• Tag resolution layer provides complete backward compatibility - existing code continues to work
• Automatic configuration and state management for seamless user experience

SILENT MIGRATION SYSTEM:
• Automatic detection and migration of legacy tasks.json format
• Complete project migration: tasks.json + config.json + state.json
• Transparent tag resolution returns old format to maintain compatibility
• Zero breaking changes - all existing functionality preserved

CONFIGURATION MANAGEMENT:
• Added global.defaultTag setting (defaults to 'master')
• New tags section with gitIntegration placeholders for future features
• Automatic config.json migration during first run
• Proper state.json creation with migration tracking

USER EXPERIENCE:
• Clean, one-time FYI notice after migration (no emojis, professional styling)
• Notice appears after 'Suggested Next Steps' and is tracked in state.json
• Silent operation - users unaware migration occurred unless explicitly shown

TECHNICAL IMPLEMENTATION:
• Enhanced readJSON() with automatic migration detection and processing
• New utility functions: getCurrentTag(), resolveTag(), getTasksForTag(), setTasksForTag()
• Complete migration orchestration via performCompleteTagMigration()
• Robust error handling and fallback mechanisms

BACKWARD COMPATIBILITY:
• 100% backward compatibility maintained
• Existing CLI commands and MCP tools continue to work unchanged
• Legacy tasks.json format automatically upgraded on first read
• All existing workflows preserved

TESTING VERIFIED:
• Complete migration from legacy state works correctly
• Config.json properly updated with tagged system settings
• State.json created with correct initial values
• Migration notice system functions as designed
• All existing functionality continues to work normally

Part 2 will implement tag management commands (add-tag, use-tag, list-tags)
and MCP tool updates for full tagged task system functionality.

Related: Task 103 - Implement Tagged Task Lists System for Multi-Context Task Management

scripts/modules/commands.js

@@ -13,7 +13,7 @@ import http from 'http';
 import inquirer from 'inquirer';
 import ora from 'ora'; // Import ora
 
-import { log, readJSON, findProjectRoot } from './utils.js';
+import { log, readJSON, writeJSON, findProjectRoot } from './utils.js';
 import {
 	parsePRD,
 	updateTasks,
@@ -74,7 +74,8 @@ import {
 	displayAvailableModels,
 	displayApiKeyStatus,
 	displayAiUsageSummary,
-	displayMultipleTasksSummary
+	displayMultipleTasksSummary,
+	displayTaggedTasksFYI
 } from './ui.js';
 
 import { initializeProject } from '../init.js';
@@ -3266,6 +3267,42 @@ async function runCLI(argv = process.argv) {
 				updateInfo.latestVersion
 			);
 		}
+
+		// Check if migration has occurred and show FYI notice once
+		try {
+			const projectRoot = findProjectRoot() || '.';
+			const tasksPath = path.join(
+				projectRoot,
+				'.taskmaster',
+				'tasks',
+				'tasks.json'
+			);
+			const statePath = path.join(projectRoot, '.taskmaster', 'state.json');
+
+			if (fs.existsSync(tasksPath)) {
+				// Read raw file to check if it has master key (bypassing tag resolution)
+				const rawData = fs.readFileSync(tasksPath, 'utf8');
+				const parsedData = JSON.parse(rawData);
+
+				if (parsedData && parsedData.master) {
+					// Migration has occurred, check if we've shown the notice
+					let stateData = { migrationNoticeShown: false };
+					if (fs.existsSync(statePath)) {
+						stateData = readJSON(statePath) || stateData;
+					}
+
+					if (!stateData.migrationNoticeShown) {
+						displayTaggedTasksFYI({ _migrationHappened: true });
+
+						// Mark as shown
+						stateData.migrationNoticeShown = true;
+						writeJSON(statePath, stateData);
+					}
+				}
+			}
+		} catch (error) {
+			// Silently ignore errors checking for migration notice
+		}
 	} catch (error) {
 		// ** Specific catch block for missing configuration file **
 		if (error instanceof ConfigurationError) {