fullstack-validation

Overview

This skill provides systematic approaches for validating full-stack applications with multiple interconnected components. It enables automatic detection of project structure, parallel validation workflows, cross-component verification, and identification of integration issues.

When to use: Full-stack projects with backend + frontend, microservices, monorepos, Docker Compose setups, or any multi-technology application.

Key innovation: Parallel validation with cross-component awareness - validates each layer independently while ensuring they work together correctly.

Project Structure Detection

Detection Patterns

Monorepo Indicators:

• Root package.json with workspaces
• lerna.json or nx.json present
• Multiple package.json files in subdirectories
• pnpm-workspace.yaml present

Separate Repos Indicators:

• Single technology stack per repository
• Docker Compose references external services
• Git submodules present

Technology Stack Detection:

Backend:
- FastAPI: requirements.txt with 'fastapi', main.py with FastAPI app
- Django: manage.py, settings.py present
- Express: package.json with 'express', app.js/index.js
- Spring Boot: pom.xml or build.gradle with spring-boot

Frontend:
- React: package.json with 'react', src/App.tsx or src/App.jsx
- Vue: package.json with 'vue', src/App.vue
- Angular: package.json with '@angular/core', angular.json
- Svelte: package.json with 'svelte', src/App.svelte

Database:
- PostgreSQL: requirements.txt with 'psycopg2', docker-compose.yml with postgres
- MySQL: package.json with 'mysql2', docker-compose.yml with mysql
- MongoDB: package.json with 'mongoose', docker-compose.yml with mongo
- Redis: docker-compose.yml with redis, requirements.txt with 'redis'

Infrastructure:
- Docker: Dockerfile, docker-compose.yml present
- Kubernetes: k8s/ or kubernetes/ directory with .yaml files
- Terraform: .tf files present
- Nginx: nginx.conf present

Validation Workflows

Backend Validation Checklist

Python/FastAPI Projects:

1. Dependency validation

- Check requirements.txt exists and is parseable - Verify all imports can be resolved - Check for version conflicts - Validate Python version compatibility

1. Type checking

- Run mypy on all source files - Check for missing type hints - Validate Pydantic model definitions - Verify return type annotations

1. Test validation

- Run pytest with coverage - Check test isolation (database cleanup) - Validate fixture dependencies - Ensure no test data pollution - Check for views/triggers blocking teardown

1. API schema validation

- Extract OpenAPI/Swagger schema - Validate all endpoints have docstrings - Check request/response models - Verify authentication decorators

1. Database migration validation

- Check Alembic migrations are sequential - Validate up/down migration pairs - Ensure migrations are reversible - Check for data loss risks

Node.js/Express Projects:

1. Dependency validation (npm/yarn/pnpm)
2. ESLint validation
3. Jest/Mocha test execution
4. API route validation
5. Database migration validation (Knex/Sequelize)

Frontend Validation Checklist

React + TypeScript Projects:

1. TypeScript validation

- Run tsc --noEmit for type checking - Detect unused imports (auto-fix available) - Check tsconfig.json strictness - Validate path aliases (@/ imports) - Generate missing .d.ts files (vite-env.d.ts, etc.)

1. Dependency validation

- Check package.json for peer dependency warnings - Detect version mismatches (React Query vs React) - Validate ESM vs CommonJS consistency - Check for deprecated packages

1. Build validation

- Run production build (npm run build / vite build) - Check bundle size (warn if > 1MB per chunk) - Validate environment variables - Check for build warnings - Validate asset optimization

1. Code quality

- Run ESLint with auto-fix - Check for console.log statements in production - Validate React hooks usage - Check for deprecated React patterns - Detect old library syntax (React Query v4 → v5)

1. API client validation

- Check all API calls have error handling - Validate API base URLs - Ensure loading/error states exist - Check authentication token handling

Vue/Angular Projects: Similar checklist adapted to framework specifics

Database Validation Checklist

1. Schema validation

- Check all tables exist - Validate foreign key constraints - Check for orphaned records - Validate indexes on frequently queried columns

1. Test isolation validation

- Detect views dependent on test tables - Check for triggers that prevent cleanup - Validate CASCADE deletion works - Ensure test data doesn't leak to other tests

1. Query validation

- Check for N+1 query problems - Validate JOIN efficiency - Check for missing indexes - Detect raw SQL strings (SQLAlchemy 2.0 requires text() wrapper)

Infrastructure Validation Checklist

Docker Compose Projects:

1. Service health checks

- Verify all services start successfully - Check healthcheck endpoints respond - Validate depends_on order is correct - Check restart policies

1. Port conflict detection

- Ensure no duplicate port mappings - Check host ports are available - Validate internal service communication

1. Volume validation

- Check mounted directories exist - Validate volume permissions - Ensure persistent data volumes are defined

1. Environment variable validation

- Check .env.example matches required vars - Validate all services receive needed env vars - Check for hardcoded credentials - Ensure secrets are not committed

Cross-Component Validation

API Contract Validation

Process:

1. Extract backend API schema

- FastAPI: GET /docs → openapi.json - Express: Parse route definitions - Django REST: GET /schema

1. Extract frontend API client calls

- Search for axios/fetch calls - Find API client service files - Parse API endpoint strings

1. Cross-validate

- Check every frontend call has matching backend endpoint - Validate HTTP methods match (GET/POST/PUT/DELETE) - Check parameter names and types match - Verify response types match frontend expectations - Detect missing error handling

Auto-fix capabilities:

• Generate missing TypeScript types from OpenAPI schema
• Generate missing API client methods
• Update deprecated endpoint calls
• Add missing error handling

Environment Variable Consistency

Process:

1. Collect all env var references

- Backend: os.getenv(), settings.py - Frontend: import.meta.env, process.env - Docker: docker-compose.yml env sections

1. Cross-validate

- Check .env.example has all referenced vars - Ensure frontend vars have VITE or REACTAPP_ prefix - Validate no secrets in frontend code - Check env vars are documented

Authentication Flow Validation

Process:

1. Identify auth mechanism (JWT, OAuth, Basic, API Key)
2. Check backend auth implementation

- Token generation/validation - Password hashing - Session management

1. Check frontend auth implementation

- Token storage (localStorage/sessionStorage/cookies) - Auth headers in API calls - Protected route guards - Token refresh logic

1. Cross-validate

- Ensure token format matches backend expectations - Check expiration handling - Validate logout clears all auth data

Parallel Validation Strategy

Execution Plan

Phase 1: Detection (Sequential)
├─ Scan project structure
├─ Identify all components
└─ Determine validation workflows

Phase 2: Component Validation (Parallel)
├─ Backend validation (background)
├─ Frontend validation (background)
├─ Database validation (background)
└─ Infrastructure validation (background)

Phase 3: Cross-Component Validation (Sequential)
├─ API contract validation (requires Phase 2 complete)
├─ Environment variable validation
└─ Authentication flow validation

Phase 4: Reporting (Sequential)
├─ Aggregate results
├─ Prioritize issues
└─ Generate recommendations

Priority Levels

Critical (🔴): Blocks deployment, requires immediate fix

• Backend tests failing
• Frontend build failing
• API contract mismatches causing runtime errors
• Database migration failures
• Security vulnerabilities

Warning (🟡): Should be fixed, doesn't block deployment

• Low test coverage (< 70%)
• Bundle size warnings
• Missing type hints
• Unused dependencies
• Performance issues

Info (🟢): Nice to have, improves quality

• Code style inconsistencies
• Missing documentation
• Optimization opportunities
• Deprecated syntax (still functional)

Auto-Fix Capabilities

Automatic Fixes (No confirmation needed)

TypeScript:

• Remove unused imports
• Add missing semicolons
• Fix indentation
• Sort imports

Python:

• Format with Black
• Sort imports with isort
• Remove unused variables (prefix with _)
• Add text() wrapper to raw SQL strings

Configuration:

• Generate missing config files (vite-env.d.ts, tsconfig.json)
• Fix ESM/CommonJS conflicts
• Update deprecated config syntax

Suggested Fixes (Requires confirmation)

TypeScript:

• Generate missing type definitions
• Update React Query v4 → v5 syntax
• Add missing error handling
• Migrate class components to hooks

Python:

• Add missing type hints
• Migrate to async/await
• Update deprecated SQLAlchemy patterns
• Add missing docstrings

Database:

• Add missing indexes
• Fix N+1 queries with joins
• Update cascade delete rules

Pattern Learning Integration

Patterns to Capture

Project Structure Patterns:

{
  "project_type": "fullstack-monorepo",
  "backend": "fastapi",
  "frontend": "react-typescript",
  "database": "postgresql",
  "infrastructure": "docker-compose",
  "patterns_detected": {
    "api_versioning": "/api/v1",
    "auth_method": "jwt",
    "orm": "sqlalchemy",
    "state_management": "react-query"
  }
}

Common Issue Patterns:

{
  "typescript_unused_imports": {
    "frequency": 12,
    "auto_fix_success_rate": 1.0,
    "common_files": ["src/components/*.tsx"]
  },
  "sqlalchemy_raw_sql": {
    "frequency": 5,
    "auto_fix_success_rate": 1.0,
    "pattern": "execute('SELECT ...') → execute(text('SELECT ...'))"
  },
  "react_query_v4_syntax": {
    "frequency": 3,
    "auto_fix_success_rate": 0.9,
    "pattern": "useQuery(['key'], fn) → useQuery({queryKey: ['key'], queryFn: fn})"
  }
}

Validation Performance Patterns:

{
  "backend_validation_time": "15s",
  "frontend_validation_time": "45s",
  "bottlenecks": ["TypeScript compilation", "npm install"],
  "optimization_opportunities": ["Use turbo for builds", "Cache dependencies"]
}

When to Apply This Skill

Automatic triggers:

• Project has both backend and frontend directories
• docker-compose.yml detected with multiple services
• Multiple package.json or requirements.txt files found
• User runs /validate-fullstack command

Manual triggers:

• User mentions "full-stack", "backend and frontend", "API integration"
• User reports issues across multiple components
• Deployment preparation
• CI/CD pipeline setup

Integration with Other Skills

Combines with:

• code-analysis: For structural analysis of each component
• quality-standards: For quality benchmarks
• testing-strategies: For test coverage validation
• pattern-learning: For capturing project-specific patterns
• validation-standards: For tool usage validation

Delegates to agents:

• frontend-analyzer: For detailed TypeScript/React validation
• api-contract-validator: For API synchronization
• build-validator: For build configuration issues
• test-engineer: For test infrastructure fixes
• quality-controller: For comprehensive quality assessment

Success Metrics

Validation effectiveness:

• Issue detection rate: % of issues found automatically
• False positive rate: < 5%
• Auto-fix success rate: > 80%
• Time savings vs manual validation: > 90%

Quality improvements:

• Issues caught before deployment: Track over time
• Deployment success rate: Should increase
• Time to fix issues: Should decrease
• Pattern reuse rate: Should increase for similar projects

Example Validation Report

✅ Full-Stack Validation Complete (2m 34s)

📊 Component Status:
├─ Backend (FastAPI + PostgreSQL)
│  ├─ ✅ Dependencies: 42 packages, 0 conflicts
│  ├─ ✅ Type hints: 98% coverage
│  ├─ ⚠️  Tests: 45 passing, 42% coverage (target: 70%)
│  └─ ✅ API schema: 23 endpoints documented
│
├─ Frontend (React + TypeScript)
│  ├─ ✅ Type check: 0 errors (auto-fixed 16)
│  ├─ ✅ Build: 882KB bundle (optimized)
│  ├─ ✅ Dependencies: 124 packages, 0 peer warnings
│  └─ ✅ Unused imports: 0 (auto-removed 5)
│
└─ Integration
   ├─ ✅ API contract: 23/23 endpoints matched
   ├─ ✅ Environment vars: 15/15 documented
   └─ ✅ Auth flow: JWT tokens validated

🔧 Auto-Fixed Issues (11):
✓ Removed 5 unused TypeScript imports
✓ Generated vite-env.d.ts
✓ Added text() wrapper to 3 SQL queries
✓ Fixed 2 React Query v5 syntax issues

⚠️  Recommended Actions (2):
1. Increase test coverage to 70% (currently 42%)
2. Add indexes to users.email and projects.created_at

🎯 Overall Score: 87/100 (Production Ready)