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                    MCP MODULE - COMPLETE FILES LISTING
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PROJECT: GoodGo Platform
MODULE: Model Context Protocol (MCP) Integration
LOCATION: apps/api/src/modules/mcp/
DATE: April 11, 2026

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1. SOURCE FILES
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📄 File 1: apps/api/src/modules/mcp/index.ts
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Type: Module Export/Index
Lines: 1
Purpose: Main module entry point
Exports: { McpIntegrationModule }

Content:
────────
export { McpIntegrationModule } from './mcp.module';

Status: ✅ Simple re-export, well-formed


📄 File 2: apps/api/src/modules/mcp/mcp.module.ts
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Type: NestJS Module Configuration
Lines: 22
Purpose: Bootstrap MCP integration module with dependencies

Key Features:
  • @Module decorator with imports, controllers
  • Implements OnModuleInit lifecycle hook
  • Configures McpCoreModule.forRoot() with settings
  • Sets up service integration (Typesense, Auth, MCP Registry)
  • Logs initialized servers on startup

Decorator: @Module({
  imports: [SearchModule, AuthModule, McpCoreModule.forRoot({...})],
  controllers: [McpTransportController],
})

Class: McpIntegrationModule implements OnModuleInit
  
Injected Dependencies:
  1. typesenseClient: TypesenseClientService (from SearchModule)
  2. mcpRegistry: McpRegistryService (from @goodgo/mcp-servers)
  3. logger: LoggerService (from SharedModule)

Lifecycle Hook:
  async onModuleInit(): Promise<void>
    - Sets Typesense client on registry
    - Re-initializes MCP servers
    - Logs server names on startup

Status: ⚠️ Partially tested (initialization logic not covered)


📄 File 3: apps/api/src/modules/mcp/presentation/mcp-transport.controller.ts
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Type: NestJS HTTP Controller
Lines: 102
Purpose: HTTP transport layer for MCP Server-Sent Events (SSE) connections

Decorators Applied:
  @ApiTags('mcp') - Swagger grouping
  @ApiBearerAuth('JWT') - API doc
  @Controller('mcp') - Route prefix
  @UseGuards(JwtAuthGuard) - Auth guard (all endpoints)

Private Properties:
  transports: Map<string, SSEServerTransport>
    → Active session tracking by sessionId

Constructor:
  McpTransportController(registry: McpRegistryService)

Endpoints (3):

  1️⃣ GET /mcp/servers
     ├── Decorator: @Get('servers')
     ├── Throttle: 30 requests per 60,000ms
     ├── Auth: JwtAuthGuard ✅
     ├── Returns: { servers: string[] }
     ├── HTTP Status: 200 OK, 401 Unauthorized
     └── Logic: Returns server.names from registry

  2️⃣ GET /mcp/:serverName/sse
     ├── Decorator: @Get(':serverName/sse')
     ├── Throttle: 5 requests per 60,000ms ⚡ (STRICTER)
     ├── Params: serverName (string)
     ├── Auth: JwtAuthGuard ✅, CurrentUser decorator
     ├── Returns: SSE stream (response.write)
     ├── HTTP Status: 200 (stream), 404 (not found), 401 (unauthorized)
     └── Logic:
         1. Verify server exists (throw NOT_FOUND if not)
         2. Create SSEServerTransport instance
         3. Store in Map[sessionId]
         4. Attach close listener for cleanup
         5. Connect transport to server

  3️⃣ POST /mcp/:serverName/messages
     ├── Decorator: @Post(':serverName/messages')
     ├── Throttle: 30 requests per 60,000ms
     ├── Params: serverName (string)
     ├── Query: sessionId (required)
     ├── Auth: JwtAuthGuard ✅, CurrentUser decorator
     ├── Returns: Delegate response to transport
     ├── HTTP Status: 200 OK, 400 (missing sessionId), 404 (not found), 401 (unauthorized)
     └── Logic:
         1. Extract sessionId from query
         2. Validate sessionId present (throw BAD_REQUEST if not)
         3. Look up transport (throw NOT_FOUND if expired)
         4. Delegate to transport.handlePostMessage()

Status: ✅ Well tested (see spec file)


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2. TEST FILES
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🧪 File 4: apps/api/src/modules/mcp/presentation/__tests__/mcp-transport.controller.spec.ts
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Type: Unit Test Suite
Lines: 174
Testing Framework: Vitest
Subject: McpTransportController

Test Coverage: 11 tests in 4 describe blocks

DESCRIBE BLOCK 1: security decorators (4 tests)
────────────────────────────────────────────────
  ✅ Test 1: has JwtAuthGuard applied at controller level
     Method: Reflect.getMetadata('__guards__', McpTransportController)
     Checks: guards exist and contain JwtAuthGuard
     
  ✅ Test 2: has Throttle metadata on listServers endpoint
     Metadata: THROTTLER:LIMITdefault
     Expected: 30
     
  ✅ Test 3: has Throttle metadata on handleSse endpoint with low limit
     Metadata: THROTTLER:LIMITdefault on handleSse
     Expected: 5 (stricter limit)
     
  ✅ Test 4: has Throttle metadata on handleMessage endpoint
     Metadata: THROTTLER:LIMITdefault
     Expected: 30

DESCRIBE BLOCK 2: listServers (2 tests)
────────────────────────────────────────
  ✅ Test 1: returns list of server names from registry
     Setup: mockRegistry.getServerNames.mockReturnValue(['search', 'listings'])
     Action: controller.listServers()
     Assert: result.servers equals ['search', 'listings']
     Verify: getServerNames called once
     
  ✅ Test 2: returns empty array when no servers registered
     Setup: mockRegistry.getServerNames.mockReturnValue([])
     Action: controller.listServers()
     Assert: result.servers equals []

DESCRIBE BLOCK 3: handleSse (3 tests)
──────────────────────────────────────
  ✅ Test 1: throws NOT_FOUND when server does not exist
     Setup: mockRegistry.getServer.mockReturnValue(null)
     Action: controller.handleSse('nonexistent', mockUser, req, res)
     Assert: Throws HttpException
     Status: HttpStatus.NOT_FOUND
     Message: Contains 'nonexistent'
     
  ✅ Test 2: creates transport and connects to server
     Setup: mockServer.connect mock resolved
     Action: controller.handleSse('search', mockUser, req, res)
     Verify:
       - getServer called with 'search'
       - connect called once
       - req.on called with 'close' event
     
  ✅ Test 3: cleans up transport on connection close
     Setup: handleSse called successfully
     Action: Simulate connection close by calling closeHandler
     Assert: Subsequent handleMessage fails with NOT_FOUND
     (proves transport was deleted from Map)

DESCRIBE BLOCK 4: handleMessage (2 tests)
──────────────────────────────────────────
  ✅ Test 1: throws BAD_REQUEST when sessionId query parameter is missing
     Setup: mockReq.query = {}
     Action: controller.handleMessage('search', mockUser, req, res)
     Assert: Throws HttpException
     Status: HttpStatus.BAD_REQUEST
     
  ✅ Test 2: throws NOT_FOUND when session does not exist
     Setup: mockReq.query = { sessionId: 'nonexistent-session' }
     Action: controller.handleMessage('search', mockUser, req, res)
     Assert: Throws HttpException
     Status: HttpStatus.NOT_FOUND

Mocking Strategies Used:
  1. vi.mock() - Module mocking (SSEServerTransport)
  2. vi.fn() - Function mocks (service methods)
  3. mockReturnValue() - Sync returns
  4. mockResolvedValue() - Async returns
  5. Manual mock objects - req/res simulation
  6. Reflect.getMetadata() - Decorator inspection

Status: ✅ Comprehensive test coverage


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3. ARCHITECTURE & DDD LAYERS
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Current Status: SIMPLIFIED ARCHITECTURE (Presentation-only)

✅ IMPLEMENTED LAYERS:

  Presentation Layer
  ├── Controllers
  │   └── mcp-transport.controller.ts (102 lines)
  │       ├── 3 HTTP endpoints
  │       ├── JWT auth protection
  │       ├── Rate limiting (throttle)
  │       └── SSE session management
  │
  └── Tests
      └── __tests__/mcp-transport.controller.spec.ts (174 lines)
          ├── 11 tests
          ├── 4 describe blocks
          └── Comprehensive coverage

❌ MISSING LAYERS:

  Domain Layer (NO FILES)
  ├── No entities/
  ├── No value-objects/
  ├── No domain-events/
  └── No repositories/ interfaces

  Application Layer (NO FILES)
  ├── No handlers/ (CQRS)
  ├── No commands/
  ├── No queries/
  └── No DTOs/

  Infrastructure Layer (NO FILES)
  ├── No repositories/ (implementations)
  ├── No services/
  └── No external-adapters/

Architecture Notes:
  • Acts as integration wrapper
  • Delegates to @goodgo/mcp-servers library
  • Simple HTTP-to-SSE bridge
  • In-memory session tracking (Map)
  • No persistence or business logic


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4. DEPENDENCIES & IMPORTS
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External Dependencies:
  • @goodgo/mcp-servers (SSEServerTransport, McpRegistryService)
  • @nestjs/common (Controller, decorators, etc.)
  • @nestjs/swagger (API documentation)
  • @nestjs/throttler (Rate limiting)

Internal Dependencies:
  • @modules/auth (JwtAuthGuard, CurrentUser)
  • @modules/search (TypesenseClientService)
  • @modules/shared (LoggerService)

Direct Imports in Module:
  import { McpTransportController } from './presentation/mcp-transport.controller';
  import { SearchModule, AuthModule } from other modules;


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5. KEY STATISTICS
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File Count:
  • Total Source Files: 4
  • Test Files: 1
  • Lines of Code: 125 (implementation only)
  • Lines of Tests: 174
  • Test/Code Ratio: 1.39:1

Test Coverage:
  • Controller Methods Tested: 3/3 (100%)
  • Endpoints Tested: 3/3 (100%)
  • Security Decorators Tested: ✅
  • Error Cases Tested: ✅
  • Happy Path Cases: ✅
  • Module Initialization: ⚠️ (Partial)

Classes & Handlers:
  • Controllers: 1 (McpTransportController)
  • Modules: 1 (McpIntegrationModule)
  • Handlers: 0 (Not using CQRS)
  • Entities: 0 (Not implemented)
  • Services: 0 (Delegated to library)


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6. TESTING PATTERNS & CONVENTIONS
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Framework: Vitest
Config: apps/api/vitest.config.ts
  • globals: true (vi, describe, it, expect available globally)
  • environment: 'node'
  • pattern: src/**/*.spec.ts

Common Patterns in Codebase:

Pattern A: Simple Handler Testing (Auth module)
  ├── Minimal mocking
  ├── Command objects for input
  └── Focused assertions

Pattern B: Complex Handler Testing (Payments module)
  ├── Multiple dependency mocks
  ├── Business rule testing
  ├── Event bus verification
  └── Error scenario coverage

Pattern C: Domain Entity Testing (Payments module)
  ├── Explicit vitest imports
  ├── Entity state transitions
  ├── Domain event verification
  ├── Value object testing
  └── Helper factory functions

Pattern D: Infrastructure Service Testing (Zalopay service)
  ├── External service simulation
  ├── Crypto/security testing
  ├── Complex test data builders
  └── Edge case coverage


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7. RECOMMENDED TEST COMMANDS
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Run all MCP tests:
  $ pnpm test -- src/modules/mcp

Run specific test file:
  $ pnpm test -- src/modules/mcp/presentation/__tests__/mcp-transport.controller.spec.ts

Run with watch mode:
  $ pnpm test -- --watch src/modules/mcp

Run with coverage:
  $ pnpm test -- --coverage src/modules/mcp

Run all tests (project-wide):
  $ pnpm test


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SUMMARY
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The MCP module is a SIMPLIFIED integration layer that:
  ✅ Exposes 3 HTTP endpoints for MCP server access
  ✅ Handles SSE connection lifecycle
  ✅ Provides rate limiting and JWT authentication
  ✅ Well-tested at controller level (174 lines of tests)

Areas for Improvement:
  ⚠️ Module initialization not tested
  ⚠️ No domain layer implementation
  ⚠️ No application handlers (CQRS)
  ⚠️ No infrastructure adapters

The module follows project conventions:
  ✅ Vitest for testing
  ✅ vi.fn() for mocking
  ✅ Decorator verification with Reflect API
  ✅ Organized __tests__/ subdirectory

For additional test examples:
  • Auth module: apps/api/src/modules/auth/application/__tests__/
  • Payments module: apps/api/src/modules/payments/
  • Search module: apps/api/src/modules/search/

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Generated: April 11, 2026
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