//! Cost-based vector index optimizer.
//!
//! This module implements selectivity-aware index selection for vector
//! search. Given (data_size, dim, requested_recall, query_density) the
//! [`index_dispatcher::OptimizerDispatcher`] picks the lowest-cost index
//! family that meets the recall floor, with a fallback chain when an
//! observed recall trips the SLA.
//!
//! Component split:
//!
//! - [`cost_model`] — explicit per-index cost formulas (HNSW: `O(log n × M × ef)`,
//! IVF: `O(n / nprobe + n_clusters)`, LSH: `O(K × L × dim + L × bucket)`,
//! PQ: `O(centroids × subquantizers + n × subquantizers)`).
//! - [`index_dispatcher`] — execution-agnostic brain that consults the cost
//! model and chooses a primary + fallback chain.
//! - [`query_stats`] — persisted per-family observation aggregates feeding
//! online cost-weight learning.
//!
//! The crate-level [`crate::index_dispatcher::IndexDispatcher`] wires this
//! brain to concrete vector-index instances (HNSW/IVF/LSH/PQ).
pub use ;
pub use ;
pub use ;