skill-reverse-engineering

skill-reverse-engineering is a skill for Claude Code, Codex from MatrixFounder/Agentic-development. It costs 15 tokens per session (862 once invoked), scanned A, original, Apache-2.0.

A codebase analysis workflow that rebuilds architecture documentation when the existing documents are missing or out of date.

In plain words
What is it for?
It scans directories, samples representative files, summarizes components and dependencies, and prepares updates to ARCHITECTURE.md and KNOWN_ISSUES.
Why use it?
It helps reveal how a project is organized without reading every file, and shows where the code no longer matches the documentation.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions AGENTS.md.

Good fit It scans directories, samples representative files, summarizes components and dependencies, and prepares updates to ARCHITECTURE.md and KNOWN_ISSUES.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/matrixfounder/agentic-development/skill-reverse-engineering
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 MatrixFounder/Agentic-development --skill skill-reverse-engineering
Clone the repo
git clone --depth 1 https://github.com/MatrixFounder/Agentic-development

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 skill-reverse-engineering

README.md
[![agentmods](https://agentmods.dev/badge/skills/matrixfounder/agentic-development/skill-reverse-engineering/github.svg)](https://agentmods.dev/skills/matrixfounder/agentic-development/skill-reverse-engineering)
Your own site
<a href="https://agentmods.dev/skills/matrixfounder/agentic-development/skill-reverse-engineering"><img src="https://agentmods.dev/badge/skills/matrixfounder/agentic-development/skill-reverse-engineering/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 skill-reverse-engineering

Your own site · 80×15
<a href="https://agentmods.dev/skills/matrixfounder/agentic-development/skill-reverse-engineering"><img src="https://agentmods.dev/badge/skills/matrixfounder/agentic-development/skill-reverse-engineering.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 15 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 862 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 $0.00015 $0.00862
Opus 5.5 $0.00006 $0.00345
Sonnet 5.5 $0.00003 $0.00172
Haiku 4.5 $0.00002 $0.00086

Measured 13d ago against content hash ea77d977f79b, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

skill-reverse-engineering 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 13d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/scan_structure.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

.agent/skills/skill-reverse-engineering/SKILL.md · 96 lines

How it starts

The opening of the file, as written. The whole thing — 96 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Reverse Engineering Skill

Purpose

Recover the mental model of a project from its codebase when documentation is outdated or missing.

When to Use

  • Documentation-code mismatch detected
  • New team member onboarding
  • Post-"quick fix" cleanup

Strategy: Automated Scan + Iterative Analysis

Phase 1: Automated Directory Scan

Tool: scripts/scan_structure.py

Usage:

python3 .agent/skills/skill-reverse-engineering/scripts/scan_structure.py . --depth 2

Goal:

  • Get high-level overview of project structure.
  • Identify dominant languages and components.
  • Avoid context overflow by NOT reading all files.

Phase 2: Local Analysis (Per-Directory)

For each key component identified in Phase 1:

  1. List files.
  2. Sample 2-3 representative files (read content).
  3. Generate Local Summary:
    • Purpose
    • Key Classes
    • Dependencies

Phase 3: Global Synthesis

Combine local summaries to update docs/ARCHITECTURE.md:

  • Update Directory Structure
  • Update Component Map
  • Identify Architecture Drift (Code != Docs)

Output Artifacts

1. ARCHITECTURE.md Update

Generate diffs for:

  • Directory Structure
  • Component Map
  • Data Flow

Figures. Write the text of a section first. Then draw its figure from that text with mermaid-authoring-guidelines; load the skill before the first figure. Each element of the figure has a supporting line in that text. A relation found only in the code goes into the text first, or stays out of the figure. A figure in a section this update leaves unchanged stays as it is.

Why. The skill's fidelity step (Step 6) accepts a line of the document as support. A line of code is not one.

2. KNOWN_ISSUES.md Updates

Identify:

  • TODO/HACK comments indicating tech debt.
  • Discrepancies between implementation and docs.

Filing format (thin index). docs/KNOWN_ISSUES.md is a hand-maintained thin index, not a flat checklist — do NOT append - [ ] lines to it. The authoritative format contract lives in the known-issues-format skill (artifact-management, TIER 0, delegates to it) — follow it:

  1. If docs/KNOWN_ISSUES.md does not exist yet, materialize it from known-issues-format's assets/templates/known_issues_md_template.md first (create-if-absent).
  2. File each finding as its own docs/issues/<slug>.md (frontmatter + H1 + body) plus one index line under the matching ## <category> heading — edit both in lockstep.
  3. If a finding needs a category/prefix the project's ledger doesn't have yet, add a new prefix → category row to that ledger's Rules / Conventions table before filing.

Read the full file on GitHub · 96 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. 13d ago Changed · +9 lines ea77d977f79b
  2. 1mo ago First seen · 87 lines · 15 tokens per session scan A f7c3d3f72e2b

Subscribe to this mod's changes

skill-reverse-engineering is a skill published in the GitHub repository MatrixFounder/Agentic-development (6 stars, last pushed yesterday), licensed Apache-2.0. It adds 15 tokens to every session and 862 once invoked, about $0.0001 per session on Opus 5.5. 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.