Comprehensive Banking API Documentation Upgrade

[devin-ai-integration]

Comprehensive Banking API Documentation Upgrade

Summary

This PR upgrades the banking application's API documentation system to provide comprehensive, interactive documentation following banking industry standards. The changes include upgrading Swagger/OpenAPI to a compatible version, adding detailed examples for all banking endpoints, documenting authentication flows, and creating standardized error response schemas.

Key Changes:

• Upgraded @nestjs/swagger from v4.5.12 to v4.8.2 for better NestJS v7.x compatibility
• Enhanced Swagger configuration with comprehensive banking API metadata, tags, and servers
• Created standardized error response DTOs for banking-specific errors
• Added detailed API documentation to all 7 controllers (Auth, Bills, Transactions, Users, Currency, Messages, Notifications)
• Implemented interactive Swagger UI with JWT authentication support
• Enhanced security configuration with rate limiting and CSP headers
• Added comprehensive operation descriptions, parameter documentation, and response schemas

Review & Testing Checklist for Human

• Critical: Verify Swagger UI loads correctly at http://localhost:3000/documentation and displays all endpoints
• Critical: Test JWT authentication flow in Swagger UI - login, obtain token, and use "Authorize" button to authenticate subsequent requests
• High Priority: Validate that banking-specific error codes and responses accurately reflect the actual API behavior
• High Priority: Test "Try it out" functionality for key banking operations (login, create transfer, get transactions) to ensure examples work
• Medium Priority: Verify no runtime errors or compilation issues were introduced by running the application locally

Recommended Test Plan:

1. Start the application locally: yarn start:dev
2. Navigate to /documentation endpoint
3. Test the complete user journey: register → login → create account → make transfer
4. Verify all error scenarios display appropriate banking error messages
5. Confirm API versioning and rate limiting information is accurate

---

Diagram

%%{ init : { "theme" : "default" }}%%
graph TD
    main["src/main.ts<br/>Application Bootstrap"]:::major-edit
    swagger["src/utils/swagger.ts<br/>Swagger Configuration"]:::major-edit
    packagejson["package.json<br/>Dependencies"]:::minor-edit
    
    main --> swagger
    
    swagger --> auth["src/modules/auth/controllers/<br/>auth.controller.ts"]:::major-edit
    swagger --> bills["src/modules/bill/controllers/<br/>bill.controller.ts"]:::major-edit
    swagger --> transactions["src/modules/transaction/controllers/<br/>transaction.controller.ts"]:::major-edit
    swagger --> users["src/modules/user/controllers/<br/>user.controller.ts"]:::major-edit
    swagger --> currency["src/modules/currency/controllers/<br/>currency.controller.ts"]:::major-edit
    swagger --> messages["src/modules/message/controllers/<br/>message.controller.ts"]:::major-edit
    swagger --> notifications["src/modules/notification/controllers/<br/>notification.controller.ts"]:::major-edit
    
    errordtos["src/common/dtos/<br/>error-response.dto.ts"]:::major-edit
    
    commonindex["src/common/dtos/<br/>index.ts"]:::minor-edit
    
    auth --> errordtos
    bills --> errordtos
    transactions --> errordtos
    users --> errordtos
    messages --> errordtos
    notifications --> errordtos
    
    errordtos --> commonindex
    
    subgraph Legend
        L1["Major Edit"]:::major-edit
        L2["Minor Edit"]:::minor-edit
        L3["Context/No Edit"]:::context
    end
    
    classDef major-edit fill:#90EE90
    classDef minor-edit fill:#87CEEB
    classDef context fill:#FFFFFF

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Notes

• Version Compatibility: Had to use @nestjs/swagger v4.8.2 instead of latest v7.x due to NestJS v7.x compatibility requirements
• Removed Examples: The older Swagger version doesn't support 'example' properties in API decorators, so detailed examples are now in operation descriptions
• Banking Standards: Implemented banking-specific error codes and response schemas following financial API conventions
• Security Enhancements: Added CSP headers and enhanced rate limiting configuration for production readiness

Session Info: Requested by Arthur Poon (@akkp-windsurf)
Devin Session: https://app.devin.ai/sessions/1dcac0e20e4d4409bb92ce2cf2bfcc08

[devin-ai-integration]

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