Model Availability and Auth Integration

[gsquared94]

Model Availability and Auth Integration

Summary

Visual agent requires Computer Use model, which may not be available on all auth
tiers. Communicate limitations clearly and fall back gracefully.

Description

The Computer Use model (required for visual delegation) has different
availability depending on authentication mode. When the visual agent is
unavailable, the browser agent should:

1. Detect the limitation before attempting visual delegation
2. Provide a clear error message explaining why
3. Suggest alternatives (e.g., more specific element descriptions)
4. Continue operating in semantic-only mode

When delegate_to_visual_agent is called but visual agent unavailable:

Error: Visual agent requires Computer Use model access.
Suggestion: Describe the element more specifically so semantic tools can locate it.

Acceptance Criteria

• Auth mode detection for model availability
• Model availability check before visual delegation
• Clear error message with helpful suggestion
• Semantic-only fallback works correctly

[jerop]

@gemini-cli /triage

[gemini-cli]

This is a medium-priority feature request to improve error handling and fallback when the visual agent model is unavailable due to authentication tiers.