systematic-debugging

A guided method for investigating bugs, failed tests, unexpected behavior, and other technical problems before attempting a fix.

In plain words
What is it for?
Use it to trace symptoms to their root cause during debugging, test failures, build problems, performance issues, and integration problems.
Why use it?
It helps prevent random patches that hide the underlying cause or create additional bugs.

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/bh-rat/steer/systematic-debugging
Any agent
npx skills add bh-rat/steer --skill systematic-debugging
Clone the repo
git clone --depth 1 https://github.com/bh-rat/steer

Made for: Claude Code, Codex.

Per session 21 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,229 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 $0.00021 $0.02229
Opus 5 $0.00010 $0.01115
Sonnet 5 $0.00004 $0.00446
Haiku 4.5 $0.00002 $0.00223

Measured 2d ago against content hash cbf5c98aa2fd, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, 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 2d ago.

The scan reads SKILL.md. This mod also ships 3 executable files (references/condition-based-waiting-example.ts, scripts/find-polluter.sh, scripts/steer.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

examples/rebuilds/systematic-debugging/SKILL.md · 222 lines

How it starts

The opening of the file, as written. The whole thing — 222 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Systematic Debugging

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.

This skill bundles its own steer runtime at scripts/steer.py; the commands below invoke it with python3 and need nothing installed. Paths are relative to this skill's directory: when your working directory is elsewhere (it usually is), use the skill's full path (python3 <path-to-this-skill>/scripts/steer.py ...).

The Iron Law

NO FIXES WITHOUT ROOT CAUSE INVESTIGATION FIRST

In this skill the law is machine-enforced: the flow below keeps the fix step locked until the investigation artifacts actually exist. You cannot propose fixes in Phase 1 because the flow will not let you get there.

When to Use

Use for ANY technical issue: test failures, bugs in production, unexpected behavior, performance problems, build failures, integration issues.

Use this 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)
  • Manager wants it fixed NOW (systematic is faster than thrashing)

Process

The four phases are an enforced flow; steps verify themselves against artifacts in out/debug/, and you cannot skip ahead.

  1. Announce: "Working through the systematic-debugging flow."
  2. Run python3 scripts/steer.py flow status (in the workspace) to see the current phase.
  3. Do what the directive says, guided by the phase notes below.
  4. Run python3 scripts/steer.py flow next and repeat until all steps report complete.

Do NOT claim the bug is fixed while python3 scripts/steer.py flow status shows incomplete steps. The flow is defined in flow.toml.

Phase 1: Root Cause Investigation (step: investigate)

Read the full file on GitHub · 222 lines

Files

What ships with it

9 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.

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. 2d ago First seen · 222 lines · 21 tokens per session scan A cbf5c98aa2fd

Subscribe to this mod's changes

systematic-debugging is a skill published in the GitHub repository bh-rat/steer (7 stars, last pushed 1mo ago), licensed MIT. It adds 21 tokens to every session and 2,229 once invoked, about $0.0001 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 2026-08-31.

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