ccc-systematic-debugging

ccc-systematic-debugging is a skill for Claude Code from KevinZai/commander. It costs 58 tokens per session (1,927 once invoked), scanned A, original, MIT.

A root-cause debugging workflow built around reproducing a problem, forming a hypothesis, checking evidence, and then fixing it. Root cause means the underlying reason a bug happens, rather than the visible symptom.

In plain words
What is it for?
Use it to investigate bugs, failing tests, error messages, configuration problems, and failures that cross several application components.
Why use it?
It reduces random patches that hide the real problem or create new bugs. The workflow requires evidence before a fix is attempted.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter. Also seen: model in frontmatter; names the AskUserQuestion tool; runs codex exec.

Good fit Use it to investigate bugs, failing tests, error messages, configuration problems, and failures that cross several application components.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/kevinzai/commander/ccc-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 KevinZai/commander --skill ccc-systematic-debugging
Clone the repo
git clone --depth 1 https://github.com/KevinZai/commander

Made for: Claude Code.

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 ccc-systematic-debugging

README.md
[![agentmods](https://agentmods.dev/badge/skills/kevinzai/commander/ccc-systematic-debugging/github.svg)](https://agentmods.dev/skills/kevinzai/commander/ccc-systematic-debugging)
Your own site
<a href="https://agentmods.dev/skills/kevinzai/commander/ccc-systematic-debugging"><img src="https://agentmods.dev/badge/skills/kevinzai/commander/ccc-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 ccc-systematic-debugging

Your own site · 80×15
<a href="https://agentmods.dev/skills/kevinzai/commander/ccc-systematic-debugging"><img src="https://agentmods.dev/badge/skills/kevinzai/commander/ccc-systematic-debugging.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 58 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,927 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
  • 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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00058 $0.01927
Opus 5.5 $0.00023 $0.00771
Sonnet 5.5 $0.00012 $0.00385
Haiku 4.5 $0.00006 $0.00193

Measured 10d ago against content hash debd102ee161, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

ccc-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 10d 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.

commander/cowork-plugin-codex/skills/ccc-systematic-debugging/SKILL.md · 146 lines

How it starts

The opening of the file, as written. The whole thing — 146 lines — stays where its author put it; the contents beside it link to each section on GitHub.

$ccc-systematic-debugging — root cause before fix

CC Commander · $ccc-systematic-debugging · a four-phase process that finds the cause, proves it, and fixes it once.

NO FIX WITHOUT CONFIRMED ROOT CAUSE

Guess-and-check fixes waste time and create new bugs; quick patches mask the real issue. Complete each phase before starting the next.

When to use / when not to

  • Use for any bug, failing or flaky test, crash, wrong output, or error whose cause is not yet proven.
  • Use even when the issue looks simple; the process is fast for simple bugs.
  • Do not use for a known, already-diagnosed change (a typo the user pointed at, a requested refactor). Make that edit directly.
  • For investigations expected to run past ~20 turns, span several systems, or need hypothesis state held across cycles, delegate (see "Decision points").

What happens

Start from $ARGUMENTS (the symptom, error text or failing test). Keep a short hypothesis log in the conversation: hypothesis, evidence, result, per cycle.

Phase 1 — Root-cause investigation (before any fix)

  1. Read the error completely: full stack trace, line numbers, error codes. Do not skim.
  2. Reproduce it. Run the exact failing command and capture the output, for example the single test: npx vitest run path/to/file.test.ts -t "<name>", pytest path/to/test_x.py::test_name -x, or node --test path/to/file.test.js. If it does not reproduce reliably, gather more data before going on; for flaky failures, run it in a loop (for i in $(seq 1 20); do <cmd> || break; done) and record the failure rate.
  3. Check recent changes: git log --oneline -15, git diff, git diff HEAD~5 --stat, new dependencies (git diff HEAD~5 -- package.json package-lock.json pyproject.toml), config changes. When a known-good commit exists, git bisect with the reproduction command finds the change.
  4. Instrument component boundaries in multi-component systems: log what enters and exits each boundary and confirm config propagates. Run once to find where it breaks before reasoning about why.
  5. Trace the bad value backward through the call stack to where it originates. The fix belongs at the source, not at the symptom.

Read the full file on GitHub · 146 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. 10d ago Changed · +27 lines · +16 tokens per session debd102ee161
  2. 1mo ago First seen · 119 lines · 42 tokens per session scan A 442081b0d876

Subscribe to this mod's changes

ccc-systematic-debugging is a skill published in the GitHub repository KevinZai/commander (6 stars, last pushed today), licensed MIT. It adds 58 tokens to every session and 1,927 once invoked, about $0.0002 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 2026-09-03.

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