systematic-debugging

systematic-debugging is a skill for Claude Code, Codex from byerlikaya/claude-starter-kit. It costs 55 tokens per session (997 once invoked), scanned A, original, MIT.

A debugging method that finds and confirms the underlying cause of a software bug before changing the code.

In plain words
What is it for?
Use it for persistent, intermittent, hard-to-reproduce, or previously attempted bugs, including crashes and failures whose cause is unclear.
Why use it?
It replaces guesswork with a repeatable process: reproduce the failure, narrow it down, test a possible cause, then verify the fix.

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/byerlikaya/claude-starter-kit/systematic-debugging
Any agent
npx skills add byerlikaya/claude-starter-kit --skill systematic-debugging
Clone the repo
git clone --depth 1 https://github.com/byerlikaya/claude-starter-kit

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-debugging

README.md
[![agentmods](https://agentmods.dev/badge/skills/byerlikaya/claude-starter-kit/systematic-debugging.svg)](https://agentmods.dev/skills/byerlikaya/claude-starter-kit/systematic-debugging)
Your own site
<a href="https://agentmods.dev/skills/byerlikaya/claude-starter-kit/systematic-debugging"><img src="https://agentmods.dev/badge/skills/byerlikaya/claude-starter-kit/systematic-debugging.svg" alt="Measured on agentmods" height="20"></a>
Per session 55 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 997 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 $0.00055 $0.00997
Opus 5 $0.00028 $0.00498
Sonnet 5 $0.00011 $0.00199
Haiku 4.5 $0.00006 $0.00100

Measured 5d ago against content hash 7c8d5d5be814, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

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 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.

claude-starter/skills/systematic-debugging/SKILL.md · 60 lines

How it starts

The opening of the file, as written. The whole thing — 60 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Systematic Debugging

Trigger phrases: "debug", "root cause", "why is this failing", "intermittent bug", "can't reproduce", "is broken", "crashes"

One rule holds the whole skill together: no fix without a confirmed root cause. A patch that makes the symptom disappear without a proven cause is not a fix — it's a coin flip that hides the bug until it returns somewhere worse. This skill is the discipline that turns "try things until it works" into "understand, then change one thing."

Kit adaptation (local, .claude/): Distinct from iterate (a self-correction loop over a task) and reflect (meta-review of an approach) — this skill is for a defect. §4 Prohibitions apply; a fix still goes through the project's review/test gates. Don't disable a test or a gate to make a symptom pass (that is masking, not fixing).

The loop (do them in order — skipping a step is why bugs come back)

  1. Reproduce — a reliable, minimal repro. Can't reproduce → that IS the first problem; see references/techniques.md (intermittent/heisenbug).
  2. Isolate — shrink the surface until the failure is in the smallest possible slice (bisect commits, halve the input, disable half the system).
  3. Hypothesize — state ONE falsifiable cause: "X fails because Y." Write it down. A vague hunch is not a hypothesis.
  4. Test the hypothesis — the cheapest observation that would disprove it (a log, a breakpoint, a probe). If it survives, you have the cause; if not, back to 3.
  5. Confirm the root cause — you can explain the full chain symptom←…←cause, and you can turn the bug on and off by touching the cause.
  6. Fix — the smallest change at the cause (not the symptom). Consider what else shares that cause.
  7. Verify — the original repro now passes, a regression test locks it, and nothing nearby broke.

Read the full file on GitHub · 60 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. 5d ago First seen · 60 lines · 55 tokens per session scan A 7c8d5d5be814

Subscribe to this mod's changes

systematic-debugging is a skill published in the GitHub repository byerlikaya/claude-starter-kit (22 stars, last pushed 5d ago), licensed MIT. It adds 55 tokens to every session and 997 once invoked, about $0.0003 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 2026-08-30.

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