4c-bugfix

v0.3.0

A disciplined, four-gate bug-fixing methodology for coding agents: Concern (failing repro) -> Cause (root cause + siblings) -> Countermeasure (fix the architecture) -> Check (red-then-green proof + hardening). Reproduce-first, regression-proof, blast-radius-free fixes.

Claude Code6 Skills

By Clock LobsterLicense: MIT0 GitHub starsUpdated 3 days ago

Directory evidence

Runtimes: Claude Code
Parsed components: 6 skill or MCP entries
Source updated: Sep 20, 2026
Manifest status: Canonical path parsed

The directory validates manifest shape and source location. It does not execute the plugin or provide a security endorsement. Review the indexing methodology →

Install 4c-bugfix for Claude Code

Installs for the current user

claude plugin marketplace add IchenDEV/agent-plugin-mkt
claude plugin marketplace update agent-plugin-marketplace
claude plugin install 4c-bugfix@agent-plugin-marketplace

Paste and run these commands in a terminal with Claude Code. They add and refresh the PluginsMP catalog, then install this plugin.

The installer fetches third-party code from the source repository shown on this page. This directory validates manifest structure and source location, but does not perform a security audit; review the manifest, components, and source before installing.

Get the source manually

$ git clone https://github.com/victorsalmon/agentic-bugfix-plugin

Clone the source repository, then follow its setup instructions to add the plugin to a compatible client. The repository root is the plugin root.

Plugin files

4c-bugfix/

├── .claude-plugin/plugin.json
├── skills/4c-bugfix/SKILL.md
├── skills/4c-cause/SKILL.md
├── skills/4c-check/SKILL.md
├── skills/4c-concern/SKILL.md
├── skills/4c-countermeasure/SKILL.md
└── skills/agentic-4c-bugfix/SKILL.md

Included Skills6

4c-bugfixskills/4c-bugfix/SKILL.md

Run a rigorous Concern-Cause-Countermeasure-Check bug fix with a committed failing reproduction, root-cause and sibling analysis, an architectural repair, property/invariant testing, changed-code mutation testing, and full regression proof. Use for non-trivial bugs, regressions, incorrect results, or data-handling defects.

4c-causeskills/4c-cause/SKILL.md

Find the root cause of a bug with 5-Whys and a codebase-wide anti-pattern search, and record it in the 4C dossier. Use after `4c-concern` has produced a committed failing test. Never start fixing until Cause is documented.

4c-checkskills/4c-check/SKILL.md

Verify a 4C bug fix, harden against the bug class, and prove a green regression-suite run. Use after `4c-countermeasure`. Produces the proof (red-then-green, full suite, blast-radius) that the fix is regression-proof.

4c-concernskills/4c-concern/SKILL.md

Red gate of the 4C pattern — pin the failure by writing and committing a failing reproduction test before any application source is modified. Use when starting any non-trivial bug fix, when the reproduction is unclear, or as the first gate of 4c-bugfix. Never skip this gate; a fix without a red repro is not a 4C fix.

4c-countermeasureskills/4c-countermeasure/SKILL.md

Implement the architectural fix for a bug and repair every in-scope sibling occurrence identified by 4c-cause. Use after `4c-cause` has documented the root cause. Fix the cause, never the symptom.

agentic-4c-bugfixskills/agentic-4c-bugfix/SKILL.md

Orchestrate a disciplined 4C (Concern-Cause-Countermeasure-Check) bug fix that is reproduced, root-caused, blast-radius-free, and regression-tested. Use when the user reports a bug, says "fix this", "why is X broken", "this used to work", "there's a regression", or wants a structured regression-proof repair. Also use for any non-trivial defect where a guess-and-patch fix is not acceptable.

Plugin manifests1

.claude-plugin/plugin.json

{
  "$schema": "https://anthropic.com/claude-code/plugin.schema.json",
  "name": "4c-bugfix",
  "version": "0.3.0",
  "description": "A disciplined, four-gate bug-fixing methodology for coding agents: Concern (failing repro) -> Cause (root cause + siblings) -> Countermeasure (fix the architecture) -> Check (red-then-green proof + hardening). Reproduce-first, regression-proof, blast-radius-free fixes.",
  "author": {
    "name": "Clock Lobster",
    "url": "https://github.com/victorsalmon/agentic-bugfix-plugin"
  },
  "homepage": "https://github.com/victorsalmon/agentic-bugfix-plugin",
  "repository": "https://github.com/victorsalmon/agentic-bugfix-plugin.git",
  "license": "MIT",
  "keywords": [
    "bugfix",
    "testing",
    "quality",
    "regression",
    "root-cause",
    "methodology",
    "4c",
    "concern-cause-countermeasure-check",
    "agent-skills"
  ],
  "category": "quality",
  "skills": "skills"
}

For maintainers

If you maintain this plugin, link to this source-backed listing from your README so users can review its manifest and indexed components.

[4c-bugfix on Agent Plugins Marketplace](https://pluginsmp.com/plugins/4c-bugfix)