Added answer an ideal to gradeable environments (#762)

paperqa/agents/task.py

@@ -86,6 +86,8 @@ def __init__(
         )
         self._evaluation_callback = evaluation_callback
         self._rewards = rewards
+        self.answer = ""
+        self.ideal = ""
 
     async def validate_sources(
         self, manifest_or_index: dict[str, DocDetails] | SearchIndex | None = None
@@ -141,10 +143,19 @@ async def step(
         evaluation = await self._evaluation_from_answer(self.state.session.answer)
         if evaluation_callback := self._evaluation_callback:
             await evaluation_callback(evaluation)
+        self.answer = evaluation.answer or ""
+        self.ideal = evaluation.ideal or ""
         return messages, reward + self._rewards[evaluation.value], done, truncated
 
     def export_frame(self) -> Frame:
-        raise NotImplementedError("Didn't yet need to export a frame.")
+        return Frame(
+            state=self.state,
+            info={
+                "query": self._query,
+                "answer": self.answer,
+                "ideal": self.ideal,
+            },
+        )
 
     def __deepcopy__(self, memo) -> Self:
         copy_state = deepcopy(self.state, memo)