root-cause-debugging

root-cause-debugging is a skill for Claude Code, Codex from gabriele-mastrapasqua/codex-lean-team. It costs 31 tokens per session (150 once invoked), scanned A, original, MIT.

An evidence-first method for investigating difficult software bugs, especially bugs that happen intermittently or cross multiple system layers. It focuses on finding the underlying cause rather than hiding the symptom.

In plain words
What is it for?
Use it to reproduce a failure, trace data across boundaries, rank possible causes, run targeted checks, fix the root cause, add a regression test, and check related failure cases.
Why use it?
It turns uncertain debugging into a sequence of smaller tests that can rule out competing explanations and reduce repeated failed fixes.

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/gabriele-mastrapasqua/codex-lean-team/root-cause-debugging
Any agent
npx skills add gabriele-mastrapasqua/codex-lean-team --skill root-cause-debugging
Clone the repo
git clone --depth 1 https://github.com/gabriele-mastrapasqua/codex-lean-team

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 root-cause-debugging

README.md
[![agentmods](https://agentmods.dev/badge/skills/gabriele-mastrapasqua/codex-lean-team/root-cause-debugging.svg)](https://agentmods.dev/skills/gabriele-mastrapasqua/codex-lean-team/root-cause-debugging)
Your own site
<a href="https://agentmods.dev/skills/gabriele-mastrapasqua/codex-lean-team/root-cause-debugging"><img src="https://agentmods.dev/badge/skills/gabriele-mastrapasqua/codex-lean-team/root-cause-debugging.svg" alt="Measured on agentmods" height="20"></a>
Per session 31 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 150 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 5.1 $0.00031 $0.00150
Opus 5 $0.00015 $0.00075
Sonnet 5 $0.00006 $0.00030
Haiku 4.5 $0.00003 $0.00015

Measured 5d ago against content hash 48bb9d3e19ae, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

root-cause-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 5d 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/root-cause-debugging/SKILL.md · 17 lines

What it actually says

Use an evidence-first debugging loop:

  1. Restate the observed failure and separate facts from assumptions.
  2. Identify the smallest reproducible path.
  3. Trace state and data across boundaries.
  4. Rank hypotheses by likelihood and discriminating evidence.
  5. Run or propose the cheapest test that eliminates the most hypotheses.
  6. Fix the root cause rather than masking the symptom.
  7. Add a regression test and verify adjacent failure modes.

Escalate to a specialist only when evidence points to that domain. Keep a short hypothesis ledger; do not dump exhaustive speculation.

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. 5d ago First seen · 17 lines · 31 tokens per session scan A 48bb9d3e19ae

Subscribe to this mod's changes

root-cause-debugging is a skill published in the GitHub repository gabriele-mastrapasqua/codex-lean-team (3 stars, last pushed 1mo ago), licensed MIT. It adds 31 tokens to every session and 150 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.

Related

Other skills, from other repositories

maintain-codex-wiki

Maintain a review-first Markdown knowledge base for Codex practices with source provenance, engineering capture, citation-aware queries, explicit archive and promotion, and deterministic linting. Use when asked to capture a durable engineering lesson, ingest Codex research, query or archive what the repository knows…

Phelan164/codex-howto · 76 tokens

orchestrate-engineering

Coordinate complex engineering work across bounded subagents while protecting the main context, preventing edit conflicts, and measuring whether delegation was worthwhile. Use when the user asks to delegate, parallelize, orchestrate, use subagents, fan out a review, or handle a large task with independent workstreams…

Phelan164/codex-howto · 78 tokens

choose-engineering-flow

Select the smallest useful Codex engineering workflow from this repository's existing skills. Use when a task spans multiple engineering concerns, the user is unsure which skill to invoke, or loading every specialist would waste context; return a recommendation only and do not execute the engineering task.

Phelan164/codex-howto · 58 tokens

operate-devops

Plan and implement infrastructure, CI/CD, container, deployment, observability, and operational configuration changes with least privilege, staged validation, and rollback awareness. Use for pipelines, infrastructure as code, Kubernetes, containers, release automation, monitoring, and production-readiness work; do not…

Phelan164/codex-howto · 69 tokens

build-backend

Build or modify backend APIs, services, jobs, persistence, and integrations while preserving contracts, authorization, data integrity, and failure behavior. Use for server-side features, database changes, background processing, backend defects, and service refactors; do not use for frontend-only or infrastructure-only…

Phelan164/codex-howto · 62 tokens

build-frontend

Build or modify frontend interfaces using repository-native components while preserving accessibility, responsive behavior, state handling, and visual verification. Use for UI features, design implementation, forms, client-side defects, and frontend refactors; do not use for backend-only or infrastructure-only work.

Phelan164/codex-howto · 57 tokens