Many files. Few handles.
Synchronous I/O.

import { OpfsVfsWorker } from '@opfs-vfs/opfs-vfs/worker';

const fs = new OpfsVfsWorker('notes.bin');
try {
  await fs.ready;
  const bytes = await fs.readFileBuffer('/note.txt');
  console.log(new TextDecoder().decode(bytes));
} finally {
  await fs.closeVfs();
}

import { VolumeProvider, useFileContent } from '@opfs-vfs/react';

function Note() {
  const note = useFileContent('/note.txt', { format: 'text' });
  if (note.status === 'pending') return <p>Loading…</p>;
  if (note.status === 'error') return <p role="alert">{note.error.message}</p>;
  return <pre>{note.data}</pre>;
}

export function App() {
  return <VolumeProvider fileName="notes.bin"><Note /></VolumeProvider>;
}

import { Effect, FileSystem, Layer } from 'effect';
import { OpfsFileSystem, Volume } from '@opfs-vfs/effect';

const live = Layer.provide(
  OpfsFileSystem.layer,
  Volume.layer({ fileName: 'notes.bin' }),
);

const readNote = Effect.gen(function* () {
  const fs = yield* FileSystem.FileSystem;
  return yield* fs.readFileString('/note.txt');
}).pipe(Effect.provide(live));

console.log(await Effect.runPromise(readNote));