Describe the bug

When using an unauthenticated cursor-agent the error returned is Some(1), which doesn't indicate to the user the steps required to rectify the error. Although likely not a common scenario if the user is already using cursor-agent, goose should indicate when the configuration is incorrect.

To Reproduce
Steps to reproduce the behavior:

1. Run cursor-agent logout if logged in
2. Launch Goose with the cursor-agent provider
3. Attempt to start a chat

Expected behavior
Goose error should point the user towards the cursor authentication flow.

Please provide following information:

• OS & Arch: MacOS 26.1 Beta (25B5062e)
• Interface: UI
• Version: v1.11.0
• Extensions enabled: todo, developer, extension-manager
• Provider & Model: cursor-agent auto