Coding Agents in the Browser

KAS is a small coding agent that runs entirely client‑side. It uses OPFS for a safe, local file sandbox. KAS can search, read, patch, and generate files with user approval.

KAS is available as the @pstdio/kas package.

What KAS Can Do

KAS provides a complete coding agent that can:

• Search and explore files using grep, ls, and tree operations
• Read and analyze code, documents, and binary files
• Patch and modify existing files with precise edits
• Create new files and directory structures
• Run shell commands in a safe OPFS environment
• Request approval for destructive operations

Key Features

• Browser-first: Runs entirely in the browser using OPFS
• Safe sandbox: All operations contained within OPFS workspace
• Approval gates: User consent required for file modifications
• Streaming responses: Real-time conversation updates
• Conversation adapters: Easy integration with UI frameworks

Quick Example

import { createKasAgent } from "@pstdio/kas";

const agent = createKasAgent({
  model: "gpt-5-mini",
  apiKey: "your-openai-key",
  workspaceDir: "/projects/my-app",
  requestApproval: async ({ tool, workspaceDir, detail }) => {
    return confirm(`Allow ${tool} in ${workspaceDir}?`);
  },
});

// Use with conversation
for await (const response of agent(messages)) {
  console.log(response);
}

Try It Out

• Quick Start Guide - Set up KAS in your app
• Live Playground - Try KAS in action
• Package Documentation - Complete API reference