diff --git a/packages/core/src/colorGrading.test.ts b/packages/core/src/colorGrading.test.ts
index 3840acb7d..6e5178b87 100644
--- a/packages/core/src/colorGrading.test.ts
+++ b/packages/core/src/colorGrading.test.ts
@@ -1,6 +1,8 @@
 import { describe, expect, it } from "vitest";
 import { COLOR_GRADING_ADVANCED_LIMITS } from "@hyperframes/parsers/color-grading-contract";
+import { unitFloatToByte } from "./colorLuts";
 import {
+  calculateHfColorGradingSecondaryMask,
   HF_COLOR_GRADING_COLOR_SPACE,
   HF_COLOR_GRADING_ACTIVE_EFFECT_KEYS,
   HF_COLOR_GRADING_EFFECT_APPLY_DEFAULTS,
@@ -198,6 +200,37 @@ describe("color grading", () => {
     });
   });
 
+  it("matches the shader's packed secondary-softness convention", () => {
+    for (const axis of ["saturation", "luma"] as const) {
+      const grading = normalizeHfColorGrading({
+        secondaries: [
+          {
+            key: {
+              hue: { center: 0, range: 180, softness: 0 },
+              saturation: { min: axis === "saturation" ? 0.5 : 0, max: 1, softness: 0.4 },
+              luma: { min: axis === "luma" ? 0.5 : 0, max: 1, softness: 0.4 },
+            },
+            correction: {},
+          },
+        ],
+      });
+      const key = grading?.secondaries[0]?.key;
+      if (!key) throw new Error("Expected a normalized secondary key");
+
+      const packedSoftness = unitFloatToByte(key[axis].softness / 0.5);
+      const shaderDecodedSoftness = (packedSoftness / 255) * 0.5;
+      const decodedKey = {
+        ...key,
+        [axis]: { ...key[axis], softness: shaderDecodedSoftness },
+      };
+      const productMask = calculateHfColorGradingSecondaryMask(0, 0.2, 0.2, key);
+      const shaderMask = calculateHfColorGradingSecondaryMask(0, 0.2, 0.2, decodedKey);
+
+      expect(productMask, axis).toBeGreaterThan(0);
+      expect(productMask, axis).toBeCloseTo(shaderMask, 2);
+    }
+  });
+
   it("merges manual adjustments over preset values", () => {
     const grading = normalizeHfColorGrading({
       preset: "warm-daylight",
diff --git a/packages/core/src/colorGrading.ts b/packages/core/src/colorGrading.ts
index a3903f695..0d24a0037 100644
--- a/packages/core/src/colorGrading.ts
+++ b/packages/core/src/colorGrading.ts
@@ -675,24 +675,19 @@ const SECONDARY_SOFT_RANGE_DEFAULT: Required<HfColorGradingSoftRange> = {
   softness: 0.05,
 };
 const DETAIL_LIMITS: Record<HfColorGradingDetailKey, { min: number; max: number }> = {
-  vignette: { min: 0, max: 1 },
-  vignetteMidpoint: { min: 0, max: 1 },
-  vignetteRoundness: { min: -1, max: 1 },
-  vignetteFeather: { min: 0, max: 1 },
-  grain: { min: 0, max: 1 },
-  grainSize: { min: 0, max: 1 },
-  grainRoughness: { min: 0, max: 1 },
+  vignette: COLOR_GRADING_ADVANCED_LIMITS.unit,
+  vignetteMidpoint: COLOR_GRADING_ADVANCED_LIMITS.unit,
+  vignetteRoundness: COLOR_GRADING_ADVANCED_LIMITS.signedUnit,
+  vignetteFeather: COLOR_GRADING_ADVANCED_LIMITS.unit,
+  grain: COLOR_GRADING_ADVANCED_LIMITS.unit,
+  grainSize: COLOR_GRADING_ADVANCED_LIMITS.unit,
+  grainRoughness: COLOR_GRADING_ADVANCED_LIMITS.unit,
 };
 
 const UNIT_LIMIT = COLOR_GRADING_ADVANCED_LIMITS.unit;
 const EFFECT_LIMIT_OVERRIDES: Partial<
   Record<HfColorGradingEffectKey, { min: number; max: number }>
-> = {
-  asciiStyle: { min: 0, max: 7 },
-  bloom: { min: 0, max: 3 },
-  bloomRadius: { min: 1, max: 100 },
-  monoScreenShape: { min: 0, max: 4 },
-};
+> = COLOR_GRADING_ADVANCED_LIMITS.effects;
 
 export const HF_COLOR_GRADING_ACTIVE_EFFECT_KEYS = [
   "blur",
@@ -1115,6 +1110,47 @@ function wrapDegrees(value: unknown, fallback = 0): number {
   return ((parsed % 360) + 360) % 360;
 }
 
+function smoothstep(min: number, max: number, value: number): number {
+  const normalized = clamp((value - min) / (max - min), 0, 1);
+  return normalized * normalized * (3 - 2 * normalized);
+}
+
+function softRangeMask(value: number, min: number, max: number, softness: number): number {
+  if (value < min) {
+    return softness <= 0 ? 0 : smoothstep(min - softness, min, value);
+  }
+  if (value > max) {
+    return softness <= 0 ? 0 : 1 - smoothstep(max, max + softness, value);
+  }
+  return 1;
+}
+
+/**
+ * Mirrors the runtime shader's HSL-secondary qualifier for Studio mattes and
+ * other non-WebGL verification surfaces.
+ */
+export function calculateHfColorGradingSecondaryMask(
+  hue: number,
+  saturation: number,
+  luma: number,
+  key: NormalizedHfColorGradingSecondary["key"],
+): number {
+  const hueDistance = Math.abs(((((hue - key.hue.center + 540) % 360) + 360) % 360) - 180);
+  const hueMask =
+    key.hue.range < 179.999 && saturation < 0.001
+      ? 0
+      : hueDistance <= key.hue.range
+        ? 1
+        : key.hue.softness <= 0
+          ? 0
+          : 1 - smoothstep(key.hue.range, key.hue.range + key.hue.softness, hueDistance);
+  return (
+    hueMask *
+    softRangeMask(saturation, key.saturation.min, key.saturation.max, key.saturation.softness) *
+    softRangeMask(luma, key.luma.min, key.luma.max, key.luma.softness)
+  );
+}
+
 function normalizeWheels(value: unknown): NormalizedHfColorGradingWheels {
   const wheels = isRecord(value) ? value : {};
   return HF_COLOR_GRADING_WHEEL_KEYS.reduce<NormalizedHfColorGradingWheels>(
diff --git a/packages/core/src/runtime/colorGrading.ts b/packages/core/src/runtime/colorGrading.ts
index 318f1a18f..a5050a722 100644
--- a/packages/core/src/runtime/colorGrading.ts
+++ b/packages/core/src/runtime/colorGrading.ts
@@ -2764,6 +2764,7 @@ const ADVANCED_SIGNATURES = new WeakMap<
     signature: string;
   }
 >();
+// Identity-keyed: normalized grading objects must be replaced, never mutated.
 
 function advancedTextureSignature(
   curves: NormalizedHfColorGradingCurves,
diff --git a/packages/parsers/src/colorGradingContract.test.ts b/packages/parsers/src/colorGradingContract.test.ts
index 7625ea92b..b8412a6bf 100644
--- a/packages/parsers/src/colorGradingContract.test.ts
+++ b/packages/parsers/src/colorGradingContract.test.ts
@@ -26,6 +26,12 @@ describe("color grading contract", () => {
       secondaryHueRange: { min: 0, max: 180 },
       secondarySoftRangeSoftness: { min: 0, max: 0.5 },
       secondaryHueShift: { min: -180, max: 180 },
+      effects: {
+        asciiStyle: { min: 0, max: 7 },
+        bloom: { min: 0, max: 3 },
+        bloomRadius: { min: 1, max: 100 },
+        monoScreenShape: { min: 0, max: 4 },
+      },
     });
   });
 
diff --git a/packages/parsers/src/colorGradingContract.ts b/packages/parsers/src/colorGradingContract.ts
index a5a147105..7949da17c 100644
--- a/packages/parsers/src/colorGradingContract.ts
+++ b/packages/parsers/src/colorGradingContract.ts
@@ -11,6 +11,12 @@ export const COLOR_GRADING_ADVANCED_LIMITS = {
   secondaryHueCombinedMax: 180,
   secondarySoftRangeSoftness: { min: 0, max: 0.5 },
   secondaryHueShift: { min: -180, max: 180 },
+  effects: {
+    asciiStyle: { min: 0, max: 7 },
+    bloom: { min: 0, max: 3 },
+    bloomRadius: { min: 1, max: 100 },
+    monoScreenShape: { min: 0, max: 4 },
+  },
 } as const;
 
 export const COLOR_GRADING_TOP_LEVEL_KEYS = [
@@ -142,12 +148,8 @@ type NumericLimit = Readonly<{ min: number; max: number }>;
 
 const UNIT_LIMIT: NumericLimit = COLOR_GRADING_ADVANCED_LIMITS.unit;
 const SIGNED_UNIT_LIMIT: NumericLimit = COLOR_GRADING_ADVANCED_LIMITS.signedUnit;
-const EFFECT_LIMIT_OVERRIDES: Readonly<Record<string, NumericLimit>> = {
-  asciiStyle: { min: 0, max: 7 },
-  bloom: { min: 0, max: 3 },
-  bloomRadius: { min: 1, max: 100 },
-  monoScreenShape: { min: 0, max: 4 },
-};
+const EFFECT_LIMIT_OVERRIDES: Readonly<Record<string, NumericLimit>> =
+  COLOR_GRADING_ADVANCED_LIMITS.effects;
 const VARIABLE_REF = /^\$(?:\{[A-Za-z0-9_.:-]+\}|[A-Za-z0-9_.:-]+)$/;
 const PALETTE_COLOR = /^#[0-9a-f]{6}$/i;