---
title: "Vibe Coding vs Spec-Driven Development"
description: "Vibe coding vs spec-driven development for non-developers: signs you have hit the vibe-coding ceiling, when to switch, and how to write a spec an agent uses."
canonical_url: "https://builderscamp.com/guides/comparison/vibe-coding-vs-spec-driven-development"
date_published: "2026-09-27"
date_modified: "2026-09-27"
author: "Andre Albuquerque"
publisher: "Builders Camp"
guide_class: "comparison"
---

# Vibe Coding vs Spec-Driven Development: A Dial, Not a Choice

**TL;DR:** Vibe coding and spec-driven development are two ends of one dial: vibe coding keeps the project's context in the chat and suits exploration, while spec-driven development keeps it in files the agent rereads and suits anything you plan to keep. Switch toward specs when fixes start breaking other things, when real users depend on the app, or when someone else has to work on it.

Vibe coding and spec-driven development differ in one thing: where the project's memory lives. In vibe coding it lives in the conversation, so it disappears when the chat ends. In spec-driven development it lives in files, so every new session starts with the same understanding. Anthropic's [Claude Code documentation](https://code.claude.com/docs/en/memory) states the constraint directly: "Each Claude Code session begins with a fresh context window."

Most people building with AI agents are still closer to the vibe end. In the [Stack Overflow 2025 Developer Survey](https://survey.stackoverflow.co/2025/ai), 72 percent of respondents said vibe coding is not part of their professional development work, and more developers said they distrust the accuracy of AI tools (46 percent) than trust it (33 percent). Those are professional developers, not PMs building their first app, so the numbers say little about how non-developers work. What they do show is that the people who ship code for a living mostly do not accept agent output on vibes alone.

## What is the difference between vibe coding and spec-driven development?

| | Vibe coding | Spec-driven development |
|---|---|---|
| Where context lives | The chat | Files in the project |
| First step | Describe the idea and see what appears | Write what it should do, for whom, and what must never happen |
| How you check the work | Click around and react | Compare against acceptance criteria written in advance |
| Best for | Demos, spikes, testing whether an idea works | Anything real users or real data depend on |
| What breaks first | Consistency as the app grows | Speed, if you spec a throwaway |
| Your main job | Steering by reaction | Deciding behaviour and edge cases up front |

Den Delimarsky, writing on the [GitHub Blog](https://github.blog/ai-and-ml/generative-ai/spec-driven-development-with-ai-get-started-with-a-new-open-source-toolkit/) when GitHub released its Spec Kit toolkit, puts the difference in how you treat the agent: "We treat coding agents like search engines when we should be treating them more like literal-minded pair programmers." His summary of vibe coding is fair to both sides: great for quick prototypes, less reliable for serious applications or existing codebases.

## Why is it a dial rather than a choice?

The two approaches are not rival methods; they are settings. A single project moves along the dial as it matures: pure vibes for the first afternoon, a short spec once the core flow works, detailed specs per change once real users arrive. Treating it as a binary causes both classic mistakes: writing a ten-page spec for an idea you will throw away on Friday, or still vibe coding a payment flow in month three.

The useful skill is noticing when to turn the dial. For a non-developer, that moment rarely announces itself. It shows up as a feeling that the agent has become less reliable, when in fact the project has outgrown what one conversation can hold.

## What are the signs you have hit the vibe-coding ceiling?

Four signals, and any one of them is enough to start writing things down.

**Fixes start breaking other things.** You ask the agent to change the booking confirmation and the calendar view stops loading. The project has more moving parts than the agent can see in one session, and without a written description of how the parts fit, each change is a guess.

**Real users or real data depend on it.** A prototype that loses its data is a lesson. An internal tool that loses a week of room bookings is an incident. Once someone other than you relies on the app, "it seemed to work when I clicked around" is not a standard.

**You come back and nobody remembers why.** After a week away, neither you nor the agent knows why the cancellation rule works the way it does. The reasoning lived in a chat that is gone.

**Someone else joins.** A colleague cannot read your chat history, and their agent cannot either. The only shared understanding a second person can pick up is one that exists in files.

For the everyday version of these failures and how to recover, see [vibe coding mistakes](https://builderscamp.com/guides/tools/vibe-coding-mistakes).

## How does a PM write a spec an agent can actually use?

If you already write PRDs, most of the thinking transfers; what changes is the reader. A human engineer fills gaps with judgment and a hallway question. An agent fills gaps with a plausible guess and keeps going. So the spec has to be explicit exactly where a PRD usually stays vague: edge cases, error states and what "done" means.

Five habits make the difference, shown here on a fictional internal tool for booking meeting rooms:

1. **Let the agent interview you first.** Before any code, describe the feature and ask the agent what it needs to know. "Can a booking span two rooms? What happens when two people book the same slot within a second?" You get a list of decisions you had not made yet.
2. **Specify behaviour at the edges, not only the happy path.** "Show bookings" becomes: an empty day says "No bookings yet, pick a slot to add one"; a failed save keeps everything the user typed and says what went wrong; a slow load shows the day grid immediately and fills it in.
3. **Describe the user, not the stack.** "An office manager on a laptop who books for six people at once" tells the agent more than "use React." Let the agent pick the technology unless you have a real constraint.
4. **Write acceptance criteria you could check by hand.** "Booking a room that is already taken shows the conflict and suggests the next free slot" is checkable. "Handles conflicts gracefully" is not.
5. **Treat the agent's first spec draft as a draft.** Ask why it chose each approach, push back on anything that adds complexity you did not ask for, and cut it before a line of code exists.

For a full template, see [how to write a PRD for Claude Code](https://builderscamp.com/guides/templates/how-to-write-a-prd-for-claude-code), and check a finished spec against the [agent-ready spec checklist](https://builderscamp.com/guides/templates/agent-ready-spec-checklist).

## Where should the context live: CLAUDE.md, business context or specs?

Spec-driven work runs on three layers of written context, each changing at a different speed.

| Layer | What it holds | How often it changes |
|---|---|---|
| Project instructions (CLAUDE.md or AGENTS.md) | Conventions, commands to run tests, always and never rules | Rarely |
| Business context | Who the product is for, the current goals, pricing, known constraints | Every quarter or so |
| Per-change specs | The behaviour, acceptance criteria and edge cases for one feature or fix | Every change |

Keeping the layers separate stops one file from bloating. Anthropic's documentation advises a size "target under 200 lines per CLAUDE.md file", because longer files consume more context and are followed less reliably. The business context and specs sit in their own files that the agent reads when a task needs them. For what to put in the first layer, see [CLAUDE.md for product managers](https://builderscamp.com/guides/tools/claude-md-for-product-managers).

## How do you move from vibe to spec without losing speed?

Explore on a branch, then commit to a spec. When you have a new idea, create a separate branch and vibe code freely: nothing you do there can damage the version people use. If the idea works, write the spec for what you want to keep, based on what you learned, and build that version against the spec on the main line. If it fails, delete the branch.

This keeps the speed of vibe coding exactly where speed matters (finding out whether something is worth building) and the discipline of specs where discipline matters (the version people rely on). It matches the division of labour Delimarsky describes for Spec Kit: "The AI generates the artifacts; you ensure they’re right."

## When is a spec the wrong tool?

The strongest case against specs is that they slow down learning. If you do not yet know whether the idea is any good, a spec formalises a guess. Writing acceptance criteria for a feature nobody has tried wastes the hour you could have spent finding out. For a weekend experiment, a demo for a stakeholder or a test of whether an API does what you hope, vibe coding is the right setting and a spec is overhead.

The honest rule: spec what you intend to keep, vibe what you intend to learn from. If you are unsure which one you are doing, you are exploring, and a lightweight [mini-PRD for vibe coding](https://builderscamp.com/guides/other/prd-for-vibe-coding) is enough. For the term itself and where it came from, see [what is vibe coding](https://builderscamp.com/guides/glossary/vibe-coding).

## Where can you learn to build with both?

[Using AI to Build Your First Product](https://builderscamp.com/bootcamps/using-ai-to-build-your-first-product) is a two-week bootcamp with 4 live sessions and 9 microlessons, directed by Andre Albuquerque and part of the Vibe Coding Expert Track. Its published topics include the vibe coding mindset and MVP design, interface prototyping, backend logic and real data, integrations such as payments and authentication, shipping and launch basics, and a post-launch iteration loop; the tools named in its syllabus include Claude Code, Lovable, Replit, Databutton and Stripe. Its practical challenge asks you to go from idea to a launched MVP: scope the smallest shippable product, prototype the interface, add real logic and one integration, then launch with an iteration plan.

Builders Camp runs live and self-paced bootcamps in product management and AI product building. See the Using AI to Build Your First Product bootcamp for dates and the full syllabus.

## Frequently asked questions

### What is the difference between vibe coding and spec-driven development?

In vibe coding you describe what you want in a chat, accept what the agent builds and steer by reaction. In spec-driven development you write down the behaviour, constraints and edge cases first, in files the agent reads, and the code is generated and checked against that written spec.

### Is spec-driven development only for professional developers?

No. A spec describes what the user sees and what must never happen, which is PM work. The agent can make the technical choices; your job is the behaviour, the edge cases and the definition of done.

### When should I stop vibe coding and write a spec?

When fixes start breaking other things, when real users or real data depend on the app, when you return after a week and cannot remember why something works the way it does, or when a second person joins. Any one of those is enough.

### Do I need a spec for a throwaway prototype?

No. For a demo, a clickable idea or a test of whether something is possible, vibe coding is faster and a spec is overhead. Write the spec when you decide to keep the thing.

### What goes in a spec for an AI coding agent?

What you are building and why, who it is for, acceptance criteria you could check by hand, constraints such as data that must not be lost, and the edge cases: empty states, errors and slow responses. Leave the stack to the agent unless you have a reason to fix it.

### What is a CLAUDE.md file?

It is the project instruction file Claude Code loads at the start of every session, holding conventions, commands and rules. Anthropic's documentation recommends keeping each one under 200 lines.

### Can I mix vibe coding and specs in one project?

Yes, and most projects should. Explore a new idea by vibe coding on a separate branch, then write the spec for the version you keep, so the main code only changes against something written down.

## Sources

- [Den Delimarsky, GitHub Blog: Spec-driven development with AI (2025)](https://github.blog/ai-and-ml/generative-ai/spec-driven-development-with-ai-get-started-with-a-new-open-source-toolkit/)
- [Stack Overflow: 2025 Developer Survey, AI section](https://survey.stackoverflow.co/2025/ai)
- [Claude Code Docs: How Claude remembers your project](https://code.claude.com/docs/en/memory)

## How this guide was made

Researched from Builders Camp's bootcamp, track and masterclass material and the sources listed on this page, drafted with AI, and fact-checked against every source cited.