diff --git a/SVSim.Bootstrap/Importers/AchievementCatalogImporter.cs b/SVSim.Bootstrap/Importers/AchievementCatalogImporter.cs
index 5d2349c0..23474266 100644
--- a/SVSim.Bootstrap/Importers/AchievementCatalogImporter.cs
+++ b/SVSim.Bootstrap/Importers/AchievementCatalogImporter.cs
@@ -3,6 +3,7 @@ using SVSim.Bootstrap.Models.Seed;
 using SVSim.Database;
 using SVSim.Database.Enums;
 using SVSim.Database.Models;
+using SVSim.Database.Services;
 
 namespace SVSim.Bootstrap.Importers;
 
@@ -24,6 +25,22 @@ public class AchievementCatalogImporter
 
         var existing = await context.AchievementCatalog
             .ToDictionaryAsync(e => (e.AchievementType, e.Level));
+        // Fail fast on drift between seed event_type values and the code-side registry.
+        // Missing prefixes silently produce counters no emitter ever writes to; typos likewise.
+        var unregistered = seed
+            .Where(s => s.EventType is not null && !MissionEventKeys.IsRegistered(s.EventType))
+            .Select(s => s.EventType!)
+            .Distinct()
+            .OrderBy(x => x)
+            .ToList();
+        if (unregistered.Count > 0)
+        {
+            throw new InvalidOperationException(
+                "[AchievementCatalogImporter] seed rows reference unregistered event_type(s): "
+                + string.Join(", ", unregistered)
+                + ". Add the top-level prefix to MissionEventKeys.RegisteredPrefixes, or fix the seed.");
+        }
+
         int created = 0, updated = 0;
         var unmappedTypes = new HashSet<int>();
         foreach (var s in seed)
diff --git a/SVSim.Bootstrap/Importers/BattlePassMonthlyMissionImporter.cs b/SVSim.Bootstrap/Importers/BattlePassMonthlyMissionImporter.cs
index 4518544a..c9f25889 100644
--- a/SVSim.Bootstrap/Importers/BattlePassMonthlyMissionImporter.cs
+++ b/SVSim.Bootstrap/Importers/BattlePassMonthlyMissionImporter.cs
@@ -3,6 +3,7 @@ using SVSim.Bootstrap.Models.Seed;
 using SVSim.Database;
 using SVSim.Database.Enums;
 using SVSim.Database.Models;
+using SVSim.Database.Services;
 
 namespace SVSim.Bootstrap.Importers;
 
@@ -22,6 +23,21 @@ public class BattlePassMonthlyMissionImporter
             return 0;
         }
 
+        // Fail fast on drift between seed event_type values and the code-side registry.
+        var unregistered = seed
+            .Where(s => s.EventType is not null && !MissionEventKeys.IsRegistered(s.EventType))
+            .Select(s => s.EventType!)
+            .Distinct()
+            .OrderBy(x => x)
+            .ToList();
+        if (unregistered.Count > 0)
+        {
+            throw new InvalidOperationException(
+                "[BattlePassMonthlyMissionImporter] seed rows reference unregistered event_type(s): "
+                + string.Join(", ", unregistered)
+                + ". Add the top-level prefix to MissionEventKeys.RegisteredPrefixes, or fix the seed.");
+        }
+
         var existing = await context.BattlePassMonthlyMissions
             .ToDictionaryAsync(e => (e.Year, e.Month, e.OrderNum));
         int created = 0, updated = 0;
diff --git a/SVSim.Bootstrap/Importers/MissionCatalogImporter.cs b/SVSim.Bootstrap/Importers/MissionCatalogImporter.cs
index 5eab6835..1187474c 100644
--- a/SVSim.Bootstrap/Importers/MissionCatalogImporter.cs
+++ b/SVSim.Bootstrap/Importers/MissionCatalogImporter.cs
@@ -3,6 +3,7 @@ using SVSim.Bootstrap.Models.Seed;
 using SVSim.Database;
 using SVSim.Database.Enums;
 using SVSim.Database.Models;
+using SVSim.Database.Services;
 
 namespace SVSim.Bootstrap.Importers;
 
@@ -21,6 +22,21 @@ public class MissionCatalogImporter
             return 0;
         }
 
+        // Fail fast on drift between seed event_type values and the code-side registry.
+        var unregistered = seed
+            .Where(s => s.EventType is not null && !MissionEventKeys.IsRegistered(s.EventType))
+            .Select(s => s.EventType!)
+            .Distinct()
+            .OrderBy(x => x)
+            .ToList();
+        if (unregistered.Count > 0)
+        {
+            throw new InvalidOperationException(
+                "[MissionCatalogImporter] seed rows reference unregistered event_type(s): "
+                + string.Join(", ", unregistered)
+                + ". Add the top-level prefix to MissionEventKeys.RegisteredPrefixes, or fix the seed.");
+        }
+
         var existing = await context.MissionCatalog.ToDictionaryAsync(e => e.Id);
         int created = 0, updated = 0;
         var unmapped = new List<int>();