/**
 * Camera permission utilities.
 *
 * Provides helpers to check, request and handle camera permissions in a
 * browser-consistent way.  All functions are purely async and do NOT throw —
 * they return a typed result so callers can handle each case explicitly.
 */
export type PermissionStatus = "granted" | "prompt" | "denied" | "unsupported" | "unknown";
export interface CameraPermissionResult {
    status: PermissionStatus;
    /** Human-readable reason (populated on denied / unsupported). */
    reason?: string;
}
/**
 * Query the current camera permission state without prompting the user.
 *
 * Uses the Permissions API when available, falls back to "unknown" on older
 * browsers (e.g. Safari < 16).
 */
export declare function queryCameraPermission(): Promise<CameraPermissionResult>;
/**
 * Request camera access and return the resulting MediaStream.
 *
 * Maps browser-specific errors onto actionable `CameraPermissionResult`
 * values so callers can show the right UI instead of catching raw DOMExceptions.
 *
 * @param constraints - Optional MediaStreamConstraints override.
 */
export declare function requestCameraAccess(constraints?: MediaStreamConstraints): Promise<{
    stream: MediaStream;
    permission: CameraPermissionResult;
}>;
/**
 * Whether a failed camera request is worth retrying. "denied" (user
 * explicitly refused) and "unsupported" (no camera device at all) can never
 * be fixed by retrying — surfacing the error immediately instead of burning
 * several seconds of backoff first. Everything else (busy camera,
 * unsupported constraints, anything unrecognized) is treated as
 * potentially transient and retried — failing open avoids turning a
 * recoverable hiccup into a hard failure on browsers that throw
 * non-standard error names (notably Safari/iOS).
 */
export declare function isRetryableCameraError(status: PermissionStatus): boolean;
/**
 * Stop all tracks on a MediaStream and release the camera.
 * Safe to call with null/undefined.
 */
export declare function releaseCameraStream(stream: MediaStream | null | undefined): void;
/**
 * Returns true if the browser supports the camera APIs needed by the SDK.
 */
export declare function isCameraSupported(): boolean;
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