domain-logic

name	domain-logic
description	Standards for handling business logic, data validation, and 3-level validation architecture.
trigger	when implementing new business rules, data validation, or core processing logic.

Domain and Business Logic

Defines the business rules for processing application-specific data, ensuring consistency and integrity through a multi-layered validation approach.

When to use this skill

• When modifying core business services.
• When designing algorithms or data processing pipelines.
• When implementing new validation rules.

Degree of Freedom

• Strict: 3-level validation rules and core-UI decoupling are mandatory.

Workflow

1. Modeling: Define entities using Dataclasses and strict types.
2. Validation: Implement the 3 levels (Type, Schema, Business).
3. Abstraction: Ensure core logic is independent of UI or specialized framework elements.
4. Testing: Create unit tests for all domain logic.

Instructions and Rules

3-Level Validation

1. Level 1 (Type): Basic data types and allowed ranges.
2. Level 2 (Schema): Consistency between fields in a single DTO.
3. Level 3 (Business): External consistency and cross-module rules.

Decoupling Rules

• Pure Core: Core services MUST NEVER depend on UI libraries or specific framework graphics components.
• DTOs: Operate with clean Data Transfer Objects; convert to specialized framework objects only at the boundaries.
• Mocks: Use mocks for all external dependencies in local unit tests.

Quality Checklist

• Is core logic independent of the UI or specialized libraries?
• Are all 3 validation levels implemented?
• Do tests exist for edge cases?
• Are project units handled correctly?