fortify-schema/docs/API-STABILITY.md

A modern TypeScript validation library designed around familiar interface syntax and powerful conditional validation. Experience schema validation that feels natural to TypeScript developers while unlocking advanced runtime validation capabilities.

# API Stability and Production Readiness

## Current Status: **STABLE** (v2.0.1)

Fortify Schema has reached **STABLE** status with v2.0.1, meaning the core API is production-ready with comprehensive stability guarantees and enterprise-grade support.

## API Stability Guarantee

### Production Ready (Stable APIs) ✅

- **Core Interface() function** - API locked, guaranteed stable
- **Basic field types** (string, number, boolean, date, email, url, uuid, phone)
- **Type constraints** (min/max, length, regex patterns, array constraints)
- **Union types** (value1|value2|value3) with full TypeScript inference
- **Optional fields** (type?) with proper null/undefined handling
- **Array types** (type[], type[](min,max)) with comprehensive validation
- **Nested objects** - Deep nesting with full type safety
- **safeParse() and parse() methods** - API locked with comprehensive error handling
- **V2 Conditional Validation** - Runtime method syntax (property.$method()) is stable
- **Performance characteristics** - Guaranteed performance levels maintained

### Recently Stabilized (v2.0.1) 🎯

- **V2 Runtime Methods** - All 8 methods ($exists, $empty, $null, $contains, $startsWith, $endsWith, $between, $in)
- **Advanced property access** - Deep nested properties, special characters, Unicode support
- **Complex default values** - Object and array defaults with proper type inference
- **Method combinations** - Logical operators (&&, ||) in conditional expressions
- **Error message formats** - Standardized, detailed error reporting
- **VS Code Extension** - Full V2 syntax support with IntelliSense

### Experimental (Use with Caution) ⚠️

- **Schema transformation utilities** (Mod.\*) - API may evolve
- **Advanced validation modes** (strict, loose) - Implementation may change
- **Custom validation functions** - Interface may be refined

## Version Compatibility & Semantic Versioning

### Semantic Versioning Promise

We follow strict semantic versioning with enterprise-grade guarantees:

- **MAJOR** (x.0.0): Breaking changes to stable APIs (rare, with 6-month notice)
- **MINOR** (0.x.0): New features, 100% backward compatible
- **PATCH** (0.0.x): Bug fixes, performance improvements, security patches

### Breaking Change Policy

- **6 months advance notice** for any breaking changes to stable APIs
- **Comprehensive migration guides** with automated tooling where possible
- **Deprecation warnings** added 3 months before removal with clear upgrade paths
- **LTS versions** supported for 18 months minimum
- **Enterprise customers** get 12 months advance notice and dedicated migration support

### Version Support Matrix

| Version    | Status             | Support Until | Production Ready   |
| ---------- | ------------------ | ------------- | ------------------ |
| **v2.0.x** | **Current Stable** | **June 2025** | **✅ Recommended** |

## Production Deployment Guidelines

### ✅ Recommended for Production (Stable APIs)

```typescript
// Production-ready schema with all stable features
const ProductionUserSchema = Interface({
  // Core identification
  id: "uuid",
  email: "email",
  username: "string(/^[a-zA-Z0-9_]{3,20}$/)",

  // Profile data with constraints
  profile: {
    firstName: "string(1,50)",
    lastName: "string(1,50)",
    avatar: "url?",
    bio: "string(,500)?",
    dateOfBirth: "date?",
    preferences: {
      theme: "light|dark|auto",
      language: "string(/^[a-z]{2}(-[A-Z]{2})?$/)",
      notifications: "boolean",
    },
  },

  // Authorization
  role: "user|moderator|admin|super_admin",
  permissions: "string[]",

  // V2 Conditional Validation (Stable)
  config: "any?",
  features: "any?",

  // Runtime property checking
  hasPermissions: "when  config.permissions.$exists() *? boolean : =false",
  hasProfile: "when config.profile.$exists() *? boolean : =false",
  isAdmin: "when role.$in(admin,super_admin) *? boolean : =false",
  betaFeatures: "when features.beta.$exists() *? string[] : =[]",

  // Complex business logic
  canModerate:
    "when role.$in(moderator,admin) && config.moderation.$exists() *? boolean : =false",

  // Audit fields
  createdAt: "date",
  updatedAt: "date",
  lastLogin: "date?",
});

// Production usage with comprehensive error handling
const result = ProductionUserSchema.safeParse(userData);
if (result.success) {
  // Fully typed, validated data
  processUser(result.data);
} else {
  // Detailed error information for logging/debugging
  logValidationErrors(result.errors);
}
```

### ⚠️ Use with Testing (Experimental APIs)

```typescript
// Experimental features - test thoroughly before production
const ExperimentalSchema = Interface({
  baseData: "string",

  // Experimental: Schema transformations
  transformedData: "string",
});

// Apply experimental transformations
const PartialSchema = Mod.partial(ExperimentalSchema); // ⚠️ API may change
const ExtendedSchema = Mod.extend(ExperimentalSchema, {
  // ⚠️ API may change
  newField: "string",
});
```

## Performance Guarantees

### Validated Performance Benchmarks

| Operation                 | Guaranteed Minimum | Typical Performance | Enterprise SLA  |
| ------------------------- | ------------------ | ------------------- | --------------- |
| **Array Validation**      | 200,000 ops/sec    | 258,910 ops/sec     | 250,000 ops/sec |
| **Union Types**           | 400,000 ops/sec    | 460,214 ops/sec     | 450,000 ops/sec |
| **Simple Schema**         | 150,000 ops/sec    | 178,496 ops/sec     | 170,000 ops/sec |
| **Complex Schema**        | 80,000 ops/sec     | 100,985 ops/sec     | 95,000 ops/sec  |
| **Memory per Validation** | <150 bytes         | <100 bytes          | <120 bytes      |

### Performance Monitoring

```typescript
// Production performance monitoring
const performanceMonitor = {
  validationCount: 0,
  totalTime: 0,
  errorCount: 0,

  validate(schema, data) {
    const start = performance.now();
    const result = schema.safeParse(data);
    const duration = performance.now() - start;

    this.validationCount++;
    this.totalTime += duration;
    if (!result.success) this.errorCount++;

    // Alert if performance degrades below SLA
    const avgTime = this.totalTime / this.validationCount;
    if (avgTime > 0.01) {
      // 10ms threshold
      console.warn("Validation performance degraded:", avgTime);
    }

    return result;
  },

  getMetrics() {
    return {
      averageTime: this.totalTime / this.validationCount,
      operationsPerSecond: 1000 / (this.totalTime / this.validationCount),
      errorRate: this.errorCount / this.validationCount,
      totalValidations: this.validationCount,
    };
  },
};
```

_See [Performance Benchmarks](./../src/bench/BENCHMARK-RESULTS.md) for up-to-date more details_

## Enterprise Production Features

### Security & Compliance

- **Input Sanitization**: Automatic XSS prevention for string fields
- **Data Validation**: Comprehensive type checking prevents injection attacks
- **Audit Logging**: Built-in validation event logging for compliance
- **GDPR Compliance**: Data validation without data retention

### Monitoring & Observability

- **Performance Metrics**: Built-in performance tracking
- **Error Analytics**: Detailed validation failure analysis
- **Health Checks**: Schema validation health endpoints
- **Custom Metrics**: Integration with monitoring systems (Prometheus, DataDog, etc.)

### Scalability & Reliability

- **Memory Management**: Predictable memory usage patterns
- **Concurrent Validation**: Thread-safe validation for high-concurrency applications
- **Caching**: Intelligent schema compilation caching
- **Failover**: Graceful degradation for validation failures

## Migration Strategy

### From v1.x to v2.0

```typescript
// v1.x (Legacy) - Still supported until December 2024
const V1Schema = Interface({
  name: "string",
  role: "admin|user",
  permissions: "when role=admin *? string[] : string[]?",
});

// v2.0 (Current) - Enhanced with runtime methods
const V2Schema = Interface({
  name: "string",
  role: "admin|user",
  config: "any?",

  // Enhanced conditional validation
  permissions: "when config.hasPermissions.$exists() *? string[] : =[]",

  // New capabilities
  advancedFeatures: "when config.features.$exists() *? any : ={}",
});

// Migration helper (provided)
const migratedSchema = migrateV1ToV2(V1Schema);
```

## Risk Assessment & Mitigation

### Low Risk (Production Ready) ✅

- **Core validation APIs**: Extensively tested, API locked
- **Performance characteristics**: Benchmarked and guaranteed
- **TypeScript integration**: Full type safety guaranteed
- **Error handling**: Comprehensive and stable

**Mitigation**: None required - production ready

### Medium Risk (Stable but Evolving) ⚠️

- **New runtime methods**: May be added in minor versions
- **Error message improvements**: May change for clarity
- **Performance optimizations**: Internal changes, API stable

**Mitigation**:

- Monitor release notes for new features
- Test thoroughly in staging before production deployment
- Use semantic versioning for controlled updates

### High Risk (Experimental) 🧪

- **Schema transformation utilities**: API may change
- **Advanced validation modes**: Implementation may change
- **Undocumented features**: No stability guarantee

**Mitigation**:

- Use only in development/testing environments
- Have rollback plans ready
- Monitor GitHub discussions for API changes

## Production Deployment Checklist

### Pre-Deployment

- [ ] **Performance Testing**: Validate performance meets requirements
- [ ] **Error Handling**: Implement comprehensive error logging
- [ ] **Monitoring**: Set up validation metrics and alerts
- [ ] **Fallback Strategy**: Plan for validation failures
- [ ] **Security Review**: Validate input sanitization requirements

### Deployment

- [ ] **Gradual Rollout**: Deploy to percentage of traffic first
- [ ] **Performance Monitoring**: Watch for performance regressions
- [ ] **Error Rate Monitoring**: Track validation failure rates
- [ ] **Memory Monitoring**: Ensure no memory leaks
- [ ] **Rollback Plan**: Ready to revert if issues arise

### Post-Deployment

- [ ] **Performance Validation**: Confirm SLA compliance
- [ ] **Error Analysis**: Review and address validation failures
- [ ] **User Feedback**: Monitor for user-reported issues
- [ ] **Optimization**: Identify opportunities for improvement

## Conclusion

**Fortify Schema v2.0 is production-ready** with comprehensive stability guarantees, enterprise-grade support, and proven performance characteristics.

### Recommendations by Use Case

**🏢 Enterprise Applications**:

- Use stable APIs with enterprise support
- Implement comprehensive monitoring
- Plan gradual migration from legacy systems

**🚀 New Projects**:

- Start with v2.0 stable APIs
- Leverage V2 conditional validation for complex business logic
- Use VS Code extension for enhanced developer experience

**🔄 Existing Projects**:

- Migrate gradually from v1.x to v2.0
- Test thoroughly in staging environments
- Take advantage of LTS support during transition

**📈 High-Performance Applications**:

- Leverage proven performance benchmarks
- Implement performance monitoring
- Use array validation for optimal performance

For questions about production deployment, contact our enterprise support team at https://github.com/Nehonix-Team/fortify-schema/discussions.