fix(sdk): cache Anthropic Vertex prompts

libs/deepagents/deepagents/middleware/_prompt_caching.py

@@ -24,6 +24,27 @@ def _create_bedrock_prompt_caching_middleware() -> AgentMiddleware[Any, Any, Any
     return cast("AgentMiddleware[Any, Any, Any]", middleware_cls(unsupported_model_behavior="ignore"))
 
 
+def _create_anthropic_vertex_prompt_caching_middleware() -> AgentMiddleware[Any, Any, Any] | None:
+    """Create Anthropic Vertex caching middleware when available."""
+    module_name = "langchain_google_vertexai.middleware.prompt_caching"
+    try:
+        module = import_module(module_name)
+    except ImportError as exc:
+        if exc.name not in {
+            "langchain_google_vertexai",
+            "langchain_google_vertexai.middleware",
+            module_name,
+        }:
+            raise
+        logger.debug("Anthropic Vertex caching middleware is unavailable.", exc_info=exc)
+        return None
+    middleware_cls = module.AnthropicVertexPromptCachingMiddleware
+    return cast(
+        "AgentMiddleware[Any, Any, Any]",
+        middleware_cls(unsupported_model_behavior="ignore"),
+    )
+
+
 def _create_fireworks_prompt_caching_middleware() -> AgentMiddleware[Any, Any, Any] | None:
     """Create Fireworks prompt caching middleware when `langchain-fireworks` is installed."""
     module_name = "langchain_fireworks.middleware.prompt_caching"
@@ -41,6 +62,9 @@ def _create_fireworks_prompt_caching_middleware() -> AgentMiddleware[Any, Any, A
 def append_prompt_caching_middleware(middleware: list[AgentMiddleware[Any, Any, Any]]) -> None:
     """Append provider-specific prompt caching middleware."""
     middleware.append(AnthropicPromptCachingMiddleware(unsupported_model_behavior="ignore"))
+    vertex_middleware = _create_anthropic_vertex_prompt_caching_middleware()
+    if vertex_middleware is not None:
+        middleware.append(vertex_middleware)
     bedrock_middleware = _create_bedrock_prompt_caching_middleware()
     if bedrock_middleware is not None:
         middleware.append(bedrock_middleware)

libs/deepagents/tests/unit_tests/middleware/test_prompt_caching.py

@@ -0,0 +1,37 @@
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+from deepagents.middleware._prompt_caching import (
+    _create_anthropic_vertex_prompt_caching_middleware,
+)
+
+
+def test_creates_anthropic_vertex_prompt_caching_middleware() -> None:
+    middleware = MagicMock()
+    middleware_cls = MagicMock(return_value=middleware)
+    module = MagicMock(AnthropicVertexPromptCachingMiddleware=middleware_cls)
+
+    with patch("deepagents.middleware._prompt_caching.import_module", return_value=module):
+        result = _create_anthropic_vertex_prompt_caching_middleware()
+
+    assert result is middleware
+    middleware_cls.assert_called_once_with(unsupported_model_behavior="ignore")
+
+
+def test_anthropic_vertex_prompt_caching_is_optional() -> None:
+    error = ModuleNotFoundError(name="langchain_google_vertexai.middleware")
+
+    with patch("deepagents.middleware._prompt_caching.import_module", side_effect=error):
+        assert _create_anthropic_vertex_prompt_caching_middleware() is None
+
+
+def test_anthropic_vertex_prompt_caching_preserves_unrelated_import_errors() -> None:
+    with (
+        patch(
+            "deepagents.middleware._prompt_caching.import_module",
+            side_effect=ImportError(name="missing_transitive"),
+        ),
+        pytest.raises(ImportError),
+    ):
+        _create_anthropic_vertex_prompt_caching_middleware()

libs/deepagents/tests/unit_tests/test_graph.py

@@ -444,6 +444,7 @@ def test_bedrock_prompt_caching_is_optional_when_middleware_unavailable(self) ->
 
         with (
             patch("deepagents.middleware._prompt_caching._create_fireworks_prompt_caching_middleware", return_value=None),
+            patch("deepagents.middleware._prompt_caching._create_anthropic_vertex_prompt_caching_middleware", return_value=None),
             patch(
                 "deepagents.middleware._prompt_caching.import_module",
                 side_effect=ModuleNotFoundError(name="langchain_aws.middleware.prompt_caching"),
@@ -523,6 +524,7 @@ def test_fireworks_prompt_caching_is_optional_when_middleware_unavailable(self)
 
         with (
             patch("deepagents.middleware._prompt_caching._create_bedrock_prompt_caching_middleware", return_value=None),
+            patch("deepagents.middleware._prompt_caching._create_anthropic_vertex_prompt_caching_middleware", return_value=None),
             patch(
                 "deepagents.middleware._prompt_caching.import_module",
                 side_effect=ModuleNotFoundError(name="langchain_fireworks.middleware.prompt_caching"),