debugging-expert

debugging-expert is a skill for Claude Code from Miaoge-Ge/coding-agent-skills. It costs 74 tokens per session (961 once invoked), scanned A, original, MIT.

A methodical guide for finding the real cause of bugs, crashes, errors, and unexpected results. It emphasizes reproducing the problem, studying evidence, and checking which change introduced it.

In plain words
What is it for?
Use it to investigate stack traces, intermittent failures, “works on my machine” bugs, race conditions, and regressions. It also helps isolate the change that caused a failure.
Why use it?
It replaces guess-and-check edits with a repeatable way to narrow down failures. This helps distinguish the cause from the part of the code where the problem first appears.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the debugging-expert plugin — 1 skill shipped together

Good fit Use it to investigate stack traces, intermittent failures, “works on my machine” bugs, race conditions, and regressions. It also helps isolate the change that caused a failure.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/miaoge-ge/coding-agent-skills/debugging-expert
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 Miaoge-Ge/coding-agent-skills --skill debugging-expert
Clone the repo
git clone --depth 1 https://github.com/Miaoge-Ge/coding-agent-skills

Made for: Claude Code.

Or install debugging-expert, the plugin that ships this one along with the rest of its 1 skill.

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 debugging-expert

README.md
[![agentmods](https://agentmods.dev/badge/skills/miaoge-ge/coding-agent-skills/debugging-expert/github.svg)](https://agentmods.dev/skills/miaoge-ge/coding-agent-skills/debugging-expert)
Your own site
<a href="https://agentmods.dev/skills/miaoge-ge/coding-agent-skills/debugging-expert"><img src="https://agentmods.dev/badge/skills/miaoge-ge/coding-agent-skills/debugging-expert/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 debugging-expert

Your own site · 80×15
<a href="https://agentmods.dev/skills/miaoge-ge/coding-agent-skills/debugging-expert"><img src="https://agentmods.dev/badge/skills/miaoge-ge/coding-agent-skills/debugging-expert.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 74 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 961 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.
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 $0.00074 $0.00961
Opus 5.5 $0.00030 $0.00384
Sonnet 5.5 $0.00015 $0.00192
Haiku 4.5 $0.00007 $0.00096

Measured 1mo ago against content hash 5962894d27cd, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

debugging-expert 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.

plugins/debugging-expert/skills/debugging-expert/SKILL.md · 78 lines

How it starts

The opening of the file, as written. The whole thing — 78 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Debugging Expert

Reproduce, then bisect. The bug is rarely where you think — follow evidence, change one variable at a time, and fix the cause (with a regression test), not the symptom.

When to Use

  • A bug, crash, exception, or wrong output to diagnose.
  • Intermittent / "works on my machine" / heisenbug situations.
  • Locating which change introduced a regression.
  • Stuck guessing and editing code at random.

When NOT to Use

  • Writing the regression test after diagnosis → testing-expert.
  • It's slow, not wrong → performance-expert.
  • Refactoring without a defect → refactoring-expert.

The Method

1. Reproduce reliably first

  • Get a minimal, deterministic reproduction before changing anything — you can't confirm a fix for a bug you can't trigger. Pin inputs, environment, versions, and timing.
  • For intermittent bugs, find what increases the rate (load, ordering, specific data, concurrency) and amplify it; add logging to capture the failing case.

2. Read the evidence

  • Read the entire error and stack trace top to bottom — the root cause is often above the most obvious frame. Don't skim or assume.
  • Check what changed: git log/git diff since it last worked, recent deploys, dependency bumps, config/env differences. Inspect logs around the failure timestamp.

3. Hypothesize → predict → test

  • Form one hypothesis, predict exactly what you'd observe if it's true, then test that prediction. Confirm or eliminate before moving on.
  • Bisect the search space: binary-search the code path, the input data, or history (git bisect). Add assertions/logging at the boundary between "still correct" and "already wrong" to bracket the defect.
  • Question assumptions, including "this library/my framework can't be the problem." Verify, don't believe.

4. Fix the cause, prevent recurrence

  • Explain why it happened before patching. Fix the root cause, not the visible symptom. Add a test that fails without the fix, then look for sibling bugs of the same class.

Read the full file on GitHub · 78 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. 1mo ago First seen · 78 lines · 74 tokens per session scan A 5962894d27cd

Subscribe to this mod's changes

debugging-expert is a skill published in the GitHub repository Miaoge-Ge/coding-agent-skills (7 stars, last pushed 4mo ago), licensed MIT. It adds 74 tokens to every session and 961 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 2026-08-31.

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