@cogineai/mafs-browser

Browser / edge-runtime bundle for MAFS — A Unified Virtual File System for AI Agents.

This is the package to use in browser SPAs, Cloudflare Workers, Vercel Edge Functions, Deno Deploy, and other non-Node JavaScript runtimes. It re-exports everything from @cogineai/mafs-core and adds:

• OPFS-backed durable storage (OPFSResource) for in-browser persistence using the Origin Private File System.
• Browser-friendly cloud storage through pre-signed URLs and Workers Driver patterns: S3Resource, R2Resource, GCSResource, OCIResource, SupabaseResource (use S3BrowserPresignedUrlProvider instead of long-lived credentials).
• HTTP transports for SaaS APIs: Slack, Discord, Trello, Linear, Notion, Langfuse, GitHub, GitHub CI, GDocs/GSheets/GSlides/GDrive, Dropbox, Box, Gmail.
• Database resources via HTTP drivers: PostgresResource (Neon Pg driver), MongoDBResource (HttpMongoDriver), VercelResource, PostHogResource, SSCholarPaperResource, SSCholarAuthorResource.

No native bindings, no FUSE, no fs — entirely portable. ~Zero Node-specific code paths in the bundle that ships to your users.

Install

npm install @cogineai/mafs-browser

Bundlers (Vite, Webpack, Rollup, esbuild, …) will pick the browser ESM entry automatically.

Quick start — in-memory agent sandbox

import { MountMode, RAMResource, Workspace } from '@cogineai/mafs-browser'

const ws = new Workspace({ '/': new RAMResource() }, { mode: MountMode.WRITE })

await ws.fs.writeFile('/notes.md', '# scratchpad\n')
await ws.execute('echo "- bullet" >> /notes.md')
const notes = await ws.fs.readFileText('/notes.md')
console.log(notes)

await ws.close()

Quick start — durable in-browser storage with OPFS

import { MountMode, OPFSResource, Workspace } from '@cogineai/mafs-browser'

const ws = new Workspace({ '/': await OPFSResource.create() }, { mode: MountMode.WRITE })

// Files written here survive page reloads.
await ws.fs.writeFile('/state.json', JSON.stringify({ ok: true }))

await ws.close()

Quick start — read-only S3 via presigned URLs

In a browser you should never ship long-lived AWS credentials. Use a presigned-URL provider that fetches short-lived URLs from your backend:

import {
  MountMode,
  S3Resource,
  type S3BrowserPresignedUrlProvider,
  Workspace,
} from '@cogineai/mafs-browser'

const presigned: S3BrowserPresignedUrlProvider = {
  async sign({ key, operation }) {
    const res = await fetch('/api/s3/presign', {
      method: 'POST',
      body: JSON.stringify({ key, operation }),
    })
    return (await res.json()).url
  },
}

const ws = new Workspace(
  {
    '/s3': new S3Resource({
      bucket: 'public-reports',
      browser: { presigned },
    }),
  },
  { mode: MountMode.READ },
)

const lines = await ws.execute('grep alert /s3/2026/05/report.csv | wc -l')
console.log(lines.stdoutText)

What's exported beyond mafs-core

The full list lives in packages/mafs/typescript/packages/browser/src/index.ts. Notable additions:

• OPFSResource, OPFSAccessor, OPFS_OPS, OPFS_COMMANDS, OPFS_PROMPT
• S3Resource with S3_BROWSER_PROMPT and S3BrowserPresignedUrlProvider
• R2Resource, R2_BROWSER_PROMPT, plus the r2ToS3Config(), ociToS3Config(), gcsToS3Config(), supabaseToS3Config() adapters that let you route alternate S3-compatible providers through one resource implementation
• PostgresResource + NeonPgDriver (HTTP-only Postgres driver — works in Workers / Edge)
• MongoDBResource + HttpMongoDriver
• SSCholarPaperResource + HttpSSCholarDriver
• VercelResource + HttpVercelDriver
• PostHogResource + HttpPostHogDriver
• NotionResource (browser-friendly MCP transport)
• All HTTP-only SaaS resources (Slack, Discord, Trello, Linear, Langfuse, GitHub, …)

What's not here (and lives in @cogineai/mafs-node instead):

• DiskResource, FUSE, native shell exec, native RedisResource/RedisStore, IMAP/SMTP EmailResource, local audio (sherpa-onnx-node), node-postgres-backed Postgres.

Companion packages

• @cogineai/mafs-cli — coginex + mafs binaries.
• @cogineai/mafs-core — runtime-agnostic primitives.
• @cogineai/mafs-node — Node-specific bundle.
• @cogineai/mafs-server — mafs-daemon HTTP server (you can talk to it from a browser to access Node-only resources).
• @cogineai/mafs-agents — agent framework adapters.

License & attribution

Apache-2.0. MAFS is a fork of Mirage; see the project-level NOTICE for attribution and the relationship to upstream.