NEO-93: Preserve LastAdvancedUtc on clock regression and guard zero timings.

Do not move the lazy-tick marker backward when nowUtc regresses; reject
non-positive catalog durations and break the phase loop when cursor stalls.

Co-authored-by: Cursor <cursoragent@cursor.com>

server/NeonSprawl.Server.Tests/Game/Npc/NpcRuntimeOperationsTests.cs

@@ -277,4 +277,43 @@ public sealed class NpcRuntimeOperationsTests
         Assert.Equal(T0.AddHours(1).AddSeconds(10), snapshot.PhaseStartedUtc);
         Assert.Equal(T0.AddHours(1).AddSeconds(10), runtime.LastAdvancedUtc);
     }
+
+    [Fact]
+    public void AdvanceAll_ShouldPreserveLastAdvancedUtc_WhenClockRegresses()
+    {
+        // Arrange
+        var (runtime, threat, behavior) = CreateFixture();
+        Advance(T0, runtime, threat, behavior);
+        runtime.LastAdvancedUtc = T0.AddSeconds(10);
+        // Act
+        Advance(T0.AddSeconds(5), runtime, threat, behavior);
+        // Assert
+        Assert.Equal(T0.AddSeconds(10), runtime.LastAdvancedUtc);
+    }
+
+    [Fact]
+    public void HasPositiveTimingDurations_ShouldRejectNonPositiveCatalogTimings()
+    {
+        // Arrange
+        var invalidCooldown = new NpcBehaviorDefRow(
+            "bad",
+            "Bad",
+            "melee_pressure",
+            100,
+            8.0,
+            16.0,
+            1.5,
+            15,
+            0.0);
+        var invalidWindup = invalidCooldown with { Id = "bad2", TelegraphWindupSeconds = 0.0 };
+        var valid = invalidCooldown with { AttackCooldownSeconds = 3.0, TelegraphWindupSeconds = 1.5 };
+        // Act
+        var cooldownOk = NpcRuntimeOperations.HasPositiveTimingDurations(invalidCooldown);
+        var windupOk = NpcRuntimeOperations.HasPositiveTimingDurations(invalidWindup);
+        var validOk = NpcRuntimeOperations.HasPositiveTimingDurations(valid);
+        // Assert
+        Assert.False(cooldownOk);
+        Assert.False(windupOk);
+        Assert.True(validOk);
+    }
 }

server/NeonSprawl.Server/Game/Npc/NpcRuntimeOperations.cs

@@ -53,7 +53,6 @@ public static class NpcRuntimeOperations
                     behaviorRegistry);
             }
 
-            runtimeStore.LastAdvancedUtc = nowUtc;
             return;
         }
 
@@ -93,6 +92,11 @@ public static class NpcRuntimeOperations
             return;
         }
 
+        if (!HasPositiveTimingDurations(behavior))
+        {
+            return;
+        }
+
         if (!runtimeStore.TryGet(npcInstanceId, out var snapshot))
         {
             return;
@@ -137,6 +141,7 @@ public static class NpcRuntimeOperations
                 return;
             }
 
+            var loopCursorBefore = cursor;
             switch (snapshot.BehaviorState)
             {
                 case NpcBehaviorState.Idle:
@@ -159,7 +164,7 @@ public static class NpcRuntimeOperations
                         cursor,
                         telegraph);
                     // telemetry: npc_state_transition (NEO-96)
-                    continue;
+                    break;
                 }
 
                 case NpcBehaviorState.TelegraphWindup:
@@ -178,7 +183,7 @@ public static class NpcRuntimeOperations
                         cursor,
                         activeTelegraph: null);
                     // telemetry: telegraph_fired / npc_state_transition (NEO-96); logical attack_execute → recover (NEO-95 applies attackDamage)
-                    continue;
+                    break;
                 }
 
                 case NpcBehaviorState.AttackExecute:
@@ -189,7 +194,7 @@ public static class NpcRuntimeOperations
                         cursor,
                         activeTelegraph: null);
                     // telemetry: npc_state_transition (NEO-96); NEO-95 applies attackDamage here
-                    continue;
+                    break;
 
                 case NpcBehaviorState.Recover:
                 {
@@ -208,15 +213,24 @@ public static class NpcRuntimeOperations
                         cursor,
                         telegraph);
                     // telemetry: npc_state_transition (NEO-96)
-                    continue;
+                    break;
                 }
 
                 default:
                     return;
             }
+
+            if (cursor <= loopCursorBefore)
+            {
+                return;
+            }
         }
     }
 
+    /// <summary>Catalog timings must be positive; CI/content gate enforces for prototype defs.</summary>
+    internal static bool HasPositiveTimingDurations(NpcBehaviorDefRow behavior) =>
+        behavior.AttackCooldownSeconds > 0 && behavior.TelegraphWindupSeconds > 0;
+
     private static bool TryHasAggroHolder(
         string npcInstanceId,
         IThreatStateStore threatStore,