/**
 * Needle Engine Claude skill installer.
 *
 * Writes a Needle Engine skill to `.claude/skills/needle-engine/SKILL.md`.
 * Claude Code auto-loads skills based on their description frontmatter, so
 * Claude will automatically have Needle Engine context when working in the project.
 *
 * The skill is only written if `.claude/` already exists in the project root
 * (i.e. the developer is already using Claude Code). Old skill files are
 * always overwritten so the skill stays up to date with the engine version.
 *
 * @param {"build" | "serve"} command
 * @param {{} | undefined | null} config
 * @param {import('../types/index.js').userSettings} userSettings
 * @returns {import('vite').Plugin | null}
 */
export function needleAI(command: "build" | "serve", config: {} | undefined | null, userSettings: import("../types/index.js").userSettings): import("vite").Plugin | null;
