app-bug-forensics

app-bug-forensics is a skill for Codex from sidiangongyuan/codex-skills-library. It costs 51 tokens per session (893 once invoked), scanned A, original, MIT.

A method for investigating application bugs from the reported symptom to the actual failing component before changing code. It uses the screen, action sequence, logs, background work, storage, and external services as evidence.

In plain words
What is it for?
Use it to diagnose or fix user-reported bugs, intermittent failures, confusing behavior, screenshots, logs, background tasks, integrations, or desktop app lifecycle problems.
Why use it?
It avoids treating the visible error message as the root cause and helps distinguish stale requests, provider failures, process mismatches, and missing capabilities.

Skill for Codex

Written for Codex: agents/openai.yaml present.

Good fit Use it to diagnose or fix user-reported bugs, intermittent failures, confusing behavior, screenshots, logs, background tasks, integrations, or desktop app lifecycle problems.

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Install with agentmods
npx agentmods add skills/sidiangongyuan/codex-skills-library/app-bug-forensics
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 sidiangongyuan/codex-skills-library --skill app-bug-forensics
Clone the repo
git clone --depth 1 https://github.com/sidiangongyuan/codex-skills-library

Made for: 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 app-bug-forensics

README.md
[![agentmods](https://agentmods.dev/badge/skills/sidiangongyuan/codex-skills-library/app-bug-forensics/github.svg)](https://agentmods.dev/skills/sidiangongyuan/codex-skills-library/app-bug-forensics)
Your own site
<a href="https://agentmods.dev/skills/sidiangongyuan/codex-skills-library/app-bug-forensics"><img src="https://agentmods.dev/badge/skills/sidiangongyuan/codex-skills-library/app-bug-forensics/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 app-bug-forensics

Your own site · 80×15
<a href="https://agentmods.dev/skills/sidiangongyuan/codex-skills-library/app-bug-forensics"><img src="https://agentmods.dev/badge/skills/sidiangongyuan/codex-skills-library/app-bug-forensics.svg" alt="Reviewed on agentmods" width="80" 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 893 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 $0.00051 $0.00893
Opus 5 $0.00026 $0.00447
Sonnet 5 $0.00010 $0.00179
Haiku 4.5 $0.00005 $0.00089

Measured 9d ago against content hash a7dcf71b5b0e, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

app-bug-forensics 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/app-bug-forensics/SKILL.md · 91 lines

How it starts

The opening of the file, as written. The whole thing — 91 lines — stays where its author put it; the contents beside it link to each section on GitHub.

App Bug Forensics

Use this skill when a user reports a bug, screenshot, intermittent failure, or confusing app behavior. The goal is root cause first, patch second.

Workflow

  1. Preserve the symptom.

    • Identify the exact screen, action sequence, visible message, and affected data scope.
    • Inspect screenshots and logs when available.
    • Do not assume the visible error string names the real failing component.
  2. Trace the path.

    • Follow the request from UI event to state store, API client, backend route, persistence, sidecar/process boundary, and external provider when relevant.
    • Search for all places that can set the visible error state.
    • Check whether the failing request still belongs to the current selection.
    • For AI failures, identify the exact provider, model, transport, profile, credential source, timeout, and whether the request reached the provider.
  3. Classify likely root cause.

    • Stale async request or route watcher race.
    • Frontend/backend version mismatch or old sidecar process.
    • Missing optional capability being treated as fatal.
    • Provider protocol, model, key, base URL, or auth mismatch.
    • Default AI profile being added when the user selected another profile.
    • Long-running provider request blocked behind an unclosable dialog.
    • Provider request timed out locally after remote token usage already began.
    • Background job result, status, reconnect, or cancellation state was lost.
    • Saved credential/profile source disappeared or was overwritten by another profile.
    • Data migration/path/access issue.
    • UI overlay, selection, scrolling, or layout state bug.
    • Result view was hidden or discarded by navigation instead of explicit clearing.
    • Installer or process lifecycle half-update.
  4. Reproduce minimally.

    • Prefer a focused test or local run over broad speculation.
    • If the issue is intermittent, add timing, request tokens, or controlled mocked delays to reproduce the race.
    • If external provider behavior is suspected, separate mock branch tests from one real minimal connectivity test.
    • For charged or slow provider paths, do not auto-retry the full generation while investigating. Probe status and run only minimal real requests.

Read the full file on GitHub · 91 lines

Files

What ships with it

4 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. 9d ago First seen · 91 lines · 51 tokens per session scan A a7dcf71b5b0e

Subscribe to this mod's changes

app-bug-forensics is a skill published in the GitHub repository sidiangongyuan/codex-skills-library (8 stars, last pushed 4d ago), licensed MIT. It adds 51 tokens to every session and 893 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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