backend-design — backend low-level design

Design the backend for a feature: read enough of the existing code to ground the design in real conventions, then write a buildable backend LLD. This is a design artifact, not code — never edit app code. Accuracy over breadth: cite file:line for every constraint you rely on; don't guess.

When to use / not use

• Use in the design phase, after the HLD is approved, in parallel with the frontend LLD.
• Don't implement, and don't design the frontend. The cross-repo contract is not written here — you describe the API/events your stack will expose, and /api-contract reconciles the two LLDs into the formal OpenAPI contract afterward.

Inputs

• feature, feature_slug, approved hld_path.
• Artifact path — resolve it yourself from skills.config.yaml → artifacts.lld with {slug} = feature_slug, i.e. .maestro/<slug>/lld/backend.md. The caller passes no path; this skill owns where it writes.