import type { FilesClient } from '@databricks/sdk-files/v2';
import type { AttachmentPutInput, AttachmentRef, AttachmentStore, StoredAttachment } from '@fabric-harness/sdk';
/**
 * Unity Catalog Volumes attachment backend (v2 migration, workstream C2).
 *
 * Implements the SDK {@link AttachmentStore} contract on a UC Volume via the
 * Databricks Files API, so attachment bytes are governed by Unity Catalog
 * grants like every other Databricks asset. Layout under the volume:
 *
 * ```
 * /Volumes/<catalog>/<schema>/<volume>/<rootPrefix>/<encodeURIComponent(scope)>/<digest[0:2]>/<digest>
 * /Volumes/<catalog>/<schema>/<volume>/<rootPrefix>/<encodeURIComponent(scope)>/<digest[0:2]>/<digest>.json
 * ```
 *
 * The bare `<digest>` file holds the raw bytes; the `<digest>.json` sidecar
 * holds the {@link AttachmentRef} metadata and doubles as the record's
 * existence marker: `put` is first-write-wins per `(scope, digest)` — when the
 * sidecar already exists the put is a no-op, so the first stored ref metadata
 * is retained (contract semantics).
 *
 * Binary transfer and pagination use the official Databricks Files SDK client.
 */
export interface UcVolumesAttachmentStoreOptions {
    client: Pick<FilesClient, 'uploadFile' | 'downloadFile' | 'deleteFile' | 'listDirectoryContents'>;
    catalog: string;
    schema: string;
    volume: string;
    /** Directory under the volume root holding all attachments. Default `fh-attachments`. */
    rootPrefix?: string;
}
export declare class UcVolumesAttachmentStore implements AttachmentStore {
    private readonly client;
    private readonly volumeRoot;
    private readonly rootPrefix;
    constructor(options: UcVolumesAttachmentStoreOptions);
    put(input: AttachmentPutInput): Promise<void>;
    get(scope: string, digest: string): Promise<StoredAttachment | null>;
    getByAttachmentId(scope: string, attachmentId: string): Promise<StoredAttachment | null>;
    list(scope: string): Promise<AttachmentRef[]>;
    delete(scope: string, digest: string): Promise<void>;
    private scopeDir;
    private bytesPath;
    private refPath;
    private writeFile;
    /** Raw file bytes, or `null` when the file does not exist (404). */
    private readFile;
    /** True when the file existed and was deleted; false on 404. */
    private deleteFile;
    /** Immediate children of a directory; empty for a missing directory (404). */
    private listDirectory;
}
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