GitHub Copilot OAuth succeeds but provider is never registered ("Provider not found: github-copilot")

Description

GitHub Copilot OAuth login appears to succeed, but OpenCode never registers the provider.

I successfully authenticate with GitHub Copilot using the device flow. After authorizing in the browser, OpenCode reports that the login completed and opencode providers list shows:

• GitHub Copilot (oauth)

However, the provider cannot actually be used.

Running:

opencode models github-copilot

always returns:

Error: Provider not found: github-copilot

As a result, I cannot select or use GitHub Copilot even though the OAuth credentials are stored successfully.

I also verified that:

• GitHub Copilot Student is active on my GitHub account.
• The OAuth credentials exist in ~/.local/share/opencode/auth.json.
• Re-authenticating multiple times does not fix the issue.
• Upgrading OpenCode to the latest version does not fix the issue.

Plugins

None

OpenCode version

1.18.16

Steps to reproduce

1. Install OpenCode 1.18.16 on macOS.
2. Run OpenCode and choose GitHub Copilot as the provider.
3. Complete the GitHub device OAuth flow successfully.
4. Verify that opencode providers list shows "GitHub Copilot (oauth)".
5. Run opencode models github-copilot.
6. Observe the error: Provider not found: github-copilot.
7. GitHub Copilot cannot be selected or used despite successful authentication.

Screenshot and/or share link

No response

Operating System

macOS Tahoe 26.5.1 (Apple Silicon)

Terminal

Apple terminal