Position
A point in 3-D space.
Distinct from Direction, Scale, and Color so the compiler stops you passing one where another is expected (they are all float-triples and trivially confused). All four are immutable, which also makes them stable Compose inputs — passing them to scene composables doesn't force needless recompositions the way the mutable Float3 did.
Interop with filament-utils vector math is a hop away: construct from a Float3 (Position(myFloat3)), or drop out with toFloat3/Float3.toPosition. Common in-domain math (translate, scale) is available as operators so you rarely need to.