feat: implement keyframe animation system

Add keyframe support for transform, opacity, and volume properties.
Includes animation engine (interpolation, mutations, resolvers), timeline
markers with selection/snapping, properties panel toggles, keyframe-aware
renderer, and full undo/redo command support.

Also refactor element command constructors to object params, extract
timeline pixel math to pixel-utils.ts, and update cursor rules.

6 files changed, 65 insertions, 16 deletions

diff --git a/apps/web/src/services/renderer/nodes/image-node.ts b/apps/web/src/services/renderer/nodes/image-node.ts
index b3a0be74..6f4f2bd8 100644
--- a/apps/web/src/services/renderer/nodes/image-node.ts
+++ b/apps/web/src/services/renderer/nodes/image-node.ts
@@ -84,6 +84,7 @@ export class ImageNode extends VisualNode<ImageNodeParams> {
 			source,
 			sourceWidth: width || renderer.width,
 			sourceHeight: height || renderer.height,
+			timelineTime: time,
 		});
 	}
 }
diff --git a/apps/web/src/services/renderer/nodes/sticker-node.ts b/apps/web/src/services/renderer/nodes/sticker-node.ts
index acf638eb..86f14fb4 100644
--- a/apps/web/src/services/renderer/nodes/sticker-node.ts
+++ b/apps/web/src/services/renderer/nodes/sticker-node.ts
@@ -62,6 +62,7 @@ export class StickerNode extends VisualNode<StickerNodeParams> {
 			source,
 			sourceWidth: width,
 			sourceHeight: height,
+			timelineTime: time,
 		});
 	}
 }
diff --git a/apps/web/src/services/renderer/nodes/text-node.ts b/apps/web/src/services/renderer/nodes/text-node.ts
index 76d78b31..0ddb4eae 100644
--- a/apps/web/src/services/renderer/nodes/text-node.ts
+++ b/apps/web/src/services/renderer/nodes/text-node.ts
@@ -12,6 +12,11 @@ import {
 	getTextBackgroundRect,
 	measureTextBlock,
 } from "@/lib/text/layout";
+import {
+	getElementLocalTime,
+	resolveOpacityAtTime,
+	resolveTransformAtTime,
+} from "@/lib/animation";
 
 function scaleFontSize({
 	fontSize,
@@ -86,16 +91,28 @@ export class TextNode extends BaseNode<TextNodeParams> {
 
 		renderer.context.save();
 
-		const x = this.params.transform.position.x + this.params.canvasCenter.x;
-		const y = this.params.transform.position.y + this.params.canvasCenter.y;
+		const localTime = getElementLocalTime({
+			timelineTime: time,
+			elementStartTime: this.params.startTime,
+			elementDuration: this.params.duration,
+		});
+		const transform = resolveTransformAtTime({
+			baseTransform: this.params.transform,
+			animations: this.params.animations,
+			localTime,
+		});
+		const opacity = resolveOpacityAtTime({
+			baseOpacity: this.params.opacity,
+			animations: this.params.animations,
+			localTime,
+		});
+		const x = transform.position.x + this.params.canvasCenter.x;
+		const y = transform.position.y + this.params.canvasCenter.y;
 
 		renderer.context.translate(x, y);
-		renderer.context.scale(
-			this.params.transform.scale,
-			this.params.transform.scale,
-		);
-		if (this.params.transform.rotate) {
-			renderer.context.rotate((this.params.transform.rotate * Math.PI) / 180);
+		renderer.context.scale(transform.scale, transform.scale);
+		if (transform.rotate) {
+			renderer.context.rotate((transform.rotate * Math.PI) / 180);
 		}
 
 		const fontWeight = this.params.fontWeight === "bold" ? "bold" : "normal";
@@ -138,7 +155,7 @@ export class TextNode extends BaseNode<TextNodeParams> {
 				? this.params.blendMode
 				: "source-over"
 		) as GlobalCompositeOperation;
-		renderer.context.globalAlpha = this.params.opacity;
+		renderer.context.globalAlpha = opacity;
 
 		if (
 			this.params.background.color &&
diff --git a/apps/web/src/services/renderer/nodes/video-node.ts b/apps/web/src/services/renderer/nodes/video-node.ts
index 8e2ddccd..9ae63661 100644
--- a/apps/web/src/services/renderer/nodes/video-node.ts
+++ b/apps/web/src/services/renderer/nodes/video-node.ts
@@ -16,7 +16,7 @@ export class VideoNode extends VisualNode<VideoNodeParams> {
 			return;
 		}
 
-		const videoTime = this.getLocalTime(time);
+		const videoTime = this.getSourceLocalTime(time);
 		const frame = await videoCache.getFrameAt({
 			mediaId: this.params.mediaId,
 			file: this.params.file,
@@ -29,6 +29,7 @@ export class VideoNode extends VisualNode<VideoNodeParams> {
 				source: frame.canvas,
 				sourceWidth: frame.canvas.width,
 				sourceHeight: frame.canvas.height,
+				timelineTime: time,
 			});
 		}
 	}
diff --git a/apps/web/src/services/renderer/nodes/visual-node.ts b/apps/web/src/services/renderer/nodes/visual-node.ts
index 7179369e..50451b4a 100644
--- a/apps/web/src/services/renderer/nodes/visual-node.ts
+++ b/apps/web/src/services/renderer/nodes/visual-node.ts
@@ -2,8 +2,13 @@ import type { CanvasRenderer } from "../canvas-renderer";
 import { BaseNode } from "./base-node";
 import type { BlendMode } from "@/types/rendering";
 import type { Transform } from "@/types/timeline";
-
-const VISUAL_EPSILON = 1 / 1000;
+import type { ElementAnimations } from "@/types/animation";
+import {
+	getElementLocalTime,
+	resolveOpacityAtTime,
+	resolveTransformAtTime,
+} from "@/lib/animation";
+import { TIME_EPSILON_SECONDS } from "@/constants/animation-constants";
 
 export interface VisualNodeParams {
 	duration: number;
@@ -11,6 +16,7 @@ export interface VisualNodeParams {
 	trimStart: number;
 	trimEnd: number;
 	transform: Transform;
+	animations?: ElementAnimations;
 	opacity: number;
 	blendMode?: BlendMode;
 }
@@ -18,14 +24,22 @@ export interface VisualNodeParams {
 export abstract class VisualNode<
 	Params extends VisualNodeParams = VisualNodeParams,
 > extends BaseNode<Params> {
-	protected getLocalTime(time: number): number {
+	protected getSourceLocalTime(time: number): number {
 		return time - this.params.timeOffset + this.params.trimStart;
 	}
 
+	protected getAnimationLocalTime(time: number): number {
+		return getElementLocalTime({
+			timelineTime: time,
+			elementStartTime: this.params.timeOffset,
+			elementDuration: this.params.duration,
+		});
+	}
+
 	protected isInRange(time: number): boolean {
-		const localTime = this.getLocalTime(time);
+		const localTime = this.getSourceLocalTime(time);
 		return (
-			localTime >= this.params.trimStart - VISUAL_EPSILON &&
+			localTime >= this.params.trimStart - TIME_EPSILON_SECONDS &&
 			localTime < this.params.trimStart + this.params.duration
 		);
 	}
@@ -35,15 +49,27 @@ export abstract class VisualNode<
 		source,
 		sourceWidth,
 		sourceHeight,
+		timelineTime,
 	}: {
 		renderer: CanvasRenderer;
 		source: CanvasImageSource;
 		sourceWidth: number;
 		sourceHeight: number;
+		timelineTime: number;
 	}): void {
 		renderer.context.save();
 
-		const { transform, opacity } = this.params;
+		const animationLocalTime = this.getAnimationLocalTime(timelineTime);
+		const transform = resolveTransformAtTime({
+			baseTransform: this.params.transform,
+			animations: this.params.animations,
+			localTime: animationLocalTime,
+		});
+		const opacity = resolveOpacityAtTime({
+			baseOpacity: this.params.opacity,
+			animations: this.params.animations,
+			localTime: animationLocalTime,
+		});
 		const containScale = Math.min(
 			renderer.width / sourceWidth,
 			renderer.height / sourceHeight,
diff --git a/apps/web/src/services/renderer/scene-builder.ts b/apps/web/src/services/renderer/scene-builder.ts
index 530b2eb3..2bbcf25f 100644
--- a/apps/web/src/services/renderer/scene-builder.ts
+++ b/apps/web/src/services/renderer/scene-builder.ts
@@ -68,6 +68,7 @@ export function buildScene(params: BuildSceneParams) {
 							trimStart: element.trimStart,
 							trimEnd: element.trimEnd,
 							transform: element.transform,
+							animations: element.animations,
 							opacity: element.opacity,
 							blendMode: element.blendMode,
 						}),
@@ -82,6 +83,7 @@ export function buildScene(params: BuildSceneParams) {
 							trimStart: element.trimStart,
 							trimEnd: element.trimEnd,
 							transform: element.transform,
+							animations: element.animations,
 							opacity: element.opacity,
 							blendMode: element.blendMode,
 							...(params.isPreview && {
@@ -112,6 +114,7 @@ export function buildScene(params: BuildSceneParams) {
 						trimStart: element.trimStart,
 						trimEnd: element.trimEnd,
 						transform: element.transform,
+						animations: element.animations,
 						opacity: element.opacity,
 						blendMode: element.blendMode,
 					}),