feat: auto-slim completed tasks to reduce tasks.json size

mcp-server/src/core/direct-functions/move-task-cross-tag.js

@@ -117,11 +117,23 @@ export async function moveTaskCrossTagDirect(args, log, context = {}) {
 				{ projectRoot }
 			);
 
+			// Check if any tasks were renumbered during the move
+			const renumberedTasks = (result.movedTasks || []).filter(
+				(t) => t.newId !== undefined
+			);
+			let message = `Successfully moved ${sourceIds.length} task(s) from "${args.sourceTag}" to "${args.targetTag}"`;
+			if (renumberedTasks.length > 0) {
+				const renumberDetails = renumberedTasks
+					.map((t) => `${t.originalId} → ${t.newId}`)
+					.join(', ');
+				message += `. Renumbered to avoid ID collisions: ${renumberDetails}`;
+			}
+
 			return {
 				success: true,
 				data: {
 					...result,
-					message: `Successfully moved ${sourceIds.length} task(s) from "${args.sourceTag}" to "${args.targetTag}"`,
+					message,
 					moveOptions,
 					sourceTag: args.sourceTag,
 					targetTag: args.targetTag

scripts/modules/config-manager.js

@@ -58,7 +58,8 @@ const DEFAULTS = {
 		responseLanguage: 'English',
 		enableCodebaseAnalysis: true,
 		enableProxy: false,
-		anonymousTelemetry: true // Allow users to opt out of Sentry telemetry for local storage
+		anonymousTelemetry: true, // Allow users to opt out of Sentry telemetry for local storage
+		slimDoneTasks: true // Auto-slim completed tasks to reduce tasks.json size
 	},
 	claudeCode: {},
 	codexCli: {},
@@ -747,6 +748,12 @@ function getAnonymousTelemetryEnabled(explicitRoot = null) {
 	return config.anonymousTelemetry !== false; // Default true if undefined
 }
 
+function isSlimDoneTasksEnabled(explicitRoot = null) {
+	// Return boolean-safe value with default true (opt-in by default)
+	const config = getGlobalConfig(explicitRoot);
+	return config.slimDoneTasks !== false; // Default true if undefined
+}
+
 function isProxyEnabled(session = null, projectRoot = null) {
 	// Priority 1: Environment variable
 	const envFlag = resolveEnvVariable(
@@ -1305,6 +1312,7 @@ export {
 	getProxyEnabled,
 	isProxyEnabled,
 	getAnonymousTelemetryEnabled,
+	isSlimDoneTasksEnabled,
 	getParametersForRole,
 	getUserId,
 	// Operating mode

scripts/modules/task-manager/move-task.js

@@ -816,6 +816,23 @@ async function resolveDependencies(
 	};
 }
 
+/**
+ * Get the next available task ID in the target tag.
+ * Finds the maximum existing ID among target tag tasks and any already-assigned
+ * new IDs from the current move batch, then returns max + 1.
+ * @param {Object} rawData - Raw data object
+ * @param {string} targetTag - Target tag name
+ * @param {Map} idRemapping - Map of old ID -> new ID for tasks already processed in this batch
+ * @returns {number} Next available task ID
+ */
+function getNextAvailableId(rawData, targetTag, idRemapping) {
+	const existingIds = rawData[targetTag].tasks.map((t) => t.id);
+	const remappedIds = Array.from(idRemapping.values());
+	const allIds = [...existingIds, ...remappedIds];
+	if (allIds.length === 0) return 1;
+	return Math.max(...allIds) + 1;
+}
+
 /**
  * Execute the actual move operation
  * @param {Array} tasksToMove - Array of task IDs to move
@@ -836,6 +853,8 @@ async function executeMoveOperation(
 ) {
 	const { projectRoot } = context;
 	const movedTasks = [];
+	// Track ID remapping: oldId -> newId (only for tasks that needed renumbering)
+	const idRemapping = new Map();
 
 	// Move each task from source to target tag
 	for (const taskId of tasksToMove) {
@@ -860,22 +879,39 @@ async function executeMoveOperation(
 		const existingTaskIndex = rawData[targetTag].tasks.findIndex(
 			(t) => t.id === normalizedTaskId
 		);
+
+		let assignedId = normalizedTaskId;
+
 		if (existingTaskIndex !== -1) {
-			throw new MoveTaskError(
-				MOVE_ERROR_CODES.TASK_ALREADY_EXISTS,
-				`Task ${taskId} already exists in target tag "${targetTag}"`,
-				{
-					conflictingId: normalizedTaskId,
-					targetTag,
-					suggestions: [
-						'Choose a different target tag without conflicting IDs',
-						'Move a different set of IDs (avoid existing ones)',
-						'If needed, move within-tag to a new ID first, then cross-tag move'
-					]
-				}
+			// ID collision detected — auto-renumber to the next available ID
+			assignedId = getNextAvailableId(rawData, targetTag, idRemapping);
+			idRemapping.set(normalizedTaskId, assignedId);
+			log(
+				'info',
+				`Task ${normalizedTaskId} conflicts with existing ID in "${targetTag}", renumbered to ${assignedId}`
 			);
 		}
 
+		// Apply the new ID to the task
+		taskToMove.id = assignedId;
+
+		// Update internal subtask dependency references that pointed to the old parent ID
+		if (Array.isArray(taskToMove.subtasks)) {
+			taskToMove.subtasks.forEach((subtask) => {
+				if (Array.isArray(subtask.dependencies)) {
+					subtask.dependencies = subtask.dependencies.map((dep) => {
+						if (typeof dep === 'string' && dep.includes('.')) {
+							const [depParent, depSub] = dep.split('.');
+							if (parseInt(depParent, 10) === normalizedTaskId) {
+								return `${assignedId}.${depSub}`;
+							}
+						}
+						return dep;
+					});
+				}
+			});
+		}
+
 		// Remove from source tag
 		rawData[sourceTag].tasks.splice(sourceTaskIndex, 1);
 
@@ -887,13 +923,65 @@ async function executeMoveOperation(
 		);
 		rawData[targetTag].tasks.push(taskWithPreservedMetadata);
 
-		movedTasks.push({
+		const moveEntry = {
 			id: taskId,
 			fromTag: sourceTag,
 			toTag: targetTag
-		});
+		};
+		if (assignedId !== normalizedTaskId) {
+			moveEntry.originalId = normalizedTaskId;
+			moveEntry.newId = assignedId;
+		}
+		movedTasks.push(moveEntry);
 
-		log('info', `Moved task ${taskId} from "${sourceTag}" to "${targetTag}"`);
+		log(
+			'info',
+			`Moved task ${taskId} from "${sourceTag}" to "${targetTag}"${assignedId !== normalizedTaskId ? ` (renumbered to ${assignedId})` : ''}`
+		);
+	}
+
+	// After all tasks are moved, update cross-references within the moved batch.
+	// If task A depended on task B and both were moved but B got renumbered,
+	// update A's dependency to point to B's new ID.
+	if (idRemapping.size > 0) {
+		for (const taskId of tasksToMove) {
+			const normalizedTaskId =
+				typeof taskId === 'string' ? parseInt(taskId, 10) : taskId;
+			// Find the task in the target tag (it may have been renumbered)
+			const finalId = idRemapping.get(normalizedTaskId) || normalizedTaskId;
+			const movedTask = rawData[targetTag].tasks.find(
+				(t) => t.id === finalId
+			);
+			if (movedTask && Array.isArray(movedTask.dependencies)) {
+				movedTask.dependencies = movedTask.dependencies.map((dep) => {
+					const normalizedDep = normalizeDependency(dep);
+					if (
+						Number.isFinite(normalizedDep) &&
+						idRemapping.has(normalizedDep)
+					) {
+						return idRemapping.get(normalizedDep);
+					}
+					return dep;
+				});
+			}
+			// Also update subtask dependencies that reference remapped IDs
+			if (movedTask && Array.isArray(movedTask.subtasks)) {
+				movedTask.subtasks.forEach((subtask) => {
+					if (Array.isArray(subtask.dependencies)) {
+						subtask.dependencies = subtask.dependencies.map((dep) => {
+							const normalizedDep = normalizeDependency(dep);
+							if (
+								Number.isFinite(normalizedDep) &&
+								idRemapping.has(normalizedDep)
+							) {
+								return idRemapping.get(normalizedDep);
+							}
+							return dep;
+						});
+					}
+				});
+			}
+		}
 	}
 
 	return { rawData, movedTasks };
@@ -922,8 +1010,19 @@ async function finalizeMove(
 	// Write the updated data
 	writeJSON(tasksPath, rawData, projectRoot, null);
 
+	// Check if any tasks were renumbered during the move
+	const renumberedTasks = movedTasks.filter((t) => t.newId !== undefined);
+
+	let message = `Successfully moved ${movedTasks.length} tasks from "${sourceTag}" to "${targetTag}"`;
+	if (renumberedTasks.length > 0) {
+		const renumberDetails = renumberedTasks
+			.map((t) => `${t.originalId} → ${t.newId}`)
+			.join(', ');
+		message += `. Renumbered to avoid ID collisions: ${renumberDetails}`;
+	}
+
 	const response = {
-		message: `Successfully moved ${movedTasks.length} tasks from "${sourceTag}" to "${targetTag}"`,
+		message,
 		movedTasks
 	};
 
@@ -938,6 +1037,14 @@ async function finalizeMove(
 		];
 	}
 
+	// If tasks were renumbered, suggest validating dependencies
+	if (renumberedTasks.length > 0) {
+		if (!response.tips) response.tips = [];
+		response.tips.push(
+			'Some tasks were renumbered to avoid ID collisions. Run "task-master validate-dependencies" to verify dependency integrity.'
+		);
+	}
+
 	return response;
 }
 

scripts/modules/task-manager/set-task-status.js

@@ -6,7 +6,7 @@ import {
 	TASK_STATUS_OPTIONS,
 	isValidTaskStatus
 } from '../../../src/constants/task-status.js';
-import { getDebugFlag } from '../config-manager.js';
+import { getDebugFlag, isSlimDoneTasksEnabled } from '../config-manager.js';
 import { validateTaskDependencies } from '../dependency-manager.js';
 import { displayBanner } from '../ui.js';
 import {
@@ -84,6 +84,9 @@ async function setTaskStatus(tasksPath, taskIdInput, newStatus, options = {}) {
 		const taskIds = taskIdInput.split(',').map((id) => id.trim());
 		const updatedTasks = [];
 
+		// Check if auto-slim on done is enabled
+		const slimOnDone = isSlimDoneTasksEnabled(projectRoot);
+
 		// Update each task and capture old status for display
 		for (const id of taskIds) {
 			// Capture old status before updating
@@ -106,7 +109,9 @@ async function setTaskStatus(tasksPath, taskIdInput, newStatus, options = {}) {
 				oldStatus = task?.status || 'pending';
 			}
 
-			await updateSingleTaskStatus(tasksPath, id, newStatus, data, !isMcpMode);
+			await updateSingleTaskStatus(tasksPath, id, newStatus, data, !isMcpMode, {
+				slimOnDone
+			});
 			updatedTasks.push({ id, oldStatus, newStatus });
 		}