Extra agents
The canonical project dest is always .agents/skills. Cursor, Codex, and other agents that already read that directory need nothing else.
An extra dest is for an agent that uses its own project directory. The common case is Claude Code, which reads .claude/skills.
This activation
skl use writing-tests -a claude-code
claude is an alias for claude-code. Other catalog ids work with -a <id> when that agent uses its own project dir. Cursor and Codex are rejected as extras because they already read .agents/skills.
Sticky extras
skl targets
skl targets add claude-code
skl targets remove claude-code
skl targets lists the canonical dest and any sticky extras stored in ~/.config/skl/config.toml under [targets].extra. Sticky extras apply to later skl use runs on this machine.
skl init and skl doctor may ask once whether you want extras. The prompt is skipped in CI, when SKL_NO_PROMPT or SKL_YES is set, and when stdin is not a TTY.