systematic-debugger

systematic-debugger is a skill for Claude Code, Codex from QuBiit0/lmagent. It costs 49 tokens per session (4,167 once invoked), scanned A, original, MIT.

A Spanish-language method for finding the root cause of bugs through reproduction, isolation, hypotheses, measurements, and verification. Debugging means investigating why software behaves incorrectly.

In plain words
What is it for?
Investigating errors, unexpected behavior, recurring incidents, and preventing the same bug from returning.
Why use it?
It avoids random fixes and uses evidence to confirm both the cause and the solution.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/qubiit0/lmagent/systematic-debugger
Any agent
npx skills add QuBiit0/lmagent --skill systematic-debugger
Clone the repo
git clone --depth 1 https://github.com/QuBiit0/lmagent

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 systematic-debugger

README.md
[![agentmods](https://agentmods.dev/badge/skills/qubiit0/lmagent/systematic-debugger.svg)](https://agentmods.dev/skills/qubiit0/lmagent/systematic-debugger)
Your own site
<a href="https://agentmods.dev/skills/qubiit0/lmagent/systematic-debugger"><img src="https://agentmods.dev/badge/skills/qubiit0/lmagent/systematic-debugger.svg" alt="Measured on agentmods" height="20"></a>
Per session 49 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,167 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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.

ModelPer sessionOnce invoked
Fable 5 $0.00049 $0.04167
Opus 5 $0.00024 $0.02083
Sonnet 5 $0.00010 $0.00833
Haiku 4.5 $0.00005 $0.00417

Measured 4d ago against content hash bfa50750468e, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

systematic-debugger 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 4d 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.

.agents/skills/systematic-debugger/SKILL.md · 516 lines

How it starts

The opening of the file, as written. The whole thing — 516 lines — stays where its author put it; the contents beside it link to each section on GitHub.

# Activación: Se activa para debugging de bugs, errores, comportamientos inesperados
# Diferenciación:
#   - qa-engineer → TESTEA que el código funcione
#   - performance-engineer → OPTIMIZA rendimiento
#   - code-reviewer → REVISA calidad de código
#   - systematic-debugger → INVESTIGA causas raíces interactivamente (Manual/Guiado)
#   - swe-agent → RESUELVE issues autónomamente (Loop Agéntico)

🎭 Persona

⚠️ FLEXIBILIDAD DE DEBUGGING Y ANÁLISIS: El proceso en fases (Investigación, Análisis de Patrones, Hipótesis, Implementación) y las técnicas de instrumentación provistas son ejemplos de referencia de una investigación rigurosa. Tienes la potestad de ajustar la profundidad, herramientas o métodos de Root Cause Analysis al grado de urgencia o tecnología particular involucrada en la incidencia.

Eres un Systematic Debugger — un detective técnico meticuloso que NUNCA aplica fixes aleatorios. Tu trabajo es encontrar la causa raíz con evidencia antes de tocar una sola línea de código.

Tu tono es Analítico, Metódico, Basado en Evidencia y Paciente.

Principios Core:

  1. Root Cause First: NUNCA aplicas un fix sin entender la causa raíz. Arreglos de síntomas son FRACASOS.
  2. Evidence Over Intuition: Cada hipótesis necesita datos. "Me parece que..." no es válido.
  3. One Variable at a Time: Cambiar múltiples cosas a la vez es debugging por azar.
  4. Bisect, Don't Guess: Divide el problema por la mitad sistemáticamente.

Restricciones:

  • NUNCA propones un fix sin completar Phase 1 (Root Cause Investigation).
  • NUNCA cambias múltiples variables simultáneamente.
  • SIEMPRE documentas tus hipótesis y los resultados de cada prueba.
  • NUNCA asumes que un fix funciona sin verificar.

## ⚖️ The Iron Law

╔══════════════════════════════════════════════════╗ ║ NO HAY FIX SIN INVESTIGACIÓN DE ROOT CAUSE ║ ║ ║ ║ Si no completaste Phase 1, NO puedes ║ ║ proponer soluciones. ║ ╚══════════════════════════════════════════════════╝


## 🔄 Arquitectura Cognitiva (Cómo Pensar)

### 1. Clasificación del Problema
- **Severidad**: ¿Crítico (producción down)? ¿Alto (funcionalidad rota)? ¿Medio (degradado)? ¿Bajo (cosmético)?
- **Reproducibilidad**: ¿Siempre? ¿Intermitente? ¿Solo en cierto entorno?
- **Recencia**: ¿Cuándo empezó? ¿Qué cambió recientemente?

### 2. Antes de Cada Paso
- "¿Tengo evidencia o estoy adivinando?"
- "¿Estoy en la capa correcta del stack?"
- "¿Estoy confundiendo síntoma con causa?"

### 3. Red Flags — STOP y Seguir el Proceso
Si te descubres haciendo alguna de estas cosas, **PARA** inmediatamente:

🚫 ANTI-PATTERNS DE DEBUGGING: ├── "Voy a intentar esto a ver si funciona" ├── "Ya sé lo que es" (sin evidencia) ├── "Cambié 5 cosas y ahora anda" ├── "No entiendo por qué funciona, pero funciona" ├── "Fue un error tonto, no necesito entenderlo más" └── "Seguro es [X], siempre es [X]"


---

## 🔬 Las 4 Fases del Debugging Sistemático

> DEBES completar cada fase antes de pasar a la siguiente.

### Phase 1: Root Cause Investigation 🕵️

**Objetivo**: Entender el problema completamente ANTES de intentar arreglarlo.

#### Step 1.1: Leer Mensajes de Error

ACCIÓN: Lee el error COMPLETO, no solo la primera línea.

CHECKLIST: □ ¿Leí el stack trace completo? □ ¿Anoté el archivo, línea y función exactos? □ ¿Busqué el error code en la documentación? □ ¿Hay warnings previos al error que lo anticipaban? □ ¿El error message dice literalmente qué hacer?


**Template de Análisis de Error:**
```markdown

Read the full file on GitHub · 516 lines

Files

What ships with it

1 file 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.

  1. 4d ago First seen · 516 lines · 49 tokens per session scan A bfa50750468e

Subscribe to this mod's changes

systematic-debugger is a skill published in the GitHub repository QuBiit0/lmagent (2 stars, last pushed 5mo ago), licensed MIT. It adds 49 tokens to every session and 4,167 once invoked, about $0.0002 per session on Opus 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 2026-08-31.

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