diff --git a/pomodoro_to_harvest.py b/pomodoro_to_harvest.py
index a5bb1df..33b7ffa 100644
--- a/pomodoro_to_harvest.py
+++ b/pomodoro_to_harvest.py
@@ -28,6 +28,11 @@ timelog = timelog.explode("description").reset_index()
 
 timelog["started"] = pd.to_datetime(timelog["started"]).dt.tz_convert("US/Eastern")
 timelog["recorded"] = pd.to_datetime(timelog["recorded"]).dt.tz_convert("US/Eastern")
+
+latest_recorded = settings.pomodoro_latest_recorded()
+if latest_recorded:
+    timelog = timelog.query("recorded>" + latest_recorded)
+
 timelog["time"] = 30
 # A pomodoro started before 3am Eastern time is considered to be a continuation
 # of the day before, so we are, effectively, on West Coast time for determining
@@ -89,6 +94,8 @@ for preferred, alternatives in replacement_project_names.items():
 # The fillna is essential or we drop entries with blank ('None') projects.
 tl = timelog.groupby(["date", timelog.project.fillna(""), "description"]).agg({"time": 'sum', "started": 'min', "recorded": 'max'}).reset_index()
 
-tl.to_csv('harvest-ready.csv', index = False)
-
-settings.pomodoro_latest_recorded(tl.recorded.max())
+if hasattr(sys, 'ps1'):
+    tl.to_csv('harvest-ready.csv', index=False)
+    settings.pomodoro_latest_recorded(tl.recorded.max())
+else:
+    print("We do not write to the harvest-ready.csv nor update the latest recorded setting when run interactively in the python shell.")