Manages bidirectional synchronization between search state (`RequestState`) and URL query parameters. Supports custom routing overrides (`readUrl`, `writeUrl`, `stateToUrl`, `urlToState`, `routeChangeHandler`) for integration with any framework (React Router, Next.js, etc.). The pattern of decoupling URL management from the core driver is reusable for any stateful UI that needs deep-linkable URLs.

A collection of pure functions for filter manipulation: `findFilterValues`, `removeSingleFilterValue`, `markSelectedFacetValuesFromFilters`, `doFilterValuesMatch`, `mergeFilters`, `serialiseFilter`, `isFilterValueRange`. These are isolated, well-tested, and can be extracted into any project that needs to manage complex filter state (value, range, boolean) with disjunctive support.

Implements a debounce and batching mechanism for search actions. It accumulates multiple state changes (e.g., typing, filter toggles) into a single API call and debounces URL pushes. The pattern is generic and can be reused in any application that needs to coalesce rapid user interactions into efficient backend requests.

Abstract base class for building Elasticsearch query DSL. Provides a `build` method that constructs a complete search request body from a `QueryConfig` object, handling facets, filters, sorting, highlighting, and pagination. Subclasses (`SearchQueryBuilder`, `ResultsAutocompleteBuilder`, `SuggestionsAutocompleteBuilder`) specialize for different search intents. The builder pattern is cleanly separated from transport and response handling, making it reusable for any Elasticsearch client.

Creates and manages a DOM-based live region for screen reader announcements. Provides a simple `announce(message)` method that updates the region's content, ensuring accessibility compliance for dynamic search results. The pattern is self-contained and can be dropped into any web application to add accessible notifications without framework dependencies.