Startup hangs for 60s+ on versions 2.1.50-2.1.52 (regression from 2.1.44)

Description

Claude Code hangs during startup for 60+ seconds on versions 2.1.50, 2.1.51, and 2.1.52. A session launched on 2.1.44 (Feb 17) continues to work fine within the same environment.

Reproduction

1. Launch claude --dangerously-skip-permissions (or just claude)
2. Process enters sleep state and never renders the UI
3. Must be killed manually — Ctrl+C doesn't work reliably

This was tested with all optional features disabled (hooks, statusline, MCP servers, plugins) — still hangs. The issue is in core startup.

Diagnostics

• Works: 2.1.44 (long-running session from Feb 17 still functional)
• Hangs: 2.1.50, 2.1.51, 2.1.52

Process state during hang

lsof shows the process establishes TCP connections to:

• Anthropic API (160.79.104.10:443) — 4 connections, all ESTABLISHED
• GitHub CDN (cdn-185-199-111-133.github.com:443) — 1 connection, ESTABLISHED
• No MCP server connections attempted yet

sample shows the main thread blocked in the event loop (kevent64 in the HTTP Client thread). The process never progresses past this point.

Latency from this network

• Anthropic API: ~70ms (fast)
• GitHub CDN: ~1.2s (slow but not timeout-level)

Config stripped during testing

All of these were disabled individually and in combination — no effect:

• statusLine (custom bash script)
• hooks (4 PreToolUse/PostToolUse hooks)
• mcpServers (3 HTTP MCP servers on localhost)
• enabledPlugins (6 plugins)

With a completely minimal settings.json (only permissions and model), the hang persists.

Environment

• OS: macOS 26.2 (Darwin 25.2.0), ARM64 (Apple Silicon)
• Shell: zsh 5.9
• Node: Bun runtime (bundled in Claude Code binary)
• Network: Corporate network, GitHub CDN is slow (~1.2s) but reachable

Expected behavior

Claude Code should start within a few seconds, as it did on 2.1.44.