feat(assistant): stop a generation

ee/api/conversation.py

@@ -1,15 +1,19 @@
 from typing import cast
 
+import pydantic
 from django.http import StreamingHttpResponse
-from pydantic import ValidationError
-from rest_framework import serializers
+from rest_framework import serializers, status
+from rest_framework.decorators import action
+from rest_framework.exceptions import ValidationError
 from rest_framework.renderers import BaseRenderer
 from rest_framework.request import Request
+from rest_framework.response import Response
 from rest_framework.viewsets import GenericViewSet
 
 from ee.hogai.assistant import Assistant
 from ee.models.assistant import Conversation
 from posthog.api.routing import TeamAndOrgViewSetMixin
+from posthog.exceptions import Conflict
 from posthog.models.user import User
 from posthog.rate_limit import AIBurstRateThrottle, AISustainedRateThrottle
 from posthog.schema import HumanMessage
@@ -24,7 +28,7 @@ def validate(self, data):
         try:
             message = HumanMessage(content=data["content"])
             data["message"] = message
-        except ValidationError:
+        except pydantic.ValidationError:
             raise serializers.ValidationError("Invalid message content.")
         return data
 
@@ -40,7 +44,6 @@ def render(self, data, accepted_media_type=None, renderer_context=None):
 class ConversationViewSet(TeamAndOrgViewSetMixin, GenericViewSet):
     scope_object = "INTERNAL"
     serializer_class = MessageSerializer
-    renderer_classes = [ServerSentEventRenderer]
     queryset = Conversation.objects.all()
     lookup_url_kwarg = "conversation"
 
@@ -51,6 +54,11 @@ def safely_get_queryset(self, queryset):
     def get_throttles(self):
         return [AIBurstRateThrottle(), AISustainedRateThrottle()]
 
+    def get_renderers(self):
+        if self.action == "create":
+            return [ServerSentEventRenderer()]
+        return super().get_renderers()
+
     def create(self, request: Request, *args, **kwargs):
         serializer = self.get_serializer(data=request.data)
         serializer.is_valid(raise_exception=True)
@@ -60,6 +68,8 @@ def create(self, request: Request, *args, **kwargs):
             conversation = self.get_object()
         else:
             conversation = self.get_queryset().create(user=request.user, team=self.team)
+        if conversation.is_locked:
+            raise Conflict("Conversation is locked.")
         assistant = Assistant(
             self.team,
             conversation,
@@ -69,3 +79,12 @@ def create(self, request: Request, *args, **kwargs):
             trace_id=serializer.validated_data["trace_id"],
         )
         return StreamingHttpResponse(assistant.stream(), content_type=ServerSentEventRenderer.media_type)
+
+    @action(detail=True, methods=["PATCH"])
+    def cancel(self, request: Request, *args, **kwargs):
+        conversation = self.get_object()
+        if conversation.status == Conversation.Status.CANCELLING:
+            raise ValidationError("Generation has already cancelled.")
+        conversation.status = Conversation.Status.CANCELLING
+        conversation.save()
+        return Response(status=status.HTTP_204_NO_CONTENT)

ee/api/test/test_conversation.py

@@ -169,3 +169,62 @@ def raise_error():
             with self.assertRaises(Exception) as context:
                 b"".join(response.streaming_content)
             self.assertTrue("Streaming error" in str(context.exception))
+
+    def test_cancel_conversation(self):
+        conversation = Conversation.objects.create(user=self.user, team=self.team)
+        response = self.client.patch(
+            f"/api/environments/{self.team.id}/conversations/{conversation.id}/cancel/",
+        )
+        self.assertEqual(response.status_code, status.HTTP_204_NO_CONTENT)
+        conversation.refresh_from_db()
+        self.assertEqual(conversation.status, Conversation.Status.CANCELLING)
+
+    def test_cancel_already_cancelling_conversation(self):
+        conversation = Conversation.objects.create(
+            user=self.user, team=self.team, status=Conversation.Status.CANCELLING
+        )
+        response = self.client.patch(
+            f"/api/environments/{self.team.id}/conversations/{conversation.id}/cancel/",
+        )
+        self.assertEqual(response.status_code, status.HTTP_400_BAD_REQUEST)
+        self.assertEqual(response.json()["detail"], "Generation has already cancelled.")
+
+    def test_cancel_other_users_conversation(self):
+        conversation = Conversation.objects.create(user=self.other_user, team=self.team)
+        response = self.client.patch(
+            f"/api/environments/{self.team.id}/conversations/{conversation.id}/cancel/",
+        )
+        self.assertEqual(response.status_code, status.HTTP_404_NOT_FOUND)
+
+    def test_cancel_other_teams_conversation(self):
+        conversation = Conversation.objects.create(user=self.user, team=self.other_team)
+        response = self.client.patch(
+            f"/api/environments/{self.team.id}/conversations/{conversation.id}/cancel/",
+        )
+        self.assertEqual(response.status_code, status.HTTP_404_NOT_FOUND)
+
+    def test_cant_use_locked_conversation(self):
+        conversation = Conversation.objects.create(
+            user=self.user, team=self.team, status=Conversation.Status.IN_PROGRESS
+        )
+        response = self.client.post(
+            f"/api/environments/{self.team.id}/conversations/",
+            {
+                "conversation": str(conversation.id),
+                "content": "test query",
+                "trace_id": str(uuid.uuid4()),
+            },
+        )
+        self.assertEqual(response.status_code, status.HTTP_409_CONFLICT)
+
+        conversation.status = Conversation.Status.CANCELLING
+        conversation.save()
+        response = self.client.post(
+            f"/api/environments/{self.team.id}/conversations/",
+            {
+                "conversation": str(conversation.id),
+                "content": "test query",
+                "trace_id": str(uuid.uuid4()),
+            },
+        )
+        self.assertEqual(response.status_code, status.HTTP_409_CONFLICT)

ee/hogai/assistant.py

@@ -1,5 +1,6 @@
 import json
 from collections.abc import Generator, Iterator
+from contextlib import contextmanager
 from typing import Any, Optional, cast
 from uuid import UUID, uuid4
 
@@ -19,6 +20,7 @@
 from ee.hogai.schema_generator.nodes import SchemaGeneratorNode
 from ee.hogai.trends.nodes import TrendsGeneratorNode
 from ee.hogai.utils.asgi import SyncIterableToAsync
+from ee.hogai.utils.exceptions import GenerationCanceled
 from ee.hogai.utils.state import (
     GraphMessageUpdateTuple,
     GraphTaskStartedUpdateTuple,
@@ -124,39 +126,55 @@ def _stream(self) -> Generator[str, None, None]:
             state, config=config, stream_mode=["messages", "values", "updates", "debug"]
         )
 
-        # Assign the conversation id to the client.
-        if self._is_new_conversation:
-            yield self._serialize_conversation()
-
-        # Send the last message with the initialized id.
-        yield self._serialize_message(self._latest_message)
-
-        try:
-            last_viz_message = None
-            for update in generator:
-                if message := self._process_update(update):
-                    if isinstance(message, VisualizationMessage):
-                        last_viz_message = message
-                    yield self._serialize_message(message)
-
-            # Check if the assistant has requested help.
-            state = self._graph.get_state(config)
-            if state.next:
-                interrupt_value = state.tasks[0].interrupts[0].value
-                feedback_message = (
-                    AssistantMessage(content=interrupt_value, id=str(uuid4()))
-                    if isinstance(interrupt_value, str)
-                    else interrupt_value
-                )
-                self._graph.update_state(config, PartialAssistantState(messages=[feedback_message]))
-                yield self._serialize_message(feedback_message)
-            else:
-                self._report_conversation_state(last_viz_message)
-        except Exception as e:
-            logger.exception("Error in assistant stream", error=e)
-            # This is an unhandled error, so we just stop further generation at this point
-            yield self._serialize_message(FailureMessage())
-            raise  # Re-raise, so that the error is printed or goes into Sentry
+        with self._lock_conversation():
+            # Assign the conversation id to the client.
+            if self._is_new_conversation:
+                yield self._serialize_conversation()
+
+            # Send the last message with the initialized id.
+            yield self._serialize_message(self._latest_message)
+
+            try:
+                last_viz_message = None
+                for update in generator:
+                    if message := self._process_update(update):
+                        if isinstance(message, VisualizationMessage):
+                            last_viz_message = message
+                        yield self._serialize_message(message)
+
+                # Check if the assistant has requested help.
+                state = self._graph.get_state(config)
+                if state.next:
+                    interrupt_messages = []
+                    for task in state.tasks:
+                        for interrupt in task.interrupts:
+                            interrupt_message = (
+                                AssistantMessage(content=interrupt.value, id=str(uuid4()))
+                                if isinstance(interrupt.value, str)
+                                else interrupt.value
+                            )
+                            interrupt_messages.append(interrupt_message)
+                            yield self._serialize_message(interrupt_message)
+
+                    self._graph.update_state(
+                        config,
+                        PartialAssistantState(
+                            messages=interrupt_messages,
+                            # LangGraph by some reason doesn't store the interrupt exceptions in checkpoints.
+                            graph_status="interrupted",
+                        ),
+                    )
+                else:
+                    self._report_conversation_state(last_viz_message)
+            except Exception as e:
+                # Reset the state, so that the next generation starts from the beginning.
+                self._graph.update_state(config, PartialAssistantState.get_reset_state())
+
+                if not isinstance(e, GenerationCanceled):
+                    logger.exception("Error in assistant stream", error=e)
+                    # This is an unhandled error, so we just stop further generation at this point
+                    yield self._serialize_message(FailureMessage())
+                    raise  # Re-raise, so that the error is printed or goes into Sentry
 
     @property
     def _initial_state(self) -> AssistantState:
@@ -174,12 +192,18 @@ def _get_config(self) -> RunnableConfig:
     def _init_or_update_state(self):
         config = self._get_config()
         snapshot = self._graph.get_state(config)
+
+        # If the graph previously hasn't reset the state, it is an interrupt. We resume from the point of interruption.
         if snapshot.next:
             saved_state = validate_state_update(snapshot.values)
-            self._state = saved_state
-            self._graph.update_state(config, PartialAssistantState(messages=[self._latest_message], resumed=True))
+            if saved_state.graph_status == "interrupted":
+                self._state = saved_state
+                self._graph.update_state(
+                    config, PartialAssistantState(messages=[self._latest_message], graph_status="resumed")
+                )
+                # Return None to indicate that we want to continue the execution from the interrupted point.
+                return None
 
-            return None
         initial_state = self._initial_state
         self._state = initial_state
         return initial_state
@@ -317,3 +341,13 @@ def _report_conversation_state(self, message: Optional[VisualizationMessage]):
                 "chat with ai",
                 {"prompt": human_message.content, "response": message.model_dump_json(exclude_none=True)},
             )
+
+    @contextmanager
+    def _lock_conversation(self):
+        try:
+            self._conversation.status = Conversation.Status.IN_PROGRESS
+            self._conversation.save()
+            yield
+        finally:
+            self._conversation.status = Conversation.Status.NOT_STARTED
+            self._conversation.save()