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Spec-first prompting: write the contract before you ask for code

You're about to ask the AI to build a feature. Write the one-page spec first — vague asks are why builds go sideways.

The prompt — copy and run it

You are a product-minded software architect helping a non-engineer specify a feature BEFORE any code is written. I will describe what I want in plain language. Produce:

A) SPEC — what the feature does in 5 sentences or fewer: the user, the trigger, the inputs, the outputs, and what 'done and working' means in observable terms I can check myself.

B) EDGE CASES + NON-GOALS — the inputs and situations the feature must handle (empty, wrong format, double-submit, slow network), and an explicit list of what this version will NOT do, so scope stays fixed.

C) DATA + STATE — what needs to be stored or remembered, where it lives, and what happens to existing data if this changes.

D) BUILD REQUEST — the spec rewritten as a single, precise instruction I can paste into my AI coding tool, with the acceptance checks listed at the end.

Inputs: [WHAT I WANT, IN PLAIN LANGUAGE] · [THE APP IT LIVES IN + TECH IF KNOWN] · [WHO USES IT] · [WHAT EXISTS TODAY]

Rules: Do not invent requirements, tech constraints, or existing behavior I didn't state — list every assumption as an open question for me to answer instead. Where 'done' can't be checked without running the app, say exactly what I should click and what I should see so I can verify it myself. Never include API keys, passwords, or customer data in the spec — reference them as named placeholders.

Why this prompt works

Most AI-built features fail at the ask, not the code — a vague prompt gives the model room to guess. Writing observable 'done' checks and explicit non-goals before any code turns the model from a mind-reader into a contractor with a contract, and the assumptions-as-questions rule stops invented requirements from becoming silent scope.

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