backend-bugfix

backend-bugfix is a skill for Claude Code from penkzhou/swiss-army-knife-plugin. It costs 88 tokens per session (2,240 once invoked), scanned A, original, no licence file.

A workflow for diagnosing backend problems in Python applications, especially projects using pytest, FastAPI, and SQLAlchemy. Backend code runs on a server, while pytest is used to test Python code.

In plain words
What is it for?
Use it to debug pytest failures, analyze Python errors, and fix FastAPI, SQLAlchemy, IntegrityError, or ValidationError problems.
Why use it?
It helps narrow test failures and common database or validation errors to their underlying cause instead of treating every failure the same way.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the swiss-army-knife plugin — 11 skills, 9 commands, 2 hooks shipped together

Good fit Use it to debug pytest failures, analyze Python errors, and fix FastAPI, SQLAlchemy, IntegrityError, or ValidationError problems.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/penkzhou/swiss-army-knife-plugin/backend-bugfix
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 penkzhou/swiss-army-knife-plugin --skill backend-bugfix
Clone the repo
git clone --depth 1 https://github.com/penkzhou/swiss-army-knife-plugin

Made for: Claude Code.

Or install swiss-army-knife, the plugin that ships this one along with the rest of its 11 skills, 9 commands, 2 hooks.

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 backend-bugfix

README.md
[![agentmods](https://agentmods.dev/badge/skills/penkzhou/swiss-army-knife-plugin/backend-bugfix/github.svg)](https://agentmods.dev/skills/penkzhou/swiss-army-knife-plugin/backend-bugfix)
Your own site
<a href="https://agentmods.dev/skills/penkzhou/swiss-army-knife-plugin/backend-bugfix"><img src="https://agentmods.dev/badge/skills/penkzhou/swiss-army-knife-plugin/backend-bugfix/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 backend-bugfix

Your own site · 80×15
<a href="https://agentmods.dev/skills/penkzhou/swiss-army-knife-plugin/backend-bugfix"><img src="https://agentmods.dev/badge/skills/penkzhou/swiss-army-knife-plugin/backend-bugfix.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 88 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,240 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 unknown 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 $0.00088 $0.02240
Opus 5 $0.00044 $0.01120
Sonnet 5 $0.00018 $0.00448
Haiku 4.5 $0.00009 $0.00224

Measured 9d ago against content hash e3d8ae84942f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

backend-bugfix 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.

swiss-army-knife/skills/backend-bugfix/SKILL.md · 352 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

Read it on GitHub

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 · 352 lines · 88 tokens per session scan A e3d8ae84942f

Subscribe to this mod's changes

backend-bugfix is a skill published in the GitHub repository penkzhou/swiss-army-knife-plugin (2 stars, last pushed 9mo ago), with no licence file. It adds 88 tokens to every session and 2,240 once invoked, about $0.0004 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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