Sandbox Isolation

Nebula provides a completely isolated sandbox environment for each miniapp. Different miniapps cannot access each other's files, storage, or runtime state.

Isolation Levels

File System Isolation

Each miniapp's file operations are restricted to its own sandbox directory:

Documents/MiniApps/
├── app-a/                 # Miniapp A's sandbox
│   ├── index.bundle
│   ├── app.json
│   └── storage/
├── app-b/                 # Miniapp B's sandbox
│   ├── index.bundle
│   ├── app.json
│   └── storage/

• Miniapp A cannot read or write to Miniapp B's directory
• All operations of the file system API (getFileSystemManager()) are confined to the current miniapp's sandbox path
• Cannot access the host application's private directories

Storage Isolation

Key-value storage is isolated by appId:

• Each miniapp has an independent 10 MB storage quota
• APIs like setStorage / getStorage are automatically scoped
• Different miniapps using the same key do not interfere with each other's data

// In miniapp A
await Miniapp.setStorage({ key: 'token', data: 'abc' });

// In miniapp B
const result = await Miniapp.getStorage({ key: 'token' });
// result.data is empty or B's own stored value; cannot read A's data

Runtime Isolation

Each miniapp has its own independent runtime environment:

Bundle Isolation

• Each miniapp loads its own JS bundle file
• JavaScript modules are not shared
• Miniapps cannot call functions or access variables from each other

Information Available Inside Sandbox

Miniapps can query their own sandbox information but cannot access other miniapps' data:

import { Miniapp } from '@nebula-rn/sdk';

// Get current miniapp's appId
const appId = Miniapp.getAppId();

// Get sandbox path
const sandboxPath = Miniapp.getSandboxPath();

// Get device info (shared across all miniapps, read-only)
const deviceInfo = Miniapp.getDeviceInfo();

Cross-Miniapp Communication

Miniapps cannot communicate directly with each other. To exchange data, it must go through the host:

Miniapp A  →  postMessageToHost()  →  Host  →  postMessageToMiniApp()  →  Miniapp B

See Host-Miniapp Messaging for details.

Security Boundaries