C:/Program Files/Git/ultraplan fails when GitHub repo is not the origin remote

Description

/ultraplan fails with "Authentication failed while accessing the git_repository source" when the GitHub remote is named something other than origin (e.g., github).

Repro

1. Have a repo with Bitbucket as origin and GitHub as a secondary remote (e.g., github)
2. Install the Claude GitHub App on the GitHub repo
3. Run /ultraplan — fails with auth error

Workaround

Rename the GitHub remote to origin — then it works.

Expected behavior

/ultraplan should check all remotes for a GitHub URL (or allow specifying which remote to use), not assume the repo is always on origin.

Environment

• Windows 11 Pro
• Claude Code CLI