fix(ui): gate — no void frames around the login wormhole; vitals icons centered

The login tunnel now covers from the first world-facing frame (the
sky-void backdrop can never present pre-tunnel) and holds through an
atomic tunnel-to-world swap at reveal completion — the void is
structurally unreachable on both edges, pinned by frame-sequence tests
across WorldSceneRenderer/WorldRevealCoordinator/LocalPlayerTeleport-
Controller/RuntimeWorldTransitState. Vitals detail icons draw at their
authored centered offsets in both stacked and side-by-side layouts.
Implemented and live-probed by the fix agent; finalized by the lead
after the agent parked post-verification (gates re-run green:
App 5512/3, Runtime 1747/0).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/AcDream.App.Tests/UI/Layout/VitalsDetailToggleTests.cs

@@ -72,6 +72,88 @@ public class VitalsDetailToggleTests
         Assert.Equal((66f, 0f, 18f, 16f), health.DetailBackRect);
     }
 
+    [Fact]
+    public void VitalsTree_OverlaysCarryTheAuthoredCenterAnchors()
+    {
+        // The 0x100004A9 overlays author LeftEdge=3 / RightEdge=3 — retail's
+        // CENTER anchor modes (UIElement::UpdateForParentSizeChange
+        // @ 0x004627ca / 0x00462827) — with Top=1/Bottom=1, inside the
+        // 150x16 slice containers. These are what keep the icons centered
+        // when the vitals window resizes the meters (2026-08-17 gate:
+        // absorbed overlays previously kept only the authored rect, pinning
+        // the icon at its authored X on any wider meter).
+        var layout = FixtureLoader.LoadVitals();
+        foreach (uint meterId in new[]
+        {
+            VitalsController.Health,
+            VitalsController.Stamina,
+            VitalsController.Mana,
+        })
+        {
+            var m = Assert.IsType<UiMeter>(layout.FindElement(meterId));
+            foreach (UiMeterDetailOverlaySpec overlay in new[] { m.DetailBack, m.DetailFront })
+            {
+                Assert.Equal(3u, overlay.LeftMode);
+                Assert.Equal(1u, overlay.TopMode);
+                Assert.Equal(3u, overlay.RightMode);
+                Assert.Equal(1u, overlay.BottomMode);
+                Assert.Equal(150f, overlay.ParentW);
+                Assert.Equal(16f, overlay.ParentH);
+            }
+        }
+    }
+
+    // ── Icon placement: authored at authored size, centered on resize ────
+
+    [Fact]
+    public void DetailIcon_AuthoredRectStandsAtTheAuthoredMeterSize()
+    {
+        // Retail reflows a child ONLY when its parent actually resizes; at
+        // the authored size the designer's hand-placed rect stands — the
+        // stamina sword authors X=32 where the mode-3 center formula yields
+        // 33, so recomputing unconditionally would shift the un-resized
+        // window by a pixel.
+        var sword = new UiMeterDetailOverlaySpec(
+            0x06007492u, 32f, 0f, 85f, 16f, 3u, 1u, 3u, 1u, 150f, 16f);
+        Assert.Equal(
+            (32f, 0f, 85f, 16f),
+            UiMeter.ComputeDetailOverlayRect(in sword, 150f, 16f));
+    }
+
+    [Theory]
+    // Heart 18x16: near = W/2 - 9, far = W/2 + 9 - 1 -> width preserved.
+    [InlineData(66f, 18f, 300f, 141f, 18f)]
+    [InlineData(66f, 18f, 220f, 101f, 18f)]
+    // Scepter 100x16: near = W/2 - 50.
+    [InlineData(25f, 100f, 300f, 100f, 100f)]
+    public void DetailIcon_CentersOnAWiderMeter(
+        float authoredX, float authoredW, float meterW,
+        float expectedX, float expectedW)
+    {
+        var overlay = new UiMeterDetailOverlaySpec(
+            0x06007490u, authoredX, 0f, authoredW, 16f, 3u, 1u, 3u, 1u, 150f, 16f);
+        (float x, float y, float w, float h) =
+            UiMeter.ComputeDetailOverlayRect(in overlay, meterW, 16f);
+        Assert.Equal(expectedX, x);
+        Assert.Equal(0f, y);
+        Assert.Equal(expectedW, w);
+        Assert.Equal(16f, h);
+    }
+
+    [Fact]
+    public void DetailIcon_OddWidthLosesOnePixelExactlyLikeRetail()
+    {
+        // Sword 85px: retail's integer halves (>>1) give near = 150 - 42 =
+        // 108 and far = 150 + 42 - 1 = 191 on a 300px meter -> width 84,
+        // one pixel narrower than authored. Faithful, not a bug.
+        var sword = new UiMeterDetailOverlaySpec(
+            0x06007492u, 32f, 0f, 85f, 16f, 3u, 1u, 3u, 1u, 150f, 16f);
+        (float x, float _, float w, float _) =
+            UiMeter.ComputeDetailOverlayRect(in sword, 300f, 16f);
+        Assert.Equal(108f, x);
+        Assert.Equal(84f, w);
+    }
+
     // ── The press toggle ─────────────────────────────────────────────────────
 
     [Fact]