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Sepia

Sepia is an agent skill (a SKILL.md file) from Nanako0129/sepia. Make AI-generated writing read as human-written, in fiction and in professional prose. It works with Claude Code, Codex, Cursor, GitHub Copilot and OpenCode and has 3,482 GitHub stars across a repository of 2 listed skills.

github.com/Nanako0129/sepia/skills/sepia (opens in a new tab)

Data as of from the GitHub API; description from the skill's SKILL.md. Report an error

View on GitHub (opens in a new tab)

Add this skill

Claude

This repository is a Claude Code plugin marketplace. In Claude Code:

/plugin marketplace add Nanako0129/sepia
/plugin install sepia@sepia

In the Claude apps, zip the sepia folder and upload it under Customize > Skills > + > Upload a skill (code execution must be on).

ChatGPT / Codex

Codex reads skills from .agents/skills/ in a repo or ~/.agents/skills/ for every project:

git clone --depth 1 https://github.com/Nanako0129/sepia.git
cp -r sepia/skills/sepia .agents/skills/sepia   # repo; ~/.agents/skills for all projects

Standalone skills also load in the ChatGPT desktop app.

Cursor

Cursor loads skills from .cursor/skills/ (or ~/.cursor/skills/) and also reads .claude/skills/:

git clone --depth 1 https://github.com/Nanako0129/sepia.git
cp -r sepia/skills/sepia .cursor/skills/sepia   # project; ~/.cursor/skills for all projects

Source (checked Oct 7, 2026): code.claude.com/docs/en/skills (opens in a new tab), code.claude.com/docs/en/plugin-marketplaces (opens in a new tab), support.claude.com/en/articles/12512180-using-skills-in-claude (opens in a new tab), learn.chatgpt.com/docs/build-skills (opens in a new tab), cursor.com/docs/context/skills (opens in a new tab)

What this skill does

Make AI-generated writing read as human-written, in fiction and in professional prose. Repairs the narrative architecture of fiction and stories (based on StoryScope, arXiv:2604.03136); routes professional text through domain rules for release notes, announcements, PR and issue replies, code-review comments, incident postmortems, tickets, work orders, technical articles, blog posts, and long-form journalism.

When it triggers

  • Use when asked to humanize, de-AI, unslop, or strip AI flavor from any text; when writing or revising any of these document types; or whenever output must not read as machine-written.

More skills in Nanako0129/sepia

2 skills are listed from this repository.

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All Docs & writing

FAQ

Sepia FAQ

Still curious? Email info@appsgit.com.

How do I install the Sepia skill?

In Claude Code, run /plugin marketplace add Nanako0129/sepia and then /plugin install sepia@sepia. For Codex or Cursor, copy the sepia folder into .agents/skills/ or .cursor/skills/.

Is the Sepia skill free?

Yes. The repository is open source under the MIT license.

Is Sepia maintained?

The repository's most recent commit was on Oct 15, 2026. Its latest release is v0.12.4. appsgit only lists skills from repositories with a commit in the last six months.