Add AgentRun.{all,new}_messages

This allows convenient access to these even if the run didn't end, at
which point they would not be available via `AgentRun.result`.

Author: tibbe

pydantic_ai_slim/pydantic_ai/run.py

@@ -135,6 +135,22 @@ def result(self) -> AgentRunResult[OutputDataT] | None:
             self._traceparent(required=False),
         )
 
+    @property
+    def all_messages(self) -> list[_messages.ModelMessage]:
+        """Return all messages.
+
+        Messages from older runs are included.
+        """
+        return self.ctx.state.message_history
+
+    @property
+    def new_messages(self) -> list[_messages.ModelMessage]:
+        """Return new messages associated with this run.
+
+        Messages from older runs are excluded.
+        """
+        return self.ctx.state.message_history[self.ctx.deps.new_message_index :]
+
     def __aiter__(
         self,
     ) -> AsyncIterator[_agent_graph.AgentNode[AgentDepsT, OutputDataT] | End[FinalResult[OutputDataT]]]: