backend-designlisted

This skill creates a backend design brief through structured conversation. It is the server-side counterpart to `design-brief`. Skip any question the codebase already answers — read first, then ask only what is unresolved. ## Example prompts - "Write a backend brief for the notifications service" - "Plan the backend for the checkout flow" - "I need to think through the data model and auth before building this API" - "Backend brief: a job queue that processes uploaded videos" ## Process 1. Ask the user for a one-paragraph description of what they want to build, who/what calls it, and any constraints they already have in mind (latency, region, compliance, expected scale). 2. Explore the existing codebase to learn what is already decided. Scan specifically for: **Fastify-specific (check first, since this is the primary stack)** - `fastify` in `package.json` and the server entry (often `server.ts`, `app.ts`, `src/server.ts`) - Plugin tree: every `fastify.register(...)` call and any files using `fastify-plugin` (`fp(...)`) — these define the encapsulation boundaries - Route definitions: `fastify.get/post/put/delete`, `fastify.route({...})`, route schemas (`schema: { body, querystring, params, response }`) - Schema strategy: raw JSON Schema, `@sinclair/typebox`, `fastify-type-provider-zod`, or `@fastify/type-provider-typebox` - Hooks in use: `onRequest`, `preParsing`, `preValidation`, `preHandler`, `preSerialization`, `onSend`, `onResponse`, `onError` - D