Sepia
Transform AI-generated writing to sound human-written across fiction and professional documents.
Installation
- Make sure Claude is on your device and in your terminal.
Skills load from
~/.claude/skills/when Claude Code starts up β so you need it on your machine first. If you don't have it yet, install it once with the command below, then runclaudein any terminal to verify.One-time setupnpm i -g @anthropic-ai/claude-codeAlready have it? Skip ahead.
- Paste into Claude Code or into your terminal.
This copies the whole skill folder into
~/.claude/skills/sepia-nanako0129/β the SKILL.md plus any scripts, reference docs, or templates the skill ships with. Safe default: works for every skill.Faster alternative (instruction-only skills)
Skips the clone and grabs only the SKILL.md file. Don't use this if the skill ships Python scripts, reference markdowns, or asset templates β they won't be downloaded and the skill will fail when it tries to load them.
Quick install (SKILL.md only)Sign up to copy - Restart Claude Code.
Quit and reopen Claude Code (or any other agent that loads from
~/.claude/skills/). New skills are picked up on startup. - Just ask Claude.
Skills auto-activate when your request matches the skill's description β no slash command needed. Trigger phrases live in the skill's own frontmatter; you can read them in the βWhat this skill doesβ section above.
Prefer to read the source first? Open on GitHub.
When Claude uses it
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, and blog posts. 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.
What this skill does
Sepia β de-AI writing
Every rule here is backed by a measured human-vs-AI gap. The load-bearing facts: in fiction, a classifier using only narrative-structure features detects AI at 93.2% macro-F1 and style editing barely moves it β so structure is fixed before style, always. In professional prose, the measured tells are different β filler density, missing stance, chatbot residue, register mismatch, format uniformity β and the fix is domain-specific. Route first, then operate.
Routing
| Text type | Load, in order |
|---|---|
| Fiction / stories / narrative essays | references/narrative-pass.md β references/discourse-pass.md β references/style-pass.md; diagnose with references/rubric.md |
| Release notes, changelogs, announcements | references/professional-pass.md + references/domains/release-notes.md |
| PR replies, issue replies, review comments | references/professional-pass.md + references/domains/dev-replies.md |
| Incident postmortems / RCA | references/professional-pass.md + references/domains/postmortems.md |
| Tickets, work orders, bug reports | references/professional-pass.md + references/domains/tickets.md |
| Technical articles, blog posts, tutorials | references/professional-pass.md + references/domains/tech-articles.md + references/discourse-pass.md Β§1β3 |
| Any other prose | references/professional-pass.md + references/style-pass.md |
Every non-fiction route ends with the vocabulary/syntax scan in references/style-pass.md Β§2β3, and long professional pieces take the whole style pass β in both cases skipping its fiction-slop table. If the text was produced by a known model, add references/model-fingerprints.md (fiction-centric; use as priors).
Operations
Any request maps to one of four operations:
| Operation | Contract |
|---|---|
| write | New content. Read the domain file before drafting β architecture and register decisions come first, they cannot be retrofitted cheaply. For fiction, follow Workflow A below. |
| review | Diagnose only β no edits. Produce the defect list (fiction: rubric report; professional: checklist findings with quoted evidence) and stop. Report findings; apply nothing until asked. |
| refactor | Minimal in-place revision preserving structure, voice, and intent. Two-stage: full defect list first, then fix item by item, deepest layer first. Skew replace/delete over insert (measured editor ratio 74/18/8). |
| recreate | Full rewrite. Extract the facts, claims, and intent from the original into a bare list; verify nothing invented; write fresh under the domain rules. Use when defects are structural and the text is short enough that surgery costs more than rebuilding. |
The two-stage protocol is not optional for refactor/recreate: paraphrasing without a defect list makes AI fingerprints more visible, not less (measured on expert detectors).
Fiction workflows
A β writing new fiction: (1) premise, genre, length β genre sets calibration targets; (2) fill the architecture sheet in references/narrative-pass.md; (3) select 3β5 human-leaning moves + one rarity move; (4) outline, run the outline/QUD checks in references/discourse-pass.md and the echo test in references/narrative-pass.md Β§2; (5) draft; (6) self-diagnose with references/rubric.md, one group at a time; (7) style pass last.
B β revising existing fiction: (1) diagnose completely first (rubric β discourse β style), no edits; (2) triage β architecture defects need scene-level surgery, tell the user how deep before cutting; (3) fix deepest first; (4) verify: re-run changed rubric groups, read key passages aloud, echo-test any added twist.
Calibration β the rule that governs all rules
| Principle | Meaning |
|---|---|
| Aim at the band, not the opposite pole | Human values are moderate (chronological discontinuity 2.4/5, not 5). Inverting every AI tell creates a new fingerprint. In professional prose the equivalent: match the venue's register, don't overshoot into forced casualness β informality alone fools no trained reader. |
| Select, don't accumulate | Human writing is diverse. Fiction: 3β5 moves per story, chosen for the premise, varied across works. Professional: fix what the checklist actually flags, nothing more. |
| Leave slack | Ordinary sentences, an underdeveloped thought, a plain paragraph. Do not sand every surface. |
Hard guardrails
- Never invent specifics. Fiction: intertextual references, brands, places must be real and correct. Professional: versions, numbers, timestamps, benchmarks, quotes come from the actual change/incident/data β missing info means ask the user or leave an explicit TODO, never fill. Confident wrong facts are themselves a top-tier tell.
- Deletion beats addition (74% replace / 18% delete / 8% insert). The only additive fix is real specificity.
- Respect the author's voice and the venue's corpus. Extract habits from the user's samples or the venue's recent artifacts before editing; edit toward that profile. Do not remove a mannerism they actually use.
- Dialogue quotes and quoted material are load-bearing β do not regularize them.
- Check the whitelists (
references/style-pass.mdΒ§7,references/professional-pass.mdlast section) before flagging: clean grammar, formal tone in formal venues, and conventional templates are not evidence of AI.
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