[BUG] Windows: ECONNRESET on first Claude Code prompt despite working HTTPS

### Preflight Checklist

- [x] I have searched [existing issues](https://github.com/anthropics/claude-code/issues?q=is%3Aissue%20state%3Aopen%20label%3Abug) 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?

[claude-code-bug-report.md](https://github.com/user-attachments/files/32141423/claude-code-bug-report.md)

[claude-code-bug-report.md](https://github.com/user-attachments/files/32141433/claude-code-bug-report.md)

## Environment

- OS: Windows 11
- Claude Code CLI: 2.1.268
- VS Code extension: Claude Code 2.1.269
- Node.js: v22.13.0
- Installation: official winget/native Windows installer

## Problem

Claude Code fails already on the first prompt with:

Connection dropped (ECONNRESET)

The issue occurs in multiple projects and also when using a mobile hotspot.

## Network tests

The following work correctly:

- DNS resolution for api.anthropic.com
- TCP connection to port 443
- TLS handshake
- curl request to https://api.anthropic.com/
- Node HTTPS request to https://api.anthropic.com/

No HTTP_PROXY, HTTPS_PROXY or custom CA environment variables are configured.

## Debug log

The Claude Code debug log contains:

- mTLS: Creating HTTPS agent with custom certificates
- Policy limits: fetch failed (http) from api.anthropic.com - socket hang up
- API REQUEST /v1/messages
- API error: Connection error
- ECONNRESET
- CCRClient: unknown certificate verification error
- SSETransport: socket connection was closed unexpectedly

The issue is reproducible before any project-specific operation is performed.

### What Should Happen?

Claude Code should maintain a stable connection and complete the first prompt successfully. The request should not fail with ECONNRESET, socket hang up, or certificate verification errors. Bootstrap, policy checks, MCP registry, CCR/SSE streaming, and /v1/messages should complete normally, with retries only for genuine transient failures.

### Error Messages/Logs

```shell

```

### Steps to Reproduce

1. Install Claude Code CLI 2.1.268 on Windows.
2. Sign in with a valid Claude account.
3. Open PowerShell in any project directory.
4. Start Claude Code with:
```powershell
claude --debug --debug-file "$env:TEMP\claude-debug.log"
```
5. Enter a minimal prompt such as:
```text
ciao
```
6. Wait for the request to start.
7. The connection fails immediately or after a short delay with:
```text
Connection dropped (ECONNRESET)
```
8. Claude retries the request repeatedly and eventually reports a connection error.
9. Repeat the same test in a different project or using a mobile hotspot. The issue remains reproducible.

### Claude Model

Opus

### Is this a regression?

Yes, this worked in a previous version

### Last Working Version

_No response_

### Claude Code Version

2.1.268 (Claude Code)

### Platform

Anthropic API

### Operating System

macOS

### Terminal/Shell

Terminal.app (macOS)

### Additional Information

_No response_

Start by reproducing through the `claude --debug --debug-file` PowerShell entry point and inspect the debug log around bootstrap, policy checks, MCP registry, CCR/SSE streaming, and `/v1/messages`. Done means the first prompt completes reliably on Windows without ECONNRESET, socket hang-up, or certificate-verification errors, while retries remain limited to genuine transient failures.

索引モデルが issue の本文から書いたものです。