[v2] Dispatcher/ServerRunner receive-path swap — replaces BaseSession (#2710)

tests/server/test_validation.py

@@ -120,6 +120,16 @@ def test_validate_tool_use_result_messages_raises_when_tool_result_without_previ
         validate_tool_use_result_messages(messages)
 
 
+def test_validate_tool_use_result_messages_raises_when_previous_message_has_no_tool_use() -> None:
+    """Raises when tool_result follows a message that has content but no tool_use."""
+    messages = [
+        SamplingMessage(role="assistant", content=TextContent(type="text", text="just text")),
+        SamplingMessage(role="user", content=ToolResultContent(type="tool_result", tool_use_id="tool-1")),
+    ]
+    with pytest.raises(ValueError, match="do not match any tool_use in the previous message"):
+        validate_tool_use_result_messages(messages)
+
+
 def test_validate_tool_use_result_messages_raises_when_tool_result_ids_dont_match_tool_use() -> None:
     """Raises when tool_result IDs don't match tool_use IDs."""
     messages = [