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Pedro Castanheira Costa
Pedro Castanheira Costa

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Stop re-explaining your codebase to every AI agent — `cast-skills`

The annoying part of AI coding tools

Every session, the agent forgets:

  • your module boundaries
  • the “every user belongs to an org” rule that lives in nobody’s file
  • which service emits which event
  • how you want features built (tests first? spec first? conventions?)

So you re-explain. It rewrites. Context drifts. Tokens burn.

Dumping a 40k-token AGENTS.md into every prompt is not a strategy. It’s a tax.

I wanted something simpler: write project knowledge once, in a format agents already understand, and install it into every tool I actually use.

That’s cast-skills.

npx cast-skills
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What it is

cast-skills is a small CLI that bootstraps cross-tool AI skills for your machine (or project):

Skill Job
using-project-skills Always-on router. When you start a feature/fix/refactor, it loads project context and routes work through the right module + workflow.
creating-project-skills Bootstrapper (/skill-creator). Reads the repo, asks sharp questions, generates a project skill tree.
explaining-changes After non-trivial work, offers a beginner-friendly explanation (ELI5 → runtime) as Markdown/HTML.

Skills use the open SKILL.md format — progressive disclosure: the agent loads what it needs, not your entire wiki every turn.

cast-skills is built around Anthropic's Agent Skills approach: instead of loading one massive prompt every session, the agent progressively loads only the knowledge it needs.


One install. Six tools.

The wizard auto-detects what you have and drops skills in the right place:

Tool Where it goes Format
Claude Code ~/.claude/skills/ native SKILL.md
GitHub Copilot ~/.copilot/skills/ native
Gemini CLI ~/.gemini/skills/ native
Codex ~/.agents/skills/ native
Cursor .cursor/skills/ (project) converted .mdc
Windsurf .windsurf/rules/ (project) converted rules

Native tools get SKILL.md as-is. Cursor/Windsurf get an auto-converted format so you’re not maintaining six copies by hand.

npx cast-skills
# or
npm i -g cast-skills && cast-skills
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Requires Node ≥ 18.


How a normal feature run feels

  1. You say: “add X / fix Y / refactor Z”
  2. using-project-skills loads domain + stack + conventions
  3. It pulls the module-level skill for the code you’re touching
  4. Work is steered through a spec-driven path (spec → failing tests → implement) when that workflow exists
  5. After a real change, explaining-changes can leave a human-readable write-up

The point isn’t another chatbot persona. It’s stable project memory that survives sessions and tools.


Why I didn’t make this Claude-only

Most of us don’t live in one harness.

Monday: Claude Code.

Tuesday: Cursor on a design-heavy UI.

Wednesday: Copilot in a boring enterprise repo.

If “project brain” only works in one tool, you still re-explain on Tuesday.

cast-skills optimizes for write once → run everywhere that speaks skills/rules.


What this is not

  • Not a full coding agent (that’s a different product surface)
  • Not magic RAG over your monorepo (skills are curated knowledge, not automatic embeddings)
  • Not a replacement for good architecture — garbage conventions in → garbage guidance out

If your team has no conventions, the bootstrapper will still force a few useful questions. That’s a feature.


Try it in 30 seconds

cd your-repo
npx cast-skills
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Pick the tools you use → let it install the three skills → start a real task and see if the agent stops inventing your architecture from scratch.

Repo: github.com/pedrocastanha/cast-skills

npm: npmjs.com/package/cast-skills


Feedback I actually want

If you try it, tell me:

  1. Which tool combo you use (e.g. Claude + Cursor)
  2. Whether the wizard put files in the right paths
  3. One rule your team has that should be a skill but isn’t obvious

Issues and PRs welcome — especially path fixes for tool updates (these CLIs move the goalposts often).


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