Claude Code 2.1.15 crashes on Windows 11 with Bun segmentation fault (address 0x113)

Environment

| Component | Value |
|-----------|-------|
| OS | Windows 11 x64 |
| Claude Code Version | 2.1.15 |
| Bundled Bun Version | 1.3.6 (d530ed99) |
| CPU | AVX512 capable (sse42 avx avx2 avx512) - running in baseline mode |
| Interface | VS Code Extension |
| Binary Path | c:\Users\...\extensions\anthropic.claude-code-2.1.15-win32-x64\resources\native-binary\claude.exe |

Description

Claude Code crashes immediately after initialization with a Bun runtime segmentation fault. The crash is 100% reproducible - the extension attempts to restart and crashes again with identical symptoms.

The extension successfully completes:

• MCP config loading
• Permission rules application (71 allow rules)
• Skills loading
• Todo file creation
• Error log sink initialization

Then crashes before it can handle any user requests.

Error Message

============================================================
Bun v1.3.6 (d530ed99) Windows x64 (baseline)
Windows v.win11_dt
CPU: sse42 avx avx2 avx512
Args: "...\claude.exe" "--output-format" "stream-json" "--verbose" "--input-format" "stream-json" "--max-thinking-tokens" "0" "-"...
Features: Bun.stderr(2) Bun.stdin(2) Bun.stdout(2) fetch jsc spawn(5) standalone_executable 
Builtins: "bun:main" "node:assert" "node:async_hooks" "node:buffer" "node:child_process" ...

Elapsed: 3128ms | User: 2500ms | Sys: 1250ms
RSS: 0.53GB | Peak: 0.53GB | Commit: 0.55GB | Faults: 138437 | Machine: 33.71GB

panic(main thread): Segmentation fault at address 0x113
oh no: Bun has crashed. This indicates a bug in Bun, not your code.

panic: Segmentation fault at address 0x113
panicked during a panic. Aborting.

Bun Crash Report URL

https://bun.report/1.3.6/e_1d530ed9GugogCCWctiuser.dllgyngBCWctiuser.dllo68fCYKERNEL32.DLLsu+JCcKERNELBASE.dll+5gmBCcKERNELBASE.dllspjlBCYKERNEL32.DLLotjPCWctiuser.dllu3ueoqmvuBiyhtD+h2xf29hpf__qyuytCA2AmR

Stack Trace Analysis

The crash report URL reveals involvement of:

• ctiuser.dll - Windows CTF (Collaborative Translation Framework) / Text Input component
• KERNEL32.DLL - Windows core library
• KERNELBASE.DLL - Windows base API library

This suggests the crash may be related to Windows text input/IME handling during Bun's initialization or I/O setup.

Steps to Reproduce

1. Install Claude Code extension 2.1.15 on VS Code (Windows 11)
2. Open any workspace
3. Extension activates and begins initialization
4. Crash occurs ~3 seconds after spawn, before any user interaction

Additional Context

• The crash happens twice in succession as the extension auto-restarts
• Both crashes have identical memory addresses (0x113) and stack traces
• Memory usage at crash: RSS 0.53GB, Peak 0.53GB
• Page faults at crash: ~138,000
• Machine has 33.71GB RAM available

Expected Behavior

Claude Code should initialize and become ready to accept user prompts.

Actual Behavior

Claude Code crashes with a Bun segmentation fault before becoming usable.

Workaround Attempted

• Reviewed existing documentation
• No workaround found

Request

This appears to be a Bun runtime issue on Windows 11 that affects Claude Code's bundled binary. Would appreciate guidance on:

1. Any known workarounds for this specific crash
2. Whether an updated Bun version in a future Claude Code release might address this
3. Any environment variables or configuration that might help avoid this crash path