<!--
DESIGN DOCUMENT TEMPLATE - TIERED BY PROJECT COMPLEXITY

PURPOSE: Document design principles, patterns, and standards that guide implementation.
NOTE: Technology stack decisions belong in the Architecture Document, not here.

PROJECT COMPLEXITY GUIDE:
🚀 ESSENTIAL (Startup/MVP, 1-3 developers, <6 months): Sections 1-2 only
🏢 CORE (Small team, 2-5 developers, 6-18 months): Sections 1-4
🏗️ ADVANCED (Enterprise, 5+ developers, 18+ months): Sections 1-5
⚡ SPECIALIZED (Mission-critical, high reliability): All sections + custom

WHAT TO INCLUDE:
✅ Design principles and patterns
✅ Naming conventions and standards
✅ Component design approaches
✅ Data modeling principles
✅ Quality attribute design strategies
❌ Technology stack choices (goes in Architecture doc)
❌ Concrete class names or implementations
❌ Code snippets or method signatures

START SMALL: Begin with Essential sections, add more as project matures.

IMPORTANT: DO NOT REMOVE THIS COMMENT HOW TO USE THE TEMPLATE!
-->

# Design Document

<!-- # 🚀 ESSENTIAL - Required for all projects -->

## 1. Naming Conventions

<!-- Standards for naming classes, methods, variables, constants, packages
     Language-specific conventions and project-specific additions
     Examples: PascalCase for classes, camelCase for methods, etc. -->

### Classes and Types

<!-- How to name classes, interfaces, enums, type definitions -->

### Methods and Functions

<!-- Method naming patterns, verb conventions, parameter naming -->

### Variables and Constants

<!-- Local variables, class fields, constants, configuration values -->

### Packages and Modules

<!-- Package/namespace organization, module naming patterns -->

## 2. Error Handling Design

<!-- Exception hierarchy design, error propagation strategies
     How errors should be categorized, handled, and communicated
     Principles for graceful degradation and error recovery -->

### Exception Design Principles

<!-- When to use checked vs unchecked exceptions, custom exception hierarchy -->

### Error Propagation Strategy

<!-- How errors flow through system layers, error boundaries -->

### Error Recovery Patterns

<!-- How system should behave when errors occur, fallback strategies -->

<!-- # 🏢 CORE - Recommended for professional projects -->

## 3. Architecture Patterns & Principles

<!-- SOLID principles, DRY, KISS, YAGNI applied to this project
     Which architectural patterns are preferred and why
     Design pattern selection criteria and usage guidelines -->

### Core Design Principles

<!-- How SOLID, DRY, KISS principles apply to this specific project -->

### Preferred Architectural Patterns

<!-- Which patterns (MVC, Repository, Observer, etc.) to use when -->

### Pattern Selection Guidelines

<!-- Criteria for choosing between different design patterns -->

## 4. Component Design Strategy

<!-- How functionality is organized into components
     Principles for component boundaries and responsibilities
     Interface design and dependency management approaches -->

### Component Boundary Principles

<!-- How to determine what belongs in each component, separation of concerns -->

### Responsibility Assignment

<!-- How to distribute functionality across components -->

### Interface Design Standards

<!-- How components should expose functionality, API design principles -->

### Dependency Management

<!-- How components depend on each other, injection patterns -->

<!-- # 🏗️ ADVANCED - For complex systems and mature teams -->

## 5. Data Design Approach

<!-- Domain modeling principles, entity design, data flow patterns
     How data structures support business requirements
     Consistency and integrity design strategies -->

### Domain Modeling Principles

<!-- How to model business concepts, entity vs value object decisions -->

### Data Transfer Patterns

<!-- DTOs, mapping between layers, data transformation strategies -->

### Data Consistency Strategy

<!-- How to maintain data integrity, transaction boundaries -->

### Data Access Design

<!-- Repository patterns, abstraction layers, query design -->

## 6. Quality Attribute Implementation

<!-- How design decisions support performance, security, maintainability
     Trade-off analysis and quality attribute prioritization
     Specific design strategies for quality goals -->

### Performance Design Strategy

<!-- How design choices impact performance, optimization approaches -->

### Security Design Principles

<!-- How security requirements influence design decisions -->

### Maintainability Design Approach

<!-- Design choices that support long-term maintenance and evolution -->

### Scalability Design Considerations

<!-- How design supports system growth and scaling -->

<!-- # ⚡ SPECIALIZED - Add based on specific project needs -->

## 7. Concurrency Design (If Applicable)

<!-- Thread safety principles, synchronization strategies
     Asynchronous processing patterns, concurrent data access -->

### Thread Safety Strategy

<!-- How to handle concurrent access, synchronization approaches -->

### Asynchronous Processing Design

<!-- Promise/Future patterns, event-driven design -->

## 8. Testing Design Philosophy (If Complex Testing Needs)

<!-- How design supports testability, test structure principles
     Mocking strategies, test data management -->

### Testability Design Principles

<!-- How to design for effective testing, dependency injection for tests -->

### Test Structure Standards

<!-- Test organization, naming, assertion patterns -->

## 9. Extension and Evolution Strategy (If Long-term Project)

<!-- How design accommodates future changes
     Extension points, plugin architectures, versioning strategies -->

### Design for Change Principles

<!-- How to create flexible designs that adapt to requirements -->

### Extension Point Design

<!-- Where and how to build extensibility into the system -->

---

# Implementation Notes

<!-- Any project-specific notes about how these design principles should be applied
     Exceptions or modifications to standard patterns
     Team agreements about design trade-offs -->
