we're basically done

apps/web/src/core/index.ts

@@ -7,6 +7,7 @@ import { RendererManager } from "./managers/renderer-manager";
 import { CommandManager } from "./managers/commands";
 import { SaveManager } from "./managers/save-manager";
 import { AudioManager } from "./managers/audio-manager";
+import { SelectionManager } from "./managers/selection-manager";
 
 export class EditorCore {
 	private static instance: EditorCore | null = null;
@@ -20,6 +21,7 @@ export class EditorCore {
 	public readonly renderer: RendererManager;
 	public readonly save: SaveManager;
 	public readonly audio: AudioManager;
+	public readonly selection: SelectionManager;
 
 	private constructor() {
 		this.command = new CommandManager();
@@ -31,6 +33,7 @@ export class EditorCore {
 		this.renderer = new RendererManager(this);
 		this.save = new SaveManager(this);
 		this.audio = new AudioManager(this);
+		this.selection = new SelectionManager(this);
 		this.save.start();
 	}
 

apps/web/src/core/managers/selection-manager.ts

@@ -0,0 +1,35 @@
+import type { EditorCore } from "@/core";
+
+type ElementRef = { trackId: string; elementId: string };
+
+export class SelectionManager {
+	private selectedElements: ElementRef[] = [];
+	private listeners = new Set<() => void>();
+
+	constructor(editor: EditorCore) {
+		void editor;
+	}
+
+	getSelectedElements(): ElementRef[] {
+		return this.selectedElements;
+	}
+
+	setSelectedElements({ elements }: { elements: ElementRef[] }): void {
+		this.selectedElements = elements;
+		this.notify();
+	}
+
+	clearSelection(): void {
+		this.selectedElements = [];
+		this.notify();
+	}
+
+	subscribe(listener: () => void): () => void {
+		this.listeners.add(listener);
+		return () => this.listeners.delete(listener);
+	}
+
+	private notify(): void {
+		this.listeners.forEach((fn) => fn());
+	}
+}

apps/web/src/core/managers/timeline-manager.ts

@@ -142,10 +142,10 @@ export class TimelineManager {
 		elements: { trackId: string; elementId: string }[];
 		splitTime: number;
 		retainSide?: "both" | "left" | "right";
-	}): string[] {
+	}): { trackId: string; elementId: string }[] {
 		const command = new SplitElementsCommand(elements, splitTime, retainSide);
 		this.editor.command.execute({ command });
-		return command.splitElementIds;
+		return command.getRightSideElements();
 	}
 
 	getTotalDuration(): number {
@@ -184,9 +184,10 @@ export class TimelineManager {
 	}: {
 		time: number;
 		clipboardItems: ClipboardItem[];
-	}): void {
+	}): { trackId: string; elementId: string }[] {
 		const command = new PasteCommand(time, clipboardItems);
 		this.editor.command.execute({ command });
+		return command.getPastedElements();
 	}
 
 	deleteElements({
@@ -230,9 +231,10 @@ export class TimelineManager {
 		elements,
 	}: {
 		elements: { trackId: string; elementId: string }[];
-	}): void {
+	}): { trackId: string; elementId: string }[] {
 		const command = new DuplicateElementsCommand({ elements });
 		this.editor.command.execute({ command });
+		return command.getDuplicatedElements();
 	}
 
 	toggleElementsVisibility({