fix(skills): make media-use frontmatter valid YAML so skills add works

[miguel-heygen]

Problem

npx skills add heygen-com/hyperframes — the install command in the README — fails for everyone:

■  Nested mappings are not allowed in compact mappings at line 2, column 14:
   description: Agent Media OS — resolve any media need (BGM, SFX, image, icon) in…
└  Installation failed

skills/media-use/SKILL.md's description: is an unquoted YAML scalar containing a mid-value : (…handles the full cascade: project cache…). YAML 1.2 reads : as a nested mapping, so the parse throws. The skills CLI aborts the whole install when any single skill fails to parse — so this one file blocks installing all 19 skills for every user following the docs.

Confirmed with the same parser the CLI uses (yaml 2.x): only media-use breaks; the other 18 parse fine.

Fix

• skills/media-use/SKILL.md — replace the offending : with —. Keeps the plain-scalar style of the other 18 skills (the description already uses — as a separator) and changes no meaning.
• scripts/lint-skills.ts — add a frontmatter guard that flags unquoted top-level scalars containing : (the exact ambiguity) so this can't regress. No new dependency.

Verification

With yaml 2.9.0 against all 19 skills:

	before	after
parser failures	1 (media-use)	0
new guard flags	1 (media-use)	0

The guard flags the original bad content and passes the fixed content — no false positives across the repo.

🤖 Generated with Claude Code

[github-actions]

Fallow audit report

Found 2 findings.

Details

Severity	Rule	Location	Description
minor	fallow/high-crap-score	scripts/lint-skills.ts:69	'lintFrontmatter' has CRAP score 42.0 (threshold: 30.0, cyclomatic 6)
minor	fallow/high-crap-score	scripts/lint-skills.ts:106	'lintFile' has CRAP score 30.0 (threshold: 30.0, cyclomatic 5)

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