Module constants 

Frontmatter field-name constants, in a neutral module that both parser and validator can import without depending on each other.

Constants

ALLOWED_FIELDS

Allowed frontmatter fields per the Agent Skills spec.

CLAUDE_FIELDS

Claude Code’s extra frontmatter fields, layered on top of ALLOWED_FIELDS when validation/reading opts in via allow_claude_fields. name, description, and allowed-tools are shared with the base spec and so are not repeated here.