Declared Size Is Allocation

A wire format declares a container's size in a length-or-count field. The parser materializes the container by passing that field directly into the runtime's default size-parameterized constructor (`new Array(n)`, `Vec::with_capacity(n)`, `make([]T, n)`, `calloc(n)`). The runtime's default allocates eagerly. The wire field's bytes scale with the digits used to encode the size; the allocation it triggers scales with the value those digits encode. Amplification ratios run six to nine orders of magnitude. The fix usually defers materialization until the actual data arrives, or replaces the eager constructor with a lazy container, without changing the wire format's promise that the size field has authority.