Day 3 · Plan: the smallest thing worth building, and how
| Runs with | Day 3, after the 30-minute briefing: Part A in the morning (about 110 minutes), Part B in the afternoon (about 115 minutes), then the 15-minute gate |
|---|---|
| Format | Prompt-based: every step is a prompt you give Claude, followed by a check you do yourself. The morning and B1–B2 run in your Claude Project; from B3, the repository set-up, prompts run in Claude Code |
| You need | Your Claude Project and Product Book from Days 1–2; Artifacts switched on in Claude.ai; two people booked for ten minutes each late in the morning to try your prototype by screen share; Claude Code, Python and Git working from Day 1 |
| You leave with | An MVP objective with a threshold set before building, a one-screen prototype tested on two people, a data model, ADR 0001, and a repository with the Product Book and a CLAUDE.md that imports it, committed |
| Gate | The Day 3 gate (Part C), closing Plan |
Where you are
Yesterday you found out whether the problem is real, for whom, and wrote a build objective for Days 3–4. Today answers: what is the smallest thing worth building, and how will it be built? You test the design on people before writing any code, and you brief Claude Code so tomorrow's build starts from your decisions, not from Claude's guesses.
| Product Book file | What it holds | Used in step |
|---|---|---|
product/01-route.md | Who you are this week, your working agreement and rules | B5 |
product/02-proposition.md | Proposition v1, first value moment, what you build first, build objective, evidence | A1, A2, A3, B1 |
product/03-plan.md | Today's work: MVP objective, prototype and test notes, data model, access rules | Every step |
product/decisions/0001-architecture.md | ADR 0001: the stack you choose and why | B2, B5 |
Your build objective reads: "By the end of Day 4, a working web app where [user] can [first value moment], with tests passing; on Day 5, one real person reaches it without help." Everything today serves that sentence.
What you are building
| Part | Where it lives | Built in step |
|---|---|---|
| MVP objective: what the MVP must prove, a metric, and a threshold written before building | product/03-plan.md | A2 |
| One-screen clickable prototype of the first value moment | A Claude.ai Artifact, linked from 03-plan.md | A3, A4 |
| Notes from two people trying the prototype, and what you changed | product/03-plan.md | A5, A6 |
| Data model and access rules for the value moment | product/03-plan.md | B1 |
| ADR 0001: Django against one alternative, with the must-pass plan | product/decisions/0001-architecture.md | B2 |
| Repository with the Product Book committed | Your repository | B3 |
CLAUDE.md importing the Product Book, committed | Repository root | B4, B5, B6 |
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