[BUG] Input freezes on Windows in v2.1.88+, characters buffer and appear all at once (regression from v2.1.86)

Environment

• OS: Windows 10 Pro (10.0.19045)
• Terminal: Windows Terminal + PowerShell 5.1
• Claude Code version: 2.1.89 (affected), 2.1.88 (affected), 2.1.86 (working)
• Node.js: v24.13.0

Description

Claude Code freezes periodically during normal use on Windows. The freeze lasts approximately 10 seconds, after which operation resumes normally. Critically, keyboard input is buffered during the freeze — characters typed during the freeze appear all at once when it unfreezes.

This indicates the Node.js process is blocking the event loop for ~10 seconds, preventing stdin reads. The OS buffers keystrokes and flushes them when the process becomes responsive again.

Reproduction

1. Install Claude Code v2.1.88 or v2.1.89 on Windows
2. Open Windows Terminal with PowerShell
3. Run
4. Start typing — after some characters (~25), input freezes for ~10 seconds
5. All buffered characters appear at once when it unfreezes

Confirmed regression from v2.1.86

Tested by running v2.1.86 via (extracted from npm pack) — no freezing observed on the same machine with the same configuration.

Troubleshooting already ruled out

• ESET antivirus SSL/TLS filtering — disabled entirely, freeze persists
• Custom statusLine command (WSL-based) — removed from settings.json, freeze persists
• — disabled, freeze persists
• (network drive) — removed, freeze persists
• Windows Defender real-time protection — already disabled
• Both Windows Terminal and classic PowerShell window — freeze occurs in both
• Network/DNS latency — tested, responds in ~120ms consistently

Notes

• v2.1.88 does not appear in the CHANGELOG.md, making it difficult to identify what changed
• The freeze happens at startup, during typing, and during tool use (file edits)
• Issue #34457 describes a similar symptom but is caused by MSYS2 hook overhead — this issue persists with all hooks disabled