feat: add metadata property to RequestContext (#302)

Fixes #301 🦕

Author: fernando-torres-blip-ai

src/a2a/server/agent_execution/context.py

@@ -1,5 +1,7 @@
 import uuid
 
+from typing import Any
+
 from a2a.server.context import ServerCallContext
 from a2a.types import (
     InvalidParamsError,
@@ -134,6 +136,13 @@ def call_context(self) -> ServerCallContext | None:
         """The server call context associated with this request."""
         return self._call_context
 
+    @property
+    def metadata(self) -> dict[str, Any]:
+        """Metadata associated with the request, if available."""
+        if not self._params:
+            return {}
+        return self._params.metadata or {}
+
     def _check_or_generate_task_id(self) -> None:
         """Ensures a task ID is present, generating one if necessary."""
         if not self._params:

tests/server/agent_execution/test_context.py

@@ -211,6 +211,17 @@ def test_message_property_with_params(self, mock_params):
         context = RequestContext(request=mock_params)
         assert context.message == mock_params.message
 
+    def test_metadata_property_without_content(self):
+        """Test metadata property returns empty dict when no content are provided."""
+        context = RequestContext()
+        assert context.metadata == {}
+
+    def test_metadata_property_with_content(self, mock_params):
+        """Test metadata property returns the metadata from params."""
+        mock_params.metadata = {'key': 'value'}
+        context = RequestContext(request=mock_params)
+        assert context.metadata == {'key': 'value'}
+
     def test_init_with_existing_ids_in_message(self, mock_message, mock_params):
         """Test initialization with existing IDs in the message."""
         mock_message.taskId = 'existing-task-id'