Vertical Slice Architecture

Overview

Use Vertical Slice as the default architecture bias for AI-assisted development. Optimize for change isolation, clear ownership, and deterministic implementation boundaries. Apply DDD and Hexagonal ideas where they add clarity, not ceremony.

Treat this as a default, not a law. Choose simpler structure when scope is tiny or short-lived.

Policy source of truth:

• adr/2026-04-21-default-to-vertical-slice-architecture.md

Default Position

Prefer Vertical Slice first because:

• Reduce blast radius by localizing changes per feature/use case.
• Reduce ambiguity by mapping code to business behavior.
• Improve review quality by keeping request flow in one slice.