Debug (reproduce -> isolate -> fix)

A step-by-step workflow for reproducing a software bug, finding its root cause, applying a focused fix, and testing the result.

In plain words
What is it for?
Use it to create a minimal reproduction, narrow down the failure, confirm the cause, make the smallest fix, and add a regression test.
Why use it?
It reduces guesswork and helps ensure the fix addresses the actual cause rather than only hiding the symptoms.

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/auravixstudio/caelo/debug
Any agent
npx skills add AuraVixStudio/caelo --skill debug
Clone the repo
git clone --depth 1 https://github.com/AuraVixStudio/caelo

Made for: Claude Code, Codex.

Per session 20 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 250 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 $0.00020 $0.00250
Opus 5 $0.00010 $0.00125
Sonnet 5 $0.00004 $0.00050
Haiku 4.5 $0.00002 $0.00025

Measured 2d ago against content hash ea5bd4cdd404, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

Debug (reproduce -> isolate -> fix) 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.

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.

caelo_core/skills/builtin/debug/SKILL.md · 26 lines

What it actually says

Debug (reproduce -> isolate -> fix)

Use this to track down a bug methodically.

Steps

  1. Reproduce. Get a reliable, minimal repro. If you can't reproduce it, gather the exact error, stack trace, inputs, and environment first.
  2. Isolate. Narrow the failure: read the stack trace, add targeted logging, bisect the input or the recent changes. Form a hypothesis about the root cause.
  3. Confirm root cause. Verify the hypothesis — don't fix symptoms. State why it fails.
  4. Fix. Apply the smallest change that addresses the root cause. Avoid unrelated edits.
  5. Verify + guard. Re-run the repro to confirm the fix, run the broader tests for regressions, and add a test that would have caught this bug.

Notes

  • Resist guess-and-check. One confirmed root cause beats five speculative edits.
  • Remove temporary logging/instrumentation before finishing.
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 · 26 lines · 20 tokens per session scan A ea5bd4cdd404

Subscribe to this mod's changes

Debug (reproduce -> isolate -> fix) is a skill published in the GitHub repository AuraVixStudio/caelo (22 stars, last pushed 20d ago), licensed Apache-2.0. It adds 20 tokens to every session and 250 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 2026-08-30.