Knowledge · Framework · SDLC · FDD4

Implement per Layer

Build bottom-up, layer by layer. Pure domain has zero I/O dependencies — just types and business logic functions. Model domain adds persistence with typed repository wrappers. Service integration connects APIs with proper error handling and credential masking. UI renders the result with server-side data loading. Each layer is testable in isolation, and cross-cutting concerns (auth, logging, error handling) are applied last.

Metadata

FDD4 BUILD

Steps

Showing 3 of 4

  1. 1 Pure Domain

    types, logic, zero I/O

  2. 2 Model Domain

    repositories, typed queries

  3. 3 Service Integration

    APIs, error handling, credential masking

Deliverables

  • Type definitions and business logic (pure functions)
  • Repository implementations with typed queries
  • API routes and adapter integrations
  • Svelte pages with server-side data loading
  • Cross-cutting concerns (auth, logging, error handling)

Example Outputs

  • PD Layer: Package type with validation rules, DeliveryStatus enum
  • MD Layer: PackageRepository with Create/Read/Update/Delete methods
  • SI Layer: /api/v1/packages endpoints with auth middleware
  • UI Layer: /packages/+page.svelte with server-loaded data grid