# bug-detective

A structured debugging workflow and error pattern guide for coding agents. It triggers on bug reports, failing tests, and broken scripts.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 404 installs · ★ 5906
- Author: Galaxy-Dawn
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/Galaxy-Dawn/claude-scholar/tree/HEAD/skills/bug-detective/SKILL.md
- Updated: 2026-10-19
- HTML: https://affpapa.org/en/nevibecode/skills/bug-detective

## What it does

This skill replaces random trial-and-error fixes with a structured debugging protocol. It guides the agent through five distinct phases: gathering error evidence, classifying the failure type, isolating the broken line, testing explicit hypotheses, and verifying the fix against regressions. The troubleshooting steps rely on stack trace tracing, binary code isolation, breakpoints, and logging.

The reference covers recurring problem patterns across Python, JavaScript, TypeScript, and Bash. The shell section focuses on assignment spacing, unquoted variables, subshell variable loss in pipelines, and exit flags. It also injects practical commands for `pdb`, Node.js inspector, `pytest`, and `git bisect`.

The workflow requires concrete evidence before touching any code. If you cannot provide an exact traceback or reproduction steps, the agent will pause and prompt for environment details and logs before making changes.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add Galaxy-Dawn/claude-scholar --skill bug-detective -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/bug-detective/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/bug-detective/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add Galaxy-Dawn/claude-scholar --skill bug-detective -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/bug-detective/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add Galaxy-Dawn/claude-scholar --skill bug-detective -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/bug-detective/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install Galaxy-Dawn/claude-scholar bug-detective
```

2. **Manually: put the files in place**
- File: `.github/skills/bug-detective/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add Galaxy-Dawn/claude-scholar --skill bug-detective -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/Galaxy-Dawn/claude-scholar --path skills/bug-detective
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/bug-detective/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add Galaxy-Dawn/claude-scholar --skill bug-detective -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/Galaxy-Dawn/claude-scholar/tree/HEAD/skills/bug-detective/SKILL.md

## When to use it
- trace call stacks to isolate the root cause of failures
- fix quoting, syntax, and subshell scope issues in Bash
- locate broken logic through binary search and logging
- formulate and verify debugging hypotheses before patching

## Example prompts
- investigate this bug: pytest fails with KeyError during response parsing
- troubleshoot this issue: bash script deletes files because variable is empty
- why is this failing: TypeError when accessing object properties

## Source text · SKILL.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: 08711618368ebb43.

BEGIN THIRD-PARTY FILE 08711618368ebb43
````text
---
name: bug-detective
description: This skill should be used when the user asks to "debug this", "fix this error", "investigate this bug", "troubleshoot this issue", "find the problem", "something is broken", "this isn't working", "why is this failing", or reports errors/exceptions/bugs. Provides systematic debugging workflow and common error patterns.
version: 0.1.0
---

# Bug Detective

A systematic debugging workflow for investigating and resolving code errors, exceptions, and failures. Provides structured debugging methods and common error pattern recognition.

## Core Philosophy

Debugging is a scientific problem-solving process that requires:
1. **Understand the problem** - Clearly define symptoms and expected behavior
2. **Gather evidence** - Collect error messages, logs, stack traces
3. **Form hypotheses** - Infer possible causes based on evidence
4. **Verify hypotheses** - Confirm or eliminate causes through experiments
5. **Resolve the issue** - Apply fixes and verify

## Debugging Workflow

### Step 1: Understand the Problem

Before starting to debug, clarify the following information:

**Required information to collect:**
- Complete error message content
- Exact location of the error (filename and line number)
- Reproduction steps (how to trigger the error)
- Expected behavior vs actual behavior
- Environment info (OS, versions, dependencies)

**Question template:**
```
1. What is the exact error message?
2. Which file and line does the error occur at?
3. How can this issue be reproduced? Provide detailed steps.
4. What was the expected result? What actually happened?
5. What recent changes might have introduced this issue?
```

### Step 2: Analyze Error Type

Choose a debugging strategy based on error type:

| Error Type | Characteristics | Debugging Method |
|-----------|----------------|-----------------|
| **Syntax Error** | Code cannot be parsed | Check syntax, bracket matching, quotes |
| **Import Error** | ModuleNotFoundError | Check module installation, path config |
| **Type Error** | TypeError | Check data types, type conversions |
| **Attribute Error** | AttributeError | Check if object attribute exists |
| **Key Error** | KeyError | Check if dictionary key exists |
| **Index Error** | IndexError | Check list/array index range |
| **Null Reference** | NoneType/NullPointerException | Check if variable is None |
| **Network Error** | ConnectionError/Timeout | Check network connection, URL, timeout settings |
| **Permission Error** | PermissionError | Check file permissions, user permissions |
| **Resource Error** | FileNotFoundError | Check if file path exists |

### Step 3: Locate the Problem Source

Use the following methods to locate the issue:

**1. Binary Search Method**
- Comment out half the code, check if the problem persists
````
END THIRD-PARTY FILE 08711618368ebb43

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---
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