import type { Store, StoreIndexOptions, StoreItem, StoreNamespace, StorePutOptions, StoreSearchOptions } from '../types/store.js';
import type { MigrationResult, SchemaMigration } from '../utils/schema-migrations.js';
import { type PostgresLikeClient } from './client.js';
import type { PostgresMigrateOptions } from './migrations.js';
/** Options for the Postgres store. */
export interface PostgresStoreOptions {
    /** Table name, optionally schema-qualified. Defaults to `nexus_store`. */
    table?: string;
    /** Enables semantic search by embedding indexed fields on write. */
    index?: StoreIndexOptions;
    /**
     * Stores embeddings as a pgvector column of this many dimensions and ranks in the database. The
     * extension must be installed. Without it, embeddings are kept as JSON and ranked in process,
     * which works on any Postgres and suits namespaces of a few thousand items.
     */
    vectorDimensions?: number;
    /** Replaces the system clock, for tests. */
    now?: () => Date;
}
/**
 * The versioned schema, which `migrate()` and `nexus db migrate` apply. Version 1 is the 2.0 schema.
 */
export declare function storeMigrations(options?: Pick<PostgresStoreOptions, 'table' | 'vectorDimensions'>): SchemaMigration[];
/** The schema, as statements. With `vectorDimensions`, pgvector's extension is created too. */
export declare function storeMigration(options?: Pick<PostgresStoreOptions, 'table' | 'vectorDimensions'>): string[];
/**
 * Long-term memory in Postgres, with pgvector when it is available.
 *
 * The same contract as `MemoryStore` and `RedisStore`, checked by the same tests. Namespace prefixes
 * are matched on a `C`-collated key, so `['tenant-7']` never matches `['tenant-70']` and an index
 * serves the match. Expired items are hidden from every read at once; `sweep()` deletes them, for a
 * retention job.
 */
export declare class PostgresStore implements Store {
    private readonly client;
    private readonly options;
    private readonly table;
    private readonly now;
    constructor(client: PostgresLikeClient, options?: PostgresStoreOptions);
    /**
     * Applies this store's pending migrations, recorded in `nexus_schema_migrations`, under a lock.
     * Never runs implicitly. Safe on a database an older release created: what exists is kept.
     */
    migrate(options?: PostgresMigrateOptions): Promise<MigrationResult>;
    /** Stores an item, keeping its original `createdAt` when it replaces one. */
    put<V>(namespace: StoreNamespace, key: string, value: V, options?: StorePutOptions): Promise<void>;
    /**
     * Stores an item only when the stored one's `version` is `expected`, or, with `expected` `null`,
     * only when none is stored. One statement, so two writers deciding on one version cannot both win.
     */
    putIfVersion<V extends {
        version: number;
    }>(namespace: StoreNamespace, key: string, value: V, expected: number | null): Promise<boolean>;
    /** Reads an item, or `undefined` when it does not exist or has expired. */
    get<V>(namespace: StoreNamespace, key: string): Promise<StoreItem<V> | undefined>;
    /** Deletes an item. */
    delete(namespace: StoreNamespace, key: string): Promise<void>;
    /**
     * Items under a namespace prefix, newest first, or ranked by similarity when a query is given.
     * Defaults to 20.
     */
    search<V>(namespacePrefix: StoreNamespace, options?: StoreSearchOptions): Promise<Array<StoreItem<V>>>;
    /** Namespaces under a prefix. Defaults to 100. */
    listNamespaces(options?: {
        prefix?: StoreNamespace;
        limit?: number;
    }): Promise<string[][]>;
    /** Deletes expired items, returning how many went. Reads already hide them. */
    sweep(): Promise<number>;
    private embed;
}