Saga MCP

Instructions

Implementation Reference

• src/tools/subtasks.ts:81-122 (handler)

  The handleSubtaskUpdate function implements the business logic for updating a subtask, including input validation, database execution, and logging activity.

  function handleSubtaskUpdate(args: Record<string, unknown>) {
    const db = getDb();
    const id = args.id as number;
  
    const oldRow = db.prepare('SELECT * FROM subtasks WHERE id = ?').get(id) as Record<string, unknown> | undefined;
    if (!oldRow) throw new Error(`Subtask ${id} not found`);
  
    const updates: string[] = [];
    const params: unknown[] = [];
  
    if (args.title !== undefined) {
      updates.push('title = ?');
      params.push(args.title);
    }
    if (args.status !== undefined) {
      updates.push('status = ?');
      params.push(args.status);
    }
    if (args.sort_order !== undefined) {
      updates.push('sort_order = ?');
      params.push(args.sort_order);
    }
  
    if (updates.length === 0) throw new Error('No fields to update');
  
    updates.push("updated_at = datetime('now')");
    params.push(id);
  
    const newRow = db
      .prepare(`UPDATE subtasks SET ${updates.join(', ')} WHERE id = ? RETURNING *`)
      .get(...params) as Record<string, unknown>;
  
    if (oldRow.status !== newRow.status) {
      logActivity(
        db, 'subtask', id, 'status_changed', 'status',
        oldRow.status as string, newRow.status as string,
        `Subtask '${newRow.title}' status: ${oldRow.status} -> ${newRow.status}`
      );
    }
  
    return newRow;
  }

• src/tools/subtasks.ts:26-40 (schema)

  The schema definition for the 'subtask_update' tool.

  {
    name: 'subtask_update',
    description: 'Update a subtask title, status, or sort order.',
    annotations: { title: 'Update Subtask', readOnlyHint: false, destructiveHint: false, idempotentHint: true, openWorldHint: false },
    inputSchema: {
      type: 'object',
      properties: {
        id: { type: 'integer', description: 'Subtask ID' },
        title: { type: 'string' },
        status: { type: 'string', enum: ['todo', 'in_progress', 'done'] },
        sort_order: { type: 'integer' },
      },
      required: ['id'],
    },
  },

• src/tools/subtasks.ts:145-149 (registration)

  Registration map linking tool names to their respective handler functions.

  export const handlers: Record<string, ToolHandler> = {
    subtask_create: handleSubtaskCreate,
    subtask_update: handleSubtaskUpdate,
    subtask_delete: handleSubtaskDelete,
  };