feat(rng-seam): ScriptedRandomSource (throw-on-overrun deterministic source)

SVSim.BattleEngine.Tests/RngSeamTests.cs

@@ -35,5 +35,21 @@ namespace SVSim.BattleEngine.Tests
             for (int i = 0; i < 8; i++)
                 Assert.That(src.NextSelf(100), Is.EqualTo(refSelf.Next(100)), $"NextSelf drift at {i}");
         }
+
+        // ScriptedRandomSource feeds a known sequence (the oracle's control + the Phase-3 replay seam).
+        // It MUST throw on overrun, not wrap: an unexpected extra roll should fail loudly so a test
+        // surfaces a miscount of engine RNG calls rather than silently reusing a value.
+        [Test]
+        public void ScriptedSource_returns_sequence_then_throws_on_overrun()
+        {
+            var src = new ScriptedRandomSource(new[] { 0.1, 0.5 }, new[] { 3 });
+
+            Assert.That(src.NextUnit(), Is.EqualTo(0.1));
+            Assert.That(src.NextUnit(), Is.EqualTo(0.5));
+            Assert.That(() => src.NextUnit(), Throws.InvalidOperationException, "should throw on unit overrun");
+
+            Assert.That(src.NextSelf(99), Is.EqualTo(3));
+            Assert.That(() => src.NextSelf(99), Throws.InvalidOperationException, "should throw on self overrun");
+        }
     }
 }