PackedArray

Heap-owned PackedFloat32Array / PackedVector3Array values. The 16-byte handle lives in malloc'd storage so the value can outlive a call frame; call free when done (destroys the engine value and releases the storage).

Element access goes through the packed_*_operator_index interface functions, which return an interior pointer (the non-const variant triggers copy-on-write first). Indices are bounds-checked on the Scala side: the engine returns null for an out-of-range index, and dereferencing that segfaults.