@bun-win32/uiautomationcore

Zero-dependency, zero-overhead Win32 UIAutomationCore bindings for Bun on Windows.

Overview

@bun-win32/uiautomationcore exposes the documented flat uiautomationcore.dll exports using Bun's FFI. It provides a single class, UIAutomationCore, which lazily binds native symbols on first use. You can optionally preload a subset or all symbols up-front via Preload().

The bindings are strongly typed for a smooth DX in TypeScript.

Features

• Bun-first ergonomics on Windows 10/11.
• Direct FFI to uiautomationcore.dll (UI Automation nodes, pattern objects, provider bridging, and event plumbing).
• In-source docs in structs/UIAutomationCore.ts with links to Microsoft Learn.
• Lazy binding on first call; optional eager preload (UIAutomationCore.Preload()).
• No wrapper overhead; calls map 1:1 to native APIs.
• Strongly-typed Win32 aliases (see types/UIAutomationCore.ts).

Requirements

• Bun runtime
• Windows 10 or later

Installation

bun add @bun-win32/uiautomationcore

Quick Start

import UIAutomationCore from '@bun-win32/uiautomationcore';

UIAutomationCore.Preload(['UiaClientsAreListening', 'UiaGetRootNode', 'UiaNodeRelease']);

console.log('UIA clients listening:', UIAutomationCore.UiaClientsAreListening() !== 0);

const rootNodeBuffer = Buffer.alloc(8);
const result = UIAutomationCore.UiaGetRootNode(rootNodeBuffer.ptr!);

if (result !== 0) {
  throw new Error(`UiaGetRootNode failed: 0x${(result >>> 0).toString(16).padStart(8, '0')}`);
}

const rootNode = rootNodeBuffer.readBigUInt64LE(0);

try {
  console.log('Root node handle:', `0x${rootNode.toString(16)}`);
} finally {
  void UIAutomationCore.UiaNodeRelease(rootNode);
}

[!NOTE] AI agents: see AI.md for the package binding contract and source-navigation guidance. It explains how to use the package without scanning the entire implementation.

Examples

Run the included examples:

bun run example:focus-radar      # animate UIA availability for the foreground window
bun run example:pattern-probe    # inspect common pattern providers on the active window

Notes

• Either rely on lazy binding or call UIAutomationCore.Preload().
• VARIANT and UiaPoint parameters are modeled as caller-packed buffers; allocate the native layout locally and pass .ptr.
• Windows only. Bun runtime required.
• SAL types & naming: nullability is in the type — Optional<T> (formally optional, SAL _*opt_) and Nullable<T> (plain [in]/[out] the docs say can be NULL), the null sentinel derived from T (null for pointers LP*/P*, 0n for handles/by-value addresses); direction is in the parameter name — _out (_Out_), _in_out (_Inout_), _In_ bare. See AI.md and the repo AGENTS.md.