perf(runtime): remove measured steady allocations

Eliminate boxed production surface-override enumeration, retain vital modifier projections until the enchantment registry mutates, and measure DAT font widths without allocating a captured delegate. Preserve exact hashes, spell stacking, and glyph advances with warmed zero-allocation tests.

Validated by the focused rendering, UI, and spell suites, a zero-error Release build, and 8,409 passing Release tests with five pre-existing skips.

Co-authored-by: Codex <codex@openai.com>

tests/AcDream.App.Tests/Rendering/CurrentRenderSceneOracleTests.cs

@@ -472,6 +472,33 @@ public sealed class CurrentRenderSceneOracleTests
             CurrentRenderSceneOracle.CreateSurfaceOverrideFingerprint(null));
     }
 
+    [Fact]
+    public void SurfaceOverrideFingerprint_DictionaryHotPathAllocatesNothing()
+    {
+        var overrides = new Dictionary<uint, uint>
+        {
+            [0x0800_0001] = 0x0500_0011,
+            [0x0800_0002] = 0x0500_0012,
+            [0x0800_0003] = 0x0500_0013,
+        };
+        RenderSceneHash128 expected =
+            CurrentRenderSceneOracle.CreateSurfaceOverrideFingerprint(
+                overrides);
+        RenderSceneHash128 actual = default;
+        long before = GC.GetAllocatedBytesForCurrentThread();
+
+        for (int iteration = 0; iteration < 10_000; iteration++)
+        {
+            actual =
+                CurrentRenderSceneOracle.CreateSurfaceOverrideFingerprint(
+                    overrides);
+        }
+
+        long allocated = GC.GetAllocatedBytesForCurrentThread() - before;
+        Assert.Equal(expected, actual);
+        Assert.Equal(0, allocated);
+    }
+
     private static CurrentRenderProjectionFingerprint CaptureSingle(
         WorldEntity entity,
         uint landblockId,

tests/AcDream.App.Tests/UI/UiDatFontTests.cs

@@ -81,4 +81,35 @@ public class UiDatFontTests
         Assert.Equal(0f, UiDatFont.MeasureWidth("", Lookup));
         Assert.Equal(0f, UiDatFont.MeasureWidth(null, Lookup));
     }
+
+    [Fact]
+    public void InstanceMeasureWidth_ReusesGlyphTableWithoutAllocating()
+    {
+        var glyphs = new Dictionary<char, FontCharDesc>
+        {
+            ['A'] = Glyph('A', width: 8, before: 1, after: 2),
+            ['B'] = Glyph('B', width: 7, before: 1, after: 1),
+        };
+        var font = new UiDatFont(
+            fgTex: 0,
+            fgW: 0,
+            fgH: 0,
+            bgTex: 0,
+            bgW: 0,
+            bgH: 0,
+            lineHeight: 16f,
+            baselineOffset: 12f,
+            glyphs);
+        const string Text = "ABBA";
+        float expected = font.MeasureWidth(Text);
+        float actual = 0f;
+        long before = GC.GetAllocatedBytesForCurrentThread();
+
+        for (int iteration = 0; iteration < 10_000; iteration++)
+            actual = font.MeasureWidth(Text);
+
+        long allocated = GC.GetAllocatedBytesForCurrentThread() - before;
+        Assert.Equal(expected, actual);
+        Assert.Equal(0, allocated);
+    }
 }

tests/AcDream.Core.Tests/Spells/SpellbookTests.cs

@@ -90,6 +90,59 @@ public sealed class SpellbookTests
         Assert.Equal(2, book.ActiveCount);
     }
 
+    [Fact]
+    public void GetVitalMod_ReusesCachedValueUntilEnchantmentsChange()
+    {
+        SpellTable table = SpellTable.Create(
+        [
+            TestSpell(42u) with { Family = 100u },
+        ]);
+        var book = new Spellbook(table);
+        book.OnEnchantmentAdded(new ActiveEnchantmentRecord(
+            SpellId: 42u,
+            LayerId: 7u,
+            Duration: 300f,
+            CasterGuid: 0u,
+            StatModKey: EnchantmentMath.StatKey.MaxHealth,
+            StatModValue: 1.5f,
+            Bucket: 1u));
+        Assert.Equal(
+            1.5f,
+            book.GetVitalMod(EnchantmentMath.StatKey.MaxHealth).Multiplier);
+        EnchantmentMath.VitalMod actual = default;
+
+        // Cross the tiered-PGO call threshold before measuring the retained
+        // lookup itself. Otherwise a full parallel solution run can attribute
+        // runtime tier-promotion bookkeeping to this thread.
+        for (int iteration = 0; iteration < 10_000; iteration++)
+            actual = book.GetVitalMod(EnchantmentMath.StatKey.MaxHealth);
+
+        long before = GC.GetAllocatedBytesForCurrentThread();
+
+        for (int iteration = 0; iteration < 10_000; iteration++)
+        {
+            actual =
+                book.GetVitalMod(EnchantmentMath.StatKey.MaxHealth);
+        }
+
+        long allocated = GC.GetAllocatedBytesForCurrentThread() - before;
+        Assert.Equal(1.5f, actual.Multiplier);
+        Assert.Equal(0, allocated);
+
+        book.OnEnchantmentAdded(new ActiveEnchantmentRecord(
+            SpellId: 42u,
+            LayerId: 7u,
+            Duration: 300f,
+            CasterGuid: 0u,
+            StatModKey: EnchantmentMath.StatKey.MaxHealth,
+            StatModValue: 1.25f,
+            Bucket: 1u));
+
+        Assert.Equal(
+            1.25f,
+            book.GetVitalMod(EnchantmentMath.StatKey.MaxHealth).Multiplier);
+    }
+
     [Fact]
     public void LiveEnchantments_NewIdentityInsertsAtRetailListHead()
     {