diff --git a/src/AcDream.Core/World/SkyState.cs b/src/AcDream.Core/World/SkyState.cs
index 5acf2d39..0120e84a 100644
--- a/src/AcDream.Core/World/SkyState.cs
+++ b/src/AcDream.Core/World/SkyState.cs
@@ -74,22 +74,15 @@ public readonly record struct SkyKeyframe(
     /// (see <see cref="SkyStateProvider.RetailSunVector"/>).
     ///
     /// <para>
-    /// Why <c>|sunVec|</c> instead of <c>DirBright</c> directly: retail's
-    /// <c>PrimD3DRender::UpdateLightsInternal</c> at <c>0x0059b57c</c>
-    /// (decomp line 424118-424119) computes
-    /// <code>D3DLIGHT9.Diffuse.r = sunlight_color.r × sqrt(x²+y²+z²)</code>
-    /// from the sun vector <c>SkyDesc::GetLighting</c> built at
-    /// <c>0x00500ac9</c> (decomp lines 261343-261353):
-    /// <code>
-    ///   sunVec.x = sin(H) × DirBright × cos(P)
-    ///   sunVec.y = cos(P)                    // NOT scaled by DirBright
-    ///   sunVec.z = DirBright × sin(P)
-    /// </code>
-    /// Because Y is unscaled by <c>DirBright</c>, <c>|sunVec|</c> ≠
-    /// <c>DirBright</c> in general — it varies with sun pitch and heading.
-    /// Using <c>DirBright</c> alone underweighted the warm directional
-    /// term, letting the cool ambient/fog dominate ⇒ acdream rendered
-    /// blue-white at keyframes where retail looked warm-gray.
+    /// <c>|sunVec|</c> is retail's <c>D3DLIGHT9.Diffuse = DirColor × sqrt(x²+y²+z²)</c>
+    /// scaling (<c>PrimD3DRender::UpdateLightsInternal</c> 0x0059b57c, decomp
+    /// 424118-424119) of the WORLD-space sun vector (<c>LScape::sunlight</c>).
+    /// Because <see cref="SkyStateProvider.RetailSunVector"/> is now the
+    /// DirBright-scaled spherical vector (magnitude == DirBright, cdb-verified —
+    /// see that method), <c>|sunVec| == DirBright</c>, so this is effectively
+    /// <c>SunColor = DirColor × DirBright</c>. (A prior bug used the un-transformed
+    /// y=cos(P) vector ⇒ |sunVec|≈1.06 ⇒ the sun was ~4–5× too bright at dawn/dusk;
+    /// [[reference-retail-ambient-values]].)
     /// </para>
     /// </summary>
     public Vector3 SunColor => DirColor * SkyStateProvider.RetailSunVector(this).Length();
@@ -301,21 +294,35 @@ public sealed class SkyStateProvider
     }
 
     /// <summary>
-    /// Retail's raw sun vector (NOT normalized) — the same vector
-    /// <c>SkyDesc::GetLighting</c> writes at <c>0x00500ac9</c>
-    /// (decomp lines 261343, 261352, 261353):
+    /// Retail's world-space sun vector (NOT normalized): the standard
+    /// spherical-to-cartesian direction (East=x, North=y, Up=z) scaled by
+    /// <c>DirBright</c>:
     /// <code>
-    ///   sunVec.x = sin(H_rad) × DirBright × cos(P_rad)
-    ///   sunVec.y = cos(P_rad)                    // NOT scaled by DirBright
-    ///   sunVec.z = DirBright × sin(P_rad)
+    ///   sunVec.x = DirBright × cos(P) × sin(H)
+    ///   sunVec.y = DirBright × cos(P) × cos(H)
+    ///   sunVec.z = DirBright × sin(P)
     /// </code>
-    /// Y is unscaled by brightness on purpose — that's what makes
-    /// <c>|sunVec|</c> ≠ <c>DirBright</c> in general (the magnitude varies
-    /// with pitch/heading, which is the basis for retail's "sun is brighter
-    /// in some configurations than others" lighting behavior). The shader's
-    /// <c>uSunDir</c> uniform uses the NORMALIZED vector for N·L; the
-    /// magnitude feeds <see cref="SkyKeyframe.SunColor"/> intensity and
-    /// the ambient brightness boost in <see cref="SkyKeyframe.AmbientColor"/>.
+    /// so <c>|sunVec| == DirBright</c> exactly (cos²P·(sin²H+cos²H)+sin²P = 1).
+    ///
+    /// <para>
+    /// GROUNDED IN A LIVE cdb CAPTURE (2026-06-18, [[reference-retail-ambient-values]]):
+    /// retail's <c>LScape::sunlight</c> read at a dawn keyframe (H=90°, P=0.9°,
+    /// DirBright≈0.224) = <c>(0.2238, ~0, 0.00352)</c> — y≈0, magnitude 0.224 =
+    /// DirBright. That fed <c>level = 0.2·|sunlight| + ambient_level = 0.2·0.224 +
+    /// 0.40 = 0.445</c>, matching the captured <c>SetWorldAmbientLight</c> level.
+    /// </para>
+    /// <para>
+    /// PRIOR BUG: an earlier version returned <c>y = cos(P)</c> (≈1) — the raw
+    /// PRE-transform value the decomp's <c>SkyDesc::GetLighting</c> writes to its
+    /// <c>arg5</c> (0x00500ac9, before <c>LScape::set_sky_position</c>'s world
+    /// transform). Porting that un-transformed vector inflated <c>|sunVec|</c> to
+    /// ~1.06 instead of ~0.22, over-brightening BOTH the ambient boost
+    /// (<see cref="SkyKeyframe.AmbientColor"/>) AND the sun colour
+    /// (<see cref="SkyKeyframe.SunColor"/>) by ~30% vs retail. The world-space
+    /// form above is what <c>LScape::sunlight</c> actually holds at runtime.
+    /// </para>
+    /// The shader uses the NORMALIZED vector for N·L; the magnitude (= DirBright)
+    /// feeds the sun-colour intensity and the ambient brightness boost.
     /// </summary>
     public static Vector3 RetailSunVector(SkyKeyframe kf)
     {
@@ -325,9 +332,9 @@ public sealed class SkyStateProvider
         float sinP = MathF.Sin(p);
         float B = kf.DirBright;
         return new Vector3(
-            MathF.Sin(h) * B * cosP,    // x = sin(H) × B × cos(P)
-            cosP,                        // y = cos(P)        ← unscaled by B
-            B * sinP);                   // z = B × sin(P)
+            B * cosP * MathF.Sin(h),    // x = DirBright × cos(P) × sin(H)
+            B * cosP * MathF.Cos(h),    // y = DirBright × cos(P) × cos(H)
+            B * sinP);                   // z = DirBright × sin(P)
     }
 
     /// <summary>
diff --git a/tests/AcDream.Core.Tests/World/SkyDescLoaderTests.cs b/tests/AcDream.Core.Tests/World/SkyDescLoaderTests.cs
index d07d0a64..4ceeddba 100644
--- a/tests/AcDream.Core.Tests/World/SkyDescLoaderTests.cs
+++ b/tests/AcDream.Core.Tests/World/SkyDescLoaderTests.cs
@@ -100,22 +100,23 @@ public sealed class SkyDescLoaderTests
     {
         // The loader stores DirColor and DirBright RAW. The SunColor property
         // composes them via |sunVec| per retail's UpdateLightsInternal at
-        // 0x59b57c (decomp 424118) — the diffuse magnitude is sqrt(x²+y²+z²)
-        // where the sun vector is built from heading/pitch/brightness with
-        // Y unscaled by brightness (decomp 261352).
+        // 0x59b57c (decomp 424118) — diffuse = DirColor × |LScape::sunlight|.
+        // cdb-verified (reference-retail-ambient-values): |LScape::sunlight| ==
+        // DirBright for every keyframe (world-space spherical vector, magnitude
+        // DirBright·sqrt(cos²P+sin²P) = DirBright).
         //
         // For this region:  H=180°, P=70°, B=1.5
-        //   sunVec = (sin(180)*1.5*cos(70), cos(70), 1.5*sin(70))
-        //          = (0, 0.342, 1.410)
-        //   |sunVec| = sqrt(0 + 0.117 + 1.988) = 1.4509
+        //   sunVec = 1.5 × (cos(70)·sin(180), cos(70)·cos(180), sin(70))
+        //          = (0, -0.513, 1.410)
+        //   |sunVec| = sqrt(0 + 0.263 + 1.988) = 1.500  (= DirBright)
         // DirColor.X = 200/255 = 0.7843
-        // SunColor.X = 0.7843 × 1.4509 = 1.138
+        // SunColor.X = 0.7843 × 1.500 = 1.1765
         var region = MakeRegion(dirBright: 1.5f, rBgrOrder: 200);
         var loaded = SkyDescLoader.LoadFromRegion(region);
         Assert.NotNull(loaded);
 
         var kf = loaded!.DayGroups[0].SkyTimes[0].Keyframe;
-        Assert.InRange(kf.SunColor.X, 1.13f, 1.15f);
+        Assert.InRange(kf.SunColor.X, 1.17f, 1.18f);
     }
 
     [Fact]
diff --git a/tests/AcDream.Core.Tests/World/SkyStateTests.cs b/tests/AcDream.Core.Tests/World/SkyStateTests.cs
index 1c677204..3d87da00 100644
--- a/tests/AcDream.Core.Tests/World/SkyStateTests.cs
+++ b/tests/AcDream.Core.Tests/World/SkyStateTests.cs
@@ -66,24 +66,33 @@ public sealed class SkyStateTests
     }
 
     [Fact]
-    public void RetailSunVector_AtHorizonNorth_MagnitudeIsOne()
+    public void RetailSunVector_MagnitudeAlwaysEqualsDirBright()
     {
-        // Sun on horizon to the north (H=0°, P=0°): cos(P)=1, sin(P)=0.
-        //   sunVec = (sin(0)×B×1, 1, B×0) = (0, 1, 0)
-        //   |sunVec| = 1   regardless of B   (because Y is unscaled by B)
-        var kf = new SkyKeyframe(
-            Begin: 0f,
-            SunHeadingDeg: 0f,
-            SunPitchDeg:   0f,
-            DirColor:      Vector3.One,
-            DirBright:     2.0f,           // anything
-            AmbColor:      Vector3.One,
-            AmbBright:     1f,
-            FogColor:      Vector3.One,
-            FogDensity:    0f);
+        // cdb-verified (2026-06-18, reference-retail-ambient-values): retail's
+        // world-space LScape::sunlight = DirBright × (cosP·sinH, cosP·cosH, sinP),
+        // whose magnitude is DirBright·sqrt(cos²P·(sin²H+cos²H)+sin²P) = DirBright
+        // for ALL headings/pitches. (The prior y=cos(P) port gave |sunVec|≈1 at the
+        // horizon — that was the ~30% over-bright bug.)
+        // Horizon north (H=0°, P=0°): (0, B, 0), |.| = B.
+        var horizon = new SkyKeyframe(
+            Begin: 0f, SunHeadingDeg: 0f, SunPitchDeg: 0f,
+            DirColor: Vector3.One, DirBright: 2.0f,
+            AmbColor: Vector3.One, AmbBright: 1f,
+            FogColor: Vector3.One, FogDensity: 0f);
+        Assert.InRange(SkyStateProvider.RetailSunVector(horizon).Length(), 1.99f, 2.01f);
 
-        var v = SkyStateProvider.RetailSunVector(kf);
-        Assert.InRange(v.Length(), 0.99f, 1.01f);
+        // Reproduce the live cdb capture: dawn keyframe H=90°, P=0.9°, DirBright=0.224
+        // → LScape::sunlight = (0.2238, ~0, 0.00352), magnitude 0.224 = DirBright.
+        var dawn = new SkyKeyframe(
+            Begin: 0f, SunHeadingDeg: 90f, SunPitchDeg: 0.9f,
+            DirColor: Vector3.One, DirBright: 0.224f,
+            AmbColor: Vector3.One, AmbBright: 0.40f,
+            FogColor: Vector3.One, FogDensity: 0f);
+        var v = SkyStateProvider.RetailSunVector(dawn);
+        Assert.InRange(v.X, 0.223f, 0.225f);   // DirBright·cosP·sin(90°) ≈ 0.224
+        Assert.InRange(v.Y, -0.001f, 0.001f);  // DirBright·cosP·cos(90°) ≈ 0   (was the bug: ≈1)
+        Assert.InRange(v.Z, 0.003f, 0.004f);   // DirBright·sin(0.9°) ≈ 0.0035
+        Assert.InRange(v.Length(), 0.223f, 0.225f);   // = DirBright
     }
 
     [Fact]