[ptr727]

Summary

Fixes a finding Copilot raised on promotion PR #3843, against the description length gate #3839 added.

skill_description in scripts/build_dist.py returned None ("states no description") for any frontmatter that was not a mapping. A SKILL.md whose frontmatter parsed to a list or a scalar was therefore never measured, and it got past the 1024-character gate. skill-lifecycle and scripts/README.md both say the gate refuses "frontmatter too malformed to measure one". The code now does the same: frontmatter that is not a mapping raises frontmatter is not a mapping, as unclosed and invalid frontmatter already did. Empty frontmatter still reads as stating no description.

• scripts/build_dist.py: refuse non-mapping frontmatter, and keep returning None for empty frontmatter.
• tests/test_build_dist.py: a refusal case for list frontmatter, and a not-measured case for empty frontmatter.

Verification

• python -m unittest discover -s tests -p test_build_dist.py: 99 tests OK.
• ruff check and ruff format --check on both files: clean.
• scripts/build_dist.py --check: generated distributions are current.
• Every SKILL.md under .agents/skills/ opens with mapping frontmatter, so no existing skill newly fails the build.
• local-strict-review: two passes recorded at the frontier tier. The first raised one finding (no test covered the empty-frontmatter branch), fixed in ce00bf3. The second raised none. The receipt covers the pushed head.

🤖 Generated with Claude Code

[ptr727]

A recorded local strict-review pass covers head ce00bf35178bd28ea312500d66e2a35900d9744d, the content this pull request carries at that commit against develop, and it recorded 0 findings.

[coderabbitai]

Important

• Trigger review

This repository does not receive automatic reviews because it has fewer than 10 stars.

Run configuration

• Source mode: Auto
• Repository: ptr727/ProjectTemplate
• Branch: feature/reject-non-mapping-skill-frontmatter
• File: .coderabbit.yaml
• Commit: ce00bf3
• Layers: Repository YAML
• Review profile: CHILL
• Plan: Advanced
• Run ID: 3d5cc71f-1829-43a7-92b1-be42bbed6ece

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[Copilot]

🟢 Approval recommended

No active review issues are recorded for the change, supporting its progression.

No open issues 🎉

What changed in this PR

This PR strengthens skill frontmatter validation so non-mapping YAML cannot bypass the description-length gate, while preserving empty frontmatter as having no description.

Changes:

• Reject list and scalar frontmatter with a mapping error.
• Preserve the existing empty-frontmatter behavior.
• Add regression coverage for list and empty frontmatter.

This pull request requires changes.

File	Summary
scripts/​build_dist.py	Validates non-mapping frontmatter, but explicit YAML null or ~ can still bypass refusal. [P1, moderate]
tests/​test_build_dist.py	Covers list and empty frontmatter, but lacks an explicit scalar refusal case. [P2, nit]

_{Review effort: Lite}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.30%. Comparing base (a5f318e) to head (ce00bf3).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #3847   +/-   ##
========================================
  Coverage    83.29%   83.30%           
========================================
  Files           29       29           
  Lines         9933     9937    +4     
========================================
+ Hits          8274     8278    +4     
  Misses        1659     1659           

Flag	Coverage Δ
python-3.13	83.30% <100.00%> (+<0.01%)	⬆️

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