Add safe deletion parity with journalist interface

Permit the deletion of a source's conversation items, without deleting
their account.

securedrop_client/api_jobs/sources.py

@@ -34,6 +34,35 @@ def call_api(self, api_client: API, session: Session) -> str:
             raise DeleteSourceJobException(error_message, self.uuid)
 
 
+class DeleteConversationJob(ApiJob):
+    def __init__(self, uuid: str) -> None:
+        super().__init__()
+        self.uuid = uuid
+
+    def call_api(self, api_client: API, session: Session) -> str:
+        """
+        Override ApiJob.
+
+        Delete a source on the server
+        """
+        try:
+            api_client.delete_conversation(uuid=self.uuid)
+            return self.uuid
+        except (RequestTimeoutError, ServerConnectionError):
+            raise
+        except Exception as e:
+            error_message = "Failed to delete conversation for source {uuid}: {exception}".format(
+                uuid=self.uuid, exception=repr(e)
+            )
+            raise DeleteConversationJobException(error_message, self.uuid)
+
+
+class DeleteConversationJobException(Exception):
+    def __init__(self, message: str, source_uuid: str):
+        super().__init__(message)
+        self.source_uuid = source_uuid
+
+
 class DeleteSourceJobException(Exception):
     def __init__(self, message: str, source_uuid: str):
         super().__init__(message)

securedrop_client/gui/main.py

@@ -147,7 +147,7 @@ def refresh_current_source_conversation(self):
         """
         Update the current conversation if the source collection has changed.
         """
-        self.main_view.on_source_changed()
+        self.main_view.refresh_source_conversations()
 
     def show_sources(self, sources: List[Source]):
         """