A structured guide to finding and fixing software problems, from defining the issue through testing the fix.

Use it to investigate bugs, errors, crashes, performance issues, unexpected results, incoming reports, and production incidents.

It replaces guesswork with reproducible observations, tested hypotheses, root-cause analysis, and verification.

debug — Skill for Claude Code and Codex by pproenca/dot-skills

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 pproenca/dot-skills --skill debug

Clone the repo

git clone --depth 1 https://github.com/pproenca/dot-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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/pproenca/dot-skills/debug/github.svg)](https://agentmods.dev/skills/pproenca/dot-skills/debug)

Your own site

<a href="https://agentmods.dev/skills/pproenca/dot-skills/debug"><img src="https://agentmods.dev/badge/skills/pproenca/dot-skills/debug/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/pproenca/dot-skills/debug"><img src="https://agentmods.dev/badge/skills/pproenca/dot-skills/debug.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 78 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,438 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. Third-party audits

Socket pass 16 Sept 2026
Snyk pass 16 Sept 2026
NVIDIA SkillSpector pass 7 Sept 2026

How audits are shown

Origin original No closer match found 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.

Model	Per session	Once invoked
Fable 5.1	$0.00078	$0.01438
Opus 5.5	$0.00031	$0.00575
Sonnet 5.5	$0.00016	$0.00288
Haiku 4.5	$0.00008	$0.00144

Measured 1mo ago against content hash cf778cd942a3, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

debug 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 1mo 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.

skills/.curated/debug/SKILL.md · 133 lines

How it starts

The opening of the file, as written. The whole thing — 133 lines — stays where its author put it; the contents beside it link to each section on GitHub.

dot-skills Debugging Best Practices

Comprehensive debugging methodology guide for software engineers, containing 54 rules across 10 categories prioritized by impact. Based on research from Andreas Zeller's "Why Programs Fail" and academic debugging curricula.

When to Apply

Reference these guidelines when:

Investigating a bug or unexpected behavior
Debugging code during development
Code produces wrong results or crashes
Performance issues need root cause analysis
Triaging incoming bug reports and prioritizing fixes
Conducting root cause analysis for incidents
Reviewing debugging approaches or code for common bug patterns

Rule Categories by Priority

Priority	Category	Impact	Prefix
1	Problem Definition	CRITICAL	`prob-`
2	Hypothesis-Driven Search	CRITICAL	`hypo-`
3	Observation Techniques	HIGH	`obs-`
4	Root Cause Analysis	HIGH	`rca-`
5	Tool Mastery	MEDIUM-HIGH	`tool-`
6	Bug Triage and Classification	MEDIUM	`triage-`
7	Common Bug Patterns	MEDIUM	`pattern-`
8	Fix Verification	MEDIUM	`verify-`
9	Anti-Patterns	MEDIUM	`anti-`
10	Prevention & Learning	LOW-MEDIUM	`prev-`

Quick Reference

1. Problem Definition (CRITICAL)

prob-reproduce-before-debug - Reproduce the bug before investigating
prob-minimal-reproduction - Create minimal reproduction cases
prob-document-symptoms - Document symptoms precisely
prob-separate-symptoms-causes - Separate symptoms from causes
prob-state-expected-actual - State expected vs actual behavior
prob-recent-changes - Check recent changes first

2. Hypothesis-Driven Search (CRITICAL)

hypo-scientific-method - Apply the scientific method
hypo-binary-search - Use binary search to localize bugs
hypo-one-change-at-time - Test one hypothesis at a time
hypo-where-not-what - Find WHERE before asking WHAT
hypo-rule-out-obvious - Rule out obvious causes first
hypo-rubber-duck - Explain the problem aloud

Read the full file on GitHub · 133 lines

Files

What ships with it

59 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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.

1mo ago First seen · 133 lines · 78 tokens per session scan A cf778cd942a3

Subscribe to this mod's changes

debug is a skill published in the GitHub repository pproenca/dot-skills (215 stars, last pushed 2mo ago), licensed MIT. It adds 78 tokens to every session and 1,438 once invoked, about $0.0003 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Debugging

debug-optimize-lcp

Guides debugging and optimizing Largest Contentful Paint (LCP) using Chrome DevTools MCP tools. Use this skill whenever the user asks about LCP performance, slow page loads, Core Web Vitals optimization, or wants to understand why their page's main content takes too long to appear. Also use when the user mentions…

ChromeDevTools/chrome-devtools-mcp · 99 tokens

systematic-debugging

Use when debugging a failing test, build error, or runtime issue that isn't immediately obvious. Guides a 4-phase root cause analysis instead of random fix attempts.

open-metadata/OpenMetadata · 37 tokens

diagnose

Trace from a reproduced symptom to the source code that causes it. Pin the specific file and approximate line, rate confidence in the cause and clarity of the fix independently, and always propose a concrete fix.

emdash-cms/emdash · 43 tokens

repro-admin

Reproduce an EmDash admin UI bug. Attach a container, start the demo dev server, drive the admin with agent-browser using the dev-bypass session, and capture the reproduction as screenshots plus a replayable transcript.

emdash-cms/emdash · 48 tokens

log-error-digest

Analyze log files to troubleshoot errors, identify peak error periods, and produce error clustering, frequency statistics, and time distribution reports. Supports JSON, syslog, and Nginx formats with automatic detection. Use when a user uploads a .log file and asks to analyze errors, find patterns, debug issues, or…

zebbern/claude-code-guide · 71 tokens

deck-retro

Run a fully local agent-deck retrospective over the user's own transcripts, Recall index and logs. Use when a user wants to find recurring failures or take their own finding from investigation through synthetic reproduction, a user-filed issue, a test-first fix and contributor PR handoff. Also use for weekly usage…

asheshgoplani/agent-deck · 86 tokens