diff --git a/SeaHaven.DataServices/Implementation/TeamPermissionOverrideDataService.cs b/SeaHaven.DataServices/Implementation/TeamPermissionOverrideDataService.cs
index 954e8a4..b968a8b 100644
--- a/SeaHaven.DataServices/Implementation/TeamPermissionOverrideDataService.cs
+++ b/SeaHaven.DataServices/Implementation/TeamPermissionOverrideDataService.cs
@@ -63,22 +63,39 @@ public sealed class TeamPermissionOverrideDataService : ITeamPermissionOverrideD
                     && permission.PermissionKey == permissionKey,
                 cancellationToken);
 
-        if (existing is null)
-        {
-            await _context.UserPermissionOverrides.AddAsync(
-                new UserPermissionOverride
-                {
-                    UserId = userId,
-                    PermissionKey = permissionKey,
-                    State = state
-                },
-                cancellationToken);
-        }
-        else
+        if (existing is not null)
         {
             existing.State = state;
+            await _context.SaveChangesAsync(cancellationToken);
+            return;
         }
 
-        await _context.SaveChangesAsync(cancellationToken);
+        var addition = new UserPermissionOverride
+        {
+            UserId = userId,
+            PermissionKey = permissionKey,
+            State = state
+        };
+        await _context.UserPermissionOverrides.AddAsync(addition, cancellationToken);
+
+        try
+        {
+            await _context.SaveChangesAsync(cancellationToken);
+        }
+        catch (DbUpdateException)
+        {
+            // A concurrent PUT inserted the same (UserId, PermissionKey) between our
+            // existence check and this save, violating PK_UserPermissionOverrides.
+            // Converge on the caller's intent by updating the persisted row.
+            _context.Entry(addition).State = EntityState.Detached;
+
+            var winner = await _context.UserPermissionOverrides
+                .SingleAsync(
+                    permission => permission.UserId == userId
+                        && permission.PermissionKey == permissionKey,
+                    cancellationToken);
+            winner.State = state;
+            await _context.SaveChangesAsync(cancellationToken);
+        }
     }
 }
diff --git a/SeaHaven.DataServices/Implementation/UserDataService.cs b/SeaHaven.DataServices/Implementation/UserDataService.cs
index 055f870..f5dbb70 100644
--- a/SeaHaven.DataServices/Implementation/UserDataService.cs
+++ b/SeaHaven.DataServices/Implementation/UserDataService.cs
@@ -135,6 +135,10 @@ namespace SeaHaven.DataServices.Implementation
                 .Where(role => role.UserId == id)
                 .ExecuteDeleteAsync(cancellationToken);
 
+            await _context.UserPermissionOverrides
+                .Where(permissionOverride => permissionOverride.UserId == id)
+                .ExecuteDeleteAsync(cancellationToken);
+
             await _context.Users
                 .Where(existingUser => existingUser.Id == id)
                 .ExecuteDeleteAsync(cancellationToken);