chore: withdraw for policy error (#907)

* chore: withdraw for policy error

Co-authored-by: you-n-g <you-n-g@users.noreply.github.com>

* Apply suggestions from code review

rdagent/utils/workflow.py

@@ -88,6 +88,9 @@ class LoopBase:
     loop_trace: dict[int, list[LoopTrace]]
 
     skip_loop_error: tuple[type[BaseException], ...] = ()  # you can define a list of error that will skip current loop
+    withdraw_loop_error: tuple[
+        type[BaseException], ...
+    ] = ()  # you can define a list of error that will withdraw current loop
 
     EXCEPTION_KEY = "_EXCEPTION"
 
@@ -183,6 +186,11 @@ class LoopBase:
                             self.step_idx = len(self.steps) - 1  # directly jump to the last step.
                             self.loop_prev_out[self.EXCEPTION_KEY] = e
                             continue
+                        elif isinstance(e, self.withdraw_loop_error):
+                            logger.warning(f"Withdraw loop {li} due to {e}")
+                            # Back to previous loop
+                            self.step_backward(li - 1)
+                            continue
                         else:
                             raise
                     finally:
@@ -207,6 +215,27 @@ class LoopBase:
 
                 self.dump(self.session_folder / f"{li}" / f"{si}_{name}")  # save a snapshot after the session
 
+    def step_backward(self, li: int) -> None:
+        prev_session_dir = self.session_folder / str(li)
+        prev_path = min(
+            (p for p in prev_session_dir.glob("*_*") if p.is_file()),
+            key=lambda item: int(item.name.split("_", 1)[0]),
+            default=None,
+        )
+        if prev_path:
+            loaded = type(self).load(
+                prev_path,
+                output_path=self.session_folder.parent,
+                do_truncate=False,
+                replace_timer=True,
+            )
+            logger.info(f"Load previous session from {prev_path}")
+            # Overwrite current instance state
+            self.__dict__ = loaded.__dict__
+        else:
+            logger.error(f"No previous dump found at {prev_session_dir}, cannot withdraw loop {li}")
+            raise
+
     def dump(self, path: str | Path) -> None:
         if RD_Agent_TIMER_wrapper.timer.started:
             RD_Agent_TIMER_wrapper.timer.update_remain_time()