diff --git a/mac_cocoa.py b/mac_cocoa.py
index 39efe5c..184dc01 100644
--- a/mac_cocoa.py
+++ b/mac_cocoa.py
@@ -142,14 +142,38 @@ class AppDelegate(NSObject):
             previous = get_previous_sunday()
             latest_dt = datetime.fromisoformat(latest.replace("Z", "+00:00"))
             previous_dt = datetime.fromisoformat(previous.replace("Z", "+00:00"))
-            user_id = os.environ.get("JELLYFIN_USER_ID")
-            if not user_id:
-                raise RuntimeError("JELLYFIN_USER_ID not set in environment")
 
-            ep_info = jellyfin.find_last_one_piece_episode(latest_dt, user_id)
-            prev_ep_info = jellyfin.find_last_one_piece_before_previous_sunday(previous_dt, user_id)
-            previous_episode = prev_ep_info["episode_number"]
+            host = os.environ.get("JELLYFIN_HOST")
+            key = os.environ.get("JELLYFIN_API_KEY")
+            user_id = os.environ.get("JELLYFIN_USER_ID")
             total_episodes = int(os.environ.get("TOTAL_EPISODES", 1155))
+
+            # If credentials are missing, provide a demo report so UI can be validated without Jellyfin
+            if not (host and key and user_id):
+                demo_ep = min(total_episodes, 1000)
+                prev_ep = max(0, demo_ep - 3)
+                watched_this_week = demo_ep - prev_ep
+                week_start, week_end, _ = current_week()
+                date_range = format_date_range(week_start, week_end)
+                report_text = (
+                    f"ONE PIECE PROGRESS (DEMO MODE) ({date_range})\n"
+                    f"Episode {demo_ep}/{total_episodes}\n"
+                    f"Around {watched_this_week} episodes watched this week!"
+                )
+                payload = {"report": report_text, "debug": "Demo mode: Jellyfin credentials not set."}
+                self.performSelectorOnMainThread_withObject_waitUntilDone_("updateUI:", payload, False)
+                return
+
+            # Try real Jellyfin calls; on failure show error (with debug logs)
+            try:
+                ep_info = jellyfin.find_last_one_piece_episode(latest_dt, user_id)
+                prev_ep_info = jellyfin.find_last_one_piece_before_previous_sunday(previous_dt, user_id)
+            except Exception as e:
+                payload = {"error": "Failed to contact Jellyfin: " + str(e), "debug": jellyfin.get_debug_logs()}
+                self.performSelectorOnMainThread_withObject_waitUntilDone_("showError:", payload, False)
+                return
+
+            previous_episode = prev_ep_info["episode_number"]
             watched_this_week = ep_info["episode_number"] - previous_episode
             week_start, week_end, _ = current_week()
             date_range = format_date_range(week_start, week_end)
@@ -162,7 +186,6 @@ class AppDelegate(NSObject):
 
             debug_output = jellyfin.get_debug_logs()
             payload = {"report": report_text, "debug": debug_output}
-            # Update UI on main thread
             self.performSelectorOnMainThread_withObject_waitUntilDone_("updateUI:", payload, False)
         except Exception as e:
             payload = {"error": str(e), "debug": jellyfin.get_debug_logs()}