Implementation notes

• Vertices retain insertion order so seeded runs do not depend on hash iteration order.
• The hopset path can use a BLAS-aware omega estimate; pass an explicit omega when byte-stable output matters.
• The reachability construction uses a CSR representation above an implementation threshold and a deque fallback below it.
• Process-level dispatch is opt-in and uses spawned workers; construction and query performance must be measured separately.

These are implementation facts, not universal complexity or speed claims.