2 files changed, 142 insertions, 7 deletions

diff --git a/apps/web/src/lib/animation/effect-param-channel.ts b/apps/web/src/lib/animation/effect-param-channel.ts
new file mode 100644
index 00000000..07efe4d8
--- /dev/null
+++ b/apps/web/src/lib/animation/effect-param-channel.ts
@@ -0,0 +1,117 @@
+import type { Effect, EffectParamValues } from "@/types/effects";
+import type {
+	ElementAnimations,
+	NumberAnimationChannel,
+} from "@/types/animation";
+import {
+	getChannel,
+	removeKeyframe,
+	setChannel,
+	upsertKeyframe,
+} from "./keyframes";
+import { getChannelValueAtTime } from "./interpolation";
+
+const EFFECT_PARAM_PATH_PREFIX = "effects.";
+const EFFECT_PARAM_PATH_SUFFIX = ".params.";
+
+function buildEffectParamPath({
+	effectId,
+	paramKey,
+}: {
+	effectId: string;
+	paramKey: string;
+}): string {
+	return `${EFFECT_PARAM_PATH_PREFIX}${effectId}${EFFECT_PARAM_PATH_SUFFIX}${paramKey}`;
+}
+
+export function resolveEffectParamsAtTime({
+	effect,
+	animations,
+	localTime,
+}: {
+	effect: Effect;
+	animations: ElementAnimations | undefined;
+	localTime: number;
+}): EffectParamValues {
+	const resolved: EffectParamValues = {};
+
+	for (const [paramKey, staticValue] of Object.entries(effect.params)) {
+		const path = buildEffectParamPath({ effectId: effect.id, paramKey });
+		const channel = getChannel({ animations, propertyPath: path });
+		if (channel && channel.keyframes.length > 0) {
+			resolved[paramKey] = getChannelValueAtTime({
+				channel,
+				time: localTime,
+				fallbackValue: staticValue,
+			}) as number | string | boolean;
+		} else {
+			resolved[paramKey] = staticValue;
+		}
+	}
+
+	return resolved;
+}
+
+const EMPTY_NUMBER_CHANNEL: NumberAnimationChannel = {
+	valueKind: "number",
+	keyframes: [],
+};
+
+export function upsertEffectParamKeyframe({
+	animations,
+	effectId,
+	paramKey,
+	time,
+	value,
+	interpolation,
+	keyframeId,
+}: {
+	animations: ElementAnimations | undefined;
+	effectId: string;
+	paramKey: string;
+	time: number;
+	value: number;
+	interpolation?: "linear" | "hold";
+	keyframeId?: string;
+}): ElementAnimations | undefined {
+	const path = buildEffectParamPath({ effectId, paramKey });
+	const channel = getChannel({ animations, propertyPath: path });
+	const targetChannel =
+		channel && channel.valueKind === "number" ? channel : EMPTY_NUMBER_CHANNEL;
+	const updatedChannel = upsertKeyframe({
+		channel: targetChannel,
+		time,
+		value,
+		interpolation: interpolation ?? "linear",
+		keyframeId,
+	});
+
+	return (
+		setChannel({
+			animations,
+			propertyPath: path,
+			channel: updatedChannel,
+		}) ?? { channels: {} }
+	);
+}
+
+export function removeEffectParamKeyframe({
+	animations,
+	effectId,
+	paramKey,
+	keyframeId,
+}: {
+	animations: ElementAnimations | undefined;
+	effectId: string;
+	paramKey: string;
+	keyframeId: string;
+}): ElementAnimations | undefined {
+	const path = buildEffectParamPath({ effectId, paramKey });
+	const channel = getChannel({ animations, propertyPath: path });
+	const updatedChannel = removeKeyframe({ channel, keyframeId });
+	return setChannel({
+		animations,
+		propertyPath: path,
+		channel: updatedChannel,
+	});
+}
diff --git a/apps/web/src/lib/animation/keyframes.ts b/apps/web/src/lib/animation/keyframes.ts
index 56f156a4..3e3613f2 100644
--- a/apps/web/src/lib/animation/keyframes.ts
+++ b/apps/web/src/lib/animation/keyframes.ts
@@ -127,7 +127,9 @@ function buildKeyframe({
 	}
 
 	if (typeof value !== "string" && typeof value !== "boolean") {
-		throw new Error("Discrete channel keyframes require boolean or string values");
+		throw new Error(
+			"Discrete channel keyframes require boolean or string values",
+		);
 	}
 
 	return {
@@ -145,14 +147,23 @@ function createEmptyChannel({
 }): AnimationChannel {
 	const propertyDefinition = getAnimationPropertyDefinition({ propertyPath });
 	if (propertyDefinition.valueKind === "number") {
-		return { valueKind: "number", keyframes: [] } satisfies NumberAnimationChannel;
+		return {
+			valueKind: "number",
+			keyframes: [],
+		} satisfies NumberAnimationChannel;
 	}
 
 	if (propertyDefinition.valueKind === "color") {
-		return { valueKind: "color", keyframes: [] } satisfies ColorAnimationChannel;
+		return {
+			valueKind: "color",
+			keyframes: [],
+		} satisfies ColorAnimationChannel;
 	}
 
-	return { valueKind: "discrete", keyframes: [] } satisfies DiscreteAnimationChannel;
+	return {
+		valueKind: "discrete",
+		keyframes: [],
+	} satisfies DiscreteAnimationChannel;
 }
 
 export function upsertKeyframe({
@@ -432,7 +443,10 @@ export function splitAnimationsAtTime({
 		const hasBoundaryOnRight = rightKeyframes.some((keyframe) =>
 			isNearlySameTime({ leftTime: keyframe.time, rightTime: 0 }),
 		);
-		if (shouldIncludeSplitBoundary && (!hasBoundaryOnLeft || !hasBoundaryOnRight)) {
+		if (
+			shouldIncludeSplitBoundary &&
+			(!hasBoundaryOnLeft || !hasBoundaryOnRight)
+		) {
 			const boundaryValue = getChannelValueAtTime({
 				channel: normalizedChannel,
 				time: splitTime,
@@ -442,7 +456,9 @@ export function splitAnimationsAtTime({
 				? (propertyPath as AnimationPropertyPath)
 				: null;
 			const boundaryInterpolation = knownPropertyPath
-				? getDefaultInterpolationForProperty({ propertyPath: knownPropertyPath })
+				? getDefaultInterpolationForProperty({
+						propertyPath: knownPropertyPath,
+					})
 				: normalizedChannel.valueKind === "discrete"
 					? "hold"
 					: "linear";
@@ -523,7 +539,9 @@ export function upsertElementKeyframe({
 		return animations;
 	}
 
-	const defaultInterpolation = getDefaultInterpolationForProperty({ propertyPath });
+	const defaultInterpolation = getDefaultInterpolationForProperty({
+		propertyPath,
+	});
 	const propertyDefinition = getAnimationPropertyDefinition({ propertyPath });
 	const channel = getChannel({ animations, propertyPath });
 	const targetChannel =