# OZON Seller API SDK Brownfield Enhancement PRD

## Intro Project Analysis and Context

### Existing Project Overview

**Analysis Source**: IDE-based fresh analysis

**Current Project State**: 
The project is a TypeScript SDK for OZON Seller API that currently implements only the Product API category out of 32 total available categories. It follows a category-based organization with:
- Core HTTP client with retry logic and idempotency
- Zod schema validation and strict TypeScript typing
- Comprehensive testing framework using Vitest + Nock
- MCP server integration planned for documentation (ozon-api-docs) and best practices (context7)

### Available Documentation Analysis

**Available Documentation**:
- ✅ Tech Stack Documentation (TypeScript, Vitest, Zod identified)
- ✅ Source Tree/Architecture (Category-based structure visible)
- ⚠️ Coding Standards (Partial - inferred from existing code)
- ✅ API Documentation (OZON API docs via MCP server)
- ✅ External API Documentation (MCP integration planned)
- ❌ UX/UI Guidelines (Not applicable - backend SDK)
- ⚠️ Technical Debt Documentation (Needs assessment)

### Enhancement Scope Definition

**Enhancement Type**:
- ✅ New Feature Addition (32 API categories to implement)
- ✅ Integration with New Systems (MCP servers)
- ✅ Performance/Scalability Improvements (Comprehensive SDK)

**Enhancement Description**: 
Expand the existing OZON Seller API SDK from 1 category (Product) to a comprehensive TypeScript SDK covering all 32 API categories with full type safety, MCP-first architecture for documentation sourcing, and enterprise-grade testing coverage.

**Impact Assessment**:
- ✅ Significant Impact (substantial existing code changes required)
  - Will require expanding core architecture patterns
  - Testing infrastructure needs scaling
  - Documentation generation workflows

### Goals and Background Context

**Goals**:
• Implement a fully typed, category-based OZON SDK covering all 32 API categories
• Achieve MCP-first architecture with ozon-api-docs as source of truth
• Maintain 95%+ test coverage across all categories with comprehensive test types
• Deliver production-ready TypeScript SDK with strict typing and enterprise standards

**Background Context**:
The current SDK implements only the Product API category but has established solid foundations with TypeScript, Zod validation, and testing infrastructure. The enhancement is needed to provide developers with a comprehensive, type-safe interface to the entire OZON Seller API ecosystem. This will eliminate the need for developers to manually interface with 31+ API categories and ensure consistency, type safety, and proper error handling across all integrations.

**Change Log**:
| Change | Date | Version | Description | Author |
|--------|------|---------|-------------|---------|
| Initial brownfield PRD creation | 2025-01-21 | v1.0 | Comprehensive SDK expansion planning | John (PM) |

## Requirements

### Functional Requirements

**FR1**: The SDK shall expand from the current Product API category to implement all 32 OZON Seller API categories while maintaining backward compatibility with existing Product API usage patterns.

**FR2**: Each new API category shall follow the established architectural pattern of the existing Product API implementation, including category-based file organization, Zod schema validation, and TypeScript strict typing.

**FR3**: The SDK shall use MCP ozon-api-docs server **during development only** to extract accurate API specifications and generate static TypeScript types, Zod schemas, and method implementations that are then compiled into a self-sufficient SDK with no runtime MCP dependencies.

**FR4**: Each API method across all categories shall include comprehensive error handling for 4xx client errors, 429 rate limiting with exponential backoff, and 5xx server errors with retry logic.

**FR5**: The SDK shall provide a unified pagination helper utility that works consistently across all categories that support pagination, eliminating the need for category-specific pagination implementations.

**FR6**: The core HTTP client shall support idempotency keys for all write operations across all categories to ensure safe retry behavior in distributed environments.

**FR7**: All API methods shall include comprehensive JSDoc documentation with practical usage examples specific to each category's business context.

**FR8**: The SDK shall provide optional live testing capabilities behind environment flags, allowing developers to test against real OZON API endpoints while maintaining comprehensive mock testing by default.

### Non-Functional Requirements

**NFR1**: The enhanced SDK must maintain existing performance characteristics with HTTP client response times under 200ms for cached operations and maintain current memory footprint within 20% variance.

**NFR2**: Test coverage shall achieve and maintain 95% or higher across all 32 categories, including unit tests for success/failure scenarios, retry logic validation, and schema validation testing.

**NFR3**: The SDK shall support TypeScript strict mode with `noImplicitAny`, `exactOptionalPropertyTypes`, and `noUncheckedIndexedAccess` enabled across all new category implementations.

**NFR4**: Build and compilation times shall not increase by more than 50% despite the 32x expansion in API surface area, maintaining developer productivity during local development.

**NFR5**: The SDK bundle size shall implement tree-shaking to allow consumers to import only needed categories, preventing unused categories from impacting application bundle size.

**NFR6**: The compiled SDK shall be completely self-contained with no external service dependencies, ensuring that end-users can use the SDK without any MCP server infrastructure or external documentation dependencies.

### Compatibility Requirements

**CR1**: All existing Product API method signatures, return types, and behavior must remain unchanged to ensure zero breaking changes for current SDK consumers.

**CR2**: The existing HTTP client configuration and authentication patterns must be preserved and extended to support all new categories without requiring configuration changes from existing users.

**CR3**: Current error handling patterns and error type hierarchy must be maintained and consistently applied across all new category implementations.

**CR4**: The existing TypeScript type definitions and export structure must remain stable while expanding to include new category types and interfaces.

**CR5**: The final SDK distribution must include all generated types, schemas, and implementations as static code, with MCP servers used only during the build/development process, not during SDK runtime.

## Technical Constraints and Integration Requirements

### Existing Technology Stack

**Languages**: TypeScript (strict mode enabled)
**Frameworks**: Node.js 18+, Vitest testing framework
**Database**: Not applicable (SDK project)
**Infrastructure**: npm package management, ESM module system
**External Dependencies**: Zod for schema validation, Nock for HTTP mocking, MCP servers for build-time documentation

### Integration Approach

**Database Integration Strategy**: Not applicable - SDK does not manage databases

**API Integration Strategy**: Build-time MCP integration for documentation extraction, runtime HTTP client for OZON API communication with retry logic and idempotency support

**Frontend Integration Strategy**: Not applicable - backend SDK only

**Testing Integration Strategy**: Scale existing Vitest + Nock testing infrastructure to support 32 categories with consistent mocking patterns

### Code Organization and Standards

**File Structure Approach**: Maintain existing category-based organization (`src/categories/{category-name}/`) with consistent internal structure

**Naming Conventions**: Follow existing TypeScript and OZON API naming patterns established in Product category

**Coding Standards**: TypeScript strict mode, Zod validation, comprehensive JSDoc, no implicit any types

**Documentation Standards**: JSDoc with practical examples, automated API documentation generation from types

### Deployment and Operations

**Build Process Integration**: Integrate MCP documentation extraction into existing TypeScript build pipeline

**Deployment Strategy**: npm package distribution with tree-shaking support and optional category imports

**Monitoring and Logging**: SDK provides structured error reporting, no built-in monitoring (consumer responsibility)

**Configuration Management**: Extend existing configuration patterns to support all categories consistently

### Risk Assessment and Mitigation

**Technical Risks**: 
- MCP server unavailability during build process
- Performance degradation from 32x API surface expansion
- Complex interdependencies between API categories

**Integration Risks**: 
- Breaking changes to existing Product API consumers
- Inconsistent patterns across different API categories
- Testing complexity scaling challenges

**Deployment Risks**: 
- Bundle size impact on consumer applications
- TypeScript compilation performance with expanded surface area
- Version management across 32 categories

**Mitigation Strategies**: 
- Graceful MCP fallback with cached documentation snapshots
- Performance monitoring at each development milestone
- Strict backward compatibility validation in CI/CD
- Tree-shaking implementation for selective category imports

## Epic and Story Structure

### Epic Approach

**Epic Structure Decision**: **Single comprehensive epic** with rationale:

Based on analysis of the existing OZON SDK project, this enhancement is structured as a **single comprehensive epic** because:

1. **Architectural Consistency**: All 32 API categories follow similar patterns established by the existing Product API implementation
2. **Shared Infrastructure**: Core components (HTTP client, authentication, error handling, testing framework) are already established and will be extended, not rebuilt
3. **MCP Build Integration**: The build-time MCP integration for documentation generation creates a unified development workflow across all categories
4. **Interdependent Components**: Categories may have cross-references and shared types that benefit from coordinated implementation
5. **Quality Standards**: Maintaining 95% test coverage and TypeScript strict mode requires coordinated approach across all categories

## Epic 1: Comprehensive OZON SDK Implementation

**Epic Goal**: Transform the existing single-category OZON SDK into a comprehensive, self-sufficient TypeScript SDK covering all 32 API categories with build-time MCP documentation integration, maintaining backward compatibility and enterprise-grade quality standards.

**Integration Requirements**: 
- Preserve existing Product API patterns and extend them across all categories
- Implement build-time MCP integration for accurate documentation sourcing without runtime dependencies
- Maintain existing HTTP client, authentication, and error handling infrastructure
- Scale testing framework to support 32x category expansion with 95%+ coverage

### Story 1.1: MCP Build Integration Foundation
**As a** SDK developer,  
**I want** build-time MCP integration that generates static TypeScript definitions from OZON API documentation,  
**so that** the SDK can be self-sufficient while maintaining accuracy with the latest API specifications.

**Acceptance Criteria**:
1. Build process successfully connects to MCP ozon-api-docs server during compilation
2. Static TypeScript types and Zod schemas are generated for all 32 API categories
3. Generated code follows existing Product API patterns and conventions
4. Build fails gracefully with clear error messages if MCP server is unavailable
5. Generated code includes comprehensive JSDoc documentation with examples

**Integration Verification**:
- IV1: Existing Product API functionality remains completely unchanged and all existing tests pass
- IV2: Build process maintains current compilation times within 20% variance
- IV3: Generated types do not conflict with existing Product API type definitions

### Story 1.2: Core Infrastructure Scaling
**As a** SDK developer,  
**I want** the core HTTP client and infrastructure components scaled to support all 32 API categories,  
**so that** each category can leverage consistent authentication, retry logic, and error handling.

**Acceptance Criteria**:
1. HTTP client supports category-specific endpoints while maintaining existing Product API endpoints
2. Authentication system works across all 32 categories without configuration changes
3. Retry logic and rate limiting work consistently for all category endpoints
4. Error handling maintains existing Product API error types while supporting new categories
5. Idempotency key generation works across all write operations in all categories

**Integration Verification**:
- IV1: All existing Product API methods continue to work without any behavioral changes
- IV2: Performance characteristics remain within NFR1 specifications (sub-200ms cached operations)
- IV3: Memory footprint stays within 20% of current baseline

### Story 1.3: Category Implementation - Core Business Categories (Analytics, Finance, Posting)
**As a** OZON seller developer,  
**I want** implementation of core business API categories (Analytics, Finance, Posting),  
**so that** I can access essential business operations through the type-safe SDK.

**Acceptance Criteria**:
1. Analytics API category fully implemented with all endpoints and proper typing
2. Finance API category fully implemented with transaction and reporting capabilities
3. Posting API category fully implemented with FBO/FBS operations
4. All methods include comprehensive JSDoc with practical usage examples
5. Category-specific error handling follows established patterns

**Integration Verification**:
- IV1: Product API continues to function normally alongside new categories
- IV2: Shared utilities (pagination, authentication) work correctly across all implemented categories
- IV3: Bundle size remains manageable with tree-shaking support for unused categories

### Story 1.4: Category Implementation - Product & Inventory Management (Product, Returns, Stocks)
**As a** OZON seller developer,  
**I want** comprehensive product and inventory management API categories,  
**so that** I can manage my entire product lifecycle through the unified SDK.

**Acceptance Criteria**:
1. Enhanced Product API category with any missing endpoints from new documentation
2. Returns API category fully implemented with return processing capabilities
3. Stocks API category implemented with inventory management operations
4. Cross-category type sharing works correctly (e.g., Product types used in Stocks)
5. All pagination helpers work consistently across these categories

**Integration Verification**:
- IV1: Existing Product API consumers experience no breaking changes
- IV2: Cross-category operations maintain data consistency and type safety
- IV3: Performance metrics remain within established NFR requirements

### Story 1.5: Category Implementation - Seller Operations (Reports, Reviews, Brand, Certificates)
**As a** OZON seller developer,  
**I want** seller operational API categories for reporting and brand management,  
**so that** I can manage seller account operations through the unified SDK.

**Acceptance Criteria**:
1. Reports API category implemented with all reporting endpoints
2. Reviews API category implemented for review management
3. Brand API category implemented for brand operations
4. Certificates API category implemented for certification management
5. All categories support optional live testing behind environment flags

**Integration Verification**:
- IV1: No regression in existing functionality across all previously implemented categories
- IV2: Live testing capabilities work without affecting mock-based testing
- IV3: Documentation generation maintains quality standards across all categories

### Story 1.6: Category Implementation - Logistics & Operations (Delivery, Supply, Warehouse, Carriages)
**As a** OZON seller developer,  
**I want** logistics and operational API categories,  
**so that** I can manage fulfillment operations through the unified SDK.

**Acceptance Criteria**:
1. Delivery API category implemented with delivery method management
2. Supply API category implemented with supply order operations
3. Warehouse API category implemented for warehouse management
4. Carriages API category implemented for carriage operations
5. Complex logistics workflows properly typed and documented

**Integration Verification**:
- IV1: All previously implemented categories continue to function correctly
- IV2: Complex data flows between logistics categories maintain type safety
- IV3: Error handling works consistently across all logistics operations

### Story 1.7: Category Implementation - Remaining Specialized Categories
**As a** OZON seller developer,  
**I want** all remaining specialized API categories implemented,  
**so that** I have complete OZON API coverage through the unified SDK.

**Acceptance Criteria**:
1. All remaining API categories (Chat, Discounts, etc.) fully implemented
2. 100% of OZON API endpoints covered across all 32 categories
3. Comprehensive test coverage achieves 95%+ across entire SDK
4. All JSDoc documentation complete with practical examples
5. Final SDK is completely self-sufficient with no runtime dependencies

**Integration Verification**:
- IV1: Complete SDK maintains all existing Product API functionality without changes
- IV2: Performance characteristics meet all NFR requirements across entire API surface
- IV3: Bundle size optimization allows tree-shaking of unused categories

### Story 1.8: Documentation, Testing & Release Preparation
**As a** SDK consumer,  
**I want** comprehensive documentation and testing coverage,  
**so that** I can confidently adopt and use the complete OZON SDK.

**Acceptance Criteria**:
1. Complete API documentation generated for all 32 categories
2. Migration guide created for existing Product API users
3. Comprehensive examples and tutorials for each major category
4. CI/CD pipeline validates all 32 categories with each build
5. Release package includes changelog and migration instructions

**Integration Verification**:
- IV1: Final release maintains 100% backward compatibility with existing Product API usage
- IV2: Documentation accurately reflects all implemented functionality
- IV3: Release package meets all quality gates and distribution requirements