Voice mode fails with 'voice connection failed' despite working network and mic permissions

Description

/voice enables successfully ("Hold Space to record") but when attempting to record, fails with "voice connection failed. Check your network and try again."

Environment

• Claude Code version: 2.1.75
• OS: macOS Darwin 25.2.0 (Sequoia)
• Shell: zsh
• SoX: installed via Homebrew

Steps to Reproduce

1. Run /voice in Claude Code
2. Voice mode enables: "Voice mode enabled. Hold Space to record."
3. Hold Space to record
4. Error: "voice connection failed. Check your network and try again"

Troubleshooting Attempted

• Network is working — curl to api.anthropic.com succeeds
• Microphone permissions enabled for terminal in System Settings → Privacy & Security → Microphone
• Tested across multiple terminal apps
• Quit other audio apps (Wispr Flow) to rule out mic contention
• Restarted Claude Code multiple times
• SoX is installed and available on PATH
• On latest version (2.1.75)

None of the above resolved the issue.