codexspec:reverse-spec

codexspec:reverse-spec is a skill for Claude Code, Codex from Zts0hg/codexspec. It costs 29 tokens per session (8,299 once invoked), scanned A, original, MIT.

A reverse-specification skill that reads a project's configuration and derives software specifications from existing code. It also controls the language used in conversations and generated documents.

In plain words
What is it for?
It is for inspecting a codebase, producing a reverse-engineered specification or design, and preparing a reconciliation report against a baseline.
Why use it?
It helps document what an existing codebase does and keeps communication and specification files in the configured languages.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: installed under .agents/ (shared by several agents).

Good fit It is for inspecting a codebase, producing a reverse-engineered specification or design, and preparing a reconciliation report against a baseline.

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Install with agentmods
npx agentmods add skills/zts0hg/codexspec/codexspec-reverse-spec
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 Zts0hg/codexspec --skill codexspec-reverse-spec
Clone the repo
git clone --depth 1 https://github.com/Zts0hg/codexspec

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 codexspec:reverse-spec

README.md
[![agentmods](https://agentmods.dev/badge/skills/zts0hg/codexspec/codexspec-reverse-spec/github.svg)](https://agentmods.dev/skills/zts0hg/codexspec/codexspec-reverse-spec)
Your own site
<a href="https://agentmods.dev/skills/zts0hg/codexspec/codexspec-reverse-spec"><img src="https://agentmods.dev/badge/skills/zts0hg/codexspec/codexspec-reverse-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.

agentmods 80×15 button for codexspec:reverse-spec

Your own site · 80×15
<a href="https://agentmods.dev/skills/zts0hg/codexspec/codexspec-reverse-spec"><img src="https://agentmods.dev/badge/skills/zts0hg/codexspec/codexspec-reverse-spec.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 29 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 8,299 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. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 $0.00029 $0.08299
Opus 5 $0.00015 $0.04150
Sonnet 5 $0.00006 $0.01660
Haiku 4.5 $0.00003 $0.00830

Measured today against content hash 5feb2bff1b0a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

codexspec:reverse-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 today.

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/codexspec-reverse-spec/SKILL.md · 600 lines

How it starts

The opening of the file, as written. The whole thing — 600 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Reverse Specification

Language Preference

Read .codexspec/config.yml. Two independent language controls apply (each falls back to language.output, then English):

  • Interaction language (language.interaction): language for all conversation with the user — questions, explanations, status messages, and codexspec CLI terminal output.
  • Document language (language.document): language for generated artifact files (the reverse-derived spec/design and the reconcile report).

Converse in the interaction language and author artifacts in the document language. Apply the project's translation standard to both: translate by meaning (not word-for-word), keep English for terms with no good native equivalent, and write as if originally in that language. Exception: in reconcile.md, location and evidence quote the code and the baseline verbatim — path, line, and the quoted spans on both sides — and MUST NOT be translated. A translated quote can no longer be checked against its source, which is exactly what the both-side evidence rule exists to make possible. Verbatim does not mean secret-bearing: apply the global sensitive-value redaction rule under Instruction and Evidence Trust before persisting or briefing any observation.

Expression Standard

IMPORTANT: Everything this command produces — documents, reviews, reports, commit messages, diagnostics, and replies — is written for a reader who cannot see your working context. Apply the rules below to every artifact and message you output:

  • Write for the reader at hand-off. Every reference must resolve without access to this session: no session-only identifiers or section numbers, no narration of what changed during the conversation, no arguments with absent reviewers. State current reality and cite committed, reachable sources.
  • Preserve every proposition. Before summarizing or trimming, list the facts a passage carries: actors, conditions, ordering, modalities (must, never), negative guarantees, and consequences. Remove only reasoning transcripts, repetition, and decoration. Shorter is not clearer if any fact is lost.
  • State what the surface requires. Diagnostics name what failed, which rule was violated, and the correction. Problem reports carry the defect, its location, its impact, and the evidence. Decisions record the alternatives they beat. Rejections give the reason in one line. Shipped work is described in the present tense; plans and open questions are labeled as such.
  • Define terms before relying on them. Prefer the concrete rule, field, or behavior over a coined label; give a project-specific term a plain-language definition at first use, then use it consistently.
  • Be honest, not agreeable. Verify claims before accepting them; fix or rebut on technical grounds. One substantiated blocker is worth more than a list of nitpicks. When a decision is needed, present only viable options, recommend one, and state the real difference between them.
  • Declare what is binding. Say explicitly which instructions are hard requirements and where judgment is required. Keep one explanation in one place and link to it, but keep at the point of use the contract a reader needs there.

Read the full file on GitHub · 600 lines

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. today Changed · +11 lines 5feb2bff1b0a
  2. 5d ago First seen · 589 lines · 29 tokens per session scan A 4216ae2e87b6

Subscribe to this mod's changes

codexspec:reverse-spec is a skill published in the GitHub repository Zts0hg/codexspec (5 stars, last pushed yesterday), licensed MIT. It adds 29 tokens to every session and 8,299 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 2026-09-03.

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