Function validateLocalSkillDirectory

src/node/services/tools/skillFileUtils.ts:177–200

(
  containmentRoot: string,
  skillDir: string
)

 * Throws a descriptive error string on any violation.
 */
export async function validateLocalSkillDirectory(
  containmentRoot: string,
  skillDir: string
): Promise<{ skillDirStat: Stats | null }> {
  // 1) Reject symlinked skills root
  const skillsRoot = path.dirname(skillDir);
  const skillsRootStat = await lstatIfExists(skillsRoot);
  if (skillsRootStat?.isSymbolicLink()) {
    throw new Error(
      "Skills root directory is a symbolic link and cannot be used for skill operations."
    );
  }

  // 2) Reject symlinked skill directory
  const skillDirStat = await lstatIfExists(skillDir);
  if (skillDirStat?.isSymbolicLink()) {
    throw new Error("Skill directory is a symlink (symbolic link) and cannot be modified.");
  }

  // 3) Verify realpath stays under containmentRoot (even for missing dirs via allow-missing resolution)
  await ensurePathContained(containmentRoot, skillDir, { allowMissing: true });

  return { skillDirStat };
}

/** Canonical filename for the skill definition file. */
export const SKILL_FILENAME = "SKILL.md";