Moved GradablePaperQAEnvironment.step to use the answer, removing Gen…

…erateAnswer parsing complexity

paperqa/agents/task.py

@@ -130,31 +130,7 @@ async def step(
         messages, reward, done, truncated = await super().step(action)
         if not done or not self._evaluation_from_answer:
             return messages, reward, done, truncated
-        valid_answers, failed_answer_messages = [], []
-        for m in messages:
-            if (
-                not isinstance(m, ToolResponseMessage)
-                or m.name != GenerateAnswer.gen_answer.__name__
-            ):
-                continue  # Filter out non-answer messages (in case parallel tool calls)
-            if answer := GenerateAnswer.extract_answer_from_message(content=m.content):
-                valid_answers.append(answer)
-            else:
-                failed_answer_messages.append(m)
-        if not valid_answers:  # No answer, so no positive reward
-            return messages, reward, done, truncated
-        if len(valid_answers) != 1:
-            raise NotImplementedError(
-                f"Expected just one answer message, got more than one in {messages}."
-            )
-        answer = valid_answers[0]
-        if failed_answer_messages:
-            logger.warning(
-                "More than one answer detected, discarding failed answer messages"
-                f" {failed_answer_messages}, continuing with answer {answer}."
-            )
-        # Okay, so we have one answer that was not a failed answer. Let's evaluate it
-        evaluation = await self._evaluation_from_answer(answer)
+        evaluation = await self._evaluation_from_answer(self.state.session.answer)
         if evaluation_callback := self._evaluation_callback:
             await evaluation_callback(evaluation)
         return messages, reward + self._rewards[evaluation.value], done, truncated