Aliases
Simple explanation
Aliases let one grammar rule appear under different names in different contexts (for example, a generic word rule surfacing as keyword somewhere). Supertypes group several symbols under one abstract name for queries.
Technical explanation
language/aliases.zig stores sparse per-production alias rules (production_id, child_index, rename-to symbol); Language.supertype_map lists each supertype's subtypes. Both behaviors are applied: when a rule is reduced, makeInteriorNode renames aliased children (so nodeType(), navigation, and queries observe the new name), and query matching expands supertype patterns to the supertype itself plus every registered subtype. The bundled s-expression grammar aliases the grouped-list production's middle child to sequence — (sequence) queries match grouped lists directly. Aliased subtrees keep their original reuse state, so they simply re-lex on the next edit instead of being spliced.