[BUG]

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?

Claude Code fails to connect to the API on every single command, including a plain "hello" prompt, with "Connection refused — a firewall or proxy may be blocking it (ConnectionRefused)", retrying through all 10 attempts and never succeeding. This happens on every launch, consistently and reproducibly.
Network connectivity itself is confirmed healthy: curl -v https://api.anthropic.com/v1/messages succeeds (TLS 1.3 handshake, HTTP/2, expected 405 response, resolved to 160.79.104.10). The failure is specific to Claude Code's HTTP client, not the network.
Environment Info
Platform: macOS (darwin), Apple Silicon
Architecture: arm64 (confirmed via file $(which claude) — Mach-O 64-bit executable arm64, matches uname -m — arm64, so no architecture mismatch)
Claude Code Version: 2.1.266 (native installer, already latest per claude update)
Terminal: default macOS Terminal

What Should Happen?

Claude Code should connect to the Anthropic API normally, the same way curl does from the identical machine and network.

Error Messages/Logs

✻ Connection refused — a firewall or proxy may be blocking it (ConnectionRefused) · Retrying in 1s · attempt 2/10

Steps to Reproduce

Launch claude
Enter any prompt, e.g. hello
Immediately get Connection refused (ConnectionRefused), retrying, all 10 attempts fail

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.266 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_