Plugin marketplace add fails to clone repository when 1Password SSH agent is configured

Description

/plugin marketplace add obra/superpowers consistently fails with:

Error: Failed to clone marketplace repository:

No additional error details are shown to the user.

Environment

• Claude Code version: 2.1.32
• OS: macOS (Darwin 25.2.0)
• Git signing: Configured with 1Password SSH agent (op-ssh-sign)

``
gpg.format=ssh
gpg.ssh.program=/Applications/1Password.app/Contents/MacOS/op-ssh-sign
``

Debug Log Analysis

From the session debug log, the sequence is:

1. SSH clone is attempted and fails:

``
[INFO] SSH clone failed for obra/superpowers despite SSH being configured, falling back to HTTPS
``

1. HTTPS fallback also silently fails (no error logged)
2. User sees: Error: Failed to clone marketplace repository:

This pattern repeats for every attempt, whether using obra/superpowers or obra/superpowers-marketplace.

What works

• git clone https://github.com/obra/superpowers works perfectly from the terminal
• ssh -T git@github.com authenticates successfully
• SSH_AUTH_SOCK="" git clone https://github.com/obra/superpowers also works (HTTPS without SSH agent)
• Other plugin marketplaces install fine (e.g., chime-claude-plugins from a private GitHub repo)

Attempted workarounds (none resolved)

1. Unsetting git URL rewrite: git config --global --unset url.git@github.com:.insteadOf
2. Disabling sandbox in Claude Code settings
3. Multiple restart/reinstall cycles

Suspected cause

Claude Code's internal git clone subprocess likely cannot communicate with the 1Password SSH agent, causing the SSH attempt to fail. The HTTPS fallback then also fails for an unknown reason within the sandboxed/subprocess context. The error message is empty, making it difficult for users to diagnose.

Suggestions

1. Log the actual error from both the SSH and HTTPS clone attempts in the debug log
2. Ensure the HTTPS fallback doesn't inherit SSH-related environment that could interfere
3. Surface more detail in the user-facing error message