Most people use AI to write code. Fewer use it to question code.
That's the gap I want to talk about. Because the moment I started treating Claude as a reviewer instead of just a writer, my build cycles got shorter and my debugging sessions almost disappeared.
Here's exactly how I do it.
The Problem With Running First
When you run code to test it, you're finding out what broke. That's fine. But it's slow. You run, it fails, you stare at a stack trace, you patch something, you run again.
If you're building solo, that loop compounds. You don't have a second set of eyes. You're the developer and the reviewer and the QA team.
Claude can be that second set of eyes, but only if you use it right.
What "First-Pass Review" Actually Means
I'm not asking Claude to rewrite my code. I'm asking it to read what I have and tell me what's probably wrong before I run it.
There's a difference. Rewriting makes Claude the author. Reviewing keeps me in control of the logic while Claude spots what I'm too close to see.
The questions I ask in a first-pass review are:
- Does the flow make sense end to end?
- Are there any assumptions that could break in production?
- Is there a case this code doesn't handle?
- Are there any race conditions, null references, or bad fallbacks hiding here?
These are the things you stop noticing after you've stared at the same function for an hour.
The Setup I Use
Before I paste anything into Claude, I give it context. Not a wall of text. Just enough to frame the review correctly.
I tell it:
- What the code is supposed to do
- What environment it runs in (Node, Python, browser, n8n workflow, whatever)
- What I'm worried about specifically
- What I don't want it to change
That last one matters. If I don't tell Claude what's off limits, it will suggest rewrites when all I wanted was a logic check. You have to be specific about what role you want it to play.
Then I paste the code and ask for the review.
The Types of Bugs This Catches
Since I started doing this consistently, Claude has caught things I would have run into 20 minutes later in a frustrating debugging session. Here are a few categories it reliably flags:
Mismatched assumptions
I write a function expecting a string. The function that calls it sometimes sends null. Claude spots that. I don't, because I wrote both pieces and assumed they'd behave.
Missing error handling
I forget to wrap an API call in a try/catch. Or I handle the success case but not the timeout. Claude reads the whole block and notices the gap.
Logic that works in one direction only
A conditional that handles true but not false. A loop that handles the happy path but breaks on an empty array. These show up all the time and Claude catches them before runtime.
Bad fallbacks in automation flows
When I'm building in n8n or Make.com, I'll wire up a flow and miss what happens if a node returns nothing. Claude reads the flow logic and asks, "What happens if this step returns an empty set?" Good question. Often I hadn't thought about it.
How This Works in Cursor Too
If you're using Cursor, you can do this in the chat panel without leaving the editor. I'll highlight a function or a file, open the chat, and ask Claude to review for logic gaps rather than style or efficiency.
The key is the framing. If you just ask "is this code good," you'll get a generic answer. If you say "I need you to act as a code reviewer, not a co-author, and tell me what assumptions this code makes that could break in a real environment," you get something useful.
Specificity in the prompt is everything.
One Rule I Never Break
I do this review before I run the code, not after something breaks.
Once something is broken, I'm in a different mental state. I'm reactive. I'm looking for the specific error, not the broader logic. Claude is useful there too, but it's a different use case.
The first-pass review is proactive. It's ten minutes of structured questioning before I test, and it saves me from spending an hour debugging something that should have been obvious on a second read.
What I Paste and What I Don't
I don't paste my entire codebase. That's noise. I paste the specific function, module, or flow that I'm about to test. Contained scope makes for a better review.
If there's a dependency that matters, I'll include a short description of what it does rather than pasting its source. "This function calls an external webhook that returns either a 200 with a JSON body or a 408 on timeout" tells Claude what it needs to know without bloating the context.
Lean context, specific question, clear scope. That's the formula.
The exact prompts and the full review framework live inside Inner Circle. If you're building solo and want to stop finding bugs at runtime, that's where to start.
Keep building
- Claude Code Hook: Auto-lint on Save from the prompt library
- Claude Code: Zero to Feature in One Session from the prompt library
- How I Gave Every Part of My Business a Name and a Voice
- The full Vaylo prompt library, new drops weekly
