citation-evidence/src/engine/index.ts

/**
 * Engine composition root.
 *
 * `createEngine()` wires in-memory repos to the services and shares a single
 * event bus. The app layer holds the returned `Engine` instance and passes
 * its services into the UI.
 *
 * Swapping the repository implementation later (ADR-0005) is a matter of
 * replacing `createInMemoryRepos()` here. The service signatures don't
 * change.
 */

import { createEventBus, type EventBus } from "./events";
import {
  createInMemoryRepos,
  type InMemoryRepos,
} from "./repos";
import {
  createAnnotationService,
  createDocumentService,
  createEvidenceService,
  type AnnotationService,
  type DocumentService,
  type EvidenceService,
} from "./services";

export * from "./events";
export * from "./repos";
export * from "./services";
export * from "./rendering";
export {
  SNAPSHOT_VERSION,
  attachPersister,
  captureSnapshot,
  documentIdsIn,
  restoreFromStorage,
  restoreSnapshot,
  type EngineSnapshot,
  type PersisterOptions,
} from "./persistence";

export interface Engine {
  readonly bus: EventBus;
  readonly repos: InMemoryRepos;
  readonly documents: DocumentService;
  readonly annotations: AnnotationService;
  readonly evidence: EvidenceService;
}

export function createEngine(): Engine {
  const bus = createEventBus();
  const repos = createInMemoryRepos();
  const documents = createDocumentService(repos.documents, repos.representations, bus);
  const annotations = createAnnotationService(repos.annotations, bus);
  const evidence = createEvidenceService(
    repos.evidenceItems,
    (id) => repos.annotations.get(id),
    bus,
  );
  return { bus, repos, documents, annotations, evidence };
}