The playable skill tree, searchable compendium, and interactive explorer are one system:
The canonical records are in skill_compendium.json, and skill_compendium.html is their generated CLI-readable cache.
The former D&D-derived design catalogue was not a playable skill tree. Its clauses remain only as source-review evidence in the D&D Skill Import Catalogue. Approved mental training is merged into the Skill Compendium; approved body and machine changes are embodiment-upgrade Items in the Item Compendium.