Module error 

Typed error enum for the shared graph engine.

Every fallible operation on CsrIndex (label interning, edge insert, edge delete) returns Result<T, GraphError>. The skill / CLAUDE.md discipline is explicit: silent casts or debug_assert! at capacity boundaries reproduce the same class of bug as the one being fixed — loud, typed errors only.

Enums

GraphError

Errors returned by graph-engine operations.

Constants

MAX_EDGE_LABELS

Hard upper bound on the number of distinct edge labels an individual CsrIndex can intern. u32::MAX is the type-theoretic ceiling; leaving one slot unused lets callers use u32::MAX as an “invalid” sentinel should they need it.