[BUG] **Title**: Claude Code 2.1.233 intermittently stalls ~3 minutes before responding on Windows (client-side, zero network connections during stall)

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?

## Summary
After upgrading from 2.1.227 to 2.1.233, requests intermittently take ~3 minutes before the response appears (and
often fail with "Connection dropped (ECONNRESET) Retrying in 1s attempt 8/10"). The same config and the exact same API
call are fast on 2.1.220 (~4.5s). Colleague on the same Windows + 2.1.233 + same config does NOT see this.

## Environment

• OS: Windows 11 Home (22621), x64
• Claude Code: 2.1.233, npm-global install (native binary)
• Custom endpoint: ANTHROPIC_BASE_URL=https://api.deepseek.com/anthropic (DeepSeek Anthropic-compatible API)
• Model override: deepseek-v4-flash[1M]
• No HTTP(S)_PROXY env, system proxy off, no proxy software running

## Steps to reproduce
Run repeatedly: claude -p "hi" (same settings.json every time).

• ~6 out of 7 runs: response appears after ~3 minutes (180–192s).
• ~1 out of 7 runs: response in ~1 second.

## Key diagnostics (already isolated)

• DeepSeek responds in 1.5–2.5s when the EXACT captured request (identical headers + 92KB body) is replayed via

curl/Node against api.deepseek.com/anthropic/v1/messages. Response is a complete, valid SSE stream including
message_stop.

• During the ~3-minute stall, netstat -ano shows the claude process has ZERO TCP connections — it is NOT

connected to the API, NOT in SYN_SENT, NOT waiting on an established socket. The stall is local client processing, not
a network wait.

• The request sent by 2.1.233 is effectively identical to 2.1.220's (same model, thinking adaptive, effort high,

stream true, same anthropic-beta header; only version/session-id differ).

• claude --version startup is fast (~1.7s) on both 2.1.220 and 2.1.233, so it's not startup.
• 2.1.220 performs the same call in ~4.5s. Machine-specific: reproducible on this machine only.

## Expected behavior
Response time comparable to 2.1.220 (~seconds).

## Actual behavior
Intermittent ~3-minute client-side stall (process alive, no network I/O) before the response completes; during the
stall, connection drops surface as ECONNRESET retries.

What Should Happen?

other

Error Messages/Logs

Steps to Reproduce

otehr

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.1.233

Platform

Other

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_