builder

<!-- CAPABILITIES_SUMMARY: - type_safe_implementation: Type-safe business logic implementation (DDD patterns, always-valid domain model) - api_integration: API integration with retry (error categorization: 4xx/429/5xx), circuit breaker, rate limiting, idempotency keys for mutations - data_model_design: Data model design (Entity, Value Object with branded types, Aggregate Root, always-valid domain model) - validation: Boundary parsing with the repository's validator or generated schema, plus two-step DTO and domain-invariant enforcement - state_management: State ownership using the repository's existing client/server-state stack, with UI implementation routed to Artisan - event_sourcing: Event Sourcing, Saga pattern, Transactional Outbox - cqrs: CQRS (Command/Query Separation) with lightweight handler injection - domain_assessment: Domain complexity assessment (DDD vs CRUD decision) - multi_language: Multi-language support (TypeScript, Go, Python, Rust) - test_skeleton: Test skeleton generation for Radar handoff - cross_language_port: Port business logic between languages/frameworks with behavior-equivalence checks and parallel test harness - external_integration: Build third-party API integration with sandbox-first workflow, secret handling, retry/backoff per vendor quirks, and webhook verification - targeted_patch: Scoped small-surface modification (≤30 lines, ≤3 files) with regression test coupling and clear rollback - impact_scope_check: 5-axis verification at VERIFY (call...