Local AI Session Routing: Connecting Multi-Model Workflows Safely

1. The Multi-Model Routing Challenge

Modern software engineering workflows increasingly require different AI models for different programming tasks. An engineer might prefer Claude 3.5 Sonnet for complex refactoring and AST transformations, ChatGPT-4o for rapid code explanations, DeepSeek R1 for algorithmic proofs, and Perplexity for querying live framework documentation.

However, managing four independent AI models locally introduces severe security and operational challenges:

• Cookie & State Collisions: If models run inside a shared browser environment or single cookie jar, cross-origin scripts and authentication tokens can leak between provider contexts.
• Insecure Key Storage: Storing raw API tokens in plain-text .env or JSON configuration files leaves developer credentials vulnerable to malicious npm packages or repository leakage.
• Latency & Interception: Passing requests through intermediate cloud relays introduces latency and violates enterprise data compliance mandates.

Proxima resolves this through a Local-First Routing Engine combining Electron partition sandboxing, hardware-backed OS keychain encryption, and a local loopback IPC socket.

2. Sandboxed Partition Isolation (persist:*)

In Proxima's desktop core (proxima/electron/main-v2.cjs), each AI provider session is allocated a dedicated, persistent Electron session.fromPartition() partition.

The four isolated web session partitions are:

• persist:chatgpt — Sandboxed OpenAI conversational container
• persist:claude — Isolated Anthropic session storage
• persist:gemini — Sandboxed Google AI workspace
• persist:perplexity — Isolated search and real-time citation context

const { session, BrowserWindow } = require('electron');

// Initializing Isolated Session Partitions with Strict Local Boundaries
function createProviderView(providerId) {
  const ses = session.fromPartition(`persist:${providerId}`, {
    cache: true
  });

  // Strict CSP & WebSecurity Enforcements
  ses.setPermissionRequestHandler((webContents, permission, callback) => {
    // Explicitly deny camera, microphone, geolocation, and notification permissions
    const allowedPermissions = ['clipboard-read'];
    return callback(allowedPermissions.includes(permission));
  });

  return ses;
}

Because partitions are completely isolated by Chromium's storage layer, IndexedDB caches, localStorage records, cookies, and HTTP connection pools are segregated. A script or token inside the persist:chatgpt partition cannot read or inspect memory from persist:claude.

3. Loopback IPC Bridge (Port 19222)

The Model Context Protocol (MCP) server runs as a separate Node.js child process spawned by your IDE over standard input/output. To route tool invocations from the MCP process to the active Electron provider window, Proxima uses an internal loopback TCP socket on port 19222.

import net from 'net';

const IPC_PORT = process.env.PROXIMA_IPC_PORT || 19222;

export function sendToElectron(payload) {
  return new Promise((resolve, reject) => {
    const client = net.createConnection({ port: IPC_PORT, host: '127.0.0.1' }, () => {
      client.write(JSON.stringify(payload) + '\n');
    });

    let rawData = '';
    client.on('data', (chunk) => {
      rawData += chunk.toString();
      if (rawData.endsWith('\n')) {
        client.end();
        try {
          const parsed = JSON.parse(rawData.trim());
          resolve(parsed);
        } catch (e) {
          reject(new Error(`Malformed IPC response: ${e.message}`));
        }
      }
    });

    client.on('error', (err) => {
      reject(new Error(`IPC Bridge connection error on port ${IPC_PORT}: ${err.message}`));
    });
  });
}

4. Hardware-Backed Encryption via Electron SafeStorage

When developers choose to use API keys instead of browser sessions, credentials must be stored securely. In proxima/electron/api/byok/keys.cjs, Proxima leverages Electron’s safeStorage API to encrypt API keys before persisting them to disk (byok.json).

SafeStorage delegates cryptography directly to the host operating system's native hardware-backed credential vaults:

• Windows: Data Protection API (DPAPI) tied to user account cryptographic keys.
• macOS: Apple Keychain with AES-128 encryption.
• Linux: Secret Service API or GNOME Keyring / KWallet.

const { safeStorage } = require('electron');
const fs = require('fs/promises');
const path = require('path');

// Encrypt API key using OS keychain before writing to ~/.proxima/byok.json
async function saveApiKey(provider, rawApiKey) {
  if (!safeStorage.isEncryptionAvailable()) {
    throw new Error('OS Keychain encryption (SafeStorage) is not available on this platform.');
  }

  const encryptedBuffer = safeStorage.encryptString(rawApiKey);
  const base64Cipher = encryptedBuffer.toString('base64');

  const configPath = path.join(process.env.USERPROFILE || process.env.HOME, '.proxima', 'byok.json');
  let currentKeys = {};
  try {
    const raw = await fs.readFile(configPath, 'utf8');
    currentKeys = JSON.parse(raw);
  } catch {
    currentKeys = {};
  }

  currentKeys[provider] = base64Cipher;
  await fs.writeFile(configPath, JSON.stringify(currentKeys, null, 2), 'utf8');
  return { success: true, provider };
}

// Decrypt API key on-demand during request execution
async function getApiKey(provider) {
  const configPath = path.join(process.env.USERPROFILE || process.env.HOME, '.proxima', 'byok.json');
  const raw = await fs.readFile(configPath, 'utf8');
  const keys = JSON.parse(raw);

  if (!keys[provider]) return null;

  const buffer = Buffer.from(keys[provider], 'base64');
  return safeStorage.decryptString(buffer);
}

5. The 12 BYOK Providers Pipeline

A codebase audit confirms that Proxima provides built-in adapter modules for exactly 12 BYOK Providers:

6. Engineering Trade-offs: Web Sessions vs BYOK API Keys

Selecting between Web Session Routing and BYOK API keys depends on your team's workflow requirements:

7. Failure Analysis & Troubleshooting

8. Architectural Takeaways

By combining strict Electron partition sandboxing, OS keychain encryption with SafeStorage, and a loopback IPC bridge on port 19222, Proxima delivers multi-model AI routing with rigorous local security boundaries.