import type { RenderMedium } from "@trackunit/react-map-adapter-shared";
export type UseMarkerMountBridgeReturn = Readonly<{
    mountingIds: ReadonlySet<string>;
}>;
/**
 * Pure transition detector — returns the subset of `currentMediums` whose
 * medium is `"dom"` and whose previous medium was `"symbol"`. Exported for
 * unit tests; the React hook below is the consumer.
 */
export declare const computeMountingFeatureIds: (currentMediums: ReadonlyMap<string, RenderMedium>, previousMediums: ReadonlyMap<string, RenderMedium>, existingIds: ReadonlySet<string>) => Set<string>;
/**
 * State-machine hook tracking `symbol → dom` transitions for adaptive markers
 * (ADR-0009 §"Mounting bridge").
 *
 * On the commit where a feature's medium first appears as `"dom"` (after
 * having been `"symbol"`), its id is included in `mountingIds`. On the next
 * commit, `mountingIds` is empty again. `<Layers>` uses this signal to
 * synthesize a first-commit render state with `isMounting: true` and
 * `selected`/`hovered: false` so consumer-side CSS animations can morph from
 * a small "default" footprint into the resting hover/select form.
 *
 * The hook is purely a state machine — it does not touch the DOM or the map
 * adapter. The caller decides what `currentMediums` reflects; in `<Layers>`'s
 * case it is derived from the published DOM portal descriptors so that the
 * transition is detected at the moment the portal first renders, with
 * non-portal adaptive features defaulting to `"symbol"`.
 *
 * Per-feature `previousMedium` is intentionally not exposed in the public
 * render state — only `isMounting` (Q5 of the SAGA-414 design grilling).
 *
 * The two-pass mechanism is owned here: an internal mount store holds the
 * `previousMediums` map and the active `mountingIds` set, and notifies
 * subscribers via `useSyncExternalStore` rather than a React `setState` (so
 * the cascading-render guard rail does not block the legitimate two-pass
 * pattern). The detection layout effect calls `advance`; the passive clear
 * effect calls `clear` after the browser has had a chance to paint the
 * populated set once.
 */
export declare const useMarkerMountBridge: (features: ReadonlyArray<{
    id: string;
}>, currentMediums: ReadonlyMap<string, RenderMedium>) => UseMarkerMountBridgeReturn;