Sepia is a de-AI writing skill for agent-compatible systems that repairs AI-generated text by addressing narrative architecture rather than surface-level word choice.
The tool solves the problem that popular humanizers focus on syntax and vocabulary, yet research shows AI fiction remains detectable through structural patterns: unexplained themes, overly tidy causality, limited emotional range, absence of real-world grounding, and linear time progression. Sepia applies a three-pass protocol targeting narrative architecture first (loosening causal chains, mixing emotion modes, adding real references), then discourse flow (varying rhythm, fixing pacing), and finally surface style. It diagnoses AI fingerprints across narrative and sentence-level layers for known model families including Claude, GPT, Gemini, and DeepSeek, using measured features from research and vendor guidance where available.
The tool works as a portable Agent Skill compatible with any agent supporting the standard specification, with native plugin packaging for Claude Code, Codex, Grok Build, and Antigravity. It offers four operations: write, review (diagnosis only), refactor (minimal edits), and recreate (full rewrite). Professional documents receive venue-matched rules for release notes, pull request replies, postmortems, tickets, and technical articles. Developers should choose this if they need AI-generated fiction or professional prose that passes structural scrutiny rather than just surface polish, and if they work within agent-compatible systems. The single canonical skill definition avoids per-platform forks.
Development activity shows sustained engagement with the research foundation underlying the tool's approach, as evidenced by the research directory containing digested studies that inform the three-pass protocol. The project maintains language support across English and Chinese variants, indicating attention to international usability. Native plugin implementations for multiple agent platforms demonstrate commitment to practical integration beyond the base specification.
