OpenCode currently supports Claude 3/4 models through various providers, but it's missing support for the latest Claude 4 models (Claude Sonnet 4 and Claude Opus 4) that are now available through Google Vertex AI.

Requested Feature

Please add support for the following new Claude 4 models available through Vertex AI:

Claude Sonnet 4 (claude-sonnet-4)
Claude Opus 4 (claude-opus-4)

Why This Matters

1. Latest AI Capabilities: Claude 4 models offer significant improvements in reasoning, coding assistance, and overall performance
2. Google Vertex AI Integration: These models are officially supported by Google Cloud's Vertex AI platform
3. Enterprise Use Cases: Many organizations use Vertex AI for their AI infrastructure and would benefit from accessing the latest Claude models through OpenCode
4. Competitive Advantage: Supporting the latest models keeps OpenCode current with the rapidly evolving AI landscape

Technical Details

Since OpenCode already supports Vertex AI through:

VERTEXAI_PROJECT environment variable
VERTEXAI_LOCATION environment variable

The implementation should be straightforward by adding the new model identifiers to the existing Vertex AI provider configuration.
Expected Configuration
Users should be able to configure Claude 4 models like this:
{
"agents": {
"coder": {
"model": "claude-sonnet-4",
"maxTokens": 8000
},
"task": {
"model": "claude-opus-4",
"maxTokens": 8000
}
}
}