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Part III Technical Design

Alp Yalay edited this page Aug 10, 2025 · 1 revision

Part III: Technical Design

Purpose

Part III creates a Technical Design Document that defines HOW to build the product outlined in your PRD using the best tools available in 2025. It makes architecture decisions, selects technology stacks, and plans implementation approaches.

Prerequisites

Required Files

  • PRD Document (from Part II) - Required for alignment
  • Research Findings (from Part I) - Optional but helpful for context

Supported Formats

  • .txt, .pdf, .docx, .md files
  • Direct text paste for short content

User Classification

Continues the three-level system:

  • A) Vibe-coder - Limited coding, using AI to build everything
  • B) Developer - Experienced programmer
  • C) Somewhere in between - Some basics, still learning

Question Structure by User Level

Path A: Vibe-coder Questions (7 Questions)

  1. Platform preference (web, mobile app, desktop, or help decide)
  2. Coding approach (no-code, AI writes all code, learning basics)
  3. Budget constraints (free only, up to $50/month, $200/month, flexible)
  4. Launch timeline (1-2 weeks, 1 month, 2-3 months, no rush)
  5. Main concerns (getting stuck, costs, security, wrong choices)
  6. Previous tool experience (any AI tools or platforms tried)
  7. Feature priorities (simple to build, perfect functionality, visual appeal, scalability)

Path B: Developer Questions (8 Questions)

  1. Platform strategy with reasoning
  2. Preferred tech stack (frontend, backend, database, infrastructure, AI integration)
  3. Architecture pattern (monolithic, microservices, serverless, JAMstack)
  4. Service integration (authentication, storage, payments, email, analytics)
  5. AI coding assistance strategy (tools and workflow)
  6. Development workflow (Git strategy, CI/CD, testing, environments)
  7. Performance and scaling (expected load, data volume, distribution)
  8. Security and compliance (data sensitivity, regulations, authentication)

Path C: In-Between Questions (7 Questions)

  1. Platform decision with guidance on trade-offs
  2. Technical comfort zone (known languages, frameworks, learning preferences)
  3. Development approach (no-code, low-code with AI, learn by doing)
  4. Technical complexity assessment of required features
  5. Budget reality check for tools and services
  6. AI assistance preferences (level of automation desired)
  7. Timeline and capacity (available hours, launch deadline, beta users)

AI Model Recommendations

Best Models for Technical Design (2025)

  • Claude 4.1 Opus - Best for architecture decisions
  • Gemini 2.5 Pro - Best for complex trade-off analysis
  • GPT-5 - Good for quick technical iterations

Generated Technical Design Documents

Output complexity varies by user level:

For Vibe-coders

  • Recommended approach with specific tool selection
  • Alternative options comparison table
  • Step-by-step setup instructions
  • Feature implementation guides for each PRD feature
  • AI assistance strategy with prompt templates
  • Deployment plan with one-click options
  • Cost breakdown development and production phases
  • Learning resources curated for their stack
  • Limitations awareness with workarounds

For Developers

  • Architecture overview with diagrams
  • Tech stack decisions with detailed rationale
  • Component design frontend and backend structures
  • Database schema with relationships
  • Feature implementation patterns and APIs
  • Security implementation authentication and authorization
  • Performance optimization caching and scaling strategies
  • Development workflow AI-assisted development
  • Testing strategy unit, integration, and E2E approaches
  • Deployment infrastructure as code
  • Monitoring observability and metrics
  • Cost analysis development and running costs
  • Risk mitigation technical and business risks

For In-Between Users

  • Balanced approach recommendation
  • Project structure with explanations
  • Implementation phases with learning objectives
  • AI prompting guide effective strategies
  • Simplified architecture conceptual understanding
  • Step-by-step implementation with checkpoints
  • Common challenges solutions and debugging approaches
  • Learning resources progressive skill development
  • Growing beyond MVP scaling path

Key Technical Areas Covered

Architecture Decisions

  • Platform selection (web, mobile, desktop)
  • Architecture patterns (monolithic, microservices, serverless)
  • Technology stack recommendations
  • Database and storage solutions
  • API design approaches

Implementation Planning

  • Development environment setup
  • Project structure organization
  • Feature implementation strategies
  • Testing approaches
  • Error handling patterns

Deployment and Operations

  • Hosting platform recommendations
  • Environment configuration
  • Monitoring and logging
  • Scaling considerations
  • Cost optimization

AI Integration Strategy

  • AI tool selection for development
  • Prompt engineering approaches
  • Code generation patterns
  • Debugging methodologies
  • Learning resources

Technology Stack Considerations

Frontend Options

  • React/Next.js for web applications
  • React Native/Flutter for mobile
  • Vanilla JavaScript for simple projects
  • No-code platforms for rapid development

Backend Options

  • Node.js/Express for JavaScript developers
  • Python/FastAPI for data-heavy applications
  • Serverless functions for simple APIs
  • Backend-as-a-Service (Supabase, Firebase)

Database Options

  • PostgreSQL for relational data
  • MongoDB for document storage
  • Supabase for integrated backend
  • SQLite for simple applications

Cost Analysis

Technical Design documents include:

  • Development costs (tools, services, time)
  • Running costs (hosting, databases, third-party services)
  • Scaling costs (projected growth scenarios)
  • Free tier utilization (maximize cost-effectiveness)

Time Investment

  • Question answering: 10-15 minutes
  • Technical design generation: 5-10 minutes
  • Total time: 15-25 minutes

Output Files

Generated Technical Design saved as:

  • TechDesign-[AppName]-MVP.md

Validation Checklist

Before proceeding to Part IV:

  • Tech stack aligns with skill level and timeline
  • Architecture supports PRD requirements
  • Cost estimates fit budget constraints
  • Deployment approach is clearly defined
  • AI assistance strategy matches user needs

Next Steps

After completing Part III:

  1. Save Technical Design as TechDesign-[AppName]-MVP.md
  2. Review alignment with PRD requirements
  3. Proceed to Part IV: AI Agent Instructions
  4. Use Technical Design to guide implementation decisions