[aajisaka]

Issue for this PR

Closes #14175

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

The google-vertex-anthropic loader now accepts a bearer token via VERTEX_ANTHROPIC_TOKEN env var or the auth flow. When present, it skips calling Google's auth endpoints. This lets you use Vertex-compatible proxies that handle their own auth.

It also

• fixes the env var fallback chains (project, location, token) to use || instead of ??, since Env.get() returns "" for unset vars — ?? would keep the empty string and skip the fallback.
• fixes the handling of baseURL. Before this fix, the URL is not correctly constructed if the baseURL is configured to non-default value.

How did you verify your code works?

Built locally, setup Google VertexAI with baseURL set to our internal proxy, and verified a few Anthropic models are working. Sample config:

    "google-vertex-anthropic": {
      "name": "Internal proxy",
      "options": {
        "baseURL": "<proxy base URL>",
        "project": "<project name>",
        "location": "<region>",
        "headers": {
          "<header key>": "<header value>",
        },
      },
    },

Screenshots / recordings

N/A

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

If you do not follow this template your PR will be automatically rejected.

[thdxr]

This branch has been upgraded to V2. We're no longer taking PRs for V1. If you think this is still relevant, please port it over and open it for V2.

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