The balance work added category_type = "balance" rows to the corpus and cog_balances() to read them, but left cog_categories() -- the discovery surface -- unable to describe them: - subtype COALESCEd only spend_subtype and revenue_subtype, so every balance row came back with subtype = NA - type rejected "balance", so there was no way to ask for the holdings taxonomy at all Both matter downstream: cog-api derives its subtype vocabulary from cog_categories(), so an NA subtype becomes an unusable API parameter. Found while implementing cog-api#26. Note cog_balances() itself still takes no subtype argument -- for holdings category is a strict coarsening of balance_subtype -- but the value belongs in the discovery surface regardless. Tests read the expected subtype set independently from the crosswalk parquet rather than from the function under test.