Marketplace add/plugin install for Claude Code uses SSH for public GitHub repos (including this one), but fails without SSH keys configured

[spiveym]

I've been unable to install this marketplace via Claude Code (v2.1.45, macOS Darwin 25.2.0) using the methods provided here. This is a public repo that should require zero authentication, but both HTTPS and SSH clone attempts fail silently. I could install via a manual workaround, but this appears to be a more pervasive issue.

Repro

claude plugin marketplace add anthropics/knowledge-work-plugins

Output

  Adding marketplace...
  SSH not configured, cloning via HTTPS: https://github.com/anthropics/knowledge-work-plugins.git
  Refreshing marketplace cache…
  Cloning repository: https://github.com/anthropics/knowledge-work-plugins.git
  HTTPS clone failed, retrying with SSH: git@github.com:anthropics/knowledge-work-plugins.git
  Refreshing marketplace cache…
  Cloning repository: git@github.com:anthropics/knowledge-work-plugins.git
  ✘ Failed to add marketplace: Failed to clone marketplace repository:

I get the same result with:

• /plugin marketplace add anthropics/knowledge-work-plugins (TUI)
• /plugin marketplace add https://github.com/anthropics/knowledge-work-plugins.git (full URL)
• /plugin marketplace add /tmp/test-kwp (local clone — blocked by reserved name validation)

Environment

• git clone https://github.com/anthropics/knowledge-work-plugins.git works fine from the terminal
• gh auth status shows authenticated (keyring, HTTPS protocol)
• gh auth setup-git run, no effect
• GITHUB_TOKEN exported via gh auth token, no effect
• GIT_TRACE=1 and GIT_TRACE=/tmp/file produce no output — suggesting Claude Code is not invoking system git at all
• Git credential helper: osxkeychain

Root cause

This appears to be a Claude Code clone subprocess bug, not an issue with this repo. However I believe this needs eyes aside from the issues that were filed upstream at anthropics/claude-code#18001 (see also anthropics/claude-code#13553).