Requirements Thinking: Engineering for Vibe Coders
AI makes it easy to jump straight from idea to code.
That speed is powerful, but it also hides a problem many vibe coders do not realize they have. If you do not decide what the system is supposed to do ahead of time, the AI will decide for you.
Requirements thinking is the practice of defining intent, boundaries, and expectations before you generate your first line of code.
What a Requirement Actually Is
A requirement is not a feature list.
A requirement describes what must be true for the system to be considered successful.
For example:
- “Users can upload files” is a feature.
- “Users must be able to upload files up to 10MB, securely store them, and retrieve them later” is a requirement.
AI coding tools are excellent at building features. They are much worse at guessing unstated expectations.
If you skip requirements thinking, you often get code that works but does not work the way you need.
🟢 Pre-prototype habit:
Before generating code, write down:
- One sentence describing the problem you are solving
- Three things the system must do correctly
- One thing the system must never do
Functional vs Non-Functional Requirements
Most vibe coders focus on what the system does.
Engineers also focus on how well it does it.
Functional requirements describe behavior:
- Create a user
- Save data
- Send a message
Non-functional requirements describe qualities:
- Performance
- Security
- Reliability
- Compliance
- Scalability
AI does not assume these qualities unless you explicitly tell it to. If you do not specify them, the system will inherit defaults that may be unsafe, slow, or fragile.
🟢 Pre-prototype habit:
For each major feature, answer:
- Who is allowed to use this?
- How fast does it need to be?
- What happens if it fails?
- Does this involve sensitive data?
Ambiguity Becomes Architecture
Vague requirements force AI to guess.
If you say “users can delete accounts,” the AI must decide:
- Is deletion permanent?
- Is data retained?
- Is the action reversible?
- Is confirmation required?
Those decisions shape your system whether you realize it or not.
Ambiguity is not neutral. It is a design decision made by default.
Clear requirements reduce rework more than better prompts ever will.
🟢 Pre-prototype habit:
After writing a requirement, ask:
- Could two people interpret this differently? If yes, clarify it before generating code.
Edge Cases Are Requirements Too
Vibe-coded prototypes often focus only on the happy path.
Real systems must handle:
- Invalid input
- Duplicate requests
- Network failures
- Unexpected user behavior
AI-generated code assumes ideal conditions unless told otherwise. That is not a flaw in the model. It is a reflection of missing requirements.
If you want resilient software, edge cases must be considered part of the requirement.
🟢 Pre-prototype habit:
For each core action, write down:
- One way it could fail
- One way it could be misused
- One way it could be triggered more than once
Include those scenarios in your prompt.
Requirements Change Over Time
Requirements are not fixed forever.
As you test prototypes and observe real usage:
- Assumptions change
- New constraints appear
- Some requirements become less important
- Others become critical
Strong builders revisit requirements before extending code. Weak ones keep stacking features on top of unclear intent.
AI works best when requirements are explicit and updated regularly.
🟢 Pre-prototype habit:
Before each major iteration, ask:
- What assumptions no longer hold?
- What confused users?
- What requirement would I rewrite today?
Update your requirements before generating more code.
Why Requirements Thinking Matters for Vibe Coders
AI accelerates coding.
That makes thinking the most valuable skill in the loop.
Requirements thinking helps you:
- Get code you understand
- Reduce rewrites
- Avoid accidental complexity
- Build prototypes that survive beyond the demo
The best vibe coders do not just prompt well.
They decide clearly before they prompt.
See the full list of free resources for vibe coders!
Still have questions or want to talk about your projects or your plans? Set up a free 30 minute consultation with me!
