fix: Fix compaction run item typing and lifecycle handling

src/agents/_run_impl.py

@@ -542,7 +542,7 @@ def process_model_response(
                 shell_calls.append(ToolRunShellCall(tool_call=output, shell_tool=shell_tool))
                 continue
             if output_type == "compaction":
-                items.append(CompactionItem(raw_item=cast(dict[str, Any], output), agent=agent))
+                items.append(CompactionItem(raw_item=cast(TResponseInputItem, output), agent=agent))
                 continue
             if output_type == "apply_patch_call":
                 items.append(ToolCallItem(raw_item=cast(Any, output), agent=agent))

src/agents/items.py

@@ -328,20 +328,14 @@ class MCPApprovalResponseItem(RunItemBase[McpApprovalResponse]):
 
 
 @dataclass
-class CompactionItem:
+class CompactionItem(RunItemBase[TResponseInputItem]):
     """Represents a compaction item from responses.compact."""
 
-    agent: Agent[Any]
-    """The agent whose run caused this item to be generated."""
-
-    raw_item: dict[str, Any]
-    """The raw compaction item containing encrypted_content."""
-
     type: Literal["compaction_item"] = "compaction_item"
 
     def to_input_item(self) -> TResponseInputItem:
         """Converts this item into an input item suitable for passing to the model."""
-        return cast(TResponseInputItem, self.raw_item)
+        return self.raw_item
 
 
 RunItem: TypeAlias = Union[