codebase overhaul (#697)

apps/web/src/lib/commands/base-command.ts

@@ -0,0 +1,11 @@
+export abstract class Command {
+	abstract execute(): void;
+
+	undo(): void {
+		throw new Error("Undo not implemented for this command");
+	}
+
+	redo(): void {
+		this.execute();
+	}
+}

apps/web/src/lib/commands/index.ts

@@ -0,0 +1,6 @@
+export { Command } from "./base-command";
+
+export * from "./timeline";
+export * from "./media";
+export * from "./scene";
+export * from "./project";

apps/web/src/lib/commands/media/add-media-asset.ts

@@ -0,0 +1,61 @@
+import { Command } from "@/lib/commands/base-command";
+import { EditorCore } from "@/core";
+import type { MediaAsset } from "@/types/assets";
+import { generateUUID } from "@/utils/id";
+import { storageService } from "@/services/storage/storage-service";
+
+export class AddMediaAssetCommand extends Command {
+	private assetId: string;
+	private savedAssets: MediaAsset[] | null = null;
+	private createdAsset: MediaAsset | null = null;
+
+	constructor(
+		private projectId: string,
+		private asset: Omit<MediaAsset, "id">,
+	) {
+		super();
+		this.assetId = generateUUID();
+	}
+
+	execute(): void {
+		const editor = EditorCore.getInstance();
+		this.savedAssets = [...editor.media.getAssets()];
+
+		this.createdAsset = {
+			...this.asset,
+			id: this.assetId,
+		};
+
+		editor.media.setAssets({
+			assets: [...this.savedAssets, this.createdAsset],
+		});
+
+		storageService
+			.saveMediaAsset({
+				projectId: this.projectId,
+				mediaAsset: this.createdAsset,
+			})
+			.catch((error) => {
+				console.error("Failed to save media item:", error);
+			});
+	}
+
+	undo(): void {
+		if (this.savedAssets) {
+			const editor = EditorCore.getInstance();
+			editor.media.setAssets({ assets: this.savedAssets });
+
+			if (this.createdAsset) {
+				storageService
+					.deleteMediaAsset({ projectId: this.projectId, id: this.assetId })
+					.catch((error) => {
+						console.error("Failed to delete media item on undo:", error);
+					});
+			}
+		}
+	}
+
+	getAssetId(): string {
+		return this.assetId;
+	}
+}

apps/web/src/lib/commands/media/index.ts

@@ -0,0 +1,2 @@
+export { AddMediaAssetCommand } from "./add-media-asset";
+export { RemoveMediaAssetCommand } from "./remove-media-asset";

apps/web/src/lib/commands/media/remove-media-asset.ts

@@ -0,0 +1,85 @@
+import { Command } from "@/lib/commands/base-command";
+import { EditorCore } from "@/core";
+import type { MediaAsset } from "@/types/assets";
+import { storageService } from "@/services/storage/storage-service";
+import { videoCache } from "@/services/media/video-cache";
+import { hasMediaId } from "@/lib/timeline/element-utils";
+import type { TimelineTrack } from "@/types/timeline";
+
+export class RemoveMediaAssetCommand extends Command {
+	private savedAssets: MediaAsset[] | null = null;
+	private savedTracks: TimelineTrack[] | null = null;
+	private removedAsset: MediaAsset | null = null;
+
+	constructor(
+		private projectId: string,
+		private assetId: string,
+	) {
+		super();
+	}
+
+	execute(): void {
+		const editor = EditorCore.getInstance();
+		const assets = editor.media.getAssets();
+
+		this.savedAssets = [...assets];
+		this.savedTracks = editor.timeline.getTracks();
+
+		this.removedAsset =
+			assets.find((media) => media.id === this.assetId) ?? null;
+
+		if (!this.removedAsset) {
+			console.error("Media asset not found:", this.assetId);
+			return;
+		}
+
+		videoCache.clearVideo({ mediaId: this.assetId });
+
+		editor.media.setAssets({
+			assets: assets.filter((media) => media.id !== this.assetId),
+		});
+
+		const elementsToRemove: Array<{ trackId: string; elementId: string }> = [];
+
+		for (const track of this.savedTracks) {
+			for (const element of track.elements) {
+				if (hasMediaId(element) && element.mediaId === this.assetId) {
+					elementsToRemove.push({ trackId: track.id, elementId: element.id });
+				}
+			}
+		}
+
+		if (elementsToRemove.length > 0) {
+			editor.timeline.deleteElements({ elements: elementsToRemove });
+		}
+
+		storageService
+			.deleteMediaAsset({ projectId: this.projectId, id: this.assetId })
+			.catch((error) => {
+				console.error("Failed to delete media item:", error);
+			});
+	}
+
+	undo(): void {
+		const editor = EditorCore.getInstance();
+
+		if (this.savedAssets) {
+			editor.media.setAssets({ assets: this.savedAssets });
+		}
+
+		if (this.savedTracks) {
+			editor.timeline.updateTracks(this.savedTracks);
+		}
+
+		if (this.removedAsset) {
+			storageService
+				.saveMediaAsset({
+					projectId: this.projectId,
+					mediaAsset: this.removedAsset,
+				})
+				.catch((error) => {
+					console.error("Failed to restore media item on undo:", error);
+				});
+		}
+	}
+}

apps/web/src/lib/commands/project/index.ts

@@ -0,0 +1 @@
+export * from "./update-project-settings";

apps/web/src/lib/commands/project/update-project-settings.ts

@@ -0,0 +1,46 @@
+import { Command } from "@/lib/commands/base-command";
+import { EditorCore } from "@/core";
+import type { TProject, TProjectSettings } from "@/types/project";
+
+export class UpdateProjectSettingsCommand extends Command {
+	private savedSettings: TProjectSettings | null = null;
+	private savedUpdatedAt: Date | null = null;
+
+	constructor(private updates: Partial<TProjectSettings>) {
+		super();
+	}
+
+	execute(): void {
+		const editor = EditorCore.getInstance();
+		const activeProject = editor.project.getActive();
+		if (!activeProject) return;
+
+		this.savedSettings = activeProject.settings;
+		this.savedUpdatedAt = activeProject.metadata.updatedAt;
+
+		const updatedProject: TProject = {
+			...activeProject,
+			settings: { ...activeProject.settings, ...this.updates },
+			metadata: { ...activeProject.metadata, updatedAt: new Date() },
+		};
+
+		editor.project.setActiveProject({ project: updatedProject });
+		editor.save.markDirty();
+	}
+
+	undo(): void {
+		if (!this.savedSettings || !this.savedUpdatedAt) return;
+		const editor = EditorCore.getInstance();
+		const activeProject = editor.project.getActive();
+		if (!activeProject) return;
+
+		const updatedProject: TProject = {
+			...activeProject,
+			settings: this.savedSettings,
+			metadata: { ...activeProject.metadata, updatedAt: this.savedUpdatedAt },
+		};
+
+		editor.project.setActiveProject({ project: updatedProject });
+		editor.save.markDirty();
+	}
+}

apps/web/src/lib/commands/scene/create-scene.ts

@@ -0,0 +1,40 @@
+import { Command } from "@/lib/commands/base-command";
+import { EditorCore } from "@/core";
+import type { TScene } from "@/types/timeline";
+import { buildDefaultScene } from "@/lib/scenes";
+
+export class CreateSceneCommand extends Command {
+	private savedScenes: TScene[] | null = null;
+	private createdScene: TScene | null = null;
+
+	constructor(
+		private name: string,
+		private isMain: boolean = false,
+	) {
+		super();
+	}
+
+	execute(): void {
+		const editor = EditorCore.getInstance();
+		this.savedScenes = [...editor.scenes.getScenes()];
+
+		this.createdScene = buildDefaultScene({
+			name: this.name,
+			isMain: this.isMain,
+		});
+
+		const updatedScenes = [...this.savedScenes, this.createdScene];
+		editor.scenes.setScenes({ scenes: updatedScenes });
+	}
+
+	undo(): void {
+		if (this.savedScenes) {
+			const editor = EditorCore.getInstance();
+			editor.scenes.setScenes({ scenes: this.savedScenes });
+		}
+	}
+
+	getSceneId(): string {
+		return this.createdScene?.id ?? "";
+	}
+}

apps/web/src/lib/commands/scene/delete-scene.ts

@@ -0,0 +1,59 @@
+import { Command } from "@/lib/commands/base-command";
+import { EditorCore } from "@/core";
+import type { TScene } from "@/types/timeline";
+import { canDeleteScene, getFallbackSceneAfterDelete } from "@/lib/scenes";
+
+export class DeleteSceneCommand extends Command {
+	private savedScenes: TScene[] | null = null;
+	private savedActiveSceneId: string | null = null;
+	private deletedScene: TScene | null = null;
+
+	constructor(private sceneId: string) {
+		super();
+	}
+
+	execute(): void {
+		const editor = EditorCore.getInstance();
+		const scenes = editor.scenes.getScenes();
+		const activeScene = editor.scenes.getActiveScene();
+
+		this.savedScenes = [...scenes];
+		this.savedActiveSceneId = activeScene?.id ?? null;
+
+		this.deletedScene = scenes.find((s) => s.id === this.sceneId) ?? null;
+
+		if (!this.deletedScene) {
+			console.error("Scene not found:", this.sceneId);
+			return;
+		}
+
+		const { canDelete, reason } = canDeleteScene({ scene: this.deletedScene });
+		if (!canDelete) {
+			console.error("Cannot delete scene:", reason);
+			return;
+		}
+
+		const updatedScenes = scenes.filter((s) => s.id !== this.sceneId);
+
+		const newActiveScene = getFallbackSceneAfterDelete({
+			scenes: updatedScenes,
+			deletedSceneId: this.sceneId,
+			currentSceneId: activeScene?.id ?? null,
+		});
+
+		editor.scenes.setScenes({
+			scenes: updatedScenes,
+			activeSceneId: newActiveScene?.id,
+		});
+	}
+
+	undo(): void {
+		if (this.savedScenes && this.deletedScene) {
+			const editor = EditorCore.getInstance();
+			editor.scenes.setScenes({
+				scenes: this.savedScenes,
+				activeSceneId: this.savedActiveSceneId ?? undefined,
+			});
+		}
+	}
+}

apps/web/src/lib/commands/scene/index.ts

@@ -0,0 +1,5 @@
+export { CreateSceneCommand } from "./create-scene";
+export { DeleteSceneCommand } from "./delete-scene";
+export { RenameSceneCommand } from "./rename-scene";
+export { ToggleBookmarkCommand } from "./toggle-bookmark";
+export { RemoveBookmarkCommand } from "./remove-bookmark";

apps/web/src/lib/commands/scene/remove-bookmark.ts

@@ -0,0 +1,59 @@
+import { Command } from "@/lib/commands/base-command";
+import { EditorCore } from "@/core";
+import type { TScene } from "@/types/timeline";
+import { updateSceneInArray } from "@/lib/scenes";
+import {
+	getFrameTime,
+	removeBookmarkFromArray,
+} from "@/lib/timeline/bookmarks";
+
+export class RemoveBookmarkCommand extends Command {
+	private savedScenes: TScene[] | null = null;
+	private frameTime: number = 0;
+
+	constructor(private time: number) {
+		super();
+	}
+
+	execute(): void {
+		const editor = EditorCore.getInstance();
+		const activeScene = editor.scenes.getActiveScene();
+		const activeProject = editor.project.getActive();
+
+		if (!activeScene || !activeProject) {
+			return;
+		}
+
+		const scenes = editor.scenes.getScenes();
+		this.savedScenes = [...scenes];
+
+		this.frameTime = getFrameTime({
+			time: this.time,
+			fps: activeProject.settings.fps,
+		});
+
+		const updatedBookmarks = removeBookmarkFromArray({
+			bookmarks: activeScene.bookmarks,
+			frameTime: this.frameTime,
+		});
+
+		if (updatedBookmarks.length === activeScene.bookmarks.length) {
+			return;
+		}
+
+		const updatedScenes = updateSceneInArray({
+			scenes,
+			sceneId: activeScene.id,
+			updates: { bookmarks: updatedBookmarks },
+		});
+
+		editor.scenes.setScenes({ scenes: updatedScenes });
+	}
+
+	undo(): void {
+		if (this.savedScenes) {
+			const editor = EditorCore.getInstance();
+			editor.scenes.setScenes({ scenes: this.savedScenes });
+		}
+	}
+}

apps/web/src/lib/commands/scene/rename-scene.ts

@@ -0,0 +1,46 @@
+import { Command } from "@/lib/commands/base-command";
+import { EditorCore } from "@/core";
+import type { TScene } from "@/types/timeline";
+import { updateSceneInArray } from "@/lib/scenes";
+
+export class RenameSceneCommand extends Command {
+	private savedScenes: TScene[] | null = null;
+	private previousName: string | null = null;
+
+	constructor(
+		private sceneId: string,
+		private newName: string,
+	) {
+		super();
+	}
+
+	execute(): void {
+		const editor = EditorCore.getInstance();
+		const scenes = editor.scenes.getScenes();
+
+		this.savedScenes = [...scenes];
+
+		const scene = scenes.find((s) => s.id === this.sceneId);
+		if (!scene) {
+			console.error("Scene not found:", this.sceneId);
+			return;
+		}
+
+		this.previousName = scene.name;
+
+		const updatedScenes = updateSceneInArray({
+			scenes,
+			sceneId: this.sceneId,
+			updates: { name: this.newName, updatedAt: new Date() },
+		});
+
+		editor.scenes.setScenes({ scenes: updatedScenes });
+	}
+
+	undo(): void {
+		if (this.savedScenes && this.previousName !== null) {
+			const editor = EditorCore.getInstance();
+			editor.scenes.setScenes({ scenes: this.savedScenes });
+		}
+	}
+}

apps/web/src/lib/commands/scene/toggle-bookmark.ts

@@ -0,0 +1,52 @@
+import { Command } from "@/lib/commands/base-command";
+import { EditorCore } from "@/core";
+import type { TScene } from "@/types/timeline";
+import { updateSceneInArray } from "@/lib/scenes";
+import { getFrameTime, toggleBookmarkInArray } from "@/lib/timeline/bookmarks";
+
+export class ToggleBookmarkCommand extends Command {
+	private savedScenes: TScene[] | null = null;
+	private frameTime: number = 0;
+
+	constructor(private time: number) {
+		super();
+	}
+
+	execute(): void {
+		const editor = EditorCore.getInstance();
+		const activeScene = editor.scenes.getActiveScene();
+		const activeProject = editor.project.getActive();
+
+		if (!activeScene || !activeProject) {
+			return;
+		}
+
+		const scenes = editor.scenes.getScenes();
+		this.savedScenes = [...scenes];
+
+		this.frameTime = getFrameTime({
+			time: this.time,
+			fps: activeProject.settings.fps,
+		});
+
+		const updatedBookmarks = toggleBookmarkInArray({
+			bookmarks: activeScene.bookmarks,
+			frameTime: this.frameTime,
+		});
+
+		const updatedScenes = updateSceneInArray({
+			scenes,
+			sceneId: activeScene.id,
+			updates: { bookmarks: updatedBookmarks },
+		});
+
+		editor.scenes.setScenes({ scenes: updatedScenes });
+	}
+
+	undo(): void {
+		if (this.savedScenes) {
+			const editor = EditorCore.getInstance();
+			editor.scenes.setScenes({ scenes: this.savedScenes });
+		}
+	}
+}

apps/web/src/lib/commands/timeline/clipboard/index.ts

@@ -0,0 +1 @@
+export { PasteCommand } from "./paste";

apps/web/src/lib/commands/timeline/clipboard/paste.ts

@@ -0,0 +1,263 @@
+import { Command } from "@/lib/commands/base-command";
+import { EditorCore } from "@/core";
+import type {
+	TimelineTrack,
+	TimelineElement,
+	ClipboardItem,
+} from "@/types/timeline";
+import { generateUUID } from "@/utils/id";
+import { wouldElementOverlap } from "@/lib/timeline/element-utils";
+import {
+	buildEmptyTrack,
+	getHighestInsertIndexForTrack,
+} from "@/lib/timeline/track-utils";
+
+export class PasteCommand extends Command {
+	private savedState: TimelineTrack[] | null = null;
+	private pastedElements: { trackId: string; elementId: string }[] = [];
+	private previousSelection: { trackId: string; elementId: string }[] = [];
+
+	constructor(
+		private time: number,
+		private clipboardItems: ClipboardItem[],
+	) {
+		super();
+	}
+
+	execute(): void {
+		if (this.clipboardItems.length === 0) return;
+
+		const editor = EditorCore.getInstance();
+		this.savedState = editor.timeline.getTracks();
+		this.previousSelection = editor.selection.getSelectedElements();
+		this.pastedElements = [];
+
+		const minStart = Math.min(
+			...this.clipboardItems.map((item) => item.element.startTime),
+		);
+
+		const updatedTracks = [...this.savedState];
+		const itemsByTrackId = groupClipboardItemsByTrackId({
+			clipboardItems: this.clipboardItems,
+		});
+
+		for (const [trackId, items] of itemsByTrackId) {
+			const elementsToAdd = buildPastedElements({
+				items,
+				minStart,
+				time: this.time,
+			});
+
+			if (elementsToAdd.length === 0) {
+				continue;
+			}
+
+			const trackType = items[0].trackType;
+			const sourceTrackIndex = updatedTracks.findIndex(
+				(track) => track.id === trackId,
+			);
+			const resolvedTargetIndex = resolveTargetTrackIndex({
+				tracks: updatedTracks,
+				sourceTrackIndex,
+				trackType,
+				elements: elementsToAdd,
+			});
+
+			if (resolvedTargetIndex >= 0) {
+				const targetTrack = updatedTracks[resolvedTargetIndex];
+				updatedTracks[resolvedTargetIndex] = {
+					...targetTrack,
+					elements: [...targetTrack.elements, ...elementsToAdd],
+				} as TimelineTrack;
+				for (const element of elementsToAdd) {
+					this.pastedElements.push({
+						trackId: targetTrack.id,
+						elementId: element.id,
+					});
+				}
+				continue;
+			}
+
+			const insertIndex = resolveInsertIndexForNewTrack({
+				tracks: updatedTracks,
+				sourceTrackIndex,
+				trackType,
+			});
+			const newTrack = buildTrackWithElements({
+				trackType,
+				elements: elementsToAdd,
+			});
+			updatedTracks.splice(insertIndex, 0, newTrack);
+			for (const element of elementsToAdd) {
+				this.pastedElements.push({
+					trackId: newTrack.id,
+					elementId: element.id,
+				});
+			}
+		}
+
+		editor.timeline.updateTracks(updatedTracks);
+
+		if (this.pastedElements.length > 0) {
+			editor.selection.setSelectedElements({ elements: this.pastedElements });
+		}
+	}
+
+	undo(): void {
+		if (this.savedState) {
+			const editor = EditorCore.getInstance();
+			editor.timeline.updateTracks(this.savedState);
+			editor.selection.setSelectedElements({ elements: this.previousSelection });
+		}
+	}
+
+	getPastedElements(): { trackId: string; elementId: string }[] {
+		return this.pastedElements;
+	}
+}
+
+function groupClipboardItemsByTrackId({
+	clipboardItems,
+}: {
+	clipboardItems: ClipboardItem[];
+}): Map<string, ClipboardItem[]> {
+	const groupedItems = new Map<string, ClipboardItem[]>();
+
+	for (const item of clipboardItems) {
+		const existingItems = groupedItems.get(item.trackId) ?? [];
+		groupedItems.set(item.trackId, [...existingItems, item]);
+	}
+
+	return groupedItems;
+}
+
+function buildPastedElements({
+	items,
+	minStart,
+	time,
+}: {
+	items: ClipboardItem[];
+	minStart: number;
+	time: number;
+}): TimelineElement[] {
+	const elementsToAdd: TimelineElement[] = [];
+
+	for (const item of items) {
+		const relativeOffset = item.element.startTime - minStart;
+		const startTime = Math.max(0, time + relativeOffset);
+		const newElementId = generateUUID();
+
+		elementsToAdd.push({
+			...item.element,
+			id: newElementId,
+			startTime,
+		} as TimelineElement);
+	}
+
+	return elementsToAdd;
+}
+
+function resolveTargetTrackIndex({
+	tracks,
+	sourceTrackIndex,
+	trackType,
+	elements,
+}: {
+	tracks: TimelineTrack[];
+	sourceTrackIndex: number;
+	trackType: ClipboardItem["trackType"];
+	elements: TimelineElement[];
+}): number {
+	if (sourceTrackIndex >= 0) {
+		const aboveIndex = sourceTrackIndex - 1;
+		if (aboveIndex < 0) {
+			return -1;
+		}
+
+		const aboveTrack = tracks[aboveIndex];
+		if (aboveTrack.type !== trackType) {
+			return -1;
+		}
+
+		const canPlaceOnAbove = canPlaceElementsOnTrack({
+			track: aboveTrack,
+			elements,
+		});
+		return canPlaceOnAbove ? aboveIndex : -1;
+	}
+
+	const highestCompatibleIndex = tracks.findIndex(
+		(track) => track.type === trackType,
+	);
+	if (highestCompatibleIndex < 0) {
+		return -1;
+	}
+
+	const highestCompatibleTrack = tracks[highestCompatibleIndex];
+	const canPlaceOnHighest = canPlaceElementsOnTrack({
+		track: highestCompatibleTrack,
+		elements,
+	});
+
+	return canPlaceOnHighest ? highestCompatibleIndex : -1;
+}
+
+function resolveInsertIndexForNewTrack({
+	tracks,
+	sourceTrackIndex,
+	trackType,
+}: {
+	tracks: TimelineTrack[];
+	sourceTrackIndex: number;
+	trackType: ClipboardItem["trackType"];
+}): number {
+	if (sourceTrackIndex >= 0) {
+		return sourceTrackIndex;
+	}
+
+	const highestCompatibleIndex = tracks.findIndex(
+		(track) => track.type === trackType,
+	);
+	if (highestCompatibleIndex >= 0) {
+		return highestCompatibleIndex;
+	}
+
+	return getHighestInsertIndexForTrack({ tracks, trackType });
+}
+
+function canPlaceElementsOnTrack({
+	track,
+	elements,
+}: {
+	track: TimelineTrack;
+	elements: TimelineElement[];
+}): boolean {
+	for (const element of elements) {
+		const endTime = element.startTime + element.duration;
+		const hasOverlap = wouldElementOverlap({
+			elements: track.elements,
+			startTime: element.startTime,
+			endTime,
+		});
+		if (hasOverlap) {
+			return false;
+		}
+	}
+
+	return true;
+}
+
+function buildTrackWithElements({
+	trackType,
+	elements,
+}: {
+	trackType: ClipboardItem["trackType"];
+	elements: TimelineElement[];
+}): TimelineTrack {
+	const newTrackId = generateUUID();
+	const newTrackBase = buildEmptyTrack({ id: newTrackId, type: trackType });
+	return {
+		...newTrackBase,
+		elements,
+	} as TimelineTrack;
+}

apps/web/src/lib/commands/timeline/element/delete-elements.ts

@@ -0,0 +1,48 @@
+import { Command } from "@/lib/commands/base-command";
+import type { TimelineTrack } from "@/types/timeline";
+import { EditorCore } from "@/core";
+import { isMainTrack } from "@/lib/timeline";
+
+export class DeleteElementsCommand extends Command {
+	private savedState: TimelineTrack[] | null = null;
+
+	constructor(private elements: { trackId: string; elementId: string }[]) {
+		super();
+	}
+
+	execute(): void {
+		const editor = EditorCore.getInstance();
+		this.savedState = editor.timeline.getTracks();
+
+		const updatedTracks = this.savedState
+			.map((track) => {
+				const hasElementsToDelete = this.elements.some(
+					(el) => el.trackId === track.id,
+				);
+
+				if (!hasElementsToDelete) {
+					return track;
+				}
+
+				return {
+					...track,
+					elements: track.elements.filter(
+						(element) =>
+							!this.elements.some(
+								(el) => el.trackId === track.id && el.elementId === element.id,
+							),
+					),
+				} as typeof track;
+			})
+			.filter((track) => track.elements.length > 0 || isMainTrack(track));
+
+		editor.timeline.updateTracks(updatedTracks);
+	}
+
+	undo(): void {
+		if (this.savedState) {
+			const editor = EditorCore.getInstance();
+			editor.timeline.updateTracks(this.savedState);
+		}
+	}
+}

apps/web/src/lib/commands/timeline/element/duplicate-elements.ts

@@ -0,0 +1,114 @@
+import { Command } from "@/lib/commands/base-command";
+import type { TimelineElement, TimelineTrack } from "@/types/timeline";
+import { generateUUID } from "@/utils/id";
+import { EditorCore } from "@/core";
+import {
+	buildEmptyTrack,
+	getHighestInsertIndexForTrack,
+} from "@/lib/timeline/track-utils";
+
+interface DuplicateElementsParams {
+	elements: { trackId: string; elementId: string }[];
+}
+
+export class DuplicateElementsCommand extends Command {
+	private duplicatedElements: { trackId: string; elementId: string }[] = [];
+	private savedState: TimelineTrack[] | null = null;
+	private previousSelection: { trackId: string; elementId: string }[] = [];
+	private elements: DuplicateElementsParams["elements"];
+
+	constructor({ elements }: DuplicateElementsParams) {
+		super();
+		this.elements = elements;
+	}
+
+	execute(): void {
+		const editor = EditorCore.getInstance();
+		this.savedState = editor.timeline.getTracks();
+		this.previousSelection = editor.selection.getSelectedElements();
+		this.duplicatedElements = [];
+
+		const updatedTracks = [...this.savedState];
+
+		for (const track of this.savedState) {
+			const elementsToDuplicate = this.elements.filter(
+				(el) => el.trackId === track.id,
+			);
+
+			if (elementsToDuplicate.length === 0) {
+				continue;
+			}
+
+			const elementIdsToDuplicate = new Set(
+				elementsToDuplicate.map((element) => element.elementId),
+			);
+			const newTrackElements: TimelineElement[] = [];
+
+			const newTrackId = generateUUID();
+			const newTrackBase = buildEmptyTrack({
+				id: newTrackId,
+				type: track.type,
+			});
+
+			for (const element of track.elements) {
+				if (!elementIdsToDuplicate.has(element.id)) {
+					continue;
+				}
+
+				const newId = generateUUID();
+				this.duplicatedElements.push({
+					trackId: newTrackId,
+					elementId: newId,
+				});
+				newTrackElements.push(
+					buildDuplicateElement({
+						element,
+						id: newId,
+						startTime: element.startTime,
+					}),
+				);
+			}
+
+			const newTrack = {
+				...newTrackBase,
+				elements: newTrackElements,
+			} as TimelineTrack;
+
+			const insertIndex = getHighestInsertIndexForTrack({
+				tracks: updatedTracks,
+				trackType: track.type,
+			});
+			updatedTracks.splice(insertIndex, 0, newTrack);
+		}
+
+		editor.timeline.updateTracks(updatedTracks);
+
+		if (this.duplicatedElements.length > 0) {
+			editor.selection.setSelectedElements({ elements: this.duplicatedElements });
+		}
+	}
+
+	undo(): void {
+		if (this.savedState) {
+			const editor = EditorCore.getInstance();
+			editor.timeline.updateTracks(this.savedState);
+			editor.selection.setSelectedElements({ elements: this.previousSelection });
+		}
+	}
+
+	getDuplicatedElements(): { trackId: string; elementId: string }[] {
+		return this.duplicatedElements;
+	}
+}
+
+function buildDuplicateElement({
+	element,
+	id,
+	startTime,
+}: {
+	element: TimelineElement;
+	id: string;
+	startTime: number;
+}): TimelineElement {
+	return { ...element, id, name: `${element.name} (copy)`, startTime };
+}

apps/web/src/lib/commands/timeline/element/index.ts

@@ -0,0 +1,11 @@
+export { InsertElementCommand } from "./insert-element";
+export { DeleteElementsCommand } from "./delete-elements";
+export { DuplicateElementsCommand } from "./duplicate-elements";
+export { UpdateElementTrimCommand } from "./update-element-trim";
+export { UpdateElementDurationCommand } from "./update-element-duration";
+export { UpdateElementStartTimeCommand } from "./update-element-start-time";
+export { SplitElementsCommand } from "./split-elements";
+export { UpdateTextElementCommand } from "./update-text-element";
+export { ToggleElementsVisibilityCommand } from "./toggle-elements-visibility";
+export { ToggleElementsMutedCommand } from "./toggle-elements-muted";
+export { MoveElementCommand } from "./move-elements";

apps/web/src/lib/commands/timeline/element/insert-element.ts

@@ -0,0 +1,311 @@
+import { Command } from "@/lib/commands/base-command";
+import { EditorCore } from "@/core";
+import type {
+	CreateTimelineElement,
+	TimelineTrack,
+	TimelineElement,
+	TrackType,
+	ElementType,
+} from "@/types/timeline";
+import { generateUUID } from "@/utils/id";
+import {
+	requiresMediaId,
+	wouldElementOverlap,
+} from "@/lib/timeline/element-utils";
+import {
+	buildEmptyTrack,
+	canElementGoOnTrack,
+	getDefaultInsertIndexForTrack,
+	validateElementTrackCompatibility,
+} from "@/lib/timeline/track-utils";
+import type { MediaAsset } from "@/types/assets";
+import { TIMELINE_CONSTANTS } from "@/constants/timeline-constants";
+
+type InsertElementPlacement =
+	| { mode: "explicit"; trackId: string }
+	| { mode: "auto"; trackType?: TrackType; insertIndex?: number };
+
+export interface InsertElementParams {
+	element: CreateTimelineElement;
+	placement: InsertElementPlacement;
+}
+
+export class InsertElementCommand extends Command {
+	private elementId: string;
+	private savedState: TimelineTrack[] | null = null;
+	private targetTrackId: string | null = null;
+
+	constructor({ element, placement }: InsertElementParams) {
+		super();
+		this.elementId = generateUUID();
+		this.element = element;
+		this.placement = placement;
+	}
+
+	private element: CreateTimelineElement;
+	private placement: InsertElementPlacement;
+
+	execute(): void {
+		const editor = EditorCore.getInstance();
+		this.savedState = editor.timeline.getTracks();
+
+		if (!this.savedState) {
+			console.error("Tracks not available");
+			return;
+		}
+
+		if (!this.validateElementBasics({ element: this.element })) {
+			return;
+		}
+
+		const totalElementsInTimeline = this.savedState.reduce(
+			(total, t) => total + t.elements.length,
+			0,
+		);
+		const isFirstElement = totalElementsInTimeline === 0;
+
+		const newElement = this.buildElement({ element: this.element });
+		const updateResult = this.resolveTracksWithElement({
+			tracks: this.savedState,
+			element: newElement,
+		});
+
+		if (!updateResult) {
+			return;
+		}
+
+		const { updatedTracks, targetTrackId } = updateResult;
+		this.targetTrackId = targetTrackId;
+
+		const isVisualMedia =
+			newElement.type === "video" || newElement.type === "image";
+
+		if (isFirstElement && isVisualMedia) {
+			const mediaAssets = editor.media.getAssets();
+			const activeProject = editor.project.getActive();
+			const asset = mediaAssets.find(
+				(item: MediaAsset) => item.id === newElement.mediaId,
+			);
+
+			if (asset?.width && asset?.height) {
+				const nextCanvasSize = { width: asset.width, height: asset.height };
+				const shouldSetOriginalCanvasSize =
+					!activeProject?.settings.originalCanvasSize;
+				editor.project.updateSettings({
+					settings: {
+						canvasSize: nextCanvasSize,
+						...(shouldSetOriginalCanvasSize
+							? { originalCanvasSize: nextCanvasSize }
+							: {}),
+					},
+					pushHistory: false,
+				});
+			}
+
+			if (asset?.type === "video" && asset?.fps) {
+				editor.project.updateSettings({
+					settings: { fps: asset.fps },
+					pushHistory: false,
+				});
+			}
+		}
+
+		editor.timeline.updateTracks(updatedTracks);
+	}
+
+	undo(): void {
+		if (this.savedState) {
+			const editor = EditorCore.getInstance();
+			editor.timeline.updateTracks(this.savedState);
+		}
+	}
+
+	getElementId(): string {
+		return this.elementId;
+	}
+
+	getTrackId(): string | null {
+		return this.targetTrackId;
+	}
+
+	private buildElement({
+		element,
+	}: {
+		element: CreateTimelineElement;
+	}): TimelineElement {
+		return {
+			...element,
+			id: this.elementId,
+			startTime: element.startTime,
+			trimStart: element.trimStart ?? 0,
+			trimEnd: element.trimEnd ?? 0,
+			duration: element.duration ?? TIMELINE_CONSTANTS.DEFAULT_ELEMENT_DURATION,
+		} as TimelineElement;
+	}
+
+	private validateElementBasics({
+		element,
+	}: {
+		element: CreateTimelineElement;
+	}): boolean {
+		if (requiresMediaId({ element }) && !("mediaId" in element)) {
+			console.error("Element requires mediaId");
+			return false;
+		}
+
+		if (
+			element.type === "audio" &&
+			element.sourceType === "library" &&
+			!element.sourceUrl
+		) {
+			console.error("Library audio element must have sourceUrl");
+			return false;
+		}
+
+		if (element.type === "sticker" && !element.iconName) {
+			console.error("Sticker element must have iconName");
+			return false;
+		}
+
+		if (element.type === "text" && !element.content) {
+			console.error("Text element must have content");
+			return false;
+		}
+
+		return true;
+	}
+
+	private resolveTracksWithElement({
+		tracks,
+		element,
+	}: {
+		tracks: TimelineTrack[];
+		element: TimelineElement;
+	}): { updatedTracks: TimelineTrack[]; targetTrackId: string } | null {
+		const placement = this.placement;
+
+		if (placement.mode === "explicit") {
+			const targetTrack = tracks.find(
+				(track) => track.id === placement.trackId,
+			);
+
+			if (!targetTrack) {
+				console.error("Track not found:", placement.trackId);
+				return null;
+			}
+
+			const validation = validateElementTrackCompatibility({
+				element,
+				track: targetTrack,
+			});
+
+			if (!validation.isValid) {
+				console.error(validation.errorMessage);
+				return null;
+			}
+
+			const updatedTracks = tracks.map((track) =>
+				track.id === targetTrack.id
+					? { ...track, elements: [...track.elements, element] }
+					: track,
+			) as TimelineTrack[];
+
+			return { updatedTracks, targetTrackId: targetTrack.id };
+		}
+
+		const trackType =
+			placement.trackType ?? this.getTrackTypeForElement({ element });
+
+		if (
+			placement.trackType &&
+			!canElementGoOnTrack({
+				elementType: element.type,
+				trackType,
+			})
+		) {
+			console.error(
+				`${element.type} elements cannot be placed on ${trackType} tracks`,
+			);
+			return null;
+		}
+
+		const elementEndTime = element.startTime + element.duration;
+		const existingTrack = tracks.find((track) => {
+			if (
+				!canElementGoOnTrack({
+					elementType: element.type,
+					trackType: track.type,
+				})
+			) {
+				return false;
+			}
+
+			return !wouldElementOverlap({
+				elements: track.elements,
+				startTime: element.startTime,
+				endTime: elementEndTime,
+			});
+		});
+
+		if (existingTrack) {
+			const updatedTracks = tracks.map((track) =>
+				track.id === existingTrack.id
+					? { ...track, elements: [...track.elements, element] }
+					: track,
+			) as TimelineTrack[];
+
+			return { updatedTracks, targetTrackId: existingTrack.id };
+		}
+
+		const newTrackId = generateUUID();
+		const newTrack = buildEmptyTrack({
+			id: newTrackId,
+			type: trackType,
+		});
+		const newTrackWithElement = {
+			...newTrack,
+			elements: [...newTrack.elements, element],
+		} as TimelineTrack;
+
+		const updatedTracks = [...tracks];
+		const insertIndex =
+			placement.insertIndex ??
+			this.getAutoInsertIndex({ tracks: updatedTracks, trackType });
+		updatedTracks.splice(insertIndex, 0, newTrackWithElement);
+
+		return { updatedTracks, targetTrackId: newTrackId };
+	}
+
+	private getAutoInsertIndex({
+		tracks,
+		trackType,
+	}: {
+		tracks: TimelineTrack[];
+		trackType: TrackType;
+	}): number {
+		if (trackType === "text") {
+			const firstVideoTrackIndex = tracks.findIndex(
+				(track) => track.type === "video",
+			);
+			if (firstVideoTrackIndex >= 0) {
+				return firstVideoTrackIndex;
+			}
+		}
+
+		return getDefaultInsertIndexForTrack({
+			tracks,
+			trackType,
+		});
+	}
+
+	private getTrackTypeForElement({
+		element,
+	}: {
+		element: { type: ElementType };
+	}): TrackType {
+		if (element.type === "video" || element.type === "image") {
+			return "video";
+		}
+		return element.type;
+	}
+}

apps/web/src/lib/commands/timeline/element/move-elements.ts

@@ -0,0 +1,127 @@
+import { Command } from "@/lib/commands/base-command";
+import { EditorCore } from "@/core";
+import type {
+	TimelineTrack,
+	TimelineElement,
+	TrackType,
+} from "@/types/timeline";
+import {
+	buildEmptyTrack,
+	isMainTrack,
+	validateElementTrackCompatibility,
+} from "@/lib/timeline/track-utils";
+
+export class MoveElementCommand extends Command {
+	private savedState: TimelineTrack[] | null = null;
+
+	constructor(
+		private sourceTrackId: string,
+		private targetTrackId: string,
+		private elementId: string,
+		private newStartTime: number,
+		private createTrack?: { type: TrackType; index: number },
+	) {
+		super();
+	}
+
+	execute(): void {
+		const editor = EditorCore.getInstance();
+		this.savedState = editor.timeline.getTracks();
+
+		const sourceTrack = this.savedState.find(
+			(t) => t.id === this.sourceTrackId,
+		);
+		const element = sourceTrack?.elements.find(
+			(el) => el.id === this.elementId,
+		);
+
+		if (!sourceTrack || !element) {
+			console.error("Source track or element not found");
+			return;
+		}
+
+		let targetTrack = this.savedState.find((t) => t.id === this.targetTrackId);
+		let tracksToUpdate = this.savedState;
+		if (!targetTrack && this.createTrack) {
+			const newTrack = buildEmptyTrack({
+				id: this.targetTrackId,
+				type: this.createTrack.type,
+			});
+			tracksToUpdate = [...this.savedState];
+			tracksToUpdate.splice(this.createTrack.index, 0, newTrack);
+			targetTrack = newTrack;
+		}
+		if (!targetTrack) {
+			console.error("Target track not found");
+			return;
+		}
+
+		const validation = validateElementTrackCompatibility({
+			element,
+			track: targetTrack,
+		});
+
+		if (!validation.isValid) {
+			console.error(validation.errorMessage);
+			return;
+		}
+
+		const movedElement: TimelineElement = {
+			...element,
+			startTime: this.newStartTime,
+		};
+
+		const isSameTrack = this.sourceTrackId === this.targetTrackId;
+
+		let updatedTracks = tracksToUpdate.map((track) => {
+			if (isSameTrack && track.id === this.sourceTrackId) {
+				return {
+					...track,
+					elements: track.elements.map((el) =>
+						el.id === this.elementId ? movedElement : el,
+					),
+				};
+			}
+
+			if (track.id === this.sourceTrackId) {
+				return {
+					...track,
+					elements: track.elements.filter((el) => el.id !== this.elementId),
+				};
+			}
+
+			if (track.id === this.targetTrackId) {
+				return {
+					...track,
+					elements: [...track.elements, movedElement],
+				};
+			}
+
+			return track;
+		}) as TimelineTrack[];
+
+		if (!isSameTrack) {
+			const sourceTrackAfterMove = updatedTracks.find(
+				(track) => track.id === this.sourceTrackId,
+			);
+			if (
+				sourceTrackAfterMove &&
+				sourceTrackAfterMove.elements.length === 0 &&
+				!isMainTrack(sourceTrackAfterMove)
+			) {
+				updatedTracks = updatedTracks.filter(
+					(track) => track.id !== this.sourceTrackId,
+				);
+			}
+		}
+
+		editor.timeline.updateTracks(updatedTracks);
+	}
+
+	undo(): void {
+		if (this.savedState) {
+			const editor = EditorCore.getInstance();
+			editor.timeline.updateTracks(this.savedState);
+		}
+	}
+}

apps/web/src/lib/commands/timeline/element/split-elements.ts

@@ -0,0 +1,133 @@
+import { Command } from "@/lib/commands/base-command";
+import type { TimelineTrack } from "@/types/timeline";
+import { generateUUID } from "@/utils/id";
+import { EditorCore } from "@/core";
+
+export class SplitElementsCommand extends Command {
+	private savedState: TimelineTrack[] | null = null;
+	private rightSideElements: { trackId: string; elementId: string }[] = [];
+	private previousSelection: { trackId: string; elementId: string }[] = [];
+
+	constructor(
+		private elements: { trackId: string; elementId: string }[],
+		private splitTime: number,
+		private retainSide: "both" | "left" | "right" = "both",
+	) {
+		super();
+	}
+
+	getRightSideElements(): { trackId: string; elementId: string }[] {
+		return this.rightSideElements;
+	}
+
+	execute(): void {
+		const editor = EditorCore.getInstance();
+		this.savedState = editor.timeline.getTracks();
+		this.previousSelection = editor.selection.getSelectedElements();
+		this.rightSideElements = [];
+
+		const updatedTracks = this.savedState.map((track) => {
+			const elementsToSplit = this.elements.filter(
+				(el) => el.trackId === track.id,
+			);
+
+			if (elementsToSplit.length === 0) {
+				return track;
+			}
+
+			return {
+				...track,
+				elements: track.elements.flatMap((element) => {
+					const shouldSplit = elementsToSplit.some(
+						(el) => el.elementId === element.id,
+					);
+
+					if (!shouldSplit) {
+						return [element];
+					}
+
+					const effectiveStart = element.startTime;
+					const effectiveEnd = element.startTime + element.duration;
+
+					if (
+						this.splitTime <= effectiveStart ||
+						this.splitTime >= effectiveEnd
+					) {
+						return [element];
+					}
+
+					const relativeTime = this.splitTime - element.startTime;
+					const leftVisibleDuration = relativeTime;
+					const rightVisibleDuration = element.duration - relativeTime;
+
+					if (this.retainSide === "left") {
+						return [
+							{
+								...element,
+								duration: leftVisibleDuration,
+								trimEnd: element.trimEnd + rightVisibleDuration,
+								name: `${element.name} (left)`,
+							},
+						];
+					}
+
+					if (this.retainSide === "right") {
+						const newId = generateUUID();
+						this.rightSideElements.push({
+							trackId: track.id,
+							elementId: newId,
+						});
+						return [
+							{
+								...element,
+								id: newId,
+								startTime: this.splitTime,
+								duration: rightVisibleDuration,
+								trimStart: element.trimStart + leftVisibleDuration,
+								name: `${element.name} (right)`,
+							},
+						];
+					}
+
+					// "both" - split into two pieces
+					const secondElementId = generateUUID();
+					this.rightSideElements.push({
+						trackId: track.id,
+						elementId: secondElementId,
+					});
+
+					return [
+						{
+							...element,
+							duration: leftVisibleDuration,
+							trimEnd: element.trimEnd + rightVisibleDuration,
+							name: `${element.name} (left)`,
+						},
+						{
+							...element,
+							id: secondElementId,
+							startTime: this.splitTime,
+							duration: rightVisibleDuration,
+							trimStart: element.trimStart + leftVisibleDuration,
+							name: `${element.name} (right)`,
+						},
+					];
+				}),
+			} as typeof track;
+		});
+
+		editor.timeline.updateTracks(updatedTracks);
+
+		if (this.rightSideElements.length > 0) {
+			editor.selection.setSelectedElements({ elements: this.rightSideElements });
+		}
+	}
+
+	undo(): void {
+		if (this.savedState) {
+			const editor = EditorCore.getInstance();
+			editor.timeline.updateTracks(this.savedState);
+			editor.selection.setSelectedElements({ elements: this.previousSelection });
+		}
+	}
+}

apps/web/src/lib/commands/timeline/element/toggle-elements-muted.ts

@@ -0,0 +1,57 @@
+import { Command } from "@/lib/commands/base-command";
+import type { TimelineTrack } from "@/types/timeline";
+import { canElementHaveAudio } from "@/lib/timeline/element-utils";
+import { EditorCore } from "@/core";
+
+export class ToggleElementsMutedCommand extends Command {
+	private savedState: TimelineTrack[] | null = null;
+
+	constructor(private elements: { trackId: string; elementId: string }[]) {
+		super();
+	}
+
+	execute(): void {
+		const editor = EditorCore.getInstance();
+		this.savedState = editor.timeline.getTracks();
+
+		const mutableElements = this.elements.filter(({ trackId, elementId }) => {
+			const track = this.savedState?.find((t) => t.id === trackId);
+			const element = track?.elements.find((e) => e.id === elementId);
+			return element && canElementHaveAudio(element);
+		});
+
+		if (mutableElements.length === 0) {
+			return;
+		}
+
+		const shouldMute = mutableElements.some(({ trackId, elementId }) => {
+			const track = this.savedState?.find((t) => t.id === trackId);
+			const element = track?.elements.find((e) => e.id === elementId);
+			return element && canElementHaveAudio(element) && !element.muted;
+		});
+
+		const updatedTracks = this.savedState.map((track) => {
+			const newElements = track.elements.map((element) => {
+				const shouldUpdate = mutableElements.some(
+					({ trackId, elementId }) =>
+						track.id === trackId && element.id === elementId,
+				);
+				return shouldUpdate &&
+					canElementHaveAudio(element) &&
+					element.muted !== shouldMute
+					? { ...element, muted: shouldMute }
+					: element;
+			});
+			return { ...track, elements: newElements } as typeof track;
+		});
+
+		editor.timeline.updateTracks(updatedTracks);
+	}
+
+	undo(): void {
+		if (this.savedState) {
+			const editor = EditorCore.getInstance();
+			editor.timeline.updateTracks(this.savedState);
+		}
+	}
+}

apps/web/src/lib/commands/timeline/element/toggle-elements-visibility.ts

@@ -0,0 +1,47 @@
+import { Command } from "@/lib/commands/base-command";
+import type { TimelineTrack } from "@/types/timeline";
+import { canElementBeHidden } from "@/lib/timeline/element-utils";
+import { EditorCore } from "@/core";
+
+export class ToggleElementsVisibilityCommand extends Command {
+	private savedState: TimelineTrack[] | null = null;
+
+	constructor(private elements: { trackId: string; elementId: string }[]) {
+		super();
+	}
+
+	execute(): void {
+		const editor = EditorCore.getInstance();
+		this.savedState = editor.timeline.getTracks();
+
+		const shouldHide = this.elements.some(({ trackId, elementId }) => {
+			const track = this.savedState?.find((t) => t.id === trackId);
+			const element = track?.elements.find((e) => e.id === elementId);
+			return element && canElementBeHidden(element) && !element.hidden;
+		});
+
+		const updatedTracks = this.savedState.map((track) => {
+			const newElements = track.elements.map((element) => {
+				const shouldUpdate = this.elements.some(
+					({ trackId, elementId }) =>
+						track.id === trackId && element.id === elementId,
+				);
+				return shouldUpdate &&
+					canElementBeHidden(element) &&
+					element.hidden !== shouldHide
+					? { ...element, hidden: shouldHide }
+					: element;
+			});
+			return { ...track, elements: newElements } as typeof track;
+		});
+
+		editor.timeline.updateTracks(updatedTracks);
+	}
+
+	undo(): void {
+		if (this.savedState) {
+			const editor = EditorCore.getInstance();
+			editor.timeline.updateTracks(this.savedState);
+		}
+	}
+}

apps/web/src/lib/commands/timeline/element/update-element-duration.ts

@@ -0,0 +1,37 @@
+import { Command } from "@/lib/commands/base-command";
+import type { TimelineTrack } from "@/types/timeline";
+import { EditorCore } from "@/core";
+
+export class UpdateElementDurationCommand extends Command {
+	private savedState: TimelineTrack[] | null = null;
+
+	constructor(
+		private trackId: string,
+		private elementId: string,
+		private duration: number,
+	) {
+		super();
+	}
+
+	execute(): void {
+		const editor = EditorCore.getInstance();
+		this.savedState = editor.timeline.getTracks();
+
+		const updatedTracks = this.savedState.map((t) => {
+			if (t.id !== this.trackId) return t;
+			const newElements = t.elements.map((el) =>
+				el.id === this.elementId ? { ...el, duration: this.duration } : el,
+			);
+			return { ...t, elements: newElements } as typeof t;
+		});
+
+		editor.timeline.updateTracks(updatedTracks);
+	}
+
+	undo(): void {
+		if (this.savedState) {
+			const editor = EditorCore.getInstance();
+			editor.timeline.updateTracks(this.savedState);
+		}
+	}
+}

apps/web/src/lib/commands/timeline/element/update-element-start-time.ts

@@ -0,0 +1,48 @@
+import { Command } from "@/lib/commands/base-command";
+import type { TimelineTrack } from "@/types/timeline";
+import { EditorCore } from "@/core";
+
+export class UpdateElementStartTimeCommand extends Command {
+	private savedState: TimelineTrack[] | null = null;
+
+	constructor(
+		private elements: { trackId: string; elementId: string }[],
+		private startTime: number,
+	) {
+		super();
+	}
+
+	execute(): void {
+		const editor = EditorCore.getInstance();
+		this.savedState = editor.timeline.getTracks();
+
+		const updatedTracks = this.savedState.map((track) => {
+			const hasElementsToUpdate = this.elements.some(
+				(el) => el.trackId === track.id,
+			);
+
+			if (!hasElementsToUpdate) {
+				return track;
+			}
+
+			const newElements = track.elements.map((element) => {
+				const shouldUpdate = this.elements.some(
+					(el) => el.elementId === element.id && el.trackId === track.id,
+				);
+				return shouldUpdate
+					? { ...element, startTime: Math.max(0, this.startTime) }
+					: element;
+			});
+			return { ...track, elements: newElements } as typeof track;
+		});
+
+		editor.timeline.updateTracks(updatedTracks);
+	}
+
+	undo(): void {
+		if (this.savedState) {
+			const editor = EditorCore.getInstance();
+			editor.timeline.updateTracks(this.savedState);
+		}
+	}
+}

apps/web/src/lib/commands/timeline/element/update-element-trim.ts

@@ -0,0 +1,48 @@
+import { Command } from "@/lib/commands/base-command";
+import type { TimelineTrack } from "@/types/timeline";
+import { EditorCore } from "@/core";
+
+export class UpdateElementTrimCommand extends Command {
+	private savedState: TimelineTrack[] | null = null;
+
+	constructor(
+		private elementId: string,
+		private trimStart: number,
+		private trimEnd: number,
+		private startTime?: number,
+		private duration?: number,
+	) {
+		super();
+	}
+
+	execute(): void {
+		const editor = EditorCore.getInstance();
+		this.savedState = editor.timeline.getTracks();
+
+		const updatedTracks = this.savedState.map((track) => {
+			const newElements = track.elements.map((element) => {
+				if (element.id !== this.elementId) {
+					return element;
+				}
+
+				return {
+					...element,
+					trimStart: this.trimStart,
+					trimEnd: this.trimEnd,
+					startTime: this.startTime ?? element.startTime,
+					duration: this.duration ?? element.duration,
+				};
+			});
+			return { ...track, elements: newElements } as typeof track;
+		});
+
+		editor.timeline.updateTracks(updatedTracks);
+	}
+
+	undo(): void {
+		if (this.savedState) {
+			const editor = EditorCore.getInstance();
+			editor.timeline.updateTracks(this.savedState);
+		}
+	}
+}

apps/web/src/lib/commands/timeline/element/update-text-element.ts

@@ -0,0 +1,52 @@
+import { Command } from "@/lib/commands/base-command";
+import type { TextElement, TimelineTrack } from "@/types/timeline";
+import { EditorCore } from "@/core";
+
+export class UpdateTextElementCommand extends Command {
+	private savedState: TimelineTrack[] | null = null;
+
+	constructor(
+		private trackId: string,
+		private elementId: string,
+		private updates: Partial<
+			Pick<
+				TextElement,
+				| "content"
+				| "fontSize"
+				| "fontFamily"
+				| "color"
+				| "backgroundColor"
+				| "textAlign"
+				| "fontWeight"
+				| "fontStyle"
+				| "textDecoration"
+			>
+		>,
+	) {
+		super();
+	}
+
+	execute(): void {
+		const editor = EditorCore.getInstance();
+		this.savedState = editor.timeline.getTracks();
+
+		const updatedTracks = this.savedState.map((t) => {
+			if (t.id !== this.trackId) return t;
+			const newElements = t.elements.map((el) =>
+				el.id === this.elementId && el.type === "text"
+					? { ...el, ...this.updates }
+					: el,
+			);
+			return { ...t, elements: newElements } as typeof t;
+		});
+
+		editor.timeline.updateTracks(updatedTracks);
+	}
+
+	undo(): void {
+		if (this.savedState) {
+			const editor = EditorCore.getInstance();
+			editor.timeline.updateTracks(this.savedState);
+		}
+	}
+}

apps/web/src/lib/commands/timeline/index.ts

@@ -0,0 +1,3 @@
+export * from "./track";
+export * from "./element";
+export * from "./clipboard";

apps/web/src/lib/commands/timeline/track/add-track.ts

@@ -0,0 +1,53 @@
+import { Command } from "@/lib/commands/base-command";
+import type { TrackType, TimelineTrack } from "@/types/timeline";
+import { generateUUID } from "@/utils/id";
+import { EditorCore } from "@/core";
+import {
+	buildEmptyTrack,
+	getDefaultInsertIndexForTrack,
+} from "@/lib/timeline/track-utils";
+
+export class AddTrackCommand extends Command {
+	private trackId: string;
+	private savedState: TimelineTrack[] | null = null;
+
+	constructor(
+		private type: TrackType,
+		private index?: number,
+	) {
+		super();
+		this.trackId = generateUUID();
+	}
+
+	execute(): void {
+		const editor = EditorCore.getInstance();
+		this.savedState = editor.timeline.getTracks();
+
+		const newTrack: TimelineTrack = buildEmptyTrack({
+			id: this.trackId,
+			type: this.type,
+		});
+
+		const updatedTracks = [...(this.savedState || [])];
+		const insertIndex =
+			this.index ??
+			getDefaultInsertIndexForTrack({
+				tracks: updatedTracks,
+				trackType: this.type,
+			});
+		updatedTracks.splice(insertIndex, 0, newTrack);
+
+		editor.timeline.updateTracks(updatedTracks);
+	}
+
+	undo(): void {
+		if (this.savedState) {
+			const editor = EditorCore.getInstance();
+			editor.timeline.updateTracks(this.savedState);
+		}
+	}
+
+	getTrackId(): string {
+		return this.trackId;
+	}
+}

apps/web/src/lib/commands/timeline/track/index.ts

@@ -0,0 +1,4 @@
+export { AddTrackCommand } from "./add-track";
+export { RemoveTrackCommand } from "./remove-track";
+export { ToggleTrackMuteCommand } from "./toggle-track-mute";
+export { ToggleTrackVisibilityCommand } from "./toggle-track-visibility";

apps/web/src/lib/commands/timeline/track/remove-track.ts

@@ -0,0 +1,35 @@
+import { Command } from "@/lib/commands/base-command";
+import { EditorCore } from "@/core";
+import type { TimelineTrack } from "@/types/timeline";
+import { getMainTrack } from "@/lib/timeline";
+
+export class RemoveTrackCommand extends Command {
+	private savedState: TimelineTrack[] | null = null;
+
+	constructor(private trackId: string) {
+		super();
+	}
+
+	execute(): void {
+		const editor = EditorCore.getInstance();
+		this.savedState = editor.timeline.getTracks();
+		const targetTrack = this.savedState.find(
+			(track) => track.id === this.trackId,
+		);
+		const mainTrack = getMainTrack({ tracks: this.savedState });
+		if (mainTrack?.id === targetTrack?.id) {
+			return;
+		}
+		const updatedTracks = this.savedState.filter(
+			(track) => track.id !== this.trackId,
+		);
+		editor.timeline.updateTracks(updatedTracks);
+	}
+
+	undo(): void {
+		if (this.savedState) {
+			const editor = EditorCore.getInstance();
+			editor.timeline.updateTracks(this.savedState);
+		}
+	}
+}

apps/web/src/lib/commands/timeline/track/toggle-track-mute.ts

@@ -0,0 +1,39 @@
+import { Command } from "@/lib/commands/base-command";
+import type { TimelineTrack } from "@/types/timeline";
+import { EditorCore } from "@/core";
+import { canTracktHaveAudio } from "@/lib/timeline";
+
+export class ToggleTrackMuteCommand extends Command {
+	private savedState: TimelineTrack[] | null = null;
+
+	constructor(private trackId: string) {
+		super();
+	}
+
+	execute(): void {
+		const editor = EditorCore.getInstance();
+		this.savedState = editor.timeline.getTracks();
+
+		const targetTrack = this.savedState.find(
+			(track) => track.id === this.trackId,
+		);
+		if (!targetTrack) {
+			return;
+		}
+
+		const updatedTracks = this.savedState.map((track) =>
+			track.id === this.trackId && canTracktHaveAudio(track)
+				? { ...track, muted: !track.muted }
+				: track,
+		);
+
+		editor.timeline.updateTracks(updatedTracks);
+	}
+
+	undo(): void {
+		if (this.savedState) {
+			const editor = EditorCore.getInstance();
+			editor.timeline.updateTracks(this.savedState);
+		}
+	}
+}

apps/web/src/lib/commands/timeline/track/toggle-track-visibility.ts

@@ -0,0 +1,40 @@
+import { Command } from "@/lib/commands/base-command";
+import type { TimelineTrack } from "@/types/timeline";
+import { EditorCore } from "@/core";
+import { canTrackBeHidden } from "@/lib/timeline";
+
+export class ToggleTrackVisibilityCommand extends Command {
+	private savedState: TimelineTrack[] | null = null;
+
+	constructor(private trackId: string) {
+		super();
+	}
+
+	execute(): void {
+		const editor = EditorCore.getInstance();
+		this.savedState = editor.timeline.getTracks();
+
+		const targetTrack = this.savedState.find(
+			(track) => track.id === this.trackId,
+		);
+		if (!targetTrack) {
+			return;
+		}
+
+		const updatedTracks = this.savedState.map((track) => {
+			if (track.id === this.trackId && canTrackBeHidden(track)) {
+				return { ...track, hidden: !track.hidden };
+			}
+			return track;
+		});
+
+		editor.timeline.updateTracks(updatedTracks);
+	}
+
+	undo(): void {
+		if (this.savedState) {
+			const editor = EditorCore.getInstance();
+			editor.timeline.updateTracks(this.savedState);
+		}
+	}
+}