Step 4: Draft a Lightweight PRD
A PRD (Product Requirements Document) is just your decisions in one place. It has a predictable skeleton — the same handful of sections every time:
PRD
├─ Problem why this exists
├─ User who it's for
├─ Goal what it does, in one line
├─ In Scope what v1 includes
├─ Non-Goals what v1 skips
├─ User Stories as a __, I want __, so that __
├─ Data Model the fields you store
└─ Done When the acceptance test
Keep it tiny. Here's a complete starter PRD you could hand to an AI:
# Book Tracker — Mini PRD
## Problem
I read a lot but lose track of what I've finished and what I thought of it.
## User
Me (a single user). No accounts needed for v1.
## Goal
A simple web app to add books, track reading status, and rate finished ones.
## In Scope (v1)
- Add a book (title, author)
- Set status: To Read / Reading / Finished
- List all books, filterable by status
- Rate finished books 1–5 stars
## Non-Goals (v1)
- User accounts / login
- Social features, sharing, recommendations
- Importing from other services
- Mobile / native apps
## Tech (keep it simple)
- Single-page web app
- Local browser storage (no backend for v1)
## Done When
I can add a book, change its status, rate it, and see my list
persist after a page refresh.
Notice the "Done When" line. That's your acceptance test — a concrete way to know you've shipped v1. Always include one. A good "Done When" is something you can physically perform: click here, type this, refresh, see that. If your done condition reads like a feeling ("when it's polished," "when it feels good"), it will never be done, because there's nothing to check against. Make it a script you could hand to a stranger.
You don't have to write the PRD by hand. A useful move is to feed your answers from the earlier steps back to the AI and let it assemble the draft, then you edit. The point of editing rather than accepting wholesale is that you have to understand and agree with every line — this document is the source of truth you'll keep pasting back, so an error here gets copied into every that follows.