JS model of buffer.hpp's allocation behavior, as two compartments:
pages → shards (page grid + shard shape) then shards → banks
(bank grid + distribution). Named layouts are presets. All values are in pages.
Sharding model
① pages → shards
how the 1D page list is folded into N-D (row-major). Volume = # pages.
same or lower rank than the page grid
② shards → banks
Click a page cell, or a shard / bank header, to toggle its highlight — selected pages light up everywhere and the rest grey out.
composition · page grid → bank
① pages → shards
② shards → banks (device pages, shards stacked per bank)