[BUG] /install-github-app does not allow to authenticate to Claude.ai on Windows (subscription model)

Environment

• Platform (select one):
• [x] Anthropic API (Claude Pro)
• [ ] AWS Bedrock
• [ ] Google Vertex AI
• Claude CLI version: 1.0.51 (Claude Code)
• Operating System: Windows 11
• Node version: v22.14.0
• Terminal: Windows Terminal (PowerShell)

Bug Description

I've been trying to set up GitHub Actions on some of my repositories, and unfortunately the /install-github-app command gets stuck on the authentication step – Claude Code does not give me a way to proceed after generating a challenge link to Claude.ai:

1. The browser opens as expected, but Claude does not pass the challenge link to the browser (see the URL in the attached screenshot), resulting in an Invalid OAuth Request. That forces me to copy and paste the challenge from the CLI.

<img width="1920" height="1032" alt="Image" src="https://github.com/user-attachments/assets/8b5fbc05-3f26-4412-9a9b-84ea8e819bad" />

1. When I do, I am able to generate a response token. However, I can't paste it anywhere to proceed.

<img width="1113" height="626" alt="Image" src="https://github.com/user-attachments/assets/126c0b89-1d85-4721-8189-5158e3d94d0d" />

This might be related to (or even a duplicate of) #3233, although I am not running Claude Code in a Linux container, but from a native terminal on Windows instead – that's why I'm creating a separate issue. The common denominator is that we're both trying to use the Claude subscription model in this flow.

Steps to Reproduce

1. Run a clean install on a Windows machine: npm install -g @anthropic-ai/claude-code, setup Claude Code
2. Run the /install-github-app command
3. Configure Claude on GitHub (the browser opens as expected), press Enter
4. Select GitHub workflows to create, press Enter
5. Select "Long lived token with Claude subscription", press Enter

Expected Behavior

One of these two scenarios:

• The browser opens as expected, and the user is allowed to authorize Claude Code on Claude.ai seamlessly;
• If the browser does not open automatically, the user should be able to paste the authentication code – the result of the challenge – in order to continue.

Actual Behavior

The link appears to be broken, so I can't authorize seamlessy. Although I am able to generate a response to the challenge when I copy the link directly from the CLI, there's no way for me to paste the response token.