bugfix

A structured investigation process for fixing bugs by tracing data across the relevant services and layers before changing code. It adapts its investigation to single-layer, multi-service, or intermittent bugs.

In plain words
What is it for?
Use it to investigate and fix reported bugs, including errors crossing service boundaries, bugs that appear only after deployment, and intermittent issues.
Why use it?
It reduces repeated fixes that reveal new problems elsewhere. Mapping the full data flow helps identify which layer actually owns the defect.

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/jotjunior/cstk/bugfix
Any agent
npx skills add JotJunior/cstk --skill bugfix
Clone the repo
git clone --depth 1 https://github.com/JotJunior/cstk

Made for: Claude Code, Codex.

Per session 54 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,553 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 1 finding. 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 $0.00054 $0.02553
Opus 5 $0.00027 $0.01277
Sonnet 5 $0.00011 $0.00511
Haiku 4.5 $0.00005 $0.00255

Measured 2d ago against content hash 34c0b46fa0fa, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade C, and why

bugfix scanned grade C with 1 finding 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.

Recursive force deletehighDestructive command

rm -rf with a variable or a broad path is one typo away from removing the wrong tree.

# Node: rm -rf node_modules/.cache && npm run build
plugins/cstk/skills/bugfix/SKILL.md · 263 lines

How it starts

The opening of the file, as written. The whole thing — 263 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Bug Fix Skill

Structured bug fix protocol designed to eliminate cascading fix-reveal-fix cycles by mapping the full data flow before touching any layer. Stack-agnostic — adapt the commands and layer names to the project you are working in.

Arguments

$ARGUMENTS should describe the bug: error message, observed behavior, expected behavior, or path to a screenshot.

Step 0: Determine Complexity

Assess bug scope before starting:

Complexity Signals Approach
Single-layer Error in one file, one service Sequential trace (Steps 1-8)
Multi-service DTOs, enums, or events cross service boundaries Parallel agent investigation (Step 3b)
Ghost bug "Works on my machine", intermittent, post-deploy Stale artifact focus (Step 2)

For multi-service bugs, create tasks to track progress across services.

Step 1: Understand the Bug

  1. Read the error message or user description carefully
  2. Identify which service/layer reported the error
  3. If a screenshot was provided, analyze it
  4. Ask which layer owns the responsibility before assuming where the fix goes
  5. For frontend-reported bugs: verify whether the fix should be backend-side first — the most common wrong initial approach is fixing the frontend when the backend is the root cause

Step 2: Check for Stale Artifacts

Before any debugging, eliminate ghost bugs. Use the commands appropriate to the project stack — the pattern is "force rebuild + verify source matches running":

# Force rebuild (stack-specific)
# Examples:
#   Go:         go build ./...
#   Node:       rm -rf node_modules/.cache && npm run build
#   Rust:       cargo clean && cargo build
#   Java/JVM:   mvn clean compile
#   Python:     rm -rf __pycache__ dist build *.egg-info

# Verify dependencies haven't drifted
# Examples: go mod verify, npm ls, pip freeze, cargo tree

# Always check git state regardless of stack
git status --short
git log --oneline -3

# For production bugs, confirm deployed commit matches source

Read the full file on GitHub · 263 lines

Files

What ships with it

1 file 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. 2d ago First seen · 263 lines · 54 tokens per session scan C 34c0b46fa0fa

Subscribe to this mod's changes

bugfix is a skill published in the GitHub repository JotJunior/cstk (22 stars, last pushed 3d ago), licensed MIT. It adds 54 tokens to every session and 2,553 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it C with 1 finding (recursive force delete). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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