REKA BYTES / FIELD NOTE
Your app idea is not the hard part. The spec is.
AI can build almost anything now. Ask anyone who's tried — the failures almost never come from the code. They come from nobody having written down what "done" means.
There's a pattern we see constantly with founders bringing ideas to us, and it shows up even more when they try to build with AI on their own: the idea is great, the conversation is energetic — and three weeks later the thing being built is not the thing that was described.
Not because anyone did it wrong. Because the description was never finished.
The three questions every spec answers
A product requirements document sounds bureaucratic. It's not — it's the answer to three questions, written down before anyone builds:
- What must it do? The list of things a user can accomplish. Every one of them, including the boring ones: "the user can reset their password," "the admin can see all orders, not just their own." Boring is where teams get ambushed.
- What must it never do? The quiet half of the list. A checkout that double-charges, a search that leaks someone else's data, a form that accepts a payment with an expired card and then silently fails. You can only avoid these if you imagine them first — that's what a requirements document is for.
- How do we know it's done? Not vibes. A checklist you can run: click here, this should happen; do that badly, and this should be the error. If "done" is a feeling, you'll never have it.
Why this matters more now, not less
Before AI, a vague idea was a small risk — a developer would ask questions as they built, and friction forced clarity eventually.
With AI, you can produce software faster than you can produce requirements, and the model will confidently fill every gap you left with something. It fills them with the average of everything it's seen, which is rarely what you actually wanted. The code isn't the bottleneck anymore. The specification is.
This is also exactly why our own academy teaches spec-writing first. Vibe coding is a real skill; it's just incomplete without knowing what you're vibing for.
The cheapest version
If you're starting from zero, do this: write the three lists above for your idea in one page. Ugly, bullet-pointed, no jargon. Hand that to anyone — a freelancer, an agency, an AI agent — and you'll get three radically different first drafts, and you'll know which one fits.
If you'd rather have that document written with a professional, that's the RM 150 PRD on our start-a-project page — consultation and mockup included, document yours to keep whoever builds it. Either way, write it down before anyone builds. The code is the easy part now.