Storage Adapter

interface DatafnStorageAdapter {
  // Record operations
  getRecord(resource: string, id: string): Promise<Record<string, unknown> | null>;
  listRecords(resource: string): Promise<Record<string, unknown>[]>;
  upsertRecord(resource: string, record: Record<string, unknown>): Promise<void>;
  deleteRecord(resource: string, id: string): Promise<void>;
  mergeRecord(resource: string, id: string, partial: Record<string, unknown>): Promise<Record<string, unknown>>;
  findRecords(resource: string, field: string, value: unknown): Promise<Record<string, unknown>[]>;

  // Join row operations (many-many relations)
  listJoinRows(relationKey: string): Promise<Array<Record<string, unknown>>>;
  getJoinRows(relationKey: string, fromId: string): Promise<Array<Record<string, unknown>>>;
  getJoinRowsInverse(relationKey: string, toId: string): Promise<Array<Record<string, unknown>>>;
  upsertJoinRow(relationKey: string, row: Record<string, unknown>): Promise<void>;
  setJoinRows(relationKey: string, rows: Array<Record<string, unknown>>): Promise<void>;
  deleteJoinRow(relationKey: string, from: string, to: string): Promise<void>;

  // Sync state
  getCursor(resource: string): Promise<string | null>;
  setCursor(resource: string, cursor: string | null): Promise<void>;
  getHydrationState(resource: string): Promise<DatafnHydrationState>;
  setHydrationState(resource: string, state: DatafnHydrationState): Promise<void>;

  // Offline changelog
  changelogAppend(entry: Omit<DatafnChangelogEntry, "seq">): Promise<DatafnChangelogEntry>;
  changelogList(options?: { limit?: number }): Promise<DatafnChangelogEntry[]>;
  changelogAck(options: { throughSeq: number }): Promise<void>;

  // Counts for reconcile
  countRecords(resource: string): Promise<number>;
  countJoinRows(relationKey: string): Promise<number>;

  // Lifecycle
  close(): Promise<void>;
  clearAll(): Promise<void>;
  healthCheck(): Promise<{ ok: boolean; issues: string[] }>;
}

type DatafnHydrationState = "notStarted" | "hydrating" | "ready";

type DatafnChangelogEntry = {
  seq: number;          // Monotonic local sequence
  clientId: string;
  mutationId: string;
  mutation: Record<string, unknown>;
  timestampMs: number;
  actorId?: string;     // Audit attribution (who performed the action)
  timestamp?: string;   // ISO 8601
};

type DatafnStorageFactory = (namespace: string) => DatafnStorageAdapter;

import { MemoryStorageAdapter, IndexedDbStorageAdapter } from "@datafn/client";

const memory = new MemoryStorageAdapter();
const idb = new IndexedDbStorageAdapter("my-app-db");

import { ns } from "@datafn/client";

const factory: DatafnStorageFactory = (namespace) =>
  IndexedDbStorageAdapter.createForNamespace("my-app", namespace);