diagnose-loop

diagnose-loop is a skill for Claude Code, Codex from tmusser/ai-engineering-skills. It costs 8 tokens per session (240 once invoked), scanned A, original, MIT.

A systematic debugging workflow for command failures, incorrect behavior, test regressions, or output that differs from the specification.

In plain words
What is it for?
Use it to investigate a failure, apply a focused correction, add a regression check when possible, and rerun the original and relevant tests.
Why use it?
It prevents guesswork by requiring the failure to be reproduced, its cause to be identified, and the smallest fix to be verified.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to investigate a failure, apply a focused correction, add a regression check when possible, and rerun the original and relevant tests.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/tmusser/ai-engineering-skills/diagnose-loop
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.

Any agent
npx skills add tmusser/ai-engineering-skills --skill diagnose-loop
Clone the repo
git clone --depth 1 https://github.com/tmusser/ai-engineering-skills

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for diagnose-loop

README.md
[![agentmods](https://agentmods.dev/badge/skills/tmusser/ai-engineering-skills/diagnose-loop/github.svg)](https://agentmods.dev/skills/tmusser/ai-engineering-skills/diagnose-loop)
Your own site
<a href="https://agentmods.dev/skills/tmusser/ai-engineering-skills/diagnose-loop"><img src="https://agentmods.dev/badge/skills/tmusser/ai-engineering-skills/diagnose-loop/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.

agentmods 80×15 button for diagnose-loop

Your own site · 80×15
<a href="https://agentmods.dev/skills/tmusser/ai-engineering-skills/diagnose-loop"><img src="https://agentmods.dev/badge/skills/tmusser/ai-engineering-skills/diagnose-loop.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 8 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 240 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00008 $0.00240
Opus 5 $0.00004 $0.00120
Sonnet 5 $0.00002 $0.00048
Haiku 4.5 $0.00001 $0.00024

Measured 9d ago against content hash b25c65d3200d, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

diagnose-loop 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 9d 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.

skills/diagnose-loop/SKILL.md · 53 lines

What it actually says

Diagnose Loop

Purpose

Debug failures systematically.

When to use

Use when a command fails, behavior is wrong, a test regresses, or output does not match the spec.

Inputs

  • Failure report
  • Exact command or reproduction case
  • Recent changes
  • Logs, traces, or output

Workflow

  1. Freeze feature work.
  2. Reproduce the failure.
  3. Identify the exact failing command or case.
  4. List hypotheses.
  5. Instrument minimally.
  6. Apply the smallest fix.
  7. Add a regression check if possible.
  8. Rerun the original failing command.
  9. Rerun relevant verification.

Outputs

  • Root-cause note
  • Smallest fix
  • Regression check when possible
  • Rerun results

Stop conditions

  • The original failure is fixed and verified.
  • The failure cannot be reproduced.
  • The next step requires a product or data decision.

Anti-patterns

  • Randomly editing files before reproducing the bug.
  • Fixing symptoms without naming the failing case.
  • Adding noisy instrumentation and leaving it behind.
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. 9d ago First seen · 53 lines · 8 tokens per session scan A b25c65d3200d

Subscribe to this mod's changes

diagnose-loop is a skill published in the GitHub repository tmusser/ai-engineering-skills (4 stars, last pushed today), licensed MIT. It adds 8 tokens to every session and 240 once invoked, about $0.0000 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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