[Bug] Voice connection fails with WebSocket upgrade on macOS despite network connectivity

Bug Description
Voice fails in both Claude Code and Claude desktop app with "Voice connection failed. Check your network and try again." Voice mode fails identically in both Claude Code (CLI) and the Claude desktop app on macOS. Both apps connect/work fine for everything else — only voice fails. Ruled out locally: - No VPN, proxy, corporate network, or DNS filtering - macOS firewall disabled; no Little Snitch / Lulu / similar - iCloud Private Relay not active; only en0 carries traffic - HTTPS to api.anthropic.com works fine; WebSocket upgrade succeeds - Anthropic status page shows all systems operational - Microphone permission granted (confirmed in ~/Library/Logs/Claude/main.log) - Fresh OAuth login on both apps after sign-out (didn't help) Desktop app log evidence: Renderer hits Web Audio API (ScriptProcessorNode is deprecated warning fires when voice initializes), then connection fails silently — no error logged on the renderer, only the UI message. Environment: - macOS 26 (Darwin 25.4.0) - Claude Code v2.1.123 (native installer) - Claude desktop app: latest - Both apps freshly signed in

Environment Info

• Platform: darwin
• Terminal: iTerm.app
• Version: 2.1.123
• Feedback ID: 9ea5aabc-a0a7-466b-ae04-aa2565824e7b

Errors

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