Vibe Coding vs Spec-Driven Development: Why One Scales and One Doesn't
Vibe coding ships demos fast. Spec-driven development ships apps that evolve. Here's the structural difference—and why it decides what happens after the demo.
Vibe coding vs spec-driven development
The terms sound similar and the demos look similar—but the architecture underneath is different, and that difference decides what happens after the demo ends. Vibe coding is prompt-driven: you chat, a model writes code, you iterate by prompting more. Spec-driven development is compilation: a structured plan is the source of truth, and the code is compiled output you regenerate by editing the plan.
TL;DR
- Vibe coding is prompt-driven: you describe what you want, a model generates code, and the chat log is the only record of why the app works the way it does.
- Spec-driven development is compilation: a structured plan is the source of truth, and the full-stack app is compiled from it.
- The split shows up after the demo: vibe coding iterates by re-prompting; spec-driven iterates by editing the plan and recompiling.
- A plan is reproducible and reviewable—a teammate can read it, version it, and reason about it—where a chat log is conversational and one-person.
- When a stronger model ships, a spec-driven app improves on recompile; a prompt-driven app needs re-prompting to catch up.
- This holds even when prompt-driven tools add backends—the chat log is still the source of truth, so the difference is architectural, not a missing feature.
- You don’t write the plan by hand—you describe the app, Remy drafts it, and you review and approve it.
What is vibe coding?
Vibe coding is prompt-driven code generation. You describe what you want in natural language, an AI model generates code, and you iterate by sending more prompts. The conversation is the workflow; the chat log is the record of what you asked for.
Tools like Lovable, Bolt, Replit Agent, and v0 work this way, and so does a coding agent like Claude Code when you’re using it to scaffold something new from scratch. You chat, it generates, you refine by chatting more. It’s fast, it’s impressive, and it works remarkably well for prototypes and demos.
The friction shows up later—when requirements change, when you want to add a feature six weeks on, and the chat context is gone.
The chat-log problem
In vibe coding, the chat log is your only history of intent. To reproduce a build, you re-prompt. To change something foundational, you dig through the conversation to find where you specified it, or start a new chat and hope the model holds the context. There’s no structured artifact that captures what the app is supposed to do and why. When models improve, you don’t get better output for free—you re-prompt your way back to where you were.
That’s the architectural fact underneath it: vibe coding is prompt-driven, and the generated code (plus the chat that produced it) is the source of truth. Even as these tools add real backends, auth, and databases, the model is still generating code from prompts with no structured plan above it. That’s not a knock on the output—prompt-driven generation is great at fast, polished frontends—it’s just a different foundation than compilation.
What is spec-driven development?
Spec-driven development means the source of truth is a structured plan, not code and not a chat log. You describe the app (or an agent drafts the plan for you), and that plan compiles into a full-stack app: backend, database, frontend, auth, tests, deployment. The plan is the program; the code is compiled output.
This isn’t a new idea—every compiler works this way. You write C, the compiler produces assembly; you write TypeScript, it produces JavaScript. Spec-driven development takes the same principle one level higher: you write a plain-language plan, and the compiler produces a full-stack application.
The plan as source of truth
The plan is a markdown document with two layers: readable prose that says what the app does, and annotations that carry precision—data types, validation rules, edge cases. When you need a change, you edit the plan and recompile. When models improve, you recompile the same plan and get better output. When someone new joins, they read the plan to understand the app. The code can’t drift from the plan, because the code is derived from it.
What it produces
A working full-stack application—a real backend with typed methods, a real database with migrations, real auth with verification codes and sessions, and a real deployment you reach with one click. Not a demo: an app that handles real users, real data, and real edge cases.
Why the difference matters
Iteration. Vibe coding iterates by adding prompts—describe the change, regenerate, test, prompt again. Spec-driven iterates by editing the plan and recompiling. Three months in, vibe coding means opening a new chat and hoping the model infers the right context; spec-driven means editing a plan that already captures the full app.
Reproducibility. The same prompt on a different day produces different code. The same plan compiles to functionally equivalent output every time. That matters for debugging, for collaboration, and for understanding what changed between versions.
Model improvements. When a stronger model ships, a vibe-coded app doesn’t improve on its own—you re-prompt everything to benefit. A spec-driven app recompiles the same plan into better code. Same source, better target—the advantage compiled languages have always had.
Collaboration. A chat log lives in one person’s session; sharing the output means sharing code without context. A plan is a document the whole team can read, edit, review, and version. It’s the shared understanding of what the app does.
When to use each
Reach for vibe coding when:
- You need a visual prototype in the next hour.
- You’re exploring an idea and don’t know what you want yet.
- The output is a throwaway demo, not something you’ll maintain.
Reach for spec-driven development when:
- You’re building an app you plan to ship to real users.
- You need a real backend with auth and a database.
- You want the build to be reproducible, and you’re working with a team.
- You want future model improvements without re-prompting.
- You’ll iterate on the same project over weeks or months.
If you’re unsure which category you’re in, default to spec-driven—it’s easier to throw away a well-structured app than to rescue a prototype when requirements grow.
The structural difference
The difference isn’t speed or polish—it’s what layer you work at. Vibe coding is prompt-driven code generation: the code is the output and the source of truth. Spec-driven development is compilation: the plan is the source of truth, the code is compiled output. It’s the same step that separated assembly from C, or C from Python—each rung up the abstraction ladder trades manual control for higher-level expressiveness. Spec-driven development is the next rung.
What about coding agents?
Coding agents like Claude Code and Cursor sit in the middle. Editing an existing codebase, they’re code-level assistants. Generating a new project from scratch, they’re vibe coding at the code layer.
Coding agents and product agents solve different jobs. Coding agents help you write and edit code faster—great for maintaining a codebase that already has structure. Product agents compile a plan into an application—great for building something new from a description. Match the tool to the job: maintaining existing code → a coding agent; building a new app from a description → spec-driven development. (Two head-to-heads: Remy vs Cursor and Remy vs Claude Code.)
How Remy implements spec-driven development
Remy is a product agent that compiles a plain-language plan into a full-stack app. You describe the app—by text or voice—Remy drafts the plan (including the precision: data types, rules, edge cases), you review and approve it, and it compiles into a TypeScript backend, a SQL database, a frontend, auth, and deployment.
Other agents ship a demo. Remy ships an app.
Real backend. Real database. Real auth. Real plumbing. Remy has it all.
When you need a change, you edit the plan (or talk to Remy to edit it) and recompile. When models improve, you recompile the same plan and get better output. This isn’t vibe coding with extra steps—it’s a different architecture: the plan is structured, version-controlled, and reproducible, and the output is a complete application, not a frontend scaffold.
FAQ
Is spec-driven development just vibe coding with a fancy name? No. The plan has structure and precision a chat log doesn’t—data types, validation rules, edge cases—and the compile step is reproducible. Vibe coding is conversational and non-deterministic. Different architecture, different guarantees.
Can I edit the generated code directly? Yes, but the right loop is to update the plan and recompile. Hand-edits to the code can drift from the plan unless you fold them back in, so use them for quick experiments and keep ongoing changes in the plan.
Do I have to write the plan by hand? No. You describe what you want to build, Remy drafts the plan, you review and refine it. You can edit it directly if you like, but most people just chat with Remy to update it.
How does Remy stay useful as AI models improve? The plan is the source of truth, so a better model means you recompile the same plan and the output improves—no re-prompting, no rebuilding from scratch.
Is spec-driven development slower than vibe coding? The first build can take a little longer because compilation is thorough, but iteration is faster—you edit a structured plan instead of re-prompting. Over a project’s life, spec-driven is faster because changes don’t mean regenerating the whole context.
What if I just want a quick prototype? Then vibe coding is great—if you need a visual mockup in the next hour and won’t maintain it, use a vibe coder. Spec-driven development is for what you plan to ship and keep.
The bottom line
Vibe coding was the first wave: prompt-driven generation proved AI models could write useful code from natural language. Spec-driven development is the next rung—the same capability wrapped in a structured compilation model, where the plan is the source, the code is the target, and the AI is the compiler. That’s what makes AI-built apps maintainable, reproducible, and production-ready.
Vibe coding ships demos. Spec-driven development ships apps. Remy is a product agent that compiles a plain-language plan into a full-stack app—backend, database, frontend, auth, and deployment—in a single step, and recompiles it into a better app as models improve. Start building with Remy →
