Architecture Decision Framework

"Requirements drive architecture. Trade-offs inform decisions. ADRs capture rationale."

Selective Reading Rule

Read ONLY files relevant to the request! Check the content map, find what you need.

File	Description	When to Read
context-discovery.md	Questions to ask, project classification	Starting architecture design
trade-off-analysis.md	ADR templates, trade-off framework	Documenting decisions
pattern-selection.md	Decision trees, anti-patterns	Choosing patterns
examples.md	MVP, SaaS, Enterprise examples	Reference implementations
patterns-reference.md	Quick lookup for patterns	Pattern comparison

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Core Principle

"Simplicity is the ultimate sophistication."

• Start simple
• Add complexity ONLY when proven necessary
• You can always add patterns later
• Removing complexity is MUCH harder than adding it

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Code Style Rules

General Principles

• Early return pattern: Always use early returns over nested conditions for better readability
• Avoid code duplication through creation of reusable functions and modules
• Decompose long (80+ lines) components/functions into smaller ones. Keep in same file if single-use; split if file exceeds 200 lines
• Keep functions focused and under 50 lines when possible
• Avoid deep nesting (max 3 levels)
• Proper error handling with typed catch blocks

Library-First Approach

• ALWAYS search for existing solutions before writing custom code
  • Check package registries for existing libraries
  • Evaluate existing services/SaaS solutions
  • Consider third-party APIs for common functionality
• Custom code IS justified when:
  • Specific business logic unique to the domain
  • Performance-critical paths with special requirements
  • When external dependencies would be overkill
  • Security-sensitive code requiring full control
• Remember: Every line of custom code is a liability that needs maintenance, testing, and documentation

Architecture and Design

• Clean Architecture & DDD Principles:
  • Follow domain-driven design and ubiquitous language
  • Separate domain entities from infrastructure concerns
  • Keep business logic independent of frameworks
  • Define use cases clearly and keep them isolated
• Naming Conventions:
  • AVOID generic names: utils, helpers, common, shared
  • USE domain-specific names: OrderCalculator, UserAuthenticator, InvoiceGenerator
  • Follow bounded context naming patterns
  • Each module should have a single, clear purpose
• Separation of Concerns:
  • Do NOT mix business logic with UI components
  • Keep database queries out of controllers
  • Maintain clear boundaries between contexts

Anti-Patterns to Avoid

• NIH (Not Invented Here) Syndrome: Don't build what already exists (auth, state management, form validation)
• Generic Naming: No utils.js with 50 unrelated functions, no helpers/misc.js as a dumping ground
• Poor Boundaries: Mixing business logic with UI, database queries in controllers, unclear separation of concerns

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Tech Stack Coverage

Languages: TypeScript, JavaScript, Python, Go, Swift, Kotlin
Frontend: React, Next.js, React Native, Flutter
Backend: Node.js, Express, GraphQL, REST APIs
Database: PostgreSQL, Prisma, NeonDB, Supabase
DevOps: Docker, Kubernetes, Terraform, GitHub Actions
Cloud: AWS, GCP, Azure

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Validation Checklist

Before finalizing architecture:

• Requirements clearly understood
• Constraints identified
• Each decision has trade-off analysis
• Simpler alternatives considered
• ADRs written for significant decisions
• Team expertise matches chosen patterns
• Code follows Clean Architecture boundaries
• No premature optimization or over-engineering