diff --git a/src/routes/+page.svelte b/src/routes/+page.svelte
index 0909715..96c1550 100644
--- a/src/routes/+page.svelte
+++ b/src/routes/+page.svelte
@@ -31,10 +31,14 @@
   let highlightedUnitId = $state<string | null>(null);
   let yoloMode = $state<boolean>(false);
 
-  // Initialize fromUnitId to first unit once data arrives
+  // Initialize fromUnitId to the base unit of the first visible group.
+  // Falls back to units[0] if no groups or the base unit isn't in the visible list.
   $effect(() => {
     if (fromUnitId === '' && units.length > 0) {
-      fromUnitId = units[0].id;
+      const firstGroupBaseId = groups.length > 0 ? groups[0].baseUnitId : null;
+      fromUnitId = (firstGroupBaseId && units.some((u) => u.id === firstGroupBaseId))
+        ? firstGroupBaseId
+        : units[0].id;
     }
   });