Module distribution 

Four distribution patterns: 1:1, 1:N, N:1, N:M.

Pure domain logic — no I/O, no file system, no async runtime. The adapter layer is responsible for parallel execution (rayon).

Functions

assign_many_to_many

Assign shards to covers for M:N (many-to-many) distribution.

assign_one_to_many

Assign shards to covers for 1:N distribution.

minimum_covers

Minimum number of covers required for a given pattern.

pack_many_payloads

Build a concatenated multi-payload with length-prefix manifest for N:1.

unpack_many_payloads

Unpack a multi-payload buffer produced by pack_many_payloads.

validate_cover_count

Validate that the cover count satisfies the distribution pattern.