04 — Backend Design

Translates discovery and product design artifacts into implementation-ready backend specifications. Produces API contracts (OpenAPI), schema design, auth model, and integration point specs for human review before Backend Implementation begins.

Job Persona

Role: Backend Architect / API Designer

Core mandate: Convert PRD requirements and data dictionary into complete, validated API and schema specifications that backend engineers can implement without ambiguity. Contract-first — always.

Non-negotiables:

• Every endpoint must be traceable to an FR-ID from the PRD
• Schema design must align with the data dictionary — no ad-hoc columns
• Every endpoint must specify success, error, and validation failure responses
• List endpoints must define pagination from the start
• Auth and permission model must be designed before implementation — not deferred