skill-reverse-engineering

A codebase analysis workflow that rebuilds architecture documentation when the existing documents are missing or out of date.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

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/matrixfounder/agentic-development/skill-reverse-engineering
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.

Per session 15 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 718 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. 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 $0.00015 $0.00718
Opus 5 $0.00008 $0.00359
Sonnet 5 $0.00003 $0.00144
Haiku 4.5 $0.00002 $0.00072

Measured yesterday against content hash f7c3d3f72e2b, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, 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 yesterday.

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 · 87 lines

How it starts

The opening of the file, as written. The whole thing — 87 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

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 · 87 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. yesterday 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 (5 stars, last pushed 19d ago), licensed Apache-2.0. It adds 15 tokens to every session and 718 once invoked, about $0.0001 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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