@bun-win32/wuapi

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

Overview

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

wuapi.dll is the Windows Update Agent COM server. Its only flat exports are the four standard in-process COM server entry points (DllCanUnloadNow, DllGetClassObject, DllRegisterServer, DllUnregisterServer). The Windows Update object model — IUpdateSession, IUpdateSearcher, ISearchResult, IUpdateHistoryEntryCollection, ... — is reached via CoCreateInstance(CLSID_UpdateSession) (ProgID Microsoft.Update.Session) and driven over the COM vtable. This package binds the flat exports and re-exports every relevant CLSID, IID, and result/operation enum from types/Wuapi.ts so consumers can drive the object model over FFI (see the examples).

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

Features

• Bun-first ergonomics on Windows 10/11.
• Direct FFI to wuapi.dll (Windows Update Agent COM server).
• In-source docs in structs/Wuapi.ts with links to Microsoft Docs.
• Lazy binding on first call; optional eager preload (Wuapi.Preload()).
• No wrapper overhead; calls map 1:1 to native APIs.
• Strongly-typed Win32 aliases (see types/Wuapi.ts).

Requirements

• Bun runtime
• Windows 10 or later

Installation

bun add @bun-win32/wuapi

Quick Start

import Wuapi, { CLSID_UpdateSession, IID_IUpdateSession } from '@bun-win32/wuapi';

// Flat export: ask the in-process server whether it can unload.
const hr = Wuapi.DllCanUnloadNow(); // 0 = S_OK, 1 = S_FALSE

// The Windows Update object model is reached via COM (CoCreateInstance of
// CLSID_UpdateSession), then driven over the interface vtable. The exported
// CLSID_*/IID_* GUID strings and the OperationResultCode / UpdateOperation /
// ServerSelection enums are all you need to walk it — see the examples for a
// complete, cast-free vtable invoker.
console.log(CLSID_UpdateSession, IID_IUpdateSession);

[!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:update-history-forensics   # exhaustive read-only servicing-history audit
bun run example:patch-constellation        # live animated star map of update history

Notes

• Either rely on lazy binding or call Wuapi.Preload().
• 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.