import type { ModelConstant } from '@qvac/sdk';
import type { ModelRegistry } from './model-registry.js';
import type { Logger } from '../../logger.js';
/** SDK loader, overridable in tests. `@qvac/sdk`'s `loadModel` is heavily
 * overloaded; this is the shape serve calls it with (free-form `modelType`
 * string), returning a bare model-id promise. The real SDK promise also carries
 * a `requestId` used for cancellation, read defensively at call time. */
export type LoadModelFn = (opts: {
    modelSrc: string | ModelConstant;
    modelType: string;
    modelConfig: Record<string, unknown>;
}) => Promise<string>;
export declare const defaultLoadFn: LoadModelFn;
/** SDK cancel/unload, injectable so the cancel + timeout paths can be tested
 * without a live SDK. */
export interface LoadManagerDeps {
    cancel?: (requestId: string) => Promise<void>;
    unload?: (modelId: string) => Promise<void>;
}
export declare class ModelLoadTimeoutError extends Error {
    constructor(alias: string, timeoutMs: number);
}
export interface LoadManagerOptions {
    /** Max simultaneous loads across distinct aliases. `1` mirrors preload's
     * sequential behavior and bounds memory under lazy request-time loads. */
    concurrency: number;
    /** Per-load deadline; on expiry the SDK load is cancelled and the load
     * rejects with {@link ModelLoadTimeoutError}. `null` = unbounded. */
    timeoutMs: number | null;
}
export interface LoadManager {
    /**
     * Load `alias` to READY, deduping concurrent callers onto one SDK load.
     * `signal` (from a request) opts this caller into disconnect-cancellation:
     * when every signalled caller has aborted and no permanent (preload) caller
     * remains, the in-flight SDK load is cancelled. A caller without a signal
     * keeps the load alive regardless of disconnects.
     */
    load: (alias: string, signal?: AbortSignal) => Promise<void>;
    isLoading: (alias: string) => boolean;
    /** Resolve when any in-flight load of `alias` settles (never rejects). */
    settled: (alias: string) => Promise<void>;
}
export declare function createLoadManager(registry: ModelRegistry, logger: Logger, options: LoadManagerOptions, getLoadFn: () => LoadModelFn, deps?: LoadManagerDeps): LoadManager;
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