ci: frontmatter validation parses the whole file via sed; rule globs and alwaysApply never validated

[TMHSDigital]

Why it matters

The rules only work if Cursor parses their frontmatter. As CLAUDE.md puts it, "changing a glob changes when the rule fires". The validator doesn't parse that frontmatter as YAML: it greps a sed range that can run past the header, and it never looks at globs or alwaysApply.

Evidence

• validate.yml:50, :77, :100: sed -n '/^---$/,/^---$/p' prints every ----delimited range in the file, not just the leading frontmatter. A Markdown horizontal rule (---) in a skill or rule body can satisfy a missing required key, or confuse the skill-name check.
• validate.yml:89-114 (rules): checks only description: and standards-version:. alwaysApply and globs are never read, so a typo such as alwaysapply: false or a malformed glob passes.
• All 9 rules/*.mdc write globs as a YAML list:

  globs:
    - "**/*.py"

  Cursor's documented .mdc form is a comma-separated string (globs: **/*.py). There are community reports of list-valued globs not triggering auto-attach. Not verified in Cursor for this repo. Please confirm in a Cursor session before changing anything.

Suggested approach

1. Replace the sed/grep checks with a small Python step that takes only the first frontmatter block (text.split('---', 2)[1]), parses it with yaml.safe_load, and asserts the required keys and types: alwaysApply is a bool, and globs is a str or list of str matching the shape Cursor accepts.
2. Verify glob triggering in Cursor: open a .py file and confirm that prefer-data-over-ops-in-loops attaches. If lists don't work, convert all 9 rules and have the validator enforce the string form.

Done when

• Frontmatter is parsed as YAML from the header only, with a falsifier: a body --- no longer masks a missing key.
• globs and alwaysApply are validated.
• The Cursor glob format is confirmed working and recorded in CONTRIBUTING.md.