[BUG] known_marketplaces.json causes silent freeze on startup (Windows, v2.1.70)

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?

Environment

• OS: Windows 11 (64-bit)
• Claude Code version: 2.1.70
• Installation: native (~/.local/bin/claude.exe)

Description
Claude Code freezes silently on startup whenever ~/.claude/plugins/known_marketplaces.json exists, regardless of its content. No error message, no timeout, no crash — the window opens and hangs indefinitely.

What Should Happen?

Root cause identified
The file references a GitHub marketplace source (anthropics/claude-plugins-official). Claude Code appears to make a blocking network call with no timeout on startup to check for marketplace updates. Even after removing the GitHub entry and keeping only a "source": "local" entry, the freeze persists.

Error Messages/Logs

Steps to Reproduce

Reproduction steps

1. Create ~/.claude/plugins/known_marketplaces.json with any content
2. Launch claude.exe
3. Window opens, no output, hangs indefinitely

Workaround
Delete known_marketplaces.json. Claude Code starts normally. The file must not be restored.

Expected behavior
Claude Code should handle unreachable marketplace sources gracefully — either with a timeout, a warning, or degraded mode startup. A missing or unreachable source should never block the entire application.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.71 (Claude Code)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

_No response_