cancelling flows

rasa/core/policies/default_flows.yml

@@ -24,6 +24,11 @@ responses:
       metadata: 
         rephrase: True
 
+  utter_flow_cancelled:
+    - text: Okay, stopping the flow {rasa_cancelled_flow}.
+      metadata:
+        rephrase: True
+
 slots:
   confirm_correction:
     type: text
@@ -65,4 +70,11 @@ flows:
         next: "3"
       - id: "3"
         action: utter_not_corrected_previous_input
+
+  pattern_cancel_flow:
+    description: A meta flow that's started when a flow is cancelled.
+
+    steps:
+      - id: "0"
+        action: utter_flow_cancelled
 

rasa/core/policies/flow_policy.py

@@ -10,18 +10,17 @@
     POLICY_PRIORITY,
 )
 from pypred import Predicate
-from rasa.shared.constants import FLOW_PREFIX
+from rasa.shared.constants import FLOW_PREFIX, CORRECTION_INTENT, CANCEL_FLOW_INTENT
 from rasa.shared.nlu.constants import (
     ACTION_NAME,
     ENTITY_ATTRIBUTE_TYPE,
     INTENT_NAME_KEY,
-    CORRECTION_INTENT,
 )
 from rasa.shared.core.constants import (
     ACTION_LISTEN_NAME,
     CORRECTED_SLOTS_SLOT,
     FLOW_STACK_SLOT,
-    PREVIOUS_FLOW_SLOT,
+    PREVIOUS_FLOW_SLOT, CANCELLED_FLOW_SLOT,
 )
 from rasa.shared.core.events import ActiveLoop, Event, SlotSet, UserUttered
 from rasa.shared.core.flows.flow import (
@@ -633,6 +632,22 @@ def _find_earliest_updated_question(
                 return question_step
         return None
 
+    def should_flow_be_cancelled(self, tracker: DialogueStateTracker) -> bool:
+        """Test whether the current flow should be cancelled.
+
+        Args:
+            tracker: the conversation state tracker
+        Returns:
+        Whether the current flow should be cancelled
+        """
+        if (
+            not tracker.latest_message
+            or tracker.latest_action_name != ACTION_LISTEN_NAME
+        ):
+            # flows can only be cancelled as a response to a user message
+            return False
+        return tracker.latest_message.intent.get(INTENT_NAME_KEY) == CANCEL_FLOW_INTENT
+
     def consider_flow_switch(self, tracker: DialogueStateTracker) -> ActionPrediction:
         """Consider switching to a new flow.
 
@@ -671,6 +686,15 @@ def advance_flows(self, tracker: DialogueStateTracker) -> ActionPrediction:
         if self.flow_stack.is_empty():
             # if there are no flows, there is nothing to do
             return ActionPrediction(None, 0.0)
+        elif self.should_flow_be_cancelled(tracker) and \
+                not self.flow_stack.is_empty():
+            top_flow = self.flow_stack.pop()
+            return ActionPrediction(
+                FLOW_PREFIX + "pattern_cancel_flow",
+                1.0,
+                metadata={"slots": {CANCELLED_FLOW_SLOT: top_flow.flow_id}},
+                events=[SlotSet(FLOW_STACK_SLOT, self.flow_stack.as_dict())],
+            )
         else:
             prediction = self._select_next_action(tracker)
             if FlowStack.from_tracker(tracker).as_dict() != self.flow_stack.as_dict():

rasa/nlu/classifiers/llm_flow_classifier.py

@@ -25,8 +25,8 @@
     ENTITY_ATTRIBUTE_END,
     ENTITY_ATTRIBUTE_TEXT,
     ENTITY_ATTRIBUTE_CONFIDENCE,
-    CORRECTION_INTENT,
 )
+from rasa.shared.constants import CORRECTION_INTENT, CANCEL_FLOW_INTENT
 from rasa.shared.nlu.training_data.message import Message
 from rasa.shared.nlu.training_data.training_data import TrainingData
 from rasa.utils.llm import (
@@ -227,7 +227,7 @@ def parse_action_list(
             if len(slot_sets) == 0 and not cancel_flow:
                 return "comment", []
             elif len(slot_sets) == 0 and cancel_flow:
-                return "cancel_flow", []
+                return CANCEL_FLOW_INTENT, []
             elif (
                 len(slot_sets) == 1
                 and isinstance(top_flow_step, QuestionFlowStep)

rasa/shared/constants.py

@@ -109,3 +109,6 @@
 CHANNEL = "channel"
 
 OPENAI_API_KEY_ENV_VAR = "OPENAI_API_KEY"
+
+CORRECTION_INTENT = "rasa_correction"
+CANCEL_FLOW_INTENT = "rasa_cancel_flow"

rasa/shared/core/constants.py

@@ -17,6 +17,8 @@
     USER_INTENT_BACK,
     USER_INTENT_OUT_OF_SCOPE,
     USER_INTENT_SESSION_START,
+    constants.CANCEL_FLOW_INTENT,
+    constants.CORRECTION_INTENT,
     constants.DEFAULT_NLU_FALLBACK_INTENT_NAME,
 ]
 
@@ -81,11 +83,13 @@
 REQUESTED_SLOT = "requested_slot"
 FLOW_STACK_SLOT = "flow_stack"
 PREVIOUS_FLOW_SLOT = "rasa_previous_flow"
+CANCELLED_FLOW_SLOT = "rasa_cancelled_flow"
 CORRECTED_SLOTS_SLOT = "rasa_corrected_slots"
 
 FLOW_SLOT_NAMES = [
     FLOW_STACK_SLOT,
     PREVIOUS_FLOW_SLOT,
+    CANCELLED_FLOW_SLOT,
     CORRECTED_SLOTS_SLOT,
 ]
 
@@ -99,6 +103,7 @@
     REQUESTED_SLOT,
     FLOW_STACK_SLOT,
     PREVIOUS_FLOW_SLOT,
+    CANCELLED_FLOW_SLOT,
     CORRECTED_SLOTS_SLOT,
     SESSION_START_METADATA_SLOT,
     SLOT_LISTED_ITEMS,

rasa/shared/nlu/constants.py

@@ -41,4 +41,3 @@
 SPLIT_ENTITIES_BY_COMMA_DEFAULT_VALUE = True
 SINGLE_ENTITY_ALLOWED_INTERLEAVING_CHARSET = {".", ",", " ", ";"}
 
-CORRECTION_INTENT = "correction"