[BUG] Bun startup segfault on Windows 11 26200 + Intel Meteor Lake (Core Ultra 5 135U) — reproduced on current 2.1.170; prior report #55219 auto-closed as stale

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Why this is not a duplicate
#55219 documented this crash family but was auto-closed as stale by github-actions last week ("Please open a new issue if this is still relevant"). It is still relevant: reproduced today on the current npm release (2.1.170). This report also adds a hardware data point the prior issues don't cover — Intel Meteor Lake (Core Ultra 5 135U) on Windows 11 — which complicates the Windows-10 Thread Director theory proposed in #51477.

Description
Claude Code crashes immediately on launch with a Bun runtime segmentation fault. claude --version prints normally, but claude and claude doctor panic before any UI renders. 100% reproducible.

Environment
Claude Code: 2.1.170 (npm global install) — also reproduced on 2.1.165
Working versions: 2.1.110 and earlier (Node-based builds); 2.1.110 currently pinned as workaround
OS: Windows 11, build 10.0.26200.8457
Hardware: Dell Latitude 5450, Intel Core Ultra 5 135U (Meteor Lake, hybrid P/E-core)
Shell: Git Bash (MINGW64), git 2.51.0.windows.1
Node v22.20.0, npm 10.9.3
Company-managed laptop, Claude Enterprise org

Additional Datapoints

• CPU is AVX2-capable but Bun runs in baseline mode (same profile as #55219).
• Hybrid P/E-core CPU as in #51477 — but on Windows 11, which has Thread Director support, so the Win10 scheduling theory from that issue doesn't fully explain this crash.
• Also affects the Desktop app: Cowork/Code tabs fail every task with "Claude Code process exited with code 3" (error_category: process_crashed in main.log) while chat works — matches #58666. The Cowork VM itself is healthy (network CONNECTED, API REACHABLE, SDK 2.1.161 installed); the bundled Code engine subprocess is what dies.
• Related: #50640 (regression boundary at v2.1.112, where the native Bun binary replaced the Node build), #20148, #11201.

In-product report
Filed via /feedback: ID e5f9ab86-fa0a-4546-803d-c9f22e5198b3. Multiple users in our Enterprise org on differing hardware are affected and filing separately.

Workaround in use
npm install -g @anthropic-ai/claude-code@2.1.110 (loses access to newer models; no equivalent pin exists for Cowork).Project contentRandomCreated by youAdd PDFs, documents, or other text to reference in this project.Content

What Should Happen?

claude and claude doctor should launch the interactive UI, as they do on the Node-based npm builds (2.1.110/2.1.111 and earlier) on this exact same machine. The Bun-based binary should not segfault before any UI renders.

Error Messages/Logs

Bun v1.3.14 (521eedd6) Windows x64 (baseline)
Windows v.win11_dt
CPU: sse42 avx avx2
panic(main thread): Segmentation fault at address 0x40FE0
panic: Segmentation fault at address 0x21B0144FFE8
panicked during a panic. Aborting.

(Crash addresses vary between runs: 0x2505E44FFE8 and 0x177B9A5FFE8 also observed on 2.1.165. First address 0x40FE0 is consistent. Same crash from `claude` and `claude doctor`. Desktop app equivalent: "Claude Code process exited with code 3", error_category: process_crashed in main.log.)

Steps to Reproduce

1. On Windows 11 (build 26200) with an Intel Core Ultra 5 135U, in Git Bash: npm install -g @anthropic-ai/claude-code@latest (2.1.170 at time of filing)
2. Run claude (or claude doctor)
3. Bun panics immediately with a segmentation fault, before any UI renders. 100% reproducible on this machine.
4. Confirm the regression boundary: npm install -g @anthropic-ai/claude-code@2.1.110 — launches normally on the same machine.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.110

Claude Code Version

2.1.170

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Other

Additional Information

Terminal: Git Bash (MINGW64), standalone window — not listed in the dropdown.
Authenticated via Claude Enterprise subscription (claude.ai), not an API key.
In-product report filed via /feedback: ID e5f9ab86-fa0a-4546-803d-c9f22e5198b3.
Multiple users in our Claude Enterprise org (differing Windows hardware) are affected and filing /feedback separately.
Workaround in use: pin npm install to 2.1.110 (loses newer models; no equivalent pin exists for Cowork in the Desktop app).