Install a skill once and make it usable across multiple AI coding agents (Claude Code, Codex CLI, Cursor, Gemini CLI, Cline, etc.) that work on the same repository. Use this when the user wants a skill / ruleset / prompt to be shared and switchable across several AI products, asks "why can only one tool use this skill", or wants cross-tool consistency. It maps each agent to its correct skill-reading directory, installs into the repo so the skill travels with Git, and documents the per-tool invocation syntax (which differs — e.g. Codex uses `$skill-name` or `/skills`, NOT gstack-style `/design` commands).
