solitaire_engine/src/difficulty_plugin.rs

@@ -54,7 +54,10 @@ impl DifficultyIndexResource {
             DifficultyLevel::Hard => &mut self.hard,
             DifficultyLevel::Expert => &mut self.expert,
             DifficultyLevel::Grandmaster => &mut self.grandmaster,
-            DifficultyLevel::Random => unreachable!("Random has no catalog"),
+            // Random has no catalog today, so seeds_for() already returned
+            // None above; if it ever gains one, a time seed is still the
+            // right answer for "Random" — never a reachable panic.
+            DifficultyLevel::Random => return seed_from_system_time(),
         };
         let seed = catalog[*cursor % catalog.len()];
         *cursor = cursor.wrapping_add(1);