/**
 * Abstract interface for object storage operations (e.g., OSS, S3, local fs).
 * Implementations must handle serialization/deserialization of values.
 */
export interface ObjectStorageClient {
    init?(): Promise<void>;
    destroy?(): Promise<void>;
    /** Overwrite (or create) the object at `key` with `value`. */
    put(key: string, value: string): Promise<void>;
    /** Read the full object at `key`. Returns `null` if the object does not exist. */
    get(key: string): Promise<string | null>;
    /**
     * Append `value` to an existing Appendable Object.
     * If the object does not exist yet, create it.
     *
     * Used by OSSAgentStore to incrementally write JSONL message lines without
     * reading the entire thread — much more efficient than read-modify-write for
     * append-only workloads.
     *
     * This method is optional: when absent, OSSAgentStore falls back to
     * get-concat-put (which is NOT atomic under concurrent writers).
     */
    append?(key: string, value: string): Promise<void>;
}