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Agent skill

Systematic Debugging

by Archive228 in Archive228/loopkit

A skill your agent uses for ANY bug, test failure, crash, or unexpected behavior.

MITAuto-check passedDevelopment

Install Systematic Debugging

skills CLI
$ npx skills add Archive228/loopkit --skill systematic-debugging -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install Archive228/loopkit systematic-debugging --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/Archive228/loopkit.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/systematic-debugging .claude/skills/systematic-debugging && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
systematic-debugging
GitHub stars
755
Token cost
~432 tokens
SKILL.md length
246 words
Files
1
Skills in repo
52
Repo updated
First seen
Licence
MIT

At a glance

A skill your agent uses for ANY bug, test failure, crash, or unexpected behavior.

  • Works in 5 steps: Read the whole error. The entire message… → Reproduce it first. If you can't… → Form one hypothesis, name it. "I think… → …
  • Unexpected behavior
  • SKILL.md covers The loop, Stop conditions and Output
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Systematic Debugging is an agent skill from Archive228/loopkit. Use for ANY bug, test failure, crash, or unexpected behavior. Forces reproduce-then-isolate before proposing a fix. Stops the agent from guessing.

Its SKILL.md is about 430 tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Development, covering Debugging and Failing and flaky tests. The repository describes itself as: 33 battle-tested skills + minimal .claude harness for any coding agent (Claude Code, Cursor, Codex, Gemini CLI). The licence is MIT.

When your agent uses it

  • Unexpected behavior
  • Tasks that involve Debugging
  • Tasks that involve Failing and flaky tests

Example prompts

  • “/systematic-debugging”

Workflow steps

5 steps, taken from the first numbered list in SKILL.md.

  1. Read the whole error. The entire message and stack trace. A TypeError can mean a
  2. Reproduce it first. If you can't reproduce it, you can't verify a fix. Write the
  3. Form one hypothesis, name it. "I think the value is null because the upstream call
  4. Change one thing. Test. Repeat. If you change three things and it works, you don't
  5. Fix the root cause, not the symptom. A null check that hides a null is not a fix.

What it can do on your machine

Read from SKILL.md and the folder at commit 5ae033e. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md.

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Systematic Debugging loads about 432 tokens when it runs. Until then it costs about 42 tokens; SKILL.md has 246 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~42
When it runs · the whole SKILL.md, loaded when a task matches
~432

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from Archive228/loopkit at commit 5ae033e, republished under its MIT licence (© Archive228). 246 words, ~432 tokens.

Download SKILL.mdSave it as .claude/skills/systematic-debugging/SKILL.md (or your agent's skills folder).
name
systematic-debugging
description
Use for ANY bug, test failure, crash, or unexpected behavior. Forces reproduce-then-isolate before proposing a fix. Stops the agent from guessing.
when_to_use
a test fails, a crash, wrong output, "it worked yesterday", a flaky failure

Systematic Debugging

The single most expensive agent failure: seeing an error and immediately generating a "fix" based on the error type, without reading what actually happened. Don't.

The loop

  1. Read the whole error. The entire message and stack trace. A TypeError can mean a hundred different things — the trace tells you which one. Quote the exact line that throws.

  2. Reproduce it first. If you can't reproduce it, you can't verify a fix. Write the smallest input that triggers it. "I think this fixes it" is gambling, not debugging.

  3. Form one hypothesis, name it. "I think the value is null because the upstream call returns 204 with no body." State it before you touch anything.

  4. Change one thing. Test. Repeat. If you change three things and it works, you don't know which one fixed it — and the other two may have added new bugs.

  5. Fix the root cause, not the symptom. A null check that hides a null is not a fix. Find why it's null. The underlying bug will resurface differently if you only patch the crash.

Stop conditions

  • If 3 hypotheses fail, STOP and report: what you tried, what you saw, what you suspect. "I've tried X and Y, here's the output, I think it's Z but I'm not sure" beats 20 silent random attempts.
  • Never add a workaround you don't understand.

Output

End with: the root cause (one sentence), the minimal fix, and the test that now proves it.

© Archive228, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in skills/systematic-debugging of Archive228/loopkit.

Open the folder on GitHubat commit 5ae033e

Compare with similar skills

Systematic Debugging next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Systematic Debugging compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Systematic Debugging this skillArchive228/loopkit755—~432Automated safety check: PassMIT
Systematic Debuggingultralisp/ultralisp25851 repos~2.4kAutomated safety check: PassNone
Exposed Bug Fix WorkflowJetBrains/Exposed9.3k—~3.8kAutomated safety check: PassApache-2.0
React Router Bug Fix Workflowremix-run/react-router57k—~1.3kAutomated safety check: PassMIT
Systematic DebuggingChrisWiles/claude-code-showcase6.1k3 repos~1.2kAutomated safety check: PassNone
Debugging and Error Recoveryaddyosmani/agent-skills102k1 repos~2.6kAutomated safety check: PassMIT

Similar skills

  • Systematic Debugging

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Categories

Questions about Systematic Debugging

What does Systematic Debugging do?

A skill your agent uses for ANY bug, test failure, crash, or unexpected behavior. Systematic Debugging is an agent skill from Archive228/loopkit. Use for ANY bug, test failure, crash, or unexpected behavior.

When should I use Systematic Debugging?

Systematic Debugging fits situations like: unexpected behavior; tasks that involve Debugging; tasks that involve Failing and flaky tests.

How do I install Systematic Debugging in Claude Code?

Run `npx skills add Archive228/loopkit --skill systematic-debugging -a claude-code`. Or copy the skill folder (skills/systematic-debugging in Archive228/loopkit) into .claude/skills/systematic-debugging in your project. Claude Code loads it when a task matches its description.

How do I install Systematic Debugging in Codex?

Run `npx skills add Archive228/loopkit --skill systematic-debugging -a codex`. Or copy the skill folder (skills/systematic-debugging in Archive228/loopkit) into .agents/skills/systematic-debugging in your project. Codex loads it when a task matches its description.

Can I use Systematic Debugging in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add Archive228/loopkit --skill systematic-debugging -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/systematic-debugging, .gemini/skills/systematic-debugging, .github/skills/systematic-debugging and .opencode/skills/systematic-debugging in your project.

What does Systematic Debugging need to run?

SKILL.md names no scripts, command-line tools or credentials: Systematic Debugging is instructions for the agent only.

Does Systematic Debugging access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Systematic Debugging safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Systematic Debugging use?

Systematic Debugging is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Systematic Debugging use?

About 432 tokens (SKILL.md is roughly 1.7k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Systematic Debugging?

Skills that share tags, products or a category with Systematic Debugging: Systematic Debugging (ultralisp/ultralisp, 258 stars), Exposed Bug Fix Workflow (JetBrains/Exposed, 9.3k stars), React Router Bug Fix Workflow (remix-run/react-router, 57k stars) and Systematic Debugging (ChrisWiles/claude-code-showcase, 6.1k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Systematic Debugging?

Archive228 (a GitHub user) maintains it in Archive228/loopkit, which has 755 GitHub stars. The repository holds 52 skills in this directory. The repository was last updated on July 14, 2026.

Source: Archive228/loopkit on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.