voice-extractor

voice-extractor is a skill for Claude Code from elvisun/newsjack. It costs 90 tokens per session (8,270 once invoked), scanned A, original, MIT.

A local tool that measures a person's writing habits from previous samples and stores them as a voice profile. The profile can then be checked against new drafts for measurable differences.

In plain words
What is it for?
Use it to create a local writing profile from five to twenty samples and check whether later newsjack drafts stay within that profile's rules.
Why use it?
It replaces vague instructions like “sound like me” with specific checks for sentence length, word choices, punctuation, and writing style.

Skill for Claude Code

Written for Claude Code: when-to-use in frontmatter. Also seen: positional $N argument.

not rated 666repo +2 7d ago A scan Socket: passSnyk: passSkillSpector: warn 90 tokens original MIT

Good fit Use it to create a local writing profile from five to twenty samples and check whether later newsjack drafts stay within that profile's rules.

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Install with agentmods
npx agentmods add skills/elvisun/newsjack/voice-extractor
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 elvisun/newsjack --skill voice-extractor
Clone the repo
git clone --depth 1 https://github.com/elvisun/newsjack

Made for: Claude Code.

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 voice-extractor

README.md
[![agentmods](https://agentmods.dev/badge/skills/elvisun/newsjack/voice-extractor/github.svg)](https://agentmods.dev/skills/elvisun/newsjack/voice-extractor)
Your own site
<a href="https://agentmods.dev/skills/elvisun/newsjack/voice-extractor"><img src="https://agentmods.dev/badge/skills/elvisun/newsjack/voice-extractor/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 voice-extractor

Your own site · 80×15
<a href="https://agentmods.dev/skills/elvisun/newsjack/voice-extractor"><img src="https://agentmods.dev/badge/skills/elvisun/newsjack/voice-extractor.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 90 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 8,270 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
  • Socket pass 13 Jun 2026
  • Snyk pass 13 Jun 2026
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 4 findings, up to high

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • high System Prompt Leakage · line 333
    Skill contains instructions that could directly expose system prompts, internal rules, or hidden instructions to users or external parties.
    Fix: Remove any instructions that reveal, print, or output system prompts or internal rules. System instructions should never be exposed to end users.
  • medium analysis-evasion · line 1
    Suspicious Unicode normalization or mixed-script content
    Fix: Review the flagged content for security risks. Ensure no credentials, secrets, or sensitive data are exposed.
  • medium Rogue Agent · line 111
    Skill establishes unauthorized persistence across sessions via cron jobs, startup scripts, or state files. Session persistence allows an attacker to maintain access beyond the current interaction.
    Fix: Remove any persistence mechanisms (cron jobs, startup scripts, state files). Skills should not maintain state across sessions without explicit user consent.
  • medium Rogue Agent · line 394
    Skill establishes unauthorized persistence across sessions via cron jobs, startup scripts, or state files. Session persistence allows an attacker to maintain access beyond the current interaction.
    Fix: Remove any persistence mechanisms (cron jobs, startup scripts, state files). Skills should not maintain state across sessions without explicit user consent.
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 $0.00090 $0.08270
Opus 5 $0.00045 $0.04135
Sonnet 5 $0.00018 $0.01654
Haiku 4.5 $0.00009 $0.00827

Measured 9d ago against content hash 6de023be622d, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

voice-extractor 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.

skills/voice-extractor/SKILL.md · 490 lines

How it starts

The opening of the file, as written. The whole thing — 490 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Voice Extractor

You are the Voice Extractor for newsjack.sh: the local voice fingerprint engine. Your job is to make copy written under the user's name sound like the user, not like a model trying to sound generally human.

You are mechanical, exacting, and suspicious of AI slop. You do not roast drafts. meanest-editor is the editorial judgment layer; you are the rule-matcher and fingerprint enforcer it can call.

The core move: a voice is a vector of measurable habits — how long sentences run and how much that varies, which function words recur, how punctuation falls, how sentences open, how casual or nominal the register is. Measure those at extraction, store each as a number with a tolerance band, then on every draft recompute the same numbers and fire a rule wherever the draft leaves the band. "Make it sound like me" becomes a set of deterministic, span-located, fixable gates.

Operating Doctrine

  • Local first. Fingerprints live at ~/.newsjack/voice/<profile_id>.yaml; active.yaml points to the active profile. Never store raw sample text inside voice.yaml.
  • Voice is a signature. Do not build a fingerprint of someone else from public writing unless the user is working with that person and has consent.
  • Capture the sender's voice, not a generic brand gloss. Pitches from "Sarah at Acme PR" should sound like Sarah, not Acme's marketing team.
  • Do not become a bot-detector evasion tool. The goal is to sound like this user specifically.
  • Respect register boundaries. Slack DMs, launch tweets, and earnings boilerplate are not automatically one voice.
  • Global anti-slop rules apply unless the user's real samples prove a word or structure belongs to them.

The Linguistic Lenses — how to measure a voice

These are the extraction engine. Each lens turns one observable in the corpus into a stored number (or set) plus the rule that fires when a draft drifts off it. Compute each lens from the samples, never from the user's job title or industry. The fingerprint is the union of these measurements; the check is recomputing them on a draft and diffing against the bands.

Read the full file on GitHub · 490 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. 9d ago First seen · 490 lines · 90 tokens per session scan A 6de023be622d

Subscribe to this mod's changes

voice-extractor is a skill published in the GitHub repository elvisun/newsjack (666 stars, last pushed 7d ago), licensed MIT. It adds 90 tokens to every session and 8,270 once invoked, about $0.0005 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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