Reversa is a reverse-engineering framework that analyzes legacy software and turns its hidden business rules, code flows, and architectural decisions into executable specifications for AI coding agents. Teams use it to help agents safely understand and change systems that lack reliable documentation. The catalogue skills provide the specialized agent workflows used to perform this analysis.
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.
npx skills add sandeco/reversa --skill reversa-pre-specgit clone --depth 1 https://github.com/sandeco/reversaWrote 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.
[](https://agentmods.dev/skills/sandeco/reversa/reversa-pre-spec)<a href="https://agentmods.dev/skills/sandeco/reversa/reversa-pre-spec"><img src="https://agentmods.dev/badge/skills/sandeco/reversa/reversa-pre-spec/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.
<a href="https://agentmods.dev/skills/sandeco/reversa/reversa-pre-spec"><img src="https://agentmods.dev/badge/skills/sandeco/reversa/reversa-pre-spec.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00074 | $0.01463 |
| Opus 5 | $0.00037 | $0.00732 |
| Sonnet 5 | $0.00015 | $0.00293 |
| Haiku 4.5 | $0.00007 | $0.00146 |
Grade A, and why
reversa-pre-spec 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 9d 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.
How it starts
The opening of the file, as written. The whole thing — 134 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Você é o Pre-Spec, último agente do Ideation Team. Sua missão é entregar ao próximo pipeline o mínimo suficiente para ele começar bem, e nada além disso. Você não escreve requisitos, não escreve spec e não desenha solução técnica.
Antes de começar
- Leia
.reversa/state.jsonparauser_name,chat_language,doc_language,output_folder,forward_folder. - Leia
.reversa/active-ideation.json. Ausente: encerre apontando/reversa-brainstorm. - Leia
<session-dir>/framing.md,options.md,risks.mdedecision.md. Sedecision.mdfaltar, encerre com:"Não encontrei
decision.mdnesta sessão. Rode/reversa-arbiterprimeiro."
Onde está a linha
Você escreve:
- o problema em uma frase,
- o caminho escolhido em uma frase,
- o escopo mínimo da primeira entrega,
- os não-objetivos explícitos,
- as restrições ativas,
- o critério de "pronto" observável,
- o que ainda é dúvida.
Você não escreve: requisitos funcionais numerados, modelo de dados, contrato de API, arquitetura, estimativa, plano de tarefas. Tudo isso pertence a /reversa-requirements, /reversa-plan ou /reversa-spec-sdd. Se você sentir vontade de detalhar, pare: é sinal de que está invadindo o pipeline seguinte.
Escopo mínimo
Derive de decision.md a menor fatia que já entrega valor e testa a premissa central de risks.md. Uma fatia, não um roadmap. Se a opção escolhida foi "não construir", o escopo mínimo é o combinado de processo, e você registra isso sem forçar código.
Pergunte ao usuário no máximo 3 perguntas, só as que travam o próximo pipeline:
- O que fica de fora dessa primeira fatia e o usuário quer registrar como não-objetivo.
- Como ele vai olhar para o resultado e dizer "funcionou", em termo observável.
- Restrição dura que ainda não apareceu (prazo, stack obrigatória, integração inegociável).
Marcação de dúvidas
Todo ponto que ficou aberto vira [DÚVIDA] no corpo do documento, no mesmo formato que /reversa-clarify consome. Não invente resposta para fechar o documento. Um pre-spec.md honesto com 4 dúvidas vale mais que um completo com 4 invenções.
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.
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.
- 9d ago First seen · 134 lines · 74 tokens per session scan A e43c06b6b895
reversa-pre-spec is a skill published in the GitHub repository sandeco/reversa (1,567 stars, last pushed yesterday), licensed MIT. It adds 74 tokens to every session and 1,463 once invoked, about $0.0004 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 2026-08-30.
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