core-engineering marketplace

core-engineering marketplace is a plugin for Claude Code, Codex from JustineDevs/premortem. Its token cost is not measured, scanned A, original, Apache-2.0.

A software-design guide covering object-oriented programming ideas and rules for writing maintainable code, with TypeScript examples.

In plain words
What is it for?
Use it when planning classes, choosing between inheritance and composition, or reviewing code against principles such as SOLID, DRY, KISS, and YAGNI.
Why use it?
It helps explain common design choices and reduce repeated, tightly connected, or unnecessarily complex code.

Plugin 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.

Claude Code
/plugin marketplace add JustineDevs/premortem
agentmods
npx agentmods add plugins/justinedevs/premortem/marketplace
Clone the repo
git clone --depth 1 https://github.com/JustineDevs/premortem

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 core-engineering marketplace

README.md
[![agentmods](https://agentmods.dev/badge/plugins/justinedevs/premortem/marketplace.svg)](https://agentmods.dev/plugins/justinedevs/premortem/marketplace)
Your own site
<a href="https://agentmods.dev/plugins/justinedevs/premortem/marketplace"><img src="https://agentmods.dev/badge/plugins/justinedevs/premortem/marketplace.svg" alt="Measured on agentmods" height="20"></a>
Per session not measured What this adds to a session before it is invoked.
When invoked not measured Not applicable: nothing here is loaded into a session.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Security

Grade A, and why

core-engineering marketplace 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 4d 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.

.agents/skills/core-engineering/.claude-plugin/marketplace.json · 20 lines

What it actually says

{
  "name": "core-engineering",
  "owner": {
    "name": "JustineDevs",
    "email": "[email protected]"
  },
  "metadata": {
    "description": "OOP four pillars, SOLID, clean code (DRY, KISS, YAGNI, Law of Demeter), composition over inheritance, and relationship types (association, aggregation, composition) with example code for AI agents and developers.",
    "pluginRoot": "."
  },
  "plugins": [
    {
      "name": "core-engineering",
      "source": ".",
      "description": "Core Engineering skill: Object-Oriented Design (Abstraction, Encapsulation, Inheritance, Polymorphism), SOLID principles, composition over inheritance, DRY/KISS/YAGNI/LoD, and association vs aggregation vs composition. Each principle includes how it looks and TypeScript examples.",
      "category": "Software Design"
    }
  ]
}
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. 4d ago First seen · 20 lines scan A 350100b00a22

Subscribe to this mod's changes

core-engineering marketplace is a plugin published in the GitHub repository JustineDevs/premortem (2 stars, last pushed 1mo ago), licensed Apache-2.0. Its token cost is not measured: this kind of file is read by the harness, not the model. 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.