pub const KDF_MEMORY_BUDGET_KIB: u64 = _; // 4_194_304u64Expand description
Total Argon2 buffer memory allowed across all concurrent derivations.
Argon2 allocates its full memory cost per derivation, and files are processed in parallel (one rayon thread per core). Without a cap, ten production-profile files on a 10-core machine would hold ~10 GiB of Argon2 buffers at once. The budget throttles concurrency by declared memory cost instead of thread count, so cheap derivations still run fully parallel.