@bun-win32/Wer

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

Overview

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

It covers two surfaces, both exported from wer.dll:

• Windows Error Reporting (werapi.h) — author a crash/hang/event report (WerReportCreate → WerReportSetParameter/WerReportAddDump/WerReportAddFile → WerReportSubmit), and inspect the on-disk report stores (WerStoreOpen/WerStoreGetReportCount/WerStoreGetFirstReportKey/WerStoreQueryReportMetadataV2/…).
• Wait Chain Traversal (wct.h) — OpenThreadWaitChainSession + GetThreadWaitChain + CloseThreadWaitChainSession: the kernel deadlock-detection API that walks which thread is blocked on which lock and reports cycles.

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

Features

• Bun-first ergonomics on Windows 10/11.
• Direct FFI to wer.dll (Windows Error Reporting report authoring/stores and Wait Chain Traversal deadlock detection).
• In-source docs in structs/Wer.ts with links to Microsoft Docs.
• Lazy binding on first call; optional eager preload (Wer.Preload()).
• No wrapper overhead; calls map 1:1 to native APIs.
• Strongly-typed Win32 aliases (see types/Wer.ts).

Requirements

• Bun runtime
• Windows 10 or later

Installation

bun add @bun-win32/wer

Quick Start

import Wer, { REPORT_STORE_TYPES } from '@bun-win32/wer';

// How many crash reports are queued machine-wide, and how big are they?
const storeOut = Buffer.alloc(8);
if (Wer.WerStoreOpen(REPORT_STORE_TYPES.E_STORE_MACHINE_QUEUE, storeOut.ptr!) === 0) {
  const hStore = storeOut.readBigUInt64LE(0);

  const countOut = Buffer.alloc(4);
  Wer.WerStoreGetReportCount(hStore, countOut.ptr!);

  const sizeOut = Buffer.alloc(8);
  Wer.WerStoreGetSizeOnDisk(hStore, sizeOut.ptr!);

  console.log(`${countOut.readUInt32LE(0)} queued reports, ${sizeOut.readBigUInt64LE(0)} bytes`);
  Wer.WerStoreClose(hStore);
}

// Open a Wait Chain Traversal session (deadlock detection).
const session = Wer.OpenThreadWaitChainSession(0, null); // bigint; 0n on failure
if (session !== 0n) Wer.CloseThreadWaitChainSession(session);

[!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/deadlock-detector.ts
bun run example/crash-report-forensics.ts

• deadlock-detector.ts — spins up two real OS worker threads that wedge on a mutual mutex deadlock, then uses Wait Chain Traversal to X-ray every thread in the process live, rendering an animated ANSI thread radar and the wedged pair's wait chain.
• crash-report-forensics.ts — opens all four WER report stores, counts/measures every queued and archived crash report, enumerates each report key, and prints an aligned forensic dossier with a fault-family histogram.

Notes

• Either rely on lazy binding or call Wer.Preload().
• Windows only. Bun runtime required.