Coding prompts

You are a senior [language] engineer mentoring a junior developer. Explain what the code below does, step by step, then point out anything unusual, risky or worth refactoring. Code: [paste code]

My [language or framework] code throws this error: [paste error and stack trace]. Here is the code involved: [paste code]. List the three most likely causes in order, tell me how to confirm each one, and give the fix for the most likely cause.

Write unit tests with [testing framework] for the function below. Cover normal input, boundary values, empty or null input and invalid types, and name each test after the behavior it checks. Function: [paste function]

Refactor this [language] code to be more readable and maintainable without changing its behavior. Use clear names, smaller functions and less duplication, and keep the public interface the same. Explain each change briefly. Code: [paste code]

Review this pull request diff as a strict but friendly reviewer. Group your comments into bugs, security, performance and style, mark each one as blocking or optional, and suggest specific code changes. Diff: [paste diff]

Write a [PostgreSQL, MySQL or SQLite] query that [describe what you need] using these tables: [paste table definitions]. Explain the query in plain English and suggest an index if the tables are large.

Write a regular expression for [language or tool] that matches [describe pattern] but not [describe exceptions]. Explain each part of the pattern, and give five strings that should match and five that should not.

Convert this [source language] code to idiomatic [target language]. Don't translate line by line; use the target language's usual libraries and patterns, and point out any behavior that differs, such as integer division or error handling. Code: [paste code]

Write a [framework] endpoint for [HTTP method] [route] that [what it should do]. Validate these input fields: [fields and rules], return clear error messages with the right status codes, and include an example request and response.

Write a [bash or PowerShell] script that [task, e.g. renames all photos in a folder by date taken]. Make it safe: add a dry-run option, stop on errors and print what it is doing. Comment each section.

This [language] function is slow on large inputs of about [input size]: [paste code]. Explain its time and memory complexity, find the bottleneck, and propose a faster version with its new complexity. The output must stay the same.

Design a database schema for [describe app, e.g. a small booking system] with these requirements: [requirements]. Give the tables, columns with types, keys and relationships, and name one design choice you would revisit as the app grows.

Add clear docstrings or comments in the standard [language] style to the code below. Describe each function's purpose, parameters, return values and possible errors, and don't change the code itself. Code: [paste code]

I'm in this Git situation: [describe what happened, e.g. committed to the wrong branch and pushed]. Explain what is going on, give me the exact commands to fix it safely, and warn me about any command that rewrites shared history.

Teach me [programming concept, e.g. recursion or closures] in [language]. Start with a short explanation and a minimal example, then give me three exercises of increasing difficulty. Wait for my answer before showing each solution.

Check this [language] code for security problems such as injection, unsafe deserialization, missing input validation, hard-coded secrets and weak authentication. For each issue, explain the risk and show the fixed code. Code: [paste code]

Write a commit message for these changes with a short imperative summary line under 72 characters and a body that explains what changed and why: [describe or paste the diff]

I need to [task] in a [language or framework] project with these constraints: [constraints, e.g. small bundle, no native dependencies]. Compare two or three common approaches or libraries in a table with pros, cons and when to use each, and tell me which details to verify in their official docs.

Build an accessible [framework, or plain HTML, CSS and JavaScript] component for [component, e.g. a tabs widget]. Requirements: [requirements]. Include keyboard support, ARIA attributes where needed and a short usage example.

Write a [language] script that reads [file type, e.g. a CSV file] with these columns: [columns], then [what to compute or transform], and writes the result to [output]. Handle missing values and malformed rows, and print a short summary at the end.