Direct add participants and allow for new participants via messages.

src/dispatch/case/flows.py

@@ -282,6 +282,16 @@ def case_new_create_flow(*, case_id: int, organization_slug: OrganizationSlug, d
                 )
                 # wait until all resources are created before adding suggested participants
                 individual_participants = [x.email for x, _ in individual_participants]
+
+                for email in individual_participants:
+                    # we don't rely on on this flow to add folks to the conversation because in this case
+                    # we want to do it in bulk
+                    case_add_or_reactivate_participant_flow(
+                        db_session=db_session,
+                        user_email=email,
+                        case_id=case.id,
+                        add_to_conversation=False,
+                    )
                 conversation_plugin.instance.add_to_thread(
                     case.conversation.channel_id,
                     case.conversation.thread_id,

src/dispatch/participant/service.py

@@ -79,6 +79,18 @@ def get_by_incident_id_and_conversation_id(
     )
 
 
+def get_by_case_id_and_conversation_id(
+    *, db_session, case_id: int, user_conversation_id: str
+) -> Optional[Participant]:
+    """Get participant by case and user_conversation id."""
+    return (
+        db_session.query(Participant)
+        .filter(Participant.case_id == case_id)
+        .filter(Participant.user_conversation_id == user_conversation_id)
+        .one_or_none()
+    )
+
+
 def get_all(*, db_session) -> List[Optional[Participant]]:
     """Get all participants."""
     return db_session.query(Participant)

src/dispatch/plugins/dispatch_slack/case/interactive.py

@@ -73,6 +73,23 @@ def assignee_select(
     )
 
 
+@message_dispatcher.add(
+    subject="case", exclude={"subtype": ["channel_join", "channel_leave"]}
+)  # we ignore channel join and leave messages
+def handle_new_participant_message(
+    ack: Ack, user: DispatchUser, context: BoltContext, db_session: Session, client: WebClient
+) -> None:
+    """Looks for new participants that have starting chatting for the first time."""
+    ack()
+    participant = case_flows.case_add_or_reactive_participant_flow(
+        case_id=context["subject"].id,
+        user_email=user.email,
+        db_session=db_session,
+        add_to_conversation=False,
+    )
+    participant.user_conversation_id = context["user_id"]
+
+
 @message_dispatcher.add(
     subject="case", exclude={"subtype": ["channel_join", "channel_leave"]}
 )  # we ignore channel join and leave messages

src/dispatch/plugins/dispatch_slack/middleware.py

@@ -198,9 +198,15 @@ def user_middleware(
         )
         db_session = refetch_db_session(slug)
 
-    participant = participant_service.get_by_incident_id_and_conversation_id(
-        db_session=db_session, incident_id=context["subject"].id, user_conversation_id=user_id
-    )
+    if context["subject"].type == "incident":
+        participant = participant_service.get_by_incident_id_and_conversation_id(
+            db_session=db_session, incident_id=context["subject"].id, user_conversation_id=user_id
+        )
+    else:
+        participant = participant_service.get_by_case_id_and_conversation_id(
+            db_session=db_session, case_id=context["subject"].id, user_conversation_id=user_id
+        )
+
     if participant:
         context["user"] = user_service.get_or_create(
             db_session=db_session,