differentiate skippable exception and non-skippable exception

eval_protocol/mcp/execution/manager.py

@@ -12,17 +12,16 @@
 import threading
 import time
 from dataclasses import asdict
-from typing import TYPE_CHECKING, Any, AsyncIterator, Callable, Dict, List, Optional, Union
+from typing import TYPE_CHECKING, Any, Callable, Dict, List, Optional, Union
 
 import anyio
-import httpx
 from openai.types import CompletionUsage
 
 from vendor.tau2.data_model.message import AssistantMessage, UserMessage
 from vendor.tau2.user.user_simulator import UserSimulator
 
-from ...models import EvaluationRow, InputMetadata, Message
-from ...types import MCPSession, MCPToolCall, TerminationReason, Trajectory
+from ...models import EvaluationRow, InputMetadata, Message, RolloutStatus
+from ...types import TerminationReason, Trajectory, NonSkippableException
 
 if TYPE_CHECKING:
     from ..session.manager import GeneralMCPVectorEnv
@@ -107,7 +106,7 @@ async def _execute_with_semaphore(idx):
                 )
 
                 # Convert trajectory to EvaluationRow immediately
-                evaluation_row = evaluation_rows[idx]
+                evaluation_row: EvaluationRow = evaluation_rows[idx]
 
                 # Handle multimodal content by extracting text from complex content structures
                 messages = []
@@ -137,16 +136,15 @@ async def _execute_with_semaphore(idx):
                 }
 
                 if trajectory.terminated:
-                    if trajectory.termination_reason == TerminationReason.ERROR:
-                        evaluation_row.rollout_status.status = "error"
-                        evaluation_row.rollout_status.termination_reason = trajectory.control_plane_summary.get(
-                            "error_message", None
-                        )
-                    else:
-                        evaluation_row.rollout_status.status = "finished"
-                        evaluation_row.rollout_status.termination_reason = trajectory.termination_reason
+                    evaluation_row.rollout_status.termination_reason = trajectory.termination_reason
+                    evaluation_row.rollout_status.status = RolloutStatus.Status.FINISHED
+                    # preserve the true error mesage if there are any
+                    if trajectory.control_plane_summary.get("error_message"):
+                        evaluation_row.rollout_status.extra_info = {
+                            "error_message": trajectory.control_plane_summary.get("error_message")
+                        }
                 else:
-                    evaluation_row.rollout_status.status = "running"
+                    evaluation_row.rollout_status.status = RolloutStatus.Status.RUNNING
 
                 return evaluation_row
 
@@ -437,31 +435,18 @@ async def _execute_rollout(
             logger.info(
                 f"✅ Rollout {rollout_idx} completed: {trajectory.steps} steps, reward: {trajectory.total_reward:.2f}, termination: {trajectory.termination_reason}, in thread {threading.current_thread().name}"
             )
-
-        except asyncio.CancelledError:
-            failure_reason = "asyncio context cancelled"
-            logger.error(
-                f"🚨 Error in rollout {session.dataset_row.id} {rollout_idx}: {failure_reason}", exc_info=True
-            )
-        except (anyio.ClosedResourceError, anyio.BrokenResourceError):
-            failure_reason = "anyioconnection/resource error"
-            logger.error(
-                f"🚨 Error in rollout {session.dataset_row.id} {rollout_idx}: {failure_reason}", exc_info=True
-            )
-        except Exception as e:
-            error_msg = str(e) if str(e) else f"{type(e).__name__}: Unexpected error"
-            logger.error(f"🚨 Error in rollout {session.dataset_row.id} {rollout_idx}: {error_msg}", exc_info=True)
-            failure_reason = error_msg
+        except NonSkippableException as e:
+            # terminate the rollout right away, no retry and preserve the current trajectory history.
+            # for other types of exceptions, keep propagate them to upper layers and handle them with retry handler.
+            trajectory.terminated = True
+            trajectory.termination_reason = TerminationReason.NON_SKIPPABLE_ERROR
+            trajectory.control_plane_summary.update({"error_message": str(e)})
+            logger.error(f"🚨 Rollout {rollout_idx} terminated due to non-skippable error: {str(e)}", exc_info=True)
         finally:
-            if failure_reason:
-                trajectory.terminated = True
-                trajectory.termination_reason = TerminationReason.ERROR
-                trajectory.control_plane_summary.update({"error_message": f"{failure_reason}"})
             try:
                 await envs.connection_manager.reset_session(session)
             except Exception as e:
                 logger.warning(f"Failed to reset session {session.session_id}: {type(e).__name__}: {e}", exc_info=True)
-
             try:
                 await envs.connection_manager.close_session(session)
             except Exception as e:

eval_protocol/models.py

@@ -1,5 +1,6 @@
 import os
 from datetime import datetime
+from enum import Enum
 from typing import Any, Dict, List, Literal, Optional, TypedDict, Union
 
 from openai.types import CompletionUsage
@@ -11,6 +12,7 @@
 
 from eval_protocol.get_pep440_version import get_pep440_version
 from eval_protocol.human_id import generate_id
+from eval_protocol.types import TerminationReason
 
 
 class ChatCompletionContentPartTextParam(BaseModel):
@@ -285,14 +287,20 @@ class RolloutStatus(BaseModel):
 
     """
     running: Unfinished rollout which is still in progress.
-    finished: Rollout finished successfully.
-    error: Rollout failed.
-    stopped: Rollout terminated unexpectedly (e.g. max step, control plane signal, user stop).
+    finished: Rollout finished.
+    error: Rollout failed due to unexpected error. The rollout record should be discard.
     """
-    status: Literal["running", "finished", "error"] = Field("running", description="Status of the rollout.")
-    termination_reason: Optional[str] = Field(
-        "", description="reason of the rollout status, mapped to values in TerminationReason"
+
+    class Status(str, Enum):
+        RUNNING = "running"
+        FINISHED = "finished"
+        ERROR = "error"
+
+    status: Status = Field(Status.RUNNING, description="Status of the rollout.")
+    termination_reason: Optional[TerminationReason] = Field(
+        None, description="reason of the rollout status, mapped to values in TerminationReason"
     )
+    extra_info: Optional[Dict[str, Any]] = Field(None, description="Extra information about the rollout status.")
 
 
 class EvaluationRow(BaseModel):

eval_protocol/pytest/utils.py

@@ -6,7 +6,7 @@
 from typing import Any, Callable, Dict, List, Literal, Optional, Union
 
 from eval_protocol.dataset_logger.dataset_logger import DatasetLogger
-from eval_protocol.models import EvalMetadata, EvaluationRow
+from eval_protocol.models import EvalMetadata, EvaluationRow, RolloutStatus
 from eval_protocol.pytest.rollout_processor import RolloutProcessor
 from eval_protocol.pytest.types import (
     CompletionParams,
@@ -248,7 +248,7 @@ async def rollout_processor_with_retry(
     """
 
     try:
-        queue = asyncio.Queue()
+        queue: asyncio.Queue[EvaluationRow] = asyncio.Queue()
         retry_counts = {r.execution_metadata.rollout_id: 0 for r in fresh_dataset}
         failed_permanently = []
 
@@ -257,7 +257,7 @@ async def retry_handler(failed_row: EvaluationRow):
             current_attempts = retry_counts.get(rollout_id, 0)
 
             if current_attempts >= max_retry:
-                assert failed_row.rollout_status and failed_row.rollout_status.status == "error", (
+                assert failed_row.rollout_status and failed_row.rollout_status.status == RolloutStatus.Status.ERROR, (
                     f"Rollout {failed_row.execution_metadata.rollout_id} did not fail with error status"
                 )
                 failed_permanently.append(failed_row)
@@ -273,10 +273,10 @@ async def retry_handler(failed_row: EvaluationRow):
 
             try:
                 retry_result = await retry_tasks[0]
-                retry_result.rollout_status.status = "finished"
+                retry_result.rollout_status.status = RolloutStatus.Status.FINISHED
                 await queue.put(retry_result)
             except Exception as e:
-                failed_row.rollout_status.status = "error"
+                failed_row.rollout_status.status = RolloutStatus.Status.ERROR
                 failed_row.rollout_status.termination_reason = str(e)
                 asyncio.create_task(retry_handler(failed_row))  # retry failed, spawn another retry
 
@@ -299,11 +299,11 @@ async def initial_processor():
 
                     try:
                         result = await task
-                        result.rollout_status.status = "finished"
+                        result.rollout_status.status = RolloutStatus.Status.FINISHED
                         await queue.put(result)
                     except Exception as e:
                         failed_row = fresh_dataset[task_index]
-                        failed_row.rollout_status.status = "error"
+                        failed_row.rollout_status.status = RolloutStatus.Status.ERROR
                         failed_row.rollout_status.termination_reason = str(e)
                         asyncio.create_task(retry_handler(failed_row))  # rollout errored, spawn retry task
 
@@ -317,7 +317,7 @@ async def initial_processor():
             finished_row = await queue.get()
 
             # only permanent failure rows are put on the queue, so we can check for them here
-            if finished_row.rollout_status and finished_row.rollout_status.status == "error":
+            if finished_row.rollout_status and finished_row.rollout_status.status == RolloutStatus.Status.ERROR:
                 if max_retry > 0 and os.getenv("EP_FAIL_ON_MAX_RETRY", "true") != "false":
                     raise RuntimeError(
                         f"Rollout {finished_row.execution_metadata.rollout_id} failed after {max_retry} retries. Errors: {finished_row.rollout_status.termination_reason}"

eval_protocol/types/__init__.py

@@ -1,3 +1,4 @@
 from .types import DatasetRow, MCPSession, MCPToolCall, TerminationReason, Trajectory
+from .errors import NonSkippableException
 
-__all__ = ["MCPSession", "MCPToolCall", "TerminationReason", "Trajectory", "DatasetRow"]
+__all__ = ["MCPSession", "MCPToolCall", "TerminationReason", "Trajectory", "DatasetRow", "NonSkippableException"]

eval_protocol/types/errors.py

@@ -0,0 +1,11 @@
+class NonSkippableException(Exception):
+    """
+    A type of custom exception raised during rollout or evaluation. This error means the rollout/evaluation result is not skippable and need to be
+    processed explicitly.
+
+    For example, if the policy (llm) returns 400 User error, we need to end the rollout but keep the trajectory.
+    It differs from other exceptions such as network error, which are retriable and the trajectory should be discarded if
+    it fails eventually after retries.
+    """
+
+    pass

eval_protocol/types/types.py

@@ -12,7 +12,8 @@ class TerminationReason(str, Enum):
     MAX_STEPS: Trajectory ends because we hit the step limit
     CONTROL_PLANE_SIGNAL: Trajectory ends because the control plane signals termination (e.g. env goal reached or failure condition)
     USER_STOP: Trajectory ends because the simulated user signals to stop
-    ERROR: Trajectory ends because of an error
+    SKIPPABLE_ERROR: Trajectory ends because of an error, this trajectory can be discarded/skipped during postprocessing/evaluation.
+    NON_SKIPPABLE_ERROR: Trajectory is interrupted due to some non-skippable error (e.g. policy returns unexpected response and we need to terminate the rollout).
     STOP: Trajectory ends by the policy (mapped to llm response stop reason "stop")
     LENGTH: Trajectory ends by the policy (mapped to llm response stop reason "length")
     TOOL_CALLS: Trajectory ends by the policy with a hanging tool call response (mapped to llm response stop reason "tool_calls")
@@ -21,7 +22,8 @@ class TerminationReason(str, Enum):
     MAX_STEPS = "max_steps"
     CONTROL_PLANE_SIGNAL = "control_plane_signal"
     USER_STOP = "user_stop"
-    ERROR = "error"
+    SKIPPABLE_ERROR = "skippable_error"
+    NON_SKIPPABLE_ERROR = "non_skippable_error"
     STOP = "stop"
     LENGTH = "length"
     TOOL_CALLS = "tool_calls"
@@ -38,8 +40,10 @@ def from_str(cls, value: str) -> "TerminationReason":
             return cls.CONTROL_PLANE_SIGNAL
         elif value == "user_stop":
             return cls.USER_STOP
-        elif value == "error":
-            return cls.ERROR
+        elif value == "skippable_error":
+            return cls.SKIPPABLE_ERROR
+        elif value == "non_skippable_error":
+            return cls.NON_SKIPPABLE_ERROR
         elif value == "tool_calls":
             return cls.TOOL_CALLS
         else: