pedro castanheiraPT
← All work

Personal project · open source

Cast Skills

Created an npm package that installs project-context skills and a spec-driven workflow into six AI coding tools.

Role
Product and development
Status
Published on npm
Stack
  • Node.js
  • JavaScript
  • SKILL.md
  • npm
codingagentrelearns the projectevery sessioncodebase +team answersnpxcast-skillsprojectskill treenative SKILL.md:Claude, Copilot, Gemini, Codexconverted:Cursor .mdc, Windsurfusing-project-skills(router)agent withcontext6 tools · published on npm

Problem

Coding agents relearn the project every session: they forget conventions, module boundaries and business rules that are not written down anywhere.

Available data

The codebase and the team’s answers to a few short bootstrapper questions, turned into a project skill tree.

Architecture decisions

An open standard as the source

SKILL.md is the canonical format. Conversion for tools with their own format (Cursor, Windsurf) happens only at install time.

Progressive disclosure

The agent loads the project map first and then only the rules of the module it is touching.

An always-on router

The using-project-skills skill kicks in at the start of any feature, fix or refactor and routes the work through project context and the spec workflow.

Implementation

  • A wizard (npx cast-skills) that detects installed tools and copies the skills: native SKILL.md for Claude Code, Copilot, Gemini and Codex; converted to .mdc for Cursor and to rules for Windsurf.
  • Three skills: using-project-skills (router), creating-project-skills (bootstrapper) and explaining-changes (explanations after a change).
  • Automated tests cover installation and format conversion using Node.

Result

  • 6tools supported

Published on npm as cast-skills.

Limits and lessons

  • The token savings quoted in the README are Anthropic’s reference numbers for the skills pattern, not a measurement of this project.
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