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v0.12.3

sepia

@nanako0129⭐ 3.1k stars

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. Four operations - write, review (diagnose AI tells without editing), refactor (minimal in-place edits), recreate (full rewrite). 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.

Choose how to use this skill

You do not need every option. Choose the path your AI client supports. The stable page stays the same; versioned files are immutable.

1. Native installer

This listing has no registered native installer command. Use the complete package or source fallback below, depending on what your client supports.

Do not guess an installer command or replace an existing version without reviewing the diff.

2. Complete package recommended

Download the ZIP when available. It includes SKILL.md plus the references, security notes and version metadata.

No complete ProSkills package is published for this listing yet.

3. Prompt-only

Copy the prompt above when the agent can read the stable page or when you want to adopt the workflow without installing a skill.

Need only the instruction file?

Download SKILL.md only if your client requires a single file. The complete ZIP is safer for a full installation because it preserves the references and release context.

No path installs or executes anything by itself. Your agent still needs access to the project files. Before updating, compare the installed version and review the diff.

—/10

// RATINGS

⭐GitHub Stars
⭐⭐⭐⭐⭐ 3.1k on GitHubGitHub ↗

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🟢ProSkills Score
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// README

sepia

English | 繁體中文 | 简体中文

behavioral eval version consistency release license: MIT

De-AI writing at the layer that actually gives AI away. Fiction gets its narrative architecture repaired before anyone touches word choice; professional documents (release notes, PR replies, postmortems, tickets, technical articles) each get rules matched to their venue.

A portable Agent Skill: any agent that speaks the standard can load it, and the Skills CLI, which supports 77+ agents, installs it with one command. Claude Code, Codex, Grok Build, Antigravity, and QwenPaw additionally get native plugin packaging. One canonical SKILL.md, no per-platform forks. Four operations: write, review (diagnose only), refactor (minimal edits), recreate (full rewrite).

Table of Contents


Why another humanizer

Every popular humanizer edits word choice and syntax. StoryScope (Russell et al., 2026: 61,608 stories, human + 5 frontier LLMs) showed that a classifier using narrative-structure features alone detects AI fiction at 93.2% macro-F1. In the same study's LAMP-edited condition, where human editors had rewritten the surface style, detection dropped only from 95.5% to 93.9%. The tells that survive are architectural: themes explained by the narrator, single-track causally-tidy plots, emotions rendered only as bodily sensation, no real-world references, no reader, linear time, endings resolved by protagonist growth and acceptance.

sepia turns those measured gaps, together with the related studies digested in research/, into a three-pass writing and revision protocol for fiction:

PassLayerExamples
1Narrative architecture (fiction)stop explaining the theme, loosen the causal chain, back-load revelations, mix emotion modes, sparse character networks, name real things
2Discourse flowde-template the paragraph-question sequence, fix the mid-story sag, vary rhythm and positions
3Surface stylethe classic layer: clichés, syntax templates, vocabulary, register

A 30-feature diagnosis rubric and per-model fingerprints across two layers apply when the writing or executing model is known:

Model familyNarrative layer (StoryScope)Sentence-level prose layer (Vendor prompting guides)
ClaudeMeasuredClaude Fable 5.1 and Mythos 5.1, Fable 5 and Mythos 5, Opus 5, Opus 4.8
GPTMeasuredGPT-5.6, GPT-6 Astra
GeminiMeasuredGemini 3 and 3.1
DeepSeekMeasuredConsulted (no guidance published)
KimiMeasuredConsulted (no guidance published)

Notice: Vendors that publish no prompt guidance are recorded as consulted, not guessed.

Professional prose fails differently, and the structure-level finding holds there too: a 2026 replication of StoryScope on 2,250 company blog posts against 11,250 AI mirrors separated them at 98.0 macro-F1 from structural features alone, with the AI shape described as tidy and self-announcing (SLOPSHAPE-2026 in the ledger, arXiv:2609.15369; a preprint whose features are LLM-scored; it tested detection of original and model-self-reworded posts, never human editing). The studies digested in research/ point at filler that carries no information, hedging where a judgment was needed, chatbot leftovers, register that ignores the venue, and formatting that looks stamped out. Each document type gets a thin rule file on top of one shared checklist:

DomainThe gist
Release notes / announcementsuser impact first, artifacts per claim, no marketing inflation
PR / issue repliesanswer first, cite file:line, no reflex praise, length ∝ stakes
Postmortemsblameless toward people, merciless toward mechanisms; timestamps, dead ends, owned action items
Tickets / work orderstitle = outcome, testable acceptance criteria, link don't repeat
Technical articlesopen at the problem, one real dead end, one committed opinion, numbers with conditions
Long-form journalism (features, investigations, data stories)lead and body in two registers, quotations keep their spoken texture, every number carries a comparison, no summary ending

Governing principle: Calibrate to the human distribution, don't invert the AI one. Humans sit at moderate values; a story with every rule applied is a new fingerprint. The skill selects 3–5 moves per story and leaves slack.

Operation entries

The complete plugin package gives Claude Code, Codex, Grok Build, and Antigravity a general router plus five direct entries. QwenPaw gets the /sepia router only, so the table below does not apply there:

OperationClaude CodeCodexGrok BuildAntigravityMeaning
write/sepia-write$sepia-write/sepia-write/sepia-writeCreate new prose
review/sepia-review$sepia-review/sepia-review/sepia-reviewDiagnose without editing
refactor/sepia-refactor$sepia-refactor/sepia-refactor/sepia-refactorMake minimal in-place edits
recreate/sepia-recreate$sepia-recreate/sepia-recreate/sepia-recreateRewrite from the source facts and intent
hemingway/sepia-hemingway$sepia-hemingway/sepia-hemingway/sepia-hemingwayWrite or refactor fiction with the built-in Hemingway voice applied

The general /sepia (Claude Code, Grok Build, Antigravity, and QwenPaw) or $sepia (Codex) router remains available; on QwenPaw the package installs the six skills into each workspace and registers no per-operation slash commands. What was verified on each platform is stated under Install.

Notice: Standalone wrapper installation is unsupported. The operation wrappers depend on their sibling canonical skill; install the complete plugin package.

Experimental: composing with voice skills

Since v0.4.0, sepia defines an interface for stacking a voice or style skill on top of it — a minimalism method, a brand voice, a persona guide. It is opt-in: tell sepia the voice skill is in play, and it loads references/voice-skills.md over the normal route. No external voice is loaded unless you say so.

The interface contract operates under fixed precedence rules across operations and routes:

Rule dimensionContract specification
Architecturesepia's architecture decisions come first.
Move selectionVoice moves are applied selectively (3–5 signature moves per piece, fewer when a sparse shape or the facts offer fewer; formula endings deliberately broken sometimes).
Review diagnosticsReview reports the voice's known costs instead of fixing them away.
Uniformity enforcementUniformity findings keep full strength: a voice does not excuse a metronome.
Professional registerOn professional routes, the venue still sets the register.

// HOW IT'S BUILT

KEY FILES

skills/sepia/SKILL.mdREADME.md

// REPO STATS

3.1k stars