Diagnose and fix `.catalog/` validation failures (schema, roster, banners, sample workflows, JSON mirror). Use when: - `make validate` or CI reports collection compliance errors - A PR adds skills but catalog was not updated - `collection.json` is out of sync with `collection.yaml` - Catalog metadata/fragments might have drifted from README/CLAUDE/SKILL golden sources Remediation is via the create-collection workflow and `catalog_yaml_to_json.py`—not by weakening checks.