reverse-document

reverse-document is a skill for Codex from frabcd/codex-ai-game-studio. It costs 24 tokens per session (2,191 once invoked), scanned A, a copy of reverse-document, MIT.

A process for creating design or architecture documents by studying an existing codebase, prototype, or system. It works backwards to explain what was built and why.

In plain words
What is it for?
Use it to create game design documents, architecture decision records, or concept documents from implementation.
Why use it?
It helps document inherited or undocumented work without requiring the original planning notes.

Skill for Codex

Written for Codex: agents/openai.yaml present. Also seen: mentions subagents; mentions Codex; $skill-name invocation.

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/frabcd/codex-ai-game-studio/reverse-document
Any agent
npx skills add frabcd/codex-ai-game-studio --skill reverse-document
Clone the repo
git clone --depth 1 https://github.com/frabcd/codex-ai-game-studio

Made for: 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 reverse-document

README.md
[![agentmods](https://agentmods.dev/badge/skills/frabcd/codex-ai-game-studio/reverse-document.svg)](https://agentmods.dev/skills/frabcd/codex-ai-game-studio/reverse-document)
Your own site
<a href="https://agentmods.dev/skills/frabcd/codex-ai-game-studio/reverse-document"><img src="https://agentmods.dev/badge/skills/frabcd/codex-ai-game-studio/reverse-document.svg" alt="Measured on agentmods" height="20"></a>
Per session 24 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,191 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 83% copy Near-identical to another mod 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 $0.00024 $0.02191
Opus 5 $0.00012 $0.01095
Sonnet 5 $0.00005 $0.00438
Haiku 4.5 $0.00002 $0.00219

Measured 2d ago against content hash 4cf418afe6e0, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

reverse-document 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 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.

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.

Origin

This is a copy

83% identical to reverse-document — 25 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

plugins/ai-game-studio/skills/reverse-document/SKILL.md · 265 lines

How it starts

The opening of the file, as written. The whole thing — 265 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Port provenance: adapted from the pinned upstream source at 984023ddac0d5e27624f2baacde6105e45de375f under MIT; see the repository parity ledger for the exact path and blob.

Reverse Documentation

This skill analyzes existing implementation (code, prototypes, systems) and generates appropriate design or architecture documentation. Use this when:

  • You built a feature without writing a design doc first
  • You inherited a codebase without documentation
  • You prototyped a mechanic and need to formalize it
  • You need to document "why" behind existing code

Workflow

Phase 1: Parse Arguments

Format: $ai-game-studio:reverse-document <type> <path>

Type options:

  • design → Generate a game design document (GDD section)
  • architecture → Generate an Architecture Decision Record (ADR)
  • concept → Generate a concept document from prototype

Path: Directory or file to analyze

  • src/gameplay/combat/ → All combat-related code
  • src/core/event-system.cpp → Specific file
  • prototypes/stealth-mech/ → Prototype directory

Examples:

$ai-game-studio:reverse-document design src/gameplay/magic-system
$ai-game-studio:reverse-document architecture src/core/entity-component
$ai-game-studio:reverse-document concept prototypes/vehicle-combat

Phase 2: Analyze Implementation

Read and understand the code/prototype:

For design docs (GDD):

  • Identify mechanics, rules, formulas
  • Extract gameplay values (damage, cooldowns, ranges)
  • Find state machines, ability systems, progression
  • Detect edge cases handled in code
  • Map dependencies (what systems interact?)

For architecture docs (ADR):

  • Identify patterns (ECS, singleton, observer, etc.)
  • Understand technical decisions (threading, serialization, etc.)
  • Map dependencies and coupling
  • Assess performance characteristics
  • Find constraints and trade-offs

For concept docs (prototype analysis):

  • Identify core mechanic
  • Extract emergent gameplay patterns
  • Note what worked vs what didn't
  • Find technical feasibility insights
  • Document player fantasy / feel

Read the full file on GitHub · 265 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 · 265 lines · 24 tokens per session scan A 4cf418afe6e0

Subscribe to this mod's changes

reverse-document is a skill published in the GitHub repository frabcd/codex-ai-game-studio (9 stars, last pushed 5d ago), licensed MIT. It adds 24 tokens to every session and 2,191 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. It is 83% identical to reverse-document, differing in 25 lines, and is treated as a copy.

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