fp-debug

fp-debug is a skill for Claude Code, Codex from MiaoY0uShan/FP. It costs 51 tokens per session (344 once invoked), scanned A, original, MIT.

A structured method for diagnosing an unknown software failure before changing code. It uses evidence, competing explanations, and small tests to narrow down the cause.

In plain words
What is it for?
Use it for bug investigations, incident diagnosis, unclear error reports, and active failures where the immediate steps are observe, contain, and restore.
Why use it?
It prevents speculative fixes and keeps debugging focused on proving what is wrong. It also defines what to do when repeated tests fail to narrow the problem.

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/miaoy0ushan/fp/debug-incident
Any agent
npx skills add MiaoY0uShan/FP --skill debug-incident
Clone the repo
git clone --depth 1 https://github.com/MiaoY0uShan/FP

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 fp-debug

README.md
[![agentmods](https://agentmods.dev/badge/skills/miaoy0ushan/fp/debug-incident.svg)](https://agentmods.dev/skills/miaoy0ushan/fp/debug-incident)
Your own site
<a href="https://agentmods.dev/skills/miaoy0ushan/fp/debug-incident"><img src="https://agentmods.dev/badge/skills/miaoy0ushan/fp/debug-incident.svg" alt="Measured on agentmods" height="20"></a>
Per session 51 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 344 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 $0.00051 $0.00344
Opus 5 $0.00026 $0.00172
Sonnet 5 $0.00010 $0.00069
Haiku 4.5 $0.00005 $0.00034

Measured 5d ago against content hash 12f96ad1b8fe, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

fp-debug 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 5d 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.

fp/skills/debug-incident/SKILL.md · 29 lines

What it actually says

FP Debug-First Diagnosis

Load ../templates/debug-incident-checklist.md for the full checklist.

Route

pin symptom → read-only baseline → falsifiable hypothesis
→ cheapest discriminating probe → decision → authorized fix
→ original reproduction + regression + negative control

Rules

  1. Read-only until a cause is supported and user authorizes a fix.
  2. Keep at most two active hypotheses; run one discriminating probe at a time.
  3. Speculative patches are never probes.
  4. Three consecutive non-narrowing probes → architecture/observability checkpoint.
  5. After hypothesis is supported, extra probes must change a named decision or fill a named acceptance row. Otherwise stop and reuse evidence.
  6. Structural methods at the three-non-narrowing-probe checkpoint, concretely: (a) git axis + deterministic reproduction → git bisect run <repro> and log the commit range in the experiment ledger; (b) oversized reproduction (>~50 lines/files) → reduce with binary-partition delta debugging (ddmin) before probing further; (c) flaky or semantic failure → no bisect auto-mode; review each candidate commit before the good/bad call.

Active incident variant: OBSERVE → CONTAIN → RESTORE → REPAIR → LEARN Preserve evidence, access, and rollback. Restore service before permanent repair.

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. 5d ago First seen · 29 lines · 51 tokens per session scan A 12f96ad1b8fe

Subscribe to this mod's changes

fp-debug is a skill published in the GitHub repository MiaoY0uShan/FP (3 stars, last pushed 29d ago), licensed MIT. It adds 51 tokens to every session and 344 once invoked, about $0.0003 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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