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 skills add itseffi/agentic-os --skill systematic-debugginggit clone --depth 1 https://github.com/itseffi/agentic-osWrote 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/itseffi/agentic-os/systematic-debugging)<a href="https://agentmods.dev/skills/itseffi/agentic-os/systematic-debugging"><img src="https://agentmods.dev/badge/skills/itseffi/agentic-os/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.
<a href="https://agentmods.dev/skills/itseffi/agentic-os/systematic-debugging"><img src="https://agentmods.dev/badge/skills/itseffi/agentic-os/systematic-debugging.svg" alt="Reviewed on agentmods" width="80" 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 5.1 | $0.00025 | $0.00752 |
| Opus 5.5 | $0.00010 | $0.00301 |
| Sonnet 5.5 | $0.00005 | $0.00150 |
| Haiku 4.5 | $0.00003 | $0.00075 |
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 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.
How it starts
The opening of the file, as written. The whole thing — 116 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Systematic Debugging
Use when encountering any bug, test failure, or unexpected behavior, before proposing fixes.
The Iron Law
NO FIXES WITHOUT ROOT CAUSE INVESTIGATION FIRST
If you haven't completed Phase 1, you cannot propose fixes.
The Four Phases
Phase 1: Root Cause Investigation
BEFORE attempting ANY fix:
-
Read Error Messages Carefully
- Don't skip past errors or warnings
- Read stack traces completely
- Note line numbers, file paths, error codes
-
Reproduce Consistently
- Can you trigger it reliably?
- What are the exact steps?
- If not reproducible, gather more data
-
Check Recent Changes
- Git diff, recent commits
- New dependencies, config changes
- Environmental differences
-
Trace Data Flow
- Where does bad value originate?
- What called this with bad value?
- Keep tracing up until you find the source
Phase 2: Pattern Analysis
-
Find Working Examples
- Locate similar working code in same codebase
-
Compare Against References
- Read reference implementation completely
- Don't skim - read every line
-
Identify Differences
- What's different between working and broken?
- List every difference, however small
Phase 3: Hypothesis and Testing
-
Form Single Hypothesis
- State clearly: "I think X is the root cause because Y"
- Write it down
-
Test Minimally
- Make the SMALLEST possible change
- One variable at a time
-
Verify Before Continuing
- Did it work? Yes -> Phase 4
- Didn't work? Form NEW hypothesis
- DON'T add more fixes on top
Phase 4: Implementation
-
Create Failing Test Case
- Use the
tdd.mdskill
- Use the
-
Implement Single Fix
- ONE change at a time
- No "while I'm here" improvements
-
Verify Fix
- Test passes now?
- No other tests broken?
-
If 3+ Fixes Failed: Question Architecture
- Is this pattern fundamentally sound?
- Should we refactor vs continue fixing symptoms?
- Discuss before attempting more fixes
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.
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.
- 1mo ago First seen · 116 lines · 25 tokens per session scan A 80f8f02bc830
systematic-debugging is a skill published in the GitHub repository itseffi/agentic-os (117 stars, last pushed 14d ago), licensed MIT. It adds 25 tokens to every session and 752 once invoked, about $0.0001 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 2026-08-30.
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