Prompty: Arbitrary File Read via ${file:path} Reference Expansion

Prompty is a markdown file format (.prompty) for LLM prompts. Prior to 2.0.0-beta.2, Prompty loaders expanded ${file:...} references in .prompty frontmatter without enforcing that resolved paths stayed within the prompt directory or allowed roots, allowing an attacker-controlled prompt file to read local files through absolute paths, .. traversal, or symlink escapes. This issue is fixed in versions 2.0.0-beta.2.