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.
npx agentmods add skills/magnus919/agent-skills/systematic-debuggingnpx skills add magnus919/agent-skills --skill systematic-debugginggit clone --depth 1 https://github.com/magnus919/agent-skillsWrote 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.
[](https://agentmods.dev/skills/magnus919/agent-skills/systematic-debugging)<a href="https://agentmods.dev/skills/magnus919/agent-skills/systematic-debugging"><img src="https://agentmods.dev/badge/skills/magnus919/agent-skills/systematic-debugging.svg" alt="Measured on agentmods" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00083 | $0.03899 |
| Opus 5 | $0.00042 | $0.01950 |
| Sonnet 5 | $0.00017 | $0.00780 |
| Haiku 4.5 | $0.00008 | $0.00390 |
Grade C, and why
systematic-debugging scanned grade C with 1 finding 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 yesterday.
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.
Recursive force deletehighDestructive command
rm -rf with a variable or a broad path is one typo away from removing the wrong tree.
2. Reset the app container (`rm -rf ~/Library/Containers/<bundle-id>/`) This is a copy
94% identical to systematic-debugging — 29 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 445 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Systematic Debugging
Overview
Random fixes waste time and create new bugs. Quick patches mask underlying issues.
Core principle: ALWAYS find root cause before attempting fixes. Symptom fixes are failure.
The Iron Law
NO FIXES WITHOUT ROOT CAUSE INVESTIGATION FIRST
If you haven't completed Phase 1, you cannot propose fixes.
When to Use
Use for ANY technical issue:
- Test failures
- Bugs in production
- Unexpected behavior
- Performance problems
- Build failures
- Integration issues
ESPECIALLY when:
- Under time pressure (emergencies make guessing tempting)
- "Just one quick fix" seems obvious
- You've already tried multiple fixes
- Previous fix didn't work
- You don't fully understand the issue
Don't skip when:
- Issue seems simple (simple bugs have root causes too)
- You're in a hurry (rushing guarantees rework)
- Someone wants it fixed NOW (systematic is faster than thrashing)
The Four Phases
Complete each phase before proceeding to the next.
Phase 1: Root Cause Investigation
BEFORE attempting ANY fix:
1. Read Error Messages Carefully
- Don't skip past errors or warnings — they often contain the exact solution
- Read stack traces completely. Note line numbers, file paths, error codes
- Action: Read the relevant source files at the error locations and search the codebase for the error string to find all related code paths.
2. Reproduce Consistently
- Can you trigger it reliably? What are the exact steps?
- If not reproducible → gather more data, don't guess
- Action: Run the failing test or trigger the bug:
pytest tests/test_module.py::test_name -v --tb=long
3. Check Recent Changes
- What changed that could cause this? Git diff, recent commits, new dependencies, config changes
- Action:
git log --oneline -10
git diff
git log -p --follow src/problematic_file.py | head -100
4. Gather Evidence in Multi-Component Systems
WHEN system has multiple components (API → service → database, CI → build → deploy):
What ships with it
4 files 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.
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.
- yesterday First seen · 445 lines · 83 tokens per session scan C 1c6ac5f63950
systematic-debugging is a skill published in the GitHub repository magnus919/agent-skills (66 stars, last pushed 2d ago), licensed MIT. It adds 83 tokens to every session and 3,899 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it C with 1 finding (recursive force delete). It is 94% identical to systematic-debugging, differing in 29 lines, and is treated as a copy.
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