docs(deepagents): add Anthropic Vertex provider setup

src/oss/deepagents/code/providers.mdx

@@ -50,11 +50,12 @@ Using a provider not listed here? See [Arbitrary providers](/oss/deepagents/code
 | Provider | Package | Credential env var | Model profiles |
 | --- | --- | --- | --- |
 | OpenAI | [`langchain-openai`](/oss/integrations/chat/openai) | `OPENAI_API_KEY` | ✅ |
-| OpenAI (Codex) | [`langchain-openai`](/oss/integrations/chat/openai) | None — [sign in with ChatGPT](#sign-in-with-chatgpt) | ✅ |
+| OpenAI (Codex) | [`langchain-openai`](/oss/integrations/chat/openai) | None; [sign in with ChatGPT](#sign-in-with-chatgpt) | ✅ |
 | Azure OpenAI | [`langchain-openai`](/oss/integrations/chat/azure_chat_openai) | `AZURE_OPENAI_API_KEY` | ✅ |
 | Anthropic | [`langchain-anthropic`](/oss/integrations/chat/anthropic) | `ANTHROPIC_API_KEY` | ✅ |
 | Google Gemini API | [`langchain-google-genai`](/oss/integrations/chat/google_generative_ai) | `GOOGLE_API_KEY` | ✅ |
 | Google Vertex AI | [`langchain-google-genai`](/oss/integrations/chat/google_generative_ai#credentials) | `GOOGLE_CLOUD_PROJECT` | ✅ |
+| Google Vertex AI (Anthropic) | [`langchain-google-vertexai`](/oss/integrations/chat/google_anthropic_vertex) | `GOOGLE_CLOUD_PROJECT`, `GOOGLE_CLOUD_LOCATION` | ✅ |
 | Baseten | [`langchain-baseten`](https://github.com/basetenlabs/langchain-baseten) | `BASETEN_API_KEY` | ✅ |
 | AWS Bedrock | [`langchain-aws`](/oss/integrations/chat/bedrock) | `AWS_ACCESS_KEY_ID`, `AWS_SECRET_ACCESS_KEY` | ✅ |
 | AWS Bedrock Converse | [`langchain-aws`](/oss/integrations/chat/bedrock) | `AWS_ACCESS_KEY_ID`, `AWS_SECRET_ACCESS_KEY` | ✅ |
@@ -74,6 +75,53 @@ Using a provider not listed here? See [Arbitrary providers](/oss/deepagents/code
 | OpenRouter | [`langchain-openrouter`](/oss/integrations/chat/openrouter) | `OPENROUTER_API_KEY` | ✅ |
 | LiteLLM | [`langchain-litellm`](/oss/integrations/chat/litellm) | Per-provider (see [docs](https://docs.litellm.ai/)) | ❌ |
 
+<Accordion title="Configure Anthropic models on Vertex AI" icon="brand-google">
+    The `google_anthropic_vertex` provider runs Claude through Anthropic's Messages API on Vertex AI. It uses Google Cloud Application Default Credentials (ADC) instead of an Anthropic API key.
+
+    To use the provider:
+
+    1. Install the Vertex AI extra:
+
+        <CodeGroup>
+            ```txt In session
+            /install vertex
+            ```
+
+            ```bash Shell
+            dcode --install vertex
+            ```
+        </CodeGroup>
+
+    2. [Enable a Claude model in your Google Cloud project](https://cloud.google.com/vertex-ai/generative-ai/docs/partner-models/use-claude), then configure ADC:
+
+        ```bash
+        gcloud auth application-default login
+        ```
+
+    3. Set your Google Cloud project and location:
+
+        ```bash
+        export GOOGLE_CLOUD_PROJECT="your-project-id"
+        export GOOGLE_CLOUD_LOCATION="global"
+        ```
+
+        You can use `DEEPAGENTS_CODE_GOOGLE_CLOUD_PROJECT` and `DEEPAGENTS_CODE_GOOGLE_CLOUD_LOCATION` to scope these values to Deep Agents Code.
+
+    4. Select a Claude model with the `google_anthropic_vertex` provider:
+
+        <CodeGroup>
+            ```txt In session
+            /model google_anthropic_vertex:claude-sonnet-4-6
+            ```
+
+            ```bash Shell
+            dcode --model google_anthropic_vertex:claude-sonnet-4-6
+            ```
+        </CodeGroup>
+
+    Use `google_vertexai` for Google models. Claude models use Anthropic's Messages API and must use `google_anthropic_vertex` instead.
+</Accordion>
+
 <Tip>
     You can scope any credential to Deep Agents Code by adding a `DEEPAGENTS_CODE_` prefix. For example, `DEEPAGENTS_CODE_OPENAI_API_KEY` takes priority over `OPENAI_API_KEY` within Deep Agents Code without affecting other tools. See [`DEEPAGENTS_CODE_` prefix](/oss/deepagents/code/configuration#deepagents_code_-prefix) for details.
 </Tip>