Added RunErrorDetails object for MaxTurnsExceeded exception (#743)

### Summary

Introduced the `RunErrorDetails` object to get partial results from a
run interrupted by `MaxTurnsExceeded` exception. In this proposal the
`RunErrorDetails` object contains all the fields from `RunResult` with
`final_output` set to `None` and `output_guardrail_results` set to an
empty list. We can decide to return less information.

@rm-openai At the moment the exception doesn't return the
`RunErrorDetails` object for the streaming mode. Do you have any
suggestions on how to deal with it? In the `_check_errors` function of
`agents/result.py` file.

### Test plan

I have not implemented any tests currently, but if needed I can
implement a basic test to retrieve partial data.

### Issue number

This PR is an attempt to solve issue #719 

### Checks

- [✅ ] I've added new tests (if relevant)
- [ ] I've added/updated the relevant documentation
- [ ✅] I've run `make lint` and `make format`
- [ ✅] I've made sure tests pass

src/agents/__init__.py

@@ -14,6 +14,7 @@ from .exceptions import (
     MaxTurnsExceeded,
     ModelBehaviorError,
     OutputGuardrailTripwireTriggered,
+    RunErrorDetails,
     UserError,
 )
 from .guardrail import (
@@ -204,6 +205,7 @@ __all__ = [
     "AgentHooks",
     "RunContextWrapper",
     "TContext",
+    "RunErrorDetails",
     "RunResult",
     "RunResultStreaming",
     "RunConfig",

src/agents/exceptions.py

@@ -1,11 +1,39 @@
-from typing import TYPE_CHECKING
+from __future__ import annotations
+
+from dataclasses import dataclass
+from typing import TYPE_CHECKING, Any
 
 if TYPE_CHECKING:
+    from .agent import Agent
     from .guardrail import InputGuardrailResult, OutputGuardrailResult
+    from .items import ModelResponse, RunItem, TResponseInputItem
+    from .run_context import RunContextWrapper
+
+from .util._pretty_print import pretty_print_run_error_details
+
+
+@dataclass
+class RunErrorDetails:
+    """Data collected from an agent run when an exception occurs."""
+    input: str | list[TResponseInputItem]
+    new_items: list[RunItem]
+    raw_responses: list[ModelResponse]
+    last_agent: Agent[Any]
+    context_wrapper: RunContextWrapper[Any]
+    input_guardrail_results: list[InputGuardrailResult]
+    output_guardrail_results: list[OutputGuardrailResult]
+
+    def __str__(self) -> str:
+        return pretty_print_run_error_details(self)
 
 
 class AgentsException(Exception):
     """Base class for all exceptions in the Agents SDK."""
+    run_data: RunErrorDetails | None
+
+    def __init__(self, *args: object) -> None:
+        super().__init__(*args)
+        self.run_data = None
 
 
 class MaxTurnsExceeded(AgentsException):
@@ -15,6 +43,7 @@ class MaxTurnsExceeded(AgentsException):
 
     def __init__(self, message: str):
         self.message = message
+        super().__init__(message)
 
 
 class ModelBehaviorError(AgentsException):
@@ -26,6 +55,7 @@ class ModelBehaviorError(AgentsException):
 
     def __init__(self, message: str):
         self.message = message
+        super().__init__(message)
 
 
 class UserError(AgentsException):
@@ -35,15 +65,16 @@ class UserError(AgentsException):
 
     def __init__(self, message: str):
         self.message = message
+        super().__init__(message)
 
 
 class InputGuardrailTripwireTriggered(AgentsException):
     """Exception raised when a guardrail tripwire is triggered."""
 
-    guardrail_result: "InputGuardrailResult"
+    guardrail_result: InputGuardrailResult
     """The result data of the guardrail that was triggered."""
 
-    def __init__(self, guardrail_result: "InputGuardrailResult"):
+    def __init__(self, guardrail_result: InputGuardrailResult):
         self.guardrail_result = guardrail_result
         super().__init__(
             f"Guardrail {guardrail_result.guardrail.__class__.__name__} triggered tripwire"
@@ -53,10 +84,10 @@ class InputGuardrailTripwireTriggered(AgentsException):
 class OutputGuardrailTripwireTriggered(AgentsException):
     """Exception raised when a guardrail tripwire is triggered."""
 
-    guardrail_result: "OutputGuardrailResult"
+    guardrail_result: OutputGuardrailResult
     """The result data of the guardrail that was triggered."""
 
-    def __init__(self, guardrail_result: "OutputGuardrailResult"):
+    def __init__(self, guardrail_result: OutputGuardrailResult):
         self.guardrail_result = guardrail_result
         super().__init__(
             f"Guardrail {guardrail_result.guardrail.__class__.__name__} triggered tripwire"

src/agents/result.py

@@ -11,14 +11,22 @@ from typing_extensions import TypeVar
 from ._run_impl import QueueCompleteSentinel
 from .agent import Agent
 from .agent_output import AgentOutputSchemaBase
-from .exceptions import InputGuardrailTripwireTriggered, MaxTurnsExceeded
+from .exceptions import (
+    AgentsException,
+    InputGuardrailTripwireTriggered,
+    MaxTurnsExceeded,
+    RunErrorDetails,
+)
 from .guardrail import InputGuardrailResult, OutputGuardrailResult
 from .items import ItemHelpers, ModelResponse, RunItem, TResponseInputItem
 from .logger import logger
 from .run_context import RunContextWrapper
 from .stream_events import StreamEvent
 from .tracing import Trace
-from .util._pretty_print import pretty_print_result, pretty_print_run_result_streaming
+from .util._pretty_print import (
+    pretty_print_result,
+    pretty_print_run_result_streaming,
+)
 
 if TYPE_CHECKING:
     from ._run_impl import QueueCompleteSentinel
@@ -206,31 +214,53 @@ class RunResultStreaming(RunResultBase):
         if self._stored_exception:
             raise self._stored_exception
 
+    def _create_error_details(self) -> RunErrorDetails:
+        """Return a `RunErrorDetails` object considering the current attributes of the class."""
+        return RunErrorDetails(
+            input=self.input,
+            new_items=self.new_items,
+            raw_responses=self.raw_responses,
+            last_agent=self.current_agent,
+            context_wrapper=self.context_wrapper,
+            input_guardrail_results=self.input_guardrail_results,
+            output_guardrail_results=self.output_guardrail_results,
+        )
+
     def _check_errors(self):
         if self.current_turn > self.max_turns:
-            self._stored_exception = MaxTurnsExceeded(f"Max turns ({self.max_turns}) exceeded")
+            max_turns_exc = MaxTurnsExceeded(f"Max turns ({self.max_turns}) exceeded")
+            max_turns_exc.run_data = self._create_error_details()
+            self._stored_exception = max_turns_exc
 
         # Fetch all the completed guardrail results from the queue and raise if needed
         while not self._input_guardrail_queue.empty():
             guardrail_result = self._input_guardrail_queue.get_nowait()
             if guardrail_result.output.tripwire_triggered:
-                self._stored_exception = InputGuardrailTripwireTriggered(guardrail_result)
+                tripwire_exc = InputGuardrailTripwireTriggered(guardrail_result)
+                tripwire_exc.run_data = self._create_error_details()
+                self._stored_exception = tripwire_exc
 
         # Check the tasks for any exceptions
         if self._run_impl_task and self._run_impl_task.done():
-            exc = self._run_impl_task.exception()
+            run_impl_exc = self._run_impl_task.exception()
-            if exc and isinstance(exc, Exception):
+            if run_impl_exc and isinstance(run_impl_exc, Exception):
-                self._stored_exception = exc
+                if isinstance(run_impl_exc, AgentsException) and run_impl_exc.run_data is None:
+                    run_impl_exc.run_data = self._create_error_details()
+                self._stored_exception = run_impl_exc
 
         if self._input_guardrails_task and self._input_guardrails_task.done():
-            exc = self._input_guardrails_task.exception()
+            in_guard_exc = self._input_guardrails_task.exception()
-            if exc and isinstance(exc, Exception):
+            if in_guard_exc and isinstance(in_guard_exc, Exception):
-                self._stored_exception = exc
+                if isinstance(in_guard_exc, AgentsException) and in_guard_exc.run_data is None:
+                    in_guard_exc.run_data = self._create_error_details()
+                self._stored_exception = in_guard_exc
 
         if self._output_guardrails_task and self._output_guardrails_task.done():
-            exc = self._output_guardrails_task.exception()
+            out_guard_exc = self._output_guardrails_task.exception()
-            if exc and isinstance(exc, Exception):
+            if out_guard_exc and isinstance(out_guard_exc, Exception):
-                self._stored_exception = exc
+                if isinstance(out_guard_exc, AgentsException) and out_guard_exc.run_data is None:
+                    out_guard_exc.run_data = self._create_error_details()
+                self._stored_exception = out_guard_exc
 
     def _cleanup_tasks(self):
         if self._run_impl_task and not self._run_impl_task.done():
@@ -244,3 +274,4 @@ class RunResultStreaming(RunResultBase):
 
     def __str__(self) -> str:
         return pretty_print_run_result_streaming(self)
+

src/agents/run.py

@@ -1,3 +1,4 @@
+
 from __future__ import annotations
 
 import asyncio
@@ -26,6 +27,7 @@ from .exceptions import (
     MaxTurnsExceeded,
     ModelBehaviorError,
     OutputGuardrailTripwireTriggered,
+    RunErrorDetails,
 )
 from .guardrail import InputGuardrail, InputGuardrailResult, OutputGuardrail, OutputGuardrailResult
 from .handoffs import Handoff, HandoffInputFilter, handoff
@@ -208,7 +210,9 @@ class Runner:
                                 data={"max_turns": max_turns},
                             ),
                         )
-                        raise MaxTurnsExceeded(f"Max turns ({max_turns}) exceeded")
+                        raise MaxTurnsExceeded(
+                            f"Max turns ({max_turns}) exceeded"
+                        )
 
                     logger.debug(
                         f"Running agent {current_agent.name} (turn {current_turn})",
@@ -283,6 +287,17 @@ class Runner:
                         raise AgentsException(
                             f"Unknown next step type: {type(turn_result.next_step)}"
                         )
+            except AgentsException as exc:
+                exc.run_data = RunErrorDetails(
+                    input=original_input,
+                    new_items=generated_items,
+                    raw_responses=model_responses,
+                    last_agent=current_agent,
+                    context_wrapper=context_wrapper,
+                    input_guardrail_results=input_guardrail_results,
+                    output_guardrail_results=[]
+                )
+                raise
             finally:
                 if current_span:
                     current_span.finish(reset_current=True)
@@ -609,6 +624,19 @@ class Runner:
                         streamed_result._event_queue.put_nowait(QueueCompleteSentinel())
                     elif isinstance(turn_result.next_step, NextStepRunAgain):
                         pass
+                except AgentsException as exc:
+                    streamed_result.is_complete = True
+                    streamed_result._event_queue.put_nowait(QueueCompleteSentinel())
+                    exc.run_data = RunErrorDetails(
+                        input=streamed_result.input,
+                        new_items=streamed_result.new_items,
+                        raw_responses=streamed_result.raw_responses,
+                        last_agent=current_agent,
+                        context_wrapper=context_wrapper,
+                        input_guardrail_results=streamed_result.input_guardrail_results,
+                        output_guardrail_results=streamed_result.output_guardrail_results,
+                    )
+                    raise
                 except Exception as e:
                     if current_span:
                         _error_tracing.attach_error_to_span(

src/agents/util/_pretty_print.py

@@ -3,6 +3,7 @@ from typing import TYPE_CHECKING
 from pydantic import BaseModel
 
 if TYPE_CHECKING:
+    from ..exceptions import RunErrorDetails
     from ..result import RunResult, RunResultBase, RunResultStreaming
 
 
@@ -38,6 +39,17 @@ def pretty_print_result(result: "RunResult") -> str:
     return output
 
 
+def pretty_print_run_error_details(result: "RunErrorDetails") -> str:
+    output = "RunErrorDetails:"
+    output += f'\n- Last agent: Agent(name="{result.last_agent.name}", ...)'
+    output += f"\n- {len(result.new_items)} new item(s)"
+    output += f"\n- {len(result.raw_responses)} raw response(s)"
+    output += f"\n- {len(result.input_guardrail_results)} input guardrail result(s)"
+    output += "\n(See `RunErrorDetails` for more details)"
+
+    return output
+
+
 def pretty_print_run_result_streaming(result: "RunResultStreaming") -> str:
     output = "RunResultStreaming:"
     output += f'\n- Current agent: Agent(name="{result.current_agent.name}", ...)'

tests/test_run_error_details.py

@@ -0,0 +1,44 @@
+import json
+
+import pytest
+
+from agents import Agent, MaxTurnsExceeded, RunErrorDetails, Runner
+
+from .fake_model import FakeModel
+from .test_responses import get_function_tool, get_function_tool_call, get_text_message
+
+
+@pytest.mark.asyncio
+async def test_run_error_includes_data():
+    model = FakeModel()
+    agent = Agent(name="test", model=model, tools=[get_function_tool("foo", "res")])
+    model.add_multiple_turn_outputs([
+        [get_text_message("1"), get_function_tool_call("foo", json.dumps({"a": "b"}))],
+        [get_text_message("done")],
+    ])
+    with pytest.raises(MaxTurnsExceeded) as exc:
+        await Runner.run(agent, input="hello", max_turns=1)
+    data = exc.value.run_data
+    assert isinstance(data, RunErrorDetails)
+    assert data.last_agent == agent
+    assert len(data.raw_responses) == 1
+    assert len(data.new_items) > 0
+
+
+@pytest.mark.asyncio
+async def test_streamed_run_error_includes_data():
+    model = FakeModel()
+    agent = Agent(name="test", model=model, tools=[get_function_tool("foo", "res")])
+    model.add_multiple_turn_outputs([
+        [get_text_message("1"), get_function_tool_call("foo", json.dumps({"a": "b"}))],
+        [get_text_message("done")],
+    ])
+    result = Runner.run_streamed(agent, input="hello", max_turns=1)
+    with pytest.raises(MaxTurnsExceeded) as exc:
+        async for _ in result.stream_events():
+            pass
+    data = exc.value.run_data
+    assert isinstance(data, RunErrorDetails)
+    assert data.last_agent == agent
+    assert len(data.raw_responses) == 1
+    assert len(data.new_items) > 0

tests/test_tracing_errors_streamed.py

@@ -168,10 +168,6 @@ async def test_tool_call_error():
                 "children": [
                     {
                         "type": "agent",
-                        "error": {
-                            "message": "Error in agent run",
-                            "data": {"error": "Invalid JSON input for tool foo: bad_json"},
-                        },
                         "data": {
                             "name": "test_agent",
                             "handoffs": [],