diff --git a/.windsurf/rules/backenddevelopmentrules.md b/.windsurf/rules/backenddevelopmentrules.md
new file mode 100644
index 00000000..f4fb83aa
--- /dev/null
+++ b/.windsurf/rules/backenddevelopmentrules.md
@@ -0,0 +1,550 @@
+---
+trigger: manual
+---
+
+# Backend Development Rules
+
+> Rules and guidelines for developing the E-Learning Platform Backend
+
+---
+
+## 🎯 General Principles
+
+### 1. Code Organization
+- Follow MVC pattern: Models (Prisma) → Controllers → Routes
+- Keep controllers thin, business logic in services
+- One file per route group (e.g., `auth.routes.js`, `courses.routes.js`)
+- Maximum 200 lines per file (split if larger)
+
+### 2. Naming Conventions
+```javascript
+// Files: kebab-case
+user-service.js
+course-controller.js
+
+// Functions: camelCase
+getUserById()
+createCourse()
+
+// Classes: PascalCase
+UserService
+CourseController
+
+// Constants: UPPER_SNAKE_CASE
+MAX_FILE_SIZE
+JWT_SECRET
+
+// Database: snake_case
+user_id
+created_at
+```
+
+### 3. Multi-Language Support
+**ALWAYS** use JSON structure for user-facing text:
+```javascript
+// ✅ Correct
+{
+  title: { th: "หลักสูตร", en: "Course" }
+}
+
+// ❌ Wrong
+{
+  title: "หลักสูตร"
+}
+```
+
+---
+
+## 🔐 Security Rules
+
+### 1. Authentication
+- **ALWAYS** validate JWT token in protected routes
+- **NEVER** trust client-side data
+- **ALWAYS** hash passwords with bcrypt (salt rounds: 10)
+- Token expiry: 24h (access), 7d (refresh)
+
+### 2. Authorization
+```javascript
+// Check authentication first
+if (!req.user) return res.status(401).json({ error: "Unauthorized" });
+
+// Then check role
+if (!["ADMIN", "INSTRUCTOR"].includes(req.user.role.code)) {
+  return res.status(403).json({ error: "Forbidden" });
+}
+
+// Finally check ownership
+if (course.instructorId !== req.user.id && req.user.role.code !== "ADMIN") {
+  return res.status(403).json({ error: "Forbidden" });
+}
+```
+
+### 3. Input Validation
+- **ALWAYS** validate with Joi or Zod
+- **NEVER** trust user input
+- Sanitize HTML content
+- Validate file types and sizes
+
+---
+
+## 📁 File Upload Rules
+
+### 1. File Validation
+```javascript
+// Check file type
+const allowedTypes = ['video/mp4', 'application/pdf', ...];
+if (!allowedTypes.includes(file.mimetype)) {
+  return error("Invalid file type");
+}
+
+// Check file size
+if (file.size > MAX_FILE_SIZE) {
+  return error("File too large");
+}
+```
+
+### 2. File Storage (MinIO/S3)
+```javascript
+// Use consistent path structure
+const videoPath = `courses/${courseId}/lessons/${lessonId}/video.mp4`;
+const attachmentPath = `lessons/${lessonId}/attachments/${uniqueFilename}`;
+
+// Generate unique filenames
+const uniqueFilename = `${Date.now()}-${uuidv4()}-${originalFilename}`;
+```
+
+### 3. File Limits
+- Video: 500 MB max
+- Attachment: 100 MB max per file
+- Max 10 attachments per lesson
+- Total 500 MB per lesson
+
+---
+
+## 🗄️ Database Rules
+
+### 1. Prisma Best Practices
+```javascript
+// ✅ Use transactions for related operations
+await prisma.$transaction([
+  prisma.lesson.create(...),
+  prisma.attachment.createMany(...)
+]);
+
+// ✅ Include relations when needed
+const course = await prisma.course.findUnique({
+  where: { id },
+  include: { chapters: { include: { lessons: true } } }
+});
+
+// ✅ Use select to limit fields
+const user = await prisma.user.findUnique({
+  where: { id },
+  select: { id: true, username: true, email: true }
+});
+```
+
+### 2. Soft Delete Pattern
+```javascript
+// ✅ Use soft delete
+await prisma.course.update({
+  where: { id },
+  data: { isDeleted: true, deletedAt: new Date() }
+});
+
+// ❌ Don't hard delete
+await prisma.course.delete({ where: { id } }); // Avoid this
+```
+
+### 3. Query Optimization
+- Use `select` to fetch only needed fields
+- Use `include` wisely (avoid N+1 queries)
+- Add indexes for frequently queried fields
+- Use pagination for large datasets
+
+---
+
+## 🎯 API Response Format
+
+### 1. Success Response
+```javascript
+// Single resource
+res.status(200).json({
+  id: 1,
+  title: { th: "...", en: "..." },
+  ...
+});
+
+// List with pagination
+res.status(200).json({
+  data: [...],
+  pagination: {
+    page: 1,
+    limit: 20,
+    total: 150,
+    totalPages: 8
+  }
+});
+```
+
+### 2. Error Response
+```javascript
+res.status(400).json({
+  error: {
+    code: "VALIDATION_ERROR",
+    message: "Invalid input data",
+    details: [
+      { field: "email", message: "Email is required" }
+    ]
+  }
+});
+```
+
+### 3. Status Codes
+- `200` OK - Success
+- `201` Created - Resource created
+- `204` No Content - Success with no response body
+- `400` Bad Request - Validation error
+- `401` Unauthorized - Not authenticated
+- `403` Forbidden - Not authorized
+- `404` Not Found - Resource not found
+- `409` Conflict - Duplicate entry
+- `422` Unprocessable Entity - Business logic error
+- `500` Internal Server Error - Server error
+
+---
+
+## 🔄 Business Logic Rules
+
+### 1. Course Management
+- New courses start as `DRAFT`
+- Must have ≥1 chapter and ≥3 lessons before submission
+- Only course owner or primary instructor can submit
+- Admin can approve/reject
+
+### 2. Lesson Prerequisites
+```javascript
+// Check prerequisites before allowing access
+const canAccess = await checkLessonAccess(userId, lessonId);
+if (!canAccess.allowed) {
+  return res.status(403).json({
+    error: {
+      code: "LESSON_LOCKED",
+      message: canAccess.reason,
+      required_lessons: canAccess.requiredLessons
+    }
+  });
+}
+```
+
+### 3. Quiz Attempts
+```javascript
+// Validate before allowing quiz attempt
+if (attempts >= quiz.maxAttempts) {
+  return error("MAX_ATTEMPTS_EXCEEDED");
+}
+
+if (lastAttempt && (now - lastAttempt) < cooldown) {
+  return error("COOLDOWN_ACTIVE");
+}
+```
+
+### 4. Video Progress
+- Save progress every 5 seconds
+- Auto-complete at ≥90% watched
+- Use `last_watched_at` for concurrent sessions
+
+### 5. Multi-Instructor
+- Cannot remove last instructor
+- Only primary instructor can manage other instructors
+- Course owner always has full access
+
+---
+
+## 🧪 Testing Rules
+
+### 1. Test Coverage
+- Write tests for all business logic
+- Test happy path AND error cases
+- Test authentication and authorization
+- Test file uploads
+
+### 2. Test Structure
+```javascript
+describe('Course API', () => {
+  describe('POST /api/instructor/courses', () => {
+    it('should create course with valid data', async () => {
+      // Arrange
+      const courseData = {...};
+      
+      // Act
+      const response = await request(app)
+        .post('/api/instructor/courses')
+        .set('Authorization', `Bearer ${token}`)
+        .send(courseData);
+      
+      // Assert
+      expect(response.status).toBe(201);
+      expect(response.body).toHaveProperty('id');
+    });
+    
+    it('should return 401 without authentication', async () => {
+      // Test unauthorized access
+    });
+  });
+});
+```
+
+---
+
+## 📝 Code Documentation
+
+### 1. JSDoc Comments
+```javascript
+/**
+ * Create a new course
+ * @param {Object} req - Express request object
+ * @param {Object} req.body - Course data
+ * @param {Object} req.body.title - Course title (th/en)
+ * @param {number} req.body.category_id - Category ID
+ * @param {Object} res - Express response object
+ * @returns {Promise<Object>} Created course
+ */
+async function createCourse(req, res) {
+  // Implementation
+}
+```
+
+### 2. Inline Comments
+```javascript
+// Only for complex logic
+// Explain WHY, not WHAT
+
+// ✅ Good
+// Use highest score to determine pass/fail (per quiz settings)
+const finalScore = Math.max(...attemptScores);
+
+// ❌ Bad
+// Get max score
+const finalScore = Math.max(...attemptScores);
+```
+
+---
+
+## 🚨 Error Handling
+
+### 1. Try-Catch Pattern
+```javascript
+async function createCourse(req, res) {
+  try {
+    // Validate input
+    const { error, value } = courseSchema.validate(req.body);
+    if (error) {
+      return res.status(400).json({
+        error: {
+          code: "VALIDATION_ERROR",
+          message: error.details[0].message
+        }
+      });
+    }
+    
+    // Business logic
+    const course = await courseService.create(value, req.user.id);
+    
+    return res.status(201).json(course);
+  } catch (err) {
+    console.error('Create course error:', err);
+    return res.status(500).json({
+      error: {
+        code: "INTERNAL_ERROR",
+        message: "Failed to create course"
+      }
+    });
+  }
+}
+```
+
+### 2. Custom Error Classes
+```javascript
+class ValidationError extends Error {
+  constructor(message, details) {
+    super(message);
+    this.name = 'ValidationError';
+    this.statusCode = 400;
+    this.details = details;
+  }
+}
+
+class UnauthorizedError extends Error {
+  constructor(message = 'Unauthorized') {
+    super(message);
+    this.name = 'UnauthorizedError';
+    this.statusCode = 401;
+  }
+}
+```
+
+---
+
+## 🔍 Logging Rules
+
+### 1. What to Log
+```javascript
+// ✅ Log important events
+logger.info('User logged in', { userId, timestamp });
+logger.info('Course created', { courseId, instructorId });
+
+// ✅ Log errors with context
+logger.error('File upload failed', { 
+  error: err.message, 
+  userId, 
+  filename 
+});
+
+// ❌ Don't log sensitive data
+logger.info('User logged in', { password }); // NEVER!
+```
+
+### 2. Log Levels
+- `error` - Errors that need attention
+- `warn` - Warnings (deprecated features, etc.)
+- `info` - Important events (login, course creation)
+- `debug` - Detailed debugging (development only)
+
+---
+
+## ⚡ Performance Rules
+
+### 1. Database Queries
+```javascript
+// ✅ Use pagination
+const courses = await prisma.course.findMany({
+  skip: (page - 1) * limit,
+  take: limit
+});
+
+// ✅ Limit relations depth
+const course = await prisma.course.findUnique({
+  include: {
+    chapters: {
+      include: { lessons: true }
+      // Don't go deeper unless necessary
+    }
+  }
+});
+```
+
+### 2. Caching (Redis)
+```javascript
+// Cache frequently accessed data
+const cacheKey = `course:${courseId}`;
+const cached = await redis.get(cacheKey);
+
+if (cached) {
+  return JSON.parse(cached);
+}
+
+const course = await prisma.course.findUnique(...);
+await redis.setex(cacheKey, 3600, JSON.stringify(course));
+return course;
+```
+
+### 3. File Processing
+```javascript
+// Process large files asynchronously
+const job = await queue.add('process-video', {
+  videoPath,
+  lessonId
+});
+
+return res.status(202).json({
+  message: 'Video processing started',
+  jobId: job.id
+});
+```
+
+---
+
+## 🔒 Environment Variables
+
+### Required Variables
+```bash
+# Application
+NODE_ENV=development
+PORT=4000
+APP_URL=http://localhost:4000
+
+# Database
+DATABASE_URL=postgresql://...
+
+# Redis
+REDIS_URL=redis://...
+
+# MinIO/S3
+S3_ENDPOINT=http://...
+S3_ACCESS_KEY=...
+S3_SECRET_KEY=...
+
+# JWT
+JWT_SECRET=...
+JWT_EXPIRES_IN=24h
+
+# Email (Mailhog in dev)
+SMTP_HOST=...
+SMTP_PORT=1025
+```
+
+### Loading Environment Variables
+```javascript
+// ✅ Use dotenv
+require('dotenv').config();
+
+// ✅ Validate required variables
+const requiredEnvVars = ['DATABASE_URL', 'JWT_SECRET', ...];
+requiredEnvVars.forEach(key => {
+  if (!process.env[key]) {
+    throw new Error(`Missing required environment variable: ${key}`);
+  }
+});
+```
+
+---
+
+## 📦 Dependencies
+
+### Core Dependencies
+- `express` - Web framework
+- `@prisma/client` - Database ORM
+- `bcrypt` - Password hashing
+- `jsonwebtoken` - JWT authentication
+- `joi` or `zod` - Input validation
+- `multer` - File uploads
+- `aws-sdk` or `minio` - S3 storage
+- `redis` - Caching
+- `winston` - Logging
+
+### Dev Dependencies
+- `nodemon` - Auto-restart
+- `jest` - Testing
+- `supertest` - API testing
+- `eslint` - Linting
+- `prettier` - Code formatting
+
+---
+
+## 🚀 Deployment Checklist
+
+- [ ] All environment variables set
+- [ ] Database migrations run
+- [ ] Redis connection tested
+- [ ] MinIO/S3 buckets created
+- [ ] JWT secret is strong and unique
+- [ ] CORS configured correctly
+- [ ] Rate limiting enabled
+- [ ] Logging configured
+- [ ] Error tracking setup (Sentry, etc.)
+- [ ] Health check endpoint working
+
+---
+
+**Remember**: Security first, code quality second, features third!
\ No newline at end of file
diff --git a/Backend/package.json b/Backend/package.json
index 1c76f430..410a43f5 100644
--- a/Backend/package.json
+++ b/Backend/package.json
@@ -7,7 +7,7 @@
         "dev": "nodemon",
         "build": "npm run tsoa:gen && tsc",
         "start": "node dist/server.js",
-        "tsoa:gen": "tsoa spec-and-routes",
+        "tsoa:gen": "tsoa spec-and-routes && node scripts/post-tsoa.js",
         "prisma:generate": "prisma generate",
         "prisma:migrate": "prisma migrate dev",
         "prisma:seed": "node prisma/seed.js",
diff --git a/Backend/scripts/post-tsoa.js b/Backend/scripts/post-tsoa.js
new file mode 100644
index 00000000..57a2062e
--- /dev/null
+++ b/Backend/scripts/post-tsoa.js
@@ -0,0 +1,37 @@
+#!/usr/bin/env node
+
+/**
+ * Post-TSOA Generation Script
+ * Fixes the multer file size limit in generated routes.ts
+ * 
+ * Run after tsoa:gen to update file size limits
+ */
+
+const fs = require('fs');
+const path = require('path');
+
+const ROUTES_FILE = path.join(__dirname, '../src/routes/routes.ts');
+const OLD_LIMIT = '"fileSize":8388608';  // 8MB (tsoa default)
+const NEW_LIMIT = '"fileSize":1073741824'; // 1GB
+
+try {
+    if (!fs.existsSync(ROUTES_FILE)) {
+        console.error('Error: routes.ts not found at', ROUTES_FILE);
+        process.exit(1);
+    }
+
+    let content = fs.readFileSync(ROUTES_FILE, 'utf8');
+    
+    if (content.includes(OLD_LIMIT)) {
+        content = content.replace(OLD_LIMIT, NEW_LIMIT);
+        fs.writeFileSync(ROUTES_FILE, content, 'utf8');
+        console.log('✅ Updated multer file size limit to 1GB in routes.ts');
+    } else if (content.includes(NEW_LIMIT)) {
+        console.log('✅ Multer file size limit already set to 1GB');
+    } else {
+        console.warn('⚠️ Could not find multer fileSize config in routes.ts');
+    }
+} catch (error) {
+    console.error('Error updating routes.ts:', error.message);
+    process.exit(1);
+}
diff --git a/Backend/src/config/minio.ts b/Backend/src/config/minio.ts
index 0c8f5c4d..ef1d102a 100644
--- a/Backend/src/config/minio.ts
+++ b/Backend/src/config/minio.ts
@@ -109,3 +109,81 @@ export async function getPresignedUrl(
         throw error;
     }
 }
+
+/**
+ * List all objects in a path prefix
+ */
+export async function listObjects(prefix: string): Promise<{ name: string; size: number; lastModified: Date }[]> {
+    return new Promise((resolve, reject) => {
+        const objects: { name: string; size: number; lastModified: Date }[] = [];
+        const stream = minioClient.listObjectsV2(config.s3.bucket, prefix, true);
+
+        stream.on('data', (obj) => {
+            if (obj.name) {
+                objects.push({
+                    name: obj.name,
+                    size: obj.size || 0,
+                    lastModified: obj.lastModified || new Date(),
+                });
+            }
+        });
+
+        stream.on('error', (err) => {
+            logger.error(`Error listing objects: ${err}`);
+            reject(err);
+        });
+
+        stream.on('end', () => {
+            resolve(objects);
+        });
+    });
+}
+
+/**
+ * List folders in a path prefix
+ * Uses listObjectsV2 with recursive=false to get folder prefixes
+ */
+export async function listFolders(prefix: string): Promise<string[]> {
+    return new Promise((resolve, reject) => {
+        const folders = new Set<string>();
+        const stream = minioClient.listObjectsV2(config.s3.bucket, prefix, false);
+
+        stream.on('data', (obj: any) => {
+            if (obj.prefix) {
+                // Direct folder prefix
+                folders.add(obj.prefix);
+            } else if (obj.name) {
+                // Extract folder part from file path
+                const path = obj.name.replace(prefix, '');
+                const folder = path.split('/')[0];
+
+                if (folder && path.includes('/')) {
+                    folders.add(prefix + folder + '/');
+                }
+            }
+        });
+
+        stream.on('error', (err) => {
+            logger.error(`Error listing folders: ${err}`);
+            reject(err);
+        });
+
+        stream.on('end', () => {
+            resolve(Array.from(folders));
+        });
+    });
+}
+
+/**
+ * Get attachments folder path for a lesson
+ */
+export function getAttachmentsFolder(courseId: number, lessonId: number): string {
+    return `courses/${courseId}/lessons/${lessonId}/attachments/`;
+}
+
+/**
+ * Get video folder path for a lesson
+ */
+export function getVideoFolder(courseId: number, lessonId: number): string {
+    return `courses/${courseId}/lessons/${lessonId}/video/`;
+}
diff --git a/Backend/src/controllers/ChaptersLessonInstructorController.ts b/Backend/src/controllers/ChaptersLessonInstructorController.ts
index c673838f..08e83689 100644
--- a/Backend/src/controllers/ChaptersLessonInstructorController.ts
+++ b/Backend/src/controllers/ChaptersLessonInstructorController.ts
@@ -260,7 +260,8 @@ export class ChaptersLessonInstructorController {
             token,
             course_id: courseId,
             chapter_id: chapterId,
-            lesson_ids: body.lesson_ids,
+            lesson_id: body.lesson_id,
+            sort_order: body.sort_order,
         });
     }
 
diff --git a/Backend/src/controllers/ChaptersLessonStudentController.ts b/Backend/src/controllers/ChaptersLessonStudentController.ts
deleted file mode 100644
index eab03410..00000000
--- a/Backend/src/controllers/ChaptersLessonStudentController.ts
+++ /dev/null
@@ -1,59 +0,0 @@
-import { Get, Path, Request, Response, Route, Security, SuccessResponse, Tags } from 'tsoa';
-import { ValidationError } from '../middleware/errorHandler';
-import { ChaptersLessonService } from '../services/ChaptersLesson.service';
-import {
-    ListChaptersResponse,
-    GetLessonResponse,
-} from '../types/ChaptersLesson.typs';
-
-const chaptersLessonService = new ChaptersLessonService();
-
-@Route('api/students/courses/{courseId}')
-@Tags('ChaptersLessons - Student')
-export class ChaptersLessonStudentController {
-
-    // ============================================
-    // Chapter Endpoints (Read-only for students)
-    // ============================================
-
-    /**
-     * ดึง chapters ทั้งหมดของ course (พร้อม lessons) - สำหรับนักเรียนที่ลงทะเบียนแล้ว
-     * Get all chapters of a course with lessons - for enrolled students
-     */
-    @Get('chapters')
-    @Security('jwt', ['student'])
-    @SuccessResponse('200', 'Chapters retrieved successfully')
-    @Response('401', 'Unauthorized')
-    @Response('403', 'Not enrolled in this course')
-    public async listChapters(@Request() request: any, @Path() courseId: number): Promise<ListChaptersResponse> {
-        const token = request.headers.authorization?.replace('Bearer ', '');
-        if (!token) throw new ValidationError('No token provided');
-        return await chaptersLessonService.listChapters({ token, course_id: courseId });
-    }
-
-    // ============================================
-    // Lesson Endpoints (Read-only for students)
-    // ============================================
-
-    /**
-     * ดึงข้อมูล lesson พร้อม attachments และ quiz - สำหรับนักเรียนที่ลงทะเบียนแล้ว
-     * Get lesson with attachments and quiz - for enrolled students
-     * หมายเหตุ: จะดูได้เฉพาะ lesson ที่ is_published = true
-     */
-    @Get('chapters/{chapterId}/lessons/{lessonId}')
-    @Security('jwt', ['student'])
-    @SuccessResponse('200', 'Lesson retrieved successfully')
-    @Response('401', 'Unauthorized')
-    @Response('403', 'Not enrolled or lesson not published')
-    @Response('404', 'Lesson not found')
-    public async getLesson(
-        @Request() request: any,
-        @Path() courseId: number,
-        @Path() chapterId: number,
-        @Path() lessonId: number
-    ): Promise<GetLessonResponse> {
-        const token = request.headers.authorization?.replace('Bearer ', '');
-        if (!token) throw new ValidationError('No token provided');
-        return await chaptersLessonService.getLesson({ token, course_id: courseId, chapter_id: chapterId, lesson_id: lessonId });
-    }
-}
diff --git a/Backend/src/services/ChaptersLesson.service.ts b/Backend/src/services/ChaptersLesson.service.ts
index 7a30c02e..5483ff81 100644
--- a/Backend/src/services/ChaptersLesson.service.ts
+++ b/Backend/src/services/ChaptersLesson.service.ts
@@ -165,7 +165,7 @@ export class ChaptersLessonService {
 
     async reorderChapter(request: ReorderChapterRequest): Promise<ReorderChapterResponse> {
         try {
-            const { token, course_id, chapter_id, sort_order } = request;
+            const { token, course_id, chapter_id, sort_order: newSortOrder } = request;
             const decodedToken = jwt.verify(token, config.jwt.secret) as { id: number };
             await CoursesInstructorService.validateCourseStatus(course_id);
             const user = await prisma.user.findUnique({ where: { id: decodedToken.id } });
@@ -176,8 +176,54 @@ export class ChaptersLessonService {
             if (!courseInstructor) {
                 throw new ForbiddenError('You are not permitted to reorder chapter');
             }
-            const chapter = await prisma.chapter.update({ where: { id: chapter_id }, data: { sort_order } });
-            return { code: 200, message: 'Chapter reordered successfully', data: [chapter as ChapterData] };
+
+            // Get current chapter to find its current sort_order
+            const currentChapter = await prisma.chapter.findUnique({ where: { id: chapter_id } });
+            if (!currentChapter) {
+                throw new NotFoundError('Chapter not found');
+            }
+            const oldSortOrder = currentChapter.sort_order;
+
+            // If same position, no need to reorder
+            if (oldSortOrder === newSortOrder) {
+                const chapters = await prisma.chapter.findMany({
+                    where: { course_id },
+                    orderBy: { sort_order: 'asc' }
+                });
+                return { code: 200, message: 'Chapter reordered successfully', data: chapters as ChapterData[] };
+            }
+
+            // Shift other chapters to make room for the insert
+            if (oldSortOrder > newSortOrder) {
+                // Moving up: shift chapters between newSortOrder and oldSortOrder-1 down by 1
+                await prisma.chapter.updateMany({
+                    where: {
+                        course_id,
+                        sort_order: { gte: newSortOrder, lt: oldSortOrder }
+                    },
+                    data: { sort_order: { increment: 1 } }
+                });
+            } else {
+                // Moving down: shift chapters between oldSortOrder+1 and newSortOrder up by 1
+                await prisma.chapter.updateMany({
+                    where: {
+                        course_id,
+                        sort_order: { gt: oldSortOrder, lte: newSortOrder }
+                    },
+                    data: { sort_order: { decrement: 1 } }
+                });
+            }
+
+            // Update the target chapter to the new position
+            await prisma.chapter.update({ where: { id: chapter_id }, data: { sort_order: newSortOrder } });
+
+            // Fetch all chapters with updated order
+            const chapters = await prisma.chapter.findMany({
+                where: { course_id },
+                orderBy: { sort_order: 'asc' }
+            });
+
+            return { code: 200, message: 'Chapter reordered successfully', data: chapters as ChapterData[] };
         } catch (error) {
             logger.error(`Error reordering chapter: ${error}`);
             throw error;
@@ -315,7 +361,7 @@ export class ChaptersLessonService {
      */
     async reorderLessons(request: ReorderLessonsRequest): Promise<ReorderLessonsResponse> {
         try {
-            const { token, course_id, chapter_id, lesson_ids } = request;
+            const { token, course_id, chapter_id, lesson_id, sort_order: newSortOrder } = request;
             const decodedToken = jwt.verify(token, config.jwt.secret) as { id: number };
             await CoursesInstructorService.validateCourseStatus(course_id);
 
@@ -331,17 +377,52 @@ export class ChaptersLessonService {
                 throw new NotFoundError('Chapter not found');
             }
 
-            // Update sort_order for each lesson
-            for (let i = 0; i < lesson_ids.length; i++) {
-                await prisma.lesson.update({
-                    where: { id: lesson_ids[i] },
-                    data: { sort_order: i }
+            // Get current lesson to find its current sort_order
+            const currentLesson = await prisma.lesson.findUnique({ where: { id: lesson_id } });
+            if (!currentLesson) {
+                throw new NotFoundError('Lesson not found');
+            }
+            if (currentLesson.chapter_id !== chapter_id) {
+                throw new NotFoundError('Lesson not found in this chapter');
+            }
+            const oldSortOrder = currentLesson.sort_order;
+
+            // If same position, no need to reorder
+            if (oldSortOrder === newSortOrder) {
+                const lessons = await prisma.lesson.findMany({
+                    where: { chapter_id },
+                    orderBy: { sort_order: 'asc' }
+                });
+                return { code: 200, message: 'Lessons reordered successfully', data: lessons as LessonData[] };
+            }
+
+            // Shift other lessons to make room for the insert
+            if (oldSortOrder > newSortOrder) {
+                // Moving up: shift lessons between newSortOrder and oldSortOrder-1 down by 1
+                await prisma.lesson.updateMany({
+                    where: {
+                        chapter_id,
+                        sort_order: { gte: newSortOrder, lt: oldSortOrder }
+                    },
+                    data: { sort_order: { increment: 1 } }
+                });
+            } else {
+                // Moving down: shift lessons between oldSortOrder+1 and newSortOrder up by 1
+                await prisma.lesson.updateMany({
+                    where: {
+                        chapter_id,
+                        sort_order: { gt: oldSortOrder, lte: newSortOrder }
+                    },
+                    data: { sort_order: { decrement: 1 } }
                 });
             }
 
-            // Fetch reordered lessons
+            // Update the target lesson to the new position
+            await prisma.lesson.update({ where: { id: lesson_id }, data: { sort_order: newSortOrder } });
+
+            // Fetch all lessons with updated order
             const lessons = await prisma.lesson.findMany({
-                where: { chapter_id: chapter_id },
+                where: { chapter_id },
                 orderBy: { sort_order: 'asc' }
             });
 
@@ -498,6 +579,7 @@ export class ChaptersLessonService {
             await CoursesInstructorService.validateCourseStatus(course_id);
 
             const user = await prisma.user.findUnique({ where: { id: decodedToken.id } });
+            logger.info(`User: ${user}`);
             if (!user) throw new UnauthorizedError('Invalid token');
 
             const courseInstructor = await CoursesInstructorService.validateCourseInstructor(token, course_id);
diff --git a/Backend/src/services/CoursesStudent.service.ts b/Backend/src/services/CoursesStudent.service.ts
index 90d1c5a8..1d9ba885 100644
--- a/Backend/src/services/CoursesStudent.service.ts
+++ b/Backend/src/services/CoursesStudent.service.ts
@@ -22,6 +22,8 @@ import {
     CompleteLessonInput,
     CompleteLessonResponse,
 } from "../types/CoursesStudent.types";
+import { getPresignedUrl, listObjects, getVideoFolder, getAttachmentsFolder } from '../config/minio';
+
 
 export class CoursesStudentService {
     async enrollCourse(input: EnrollCourseInput): Promise<EnrollCourseResponse> {
@@ -265,6 +267,8 @@ export class CoursesStudentService {
             const { token, course_id, lesson_id } = input;
             const decoded = jwt.verify(token, config.jwt.secret) as { id: number; type: string };
 
+            // Import MinIO functions
+            
             // Check enrollment
             const enrollment = await prisma.enrollment.findUnique({
                 where: {
@@ -319,6 +323,80 @@ export class CoursesStudentService {
             const prevLessonId = currentIndex > 0 ? allLessons[currentIndex - 1].id : null;
             const nextLessonId = currentIndex < allLessons.length - 1 ? allLessons[currentIndex + 1].id : null;
 
+            // Get course_id from chapter
+            const chapter_course_id = lesson.chapter.course_id;
+
+            // Import additional MinIO functions
+            // Using MinIO functions imported above
+
+            // Get video URL from video folder (first file)
+            let video_url: string | null = null;
+            try {
+                const videoPrefix = getVideoFolder(chapter_course_id, lesson_id);
+                const videoFiles = await listObjects(videoPrefix);
+                if (videoFiles.length > 0) {
+                    // Get presigned URL for the first video file
+                    video_url = await getPresignedUrl(videoFiles[0].name, 3600);
+                }
+            } catch (err) {
+                logger.error(`Failed to get video from MinIO: ${err}`);
+            }
+
+            // Get attachments from MinIO folder
+            const attachmentsWithUrls: {
+                file_name: string;
+                file_path: string;
+                file_size: number;
+                mime_type: string;
+                presigned_url: string | null;
+            }[] = [];
+
+            try {
+                const attachmentsPrefix = getAttachmentsFolder(chapter_course_id, lesson_id);
+                const attachmentFiles = await listObjects(attachmentsPrefix);
+
+                for (const file of attachmentFiles) {
+                    let presigned_url: string | null = null;
+                    try {
+                        presigned_url = await getPresignedUrl(file.name, 3600);
+                    } catch (err) {
+                        logger.error(`Failed to generate presigned URL for ${file.name}: ${err}`);
+                    }
+
+                    // Extract filename from path
+                    const fileName = file.name.split('/').pop() || file.name;
+                    // Guess mime type from extension
+                    const ext = fileName.split('.').pop()?.toLowerCase() || '';
+                    const mimeTypes: { [key: string]: string } = {
+                        'pdf': 'application/pdf',
+                        'doc': 'application/msword',
+                        'docx': 'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
+                        'ppt': 'application/vnd.ms-powerpoint',
+                        'pptx': 'application/vnd.openxmlformats-officedocument.presentationml.presentation',
+                        'xls': 'application/vnd.ms-excel',
+                        'xlsx': 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
+                        'png': 'image/png',
+                        'jpg': 'image/jpeg',
+                        'jpeg': 'image/jpeg',
+                        'gif': 'image/gif',
+                        'mp4': 'video/mp4',
+                        'zip': 'application/zip',
+                    };
+                    const mime_type = mimeTypes[ext] || 'application/octet-stream';
+
+                    attachmentsWithUrls.push({
+                        file_name: fileName,
+                        file_path: file.name,
+                        file_size: file.size,
+                        mime_type,
+                        presigned_url,
+                    });
+                }
+            } catch (err) {
+                logger.error(`Failed to list attachments from MinIO: ${err}`);
+            }
+
+
             return {
                 code: 200,
                 message: 'Lesson retrieved successfully',
@@ -332,14 +410,8 @@ export class CoursesStudentService {
                     is_sequential: lesson.is_sequential,
                     prerequisite_lesson_ids: lesson.prerequisite_lesson_ids as number[] | null,
                     require_pass_quiz: lesson.require_pass_quiz,
-                    attachments: lesson.attachments.map(att => ({
-                        id: att.id,
-                        file_name: att.file_name,
-                        file_path: att.file_path,
-                        file_size: att.file_size,
-                        mime_type: att.mime_type,
-                        description: att.description as { th: string; en: string } | null,
-                    })),
+                    video_url, // Presigned URL for video
+                    attachments: attachmentsWithUrls,
                     quiz: lesson.quiz ? {
                         id: lesson.quiz.id,
                         title: lesson.quiz.title as { th: string; en: string },
diff --git a/Backend/src/types/ChaptersLesson.typs.ts b/Backend/src/types/ChaptersLesson.typs.ts
index 92f6d127..b2936a6a 100644
--- a/Backend/src/types/ChaptersLesson.typs.ts
+++ b/Backend/src/types/ChaptersLesson.typs.ts
@@ -325,7 +325,8 @@ export interface ReorderLessonsRequest {
     token: string;
     course_id: number;
     chapter_id: number;
-    lesson_ids: number[]; // Ordered array of lesson IDs
+    lesson_id: number;
+    sort_order: number;
 }
 
 // ============================================
@@ -521,7 +522,8 @@ export interface UpdateLessonBody {
 }
 
 export interface ReorderLessonsBody {
-    lesson_ids: number[];
+    lesson_id: number;
+    sort_order: number;
 }
 
 export interface AddQuestionBody {
diff --git a/Backend/src/types/CoursesStudent.types.ts b/Backend/src/types/CoursesStudent.types.ts
index 9efa163a..74a43d5b 100644
--- a/Backend/src/types/CoursesStudent.types.ts
+++ b/Backend/src/types/CoursesStudent.types.ts
@@ -141,15 +141,16 @@ export interface LessonContentData {
     is_sequential: boolean;
     prerequisite_lesson_ids: number[] | null;
     require_pass_quiz: boolean;
+    video_url: string | null; // Presigned URL for video
     attachments: {
-        id: number;
         file_name: string;
         file_path: string;
         file_size: number;
         mime_type: string;
-        description: MultiLangText | null;
+        presigned_url: string | null; // Presigned URL for attachment
     }[];
     quiz?: {
+
         id: number;
         title: MultiLangText;
         description: MultiLangText | null;
@@ -163,6 +164,7 @@ export interface LessonContentData {
     next_lesson_id: number | null;
 }
 
+
 export interface GetLessonContentResponse {
     code: number;
     message: string;
diff --git a/Backend/tsoa.json b/Backend/tsoa.json
index a9ffe71b..c88d4762 100644
--- a/Backend/tsoa.json
+++ b/Backend/tsoa.json
@@ -25,6 +25,11 @@
     "routes": {
         "routesDir": "src/routes",
         "middleware": "express",
-        "authenticationModule": "./src/middleware/authentication.ts"
+        "authenticationModule": "./src/middleware/authentication.ts",
+        "multerOpts": {
+            "limits": {
+                "fileSize": 1073741824
+            }
+        }
     }
 }
\ No newline at end of file