dev-systematic-debugging

dev-systematic-debugging is a skill for Claude Code, Codex from kevinnft/ai-agent-skills. It costs 17 tokens per session (2,651 once invoked), scanned A, a copy of systematic-debugging, MIT.

A four-phase method for finding the underlying cause of a software bug before changing the code.

In plain words
What is it for?
It helps investigate symptoms, trace the cause, test explanations, and then choose a verified fix.
Why use it?
It prevents quick patches from hiding the real problem or creating new failures.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions subagents.

Good fit It helps investigate symptoms, trace the cause, test explanations, and then choose a verified fix.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/kevinnft/ai-agent-skills/systematic-debugging
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add kevinnft/ai-agent-skills --skill systematic-debugging
Clone the repo
git clone --depth 1 https://github.com/kevinnft/ai-agent-skills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for dev-systematic-debugging

README.md
[![agentmods](https://agentmods.dev/badge/skills/kevinnft/ai-agent-skills/systematic-debugging/github.svg)](https://agentmods.dev/skills/kevinnft/ai-agent-skills/systematic-debugging)
Your own site
<a href="https://agentmods.dev/skills/kevinnft/ai-agent-skills/systematic-debugging"><img src="https://agentmods.dev/badge/skills/kevinnft/ai-agent-skills/systematic-debugging/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for dev-systematic-debugging

Your own site · 80×15
<a href="https://agentmods.dev/skills/kevinnft/ai-agent-skills/systematic-debugging"><img src="https://agentmods.dev/badge/skills/kevinnft/ai-agent-skills/systematic-debugging.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 17 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,651 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin 89% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00017 $0.02651
Opus 5 $0.00009 $0.01326
Sonnet 5 $0.00003 $0.00530
Haiku 4.5 $0.00002 $0.00265

Measured 9d ago against content hash 87d30801373b, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

dev-systematic-debugging scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

89% identical to systematic-debugging — 44 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/software-development/systematic-debugging/SKILL.md · 388 lines

How it starts

The opening of the file, as written. The whole thing — 388 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Systematic Debugging

Overview

Random fixes waste time and create new bugs. Quick patches mask underlying issues. This skill enforces a 4-phase approach: understand the bug before fixing it.

Common Pitfalls

Bash Installer Scripts

Invalid Commands: Check command exists before using (e.g., hermes config get doesn't exist, use hermes config show or grep config file directly)

Missing Auth Checks: After installing CLI tools (gh, glab), check authentication before using (e.g., gh auth status)

Wrong Installation Paths: When cloning repos with nested structure, copy inner content not outer directory

Hardcoded Values: Detect username/repo dynamically, don't hardcode specific user

Variable Expansion: Use << EOF (no quotes) for variable expansion in heredocs, << 'EOF' to prevent

Error Messages: Include troubleshooting hints (possible causes, manual steps), not just "failed"

The 4-Phase Approach

Violating the letter of this process is violating the spirit of debugging.

The Iron Law

NO FIXES WITHOUT ROOT CAUSE INVESTIGATION FIRST

If you haven't completed Phase 1, you cannot propose fixes.

When to Use

Use for ANY technical issue:

  • Test failures
  • Bugs in production
  • Unexpected behavior
  • Performance problems
  • Build failures
  • Integration issues

Use this ESPECIALLY when:

  • Under time pressure (emergencies make guessing tempting)
  • "Just one quick fix" seems obvious
  • You've already tried multiple fixes
  • Previous fix didn't work
  • You don't fully understand the issue

Don't skip when:

  • Issue seems simple (simple bugs have root causes too)
  • You're in a hurry (rushing guarantees rework)
  • Someone wants it fixed NOW (systematic is faster than thrashing)

The Four Phases

You MUST complete each phase before proceeding to the next.


Phase 1: Root Cause Investigation

BEFORE attempting ANY fix:

1. Read Error Messages Carefully

  • Don't skip past errors or warnings
  • They often contain the exact solution
  • Read stack traces completely
  • Note line numbers, file paths, error codes

Read the full file on GitHub · 388 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 9d ago First seen · 388 lines · 17 tokens per session scan A 87d30801373b

Subscribe to this mod's changes

dev-systematic-debugging is a skill published in the GitHub repository kevinnft/ai-agent-skills (14 stars, last pushed 1mo ago), licensed MIT. It adds 17 tokens to every session and 2,651 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. It is 89% identical to systematic-debugging, differing in 44 lines, and is treated as a copy.

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