NEO-104: Use subset check for all-targets-defeated predicate.

Matches documented semantics; extra defeated ids via direct store
calls no longer block completion readiness (Bugbot PR #143).

server/NeonSprawl.Server.Tests/Game/Encounters/EncounterProgressOperationsTests.cs

@@ -180,6 +180,28 @@ public sealed class EncounterProgressOperationsTests
         Assert.True(allDefeated);
     }
 
+    [Fact]
+    public async Task IsAllRequiredTargetsDefeated_ShouldReturnTrue_WhenDefeatedSetIsSupersetOfRequired()
+    {
+        // Arrange
+        await using var factory = new InMemoryWebApplicationFactory();
+        var registry = factory.Services.GetRequiredService<IEncounterDefinitionRegistry>();
+        var progress = factory.Services.GetRequiredService<IEncounterProgressStore>();
+        _ = progress.TryActivate(PlayerId, EncounterId);
+        _ = progress.TryAddDefeatedTarget(PlayerId, EncounterId, MeleeNpc);
+        _ = progress.TryAddDefeatedTarget(PlayerId, EncounterId, RangedNpc);
+        _ = progress.TryAddDefeatedTarget(PlayerId, EncounterId, EliteNpc);
+        _ = progress.TryAddDefeatedTarget(PlayerId, EncounterId, "extra_non_required_npc");
+        // Act
+        var allDefeated = EncounterProgressOperations.IsAllRequiredTargetsDefeated(
+            PlayerId,
+            EncounterId,
+            registry,
+            progress);
+        // Assert
+        Assert.True(allDefeated);
+    }
+
     [Fact]
     public async Task TryMarkCompleted_ShouldReturnFalseOnSecondAttempt_WhenUsingCompletionStoreDirectly()
     {

server/NeonSprawl.Server/Game/Encounters/EncounterProgressOperations.cs

@@ -142,6 +142,6 @@ public static class EncounterProgressOperations
             return false;
         }
 
-        return required.SetEquals(progress.DefeatedNpcInstanceIds);
+        return required.IsSubsetOf(progress.DefeatedNpcInstanceIds);
     }
 }