Module expert 

2026-09-25: Expert identity and on-disk record geometry for MoE expert streaming. A record holds one (moe_layer, expert)’s gate, up and down NVFP4 projections behind a fixed header; each MoE layer’s file holds num_experts records at one stride, which the whole model shares.

Owner: metrale-storage experts. Invariants:

• Inside a record the header comes first, then gate, up and down (packed, then scale, for each), every sub-buffer at a multiple of sub_align and none overlapping.
• record_stride is raw_bytes rounded up to a multiple of fs_block_size.

Structs

ExpertKey

2026-09-25: One expert’s record. layer is the dense MoE-layer index (0..num_moe_layers), not the model layer; ExpertIndex::moe_layer_to_model_layer maps one to the other.

ExpertLayout

2026-09-25: File geometry of an expert store: one file per MoE layer (ExpertIndex::file_name), each holding num_experts records back to back at record_stride.

ExpertRecordHeader

2026-09-25: The fixed, versioned header at the front of every expert record. It carries what the dims do not give, each projection’s weight_scale_2 and input_scale, plus layer, expert and shape so a mismatched file can be recognised.

ExpertRecordId

2026-09-25: Dense record id across the model: layer · num_experts + expert.

ExpertRecordSpec

2026-09-25: Where each sub-buffer of an expert record sits, relative to the record base; pack_record and unpack_record place and read bytes by it. Every offset is a multiple of sub_align:

ProjBytes

2026-09-25: Byte sizes of one NVFP4 projection’s two buffers: packed, two 4-bit values per byte (n·k/2), and scale, one byte per group_size values (n·k/group_size). The per-projection scalars weight_scale_2 and input_scale are in the record header instead.

Enums

Proj

2026-09-25: The three projections of an expert. Their order is the order of the sub-buffers in a record and of the header’s per-projection fields, so changing it changes the on-disk format that ExpertRecordHeader::VERSION identifies.