Support for nested frontmatter keys

[dallinwilcox]

Doesn't seem to support nested frontmatter keys. Would love to use this for validating required metadata keys as defined in the Agent Skills spec: https://agentskills.io/specification#metadata-field

Example from the spec, would like to validate author and version and similarly defined keys

metadata:
  author: example-org
  version: "1.0"

[jackchuka]

Hi @dallinwilcox — thanks for raising this! Nested frontmatter keys are now supported via dot-notation, shipped in v0.13.0 (#64).

For your Agent Skills metadata example, the schema would look like:

frontmatter:
  fields:
    - { name: "metadata", type: object }
    - { name: "metadata.author" }
    - { name: "metadata.version" }

A few notes:

• Mark the parent (metadata) as type: object to assert it's a map.
• Child paths like metadata.author traverse into it — required by default, add optional: true to relax.
• If a real key contains a literal dot, escape it with a backslash (weird\.key).

Give it a try and let me know if anything looks off for the agentskills.io spec — happy to reopen if you hit edge cases.