fix: copy shortcut must not swallow the page's default copy

src/core/inputs/controls.ts

@@ -171,9 +171,13 @@ export class Controls {
 			}
 			case "KeyC": {
 				if (event.metaKey || event.ctrlKey) {
-					event.preventDefault();
+					// Clip copy must not swallow the page's default copy: defer to the browser when the
+					// user has text selected anywhere in the document, or when no clip is targeted.
+					const selection = window.getSelection();
+					if (selection && !selection.isCollapsed) break;
 					const selected = this.edit.getSelectedClipInfo();
 					if (selected) {
+						event.preventDefault();
 						this.edit.copyClip(selected.trackIndex, selected.clipIndex);
 					}
 				}

tests/controls-copy.test.ts

@@ -0,0 +1,103 @@
+/**
+ * @jest-environment jsdom
+ *
+ * Copy Shortcut Guard Tests
+ *
+ * Cmd/Ctrl+C must only be intercepted when it will act on a clip: with no clip
+ * selected, or with an active text selection anywhere in the document, the
+ * browser's default copy has to run so host-app text stays copyable.
+ */
+import { Controls } from "@core/inputs/controls";
+
+import type { Edit } from "@core/edit-session";
+
+interface MockEdit {
+	getSelectedClipInfo: jest.Mock;
+	copyClip: jest.Mock;
+}
+
+function makeEdit(selected: { trackIndex: number; clipIndex: number } | null): MockEdit {
+	return {
+		getSelectedClipInfo: jest.fn().mockReturnValue(selected),
+		copyClip: jest.fn()
+	};
+}
+
+function dispatchCopy(target: EventTarget): KeyboardEvent {
+	const event = new KeyboardEvent("keydown", {
+		code: "KeyC",
+		key: "c",
+		metaKey: true,
+		bubbles: true,
+		cancelable: true
+	});
+	target.dispatchEvent(event);
+	return event;
+}
+
+function selectText(text: string): void {
+	const container = document.createElement("div");
+	container.textContent = text;
+	document.body.appendChild(container);
+	const range = document.createRange();
+	range.selectNodeContents(container);
+	const selection = window.getSelection();
+	selection?.removeAllRanges();
+	selection?.addRange(range);
+}
+
+describe("Controls copy shortcut", () => {
+	let controls: Controls;
+	let edit: MockEdit;
+
+	async function loadControls(selected: { trackIndex: number; clipIndex: number } | null): Promise<void> {
+		edit = makeEdit(selected);
+		controls = new Controls(edit as unknown as Edit);
+		await controls.load();
+	}
+
+	afterEach(() => {
+		controls.dispose();
+		window.getSelection()?.removeAllRanges();
+		document.body.innerHTML = "";
+	});
+
+	it("lets the browser handle copy when no clip is selected", async () => {
+		await loadControls(null);
+
+		const event = dispatchCopy(document.body);
+
+		expect(event.defaultPrevented).toBe(false);
+		expect(edit.copyClip).not.toHaveBeenCalled();
+	});
+
+	it("copies the selected clip when nothing else claims the shortcut", async () => {
+		await loadControls({ trackIndex: 1, clipIndex: 2 });
+
+		const event = dispatchCopy(document.body);
+
+		expect(event.defaultPrevented).toBe(true);
+		expect(edit.copyClip).toHaveBeenCalledWith(1, 2);
+	});
+
+	it("prefers an active text selection over the selected clip", async () => {
+		await loadControls({ trackIndex: 1, clipIndex: 2 });
+		selectText("copy this message text");
+
+		const event = dispatchCopy(document.body);
+
+		expect(event.defaultPrevented).toBe(false);
+		expect(edit.copyClip).not.toHaveBeenCalled();
+	});
+
+	it("stays exempt inside editable fields", async () => {
+		await loadControls({ trackIndex: 1, clipIndex: 2 });
+		const textarea = document.createElement("textarea");
+		document.body.appendChild(textarea);
+
+		const event = dispatchCopy(textarea);
+
+		expect(event.defaultPrevented).toBe(false);
+		expect(edit.copyClip).not.toHaveBeenCalled();
+	});
+});