fix: Expand add_memory to accept MemoryEntry

The `add_memory` methods in `Context` and `BaseMemoryService` now accept `MemoryEntry` objects in addition to strings. The Vertex AI Memory Bank service implementation is updated to handle these new types

Co-authored-by: George Weale <gweale@google.com>
PiperOrigin-RevId: 872108561

tests/unittests/agents/test_callback_context.py

@@ -22,7 +22,9 @@ from google.adk.agents.callback_context import CallbackContext
 from google.adk.auth.auth_credential import AuthCredential
 from google.adk.auth.auth_credential import AuthCredentialTypes
 from google.adk.auth.auth_tool import AuthConfig
+from google.adk.memory.memory_entry import MemoryEntry
 from google.adk.tools.tool_context import ToolContext
+from google.genai import types
 from google.genai.types import Part
 import pytest
 
@@ -417,7 +419,9 @@ class TestCallbackContextAddEventsToMemory:
     """Tests that add_memory forwards memories and metadata."""
     memory_service = AsyncMock()
     mock_invocation_context.memory_service = memory_service
-    memories = ["fact one"]
+    memories = [
+        MemoryEntry(content=types.Content(parts=[types.Part(text="fact one")]))
+    ]
     metadata = {"ttl": "6000s"}
 
     context = CallbackContext(mock_invocation_context)
@@ -430,6 +434,27 @@ class TestCallbackContextAddEventsToMemory:
         custom_metadata=metadata,
     )
 
+  @pytest.mark.asyncio
+  async def test_add_memory_accepts_memory_entries(
+      self, mock_invocation_context
+  ):
+    """Tests that add_memory forwards MemoryEntry inputs unchanged."""
+    memory_service = AsyncMock()
+    mock_invocation_context.memory_service = memory_service
+    memory_entry = MemoryEntry(
+        content=types.Content(parts=[types.Part(text="fact one")])
+    )
+
+    context = CallbackContext(mock_invocation_context)
+    await context.add_memory(memories=[memory_entry])
+
+    memory_service.add_memory.assert_called_once_with(
+        app_name=mock_invocation_context.session.app_name,
+        user_id=mock_invocation_context.session.user_id,
+        memories=[memory_entry],
+        custom_metadata=None,
+    )
+
   @pytest.mark.asyncio
   async def test_add_memory_no_service_raises(self, mock_invocation_context):
     """Tests that add_memory raises ValueError with no service."""
@@ -441,7 +466,13 @@ class TestCallbackContextAddEventsToMemory:
         ValueError,
         match=r"Cannot add memory: memory service is not available\.",
     ):
-      await context.add_memory(memories=["fact one"])
+      await context.add_memory(
+          memories=[
+              MemoryEntry(
+                  content=types.Content(parts=[types.Part(text="fact one")])
+              )
+          ]
+      )
 
 
 class TestToolContextAddSessionToMemory: