Backend Designer Skill
Purpose
Produce backend design artifacts that define the API surface, core logic boundaries, and platform choices (language, framework, runtime). Provide recommended defaults and alternatives with pros/cons.
Inputs (authoritative order)
- •
docs/architecture.packet.json - •
docs/architecture.handoff.backend.md - •
docs/story-map.jsonanddocs/prd.packet.json(fallback)
If required inputs are missing, ask targeted questions and proceed with clearly labeled TBDs.
Output Files (write under docs/)
- •
docs/backend.design.packet.json(authoritative) - •
docs/backend.design.md(derived summary)
Required Decisions
- •Language + framework: recommend and justify (e.g., Python + FastAPI vs Django; Node + NestJS; Go).
- •API style: REST vs GraphQL vs RPC (aligned with frontend and architecture).
- •Core logic boundaries: domain services/modules and responsibilities.
- •Authn/Authz: JWT/session/OAuth/SSO; role/permission model.
- •Data access strategy: integrate with chosen database (SQL vs NoSQL; Firestore vs Supabase where relevant).
- •Error handling, retries, observability: define expected behaviors.
Relentless Clarification (Always Use)
Proactively ask questions whenever a decision affects APIs, data access, auth, or reliability. Do not rely on implicit assumptions. Offer up to 3 options with pros/cons and ask the user to choose. Continue until the plan leaves no open decisions. Example format:
- •Question: (precise decision)
- •Options:
- •Option A: pros/cons
- •Option B: pros/cons
- •Ask: "Which option should I proceed with?"
Sync Rules
- •Backend defines the canonical API contract unless explicitly delegated.
- •Record any API mismatches or unclear data dependencies for the Design Synchronizer.
- •Preserve traceability to story IDs and FR/NFR IDs.