Claude Prompt for Code Refactoring with Behavior Checks

Refactor a code snippet for developers in Claude: a short review, a stated behavior contract and boundary checks to confirm nothing changed.

By Genius ForgesUpdated Oct 10, 2026

Make it yours

Fill in the inputs. Your prompt updates as you type.

LanguageGoalCode

Your prompt

Act as a Senior Principal Software Engineer and Architect. I am submitting a code snippet in {{language}} that needs refactoring.
My Goal: {{goal}}
The Code:


{{code}}


Your Task:
Please analyze and refactor this code in 3 distinct sections.
Section 1: The Code Review (Constructive Review)
Briefly list 3-5 critical issues in the original code regarding:
Performance: (Time/Space complexity)
Readability: (Naming conventions, structure)
Security/Best Practices: (Potential vulnerabilities or anti-patterns)
Section 2: The Refactored Solution
Rewrite the code completely.
Apply modern syntax and patterns (e.g., functional programming, strict typing).
Add robust error handling.
Include JSDoc/Docstring comments explaining complex logic.
Constraint: Supply a reviewable candidate patch and tests; do not claim production readiness without execution.
Section 3: The "Why" (Education)
Explain the specific changes you made and why they are better. Use a "Before vs. After" comparison logic to help me learn.
Output everything in clean Markdown.

Preserve provided facts. Identify missing evidence and assumptions. Do not promise rankings, replies, hiring, perfect fidelity or measured performance without supporting tests.

3 inputs still blank. Empty inputs stay as placeholders when copied.

Use it on

Open Claude

Get one tested prompt a week

One workflow, one prompt, one tool and one quality check by email. No spam, unsubscribe any time.

Example result

Fictional JavaScript input: const sum = xs => xs.reduce((a,b) => a+b, 0); Refactor only if the stated goal requires it. Tests: sum([])=0; sum([2,3])=5. Discuss numeric strings separately instead of silently changing the contract. This fixture is illustrative until executed in the reader's environment.

Illustrative example; results vary by input and platform.

How to use this prompt

1Supply the language, code and behavior that must remain unchanged.
2Review the proposed diff before execution; reject unrelated dependencies and commands.
3Run the relevant existing checks plus one known boundary case. A generated snippet is a candidate patch, not a production-ready guarantee.

Tips & limitations

Editorial example, not a recorded platform test. Use the current model available in your account; no model settings are recommended from an unobserved run.