Explicit Contracts

Kind: principle

Layer: Contracts Core

Record: architecture:explicit-contracts

Severity: mandatory

Scope: API, service, data, protocol

Canonical: Ontology

A design rule that every boundary declares the shape and meaning of what crosses it in a typed contract.

Listed in Architecture principles, after Design by Contract and before Stable Interfaces.

Requires

• Stable Interfaces
• Type Safety

Reinforces

• Predictability
• Interoperability

Enables

• Contract-First Design

Conflicts with

• Implicit Contract

In tension with

• Rapid Prototyping

Tensions

• Explicit Contracts / Rapid Prototyping

Contracts

• Contracts Core
• PAG Authoring Kernel

Violated by

• Dynamic Untyped Boundaries
• Untyped Payloads

Refactored by

• Introduce Boundary DTO
• Schema Validation
• Extract Interface

Severity

• mandatory

Category

• Contracts / Interfaces / Compatibility

Enforced by

• codemods/entrypoints/binding.entrypoint.ts
• rules/eslint/no-undeclared-dependency.eslint.rule.ts

Required by

• Consumer-Driven Contracts
• Autonomy

Linked from

• What PAG is
• Anti-patterns
• Contracts / Interfaces / Compatibility
• Correctness / Determinism / Verification
• Core Modular Design
• Schema / Canonical Data / Semantics
• Contracts / Interfaces / Compatibility
• Schema / Canonical Data / Semantics
• SOLID / Object-Oriented Design
• Architectural Clusters
• Pattern Abstract Grammar
• Severity levels
• The resolutions