test(annotation): expand AnnotationLayer coverage

Container style branches (cursor with/without canDraw, touch-action),
drawing pointer flow (canDraw=false skips, pointerdown on existing
annotation skips, no preview when not drawing, pointermove without
draw, pointerup without draw).

7 new tests, +14 covered branches.

Refs #496.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/lib/document/annotation/AnnotationLayer.svelte.test.ts

@@ -157,4 +157,132 @@ describe('AnnotationLayer', () => {
 			expect(el.classList.contains('annotation-flash')).toBe(false);
 		});
 	});
+
+	describe('container style', () => {
+		it('uses crosshair cursor when canDraw is true', async () => {
+			render(AnnotationLayer, {
+				annotations: [],
+				canDraw: true,
+				color: '#00c7b1',
+				onDraw: () => {}
+			});
+
+			const wrapper = document.querySelector('[role="presentation"]') as HTMLElement;
+			expect(wrapper.style.cursor).toContain('crosshair');
+			expect(wrapper.style.touchAction).toBe('none');
+		});
+
+		it('omits crosshair cursor when canDraw is false', async () => {
+			render(AnnotationLayer, {
+				annotations: [],
+				canDraw: false,
+				color: '#00c7b1',
+				onDraw: () => {}
+			});
+
+			const wrapper = document.querySelector('[role="presentation"]') as HTMLElement;
+			expect(wrapper.style.cursor).not.toContain('crosshair');
+		});
+	});
+
+	describe('drawing pointer flow', () => {
+		it('does not start a draw when canDraw is false', async () => {
+			render(AnnotationLayer, {
+				annotations: [],
+				canDraw: false,
+				color: '#00c7b1',
+				onDraw: () => {}
+			});
+
+			const wrapper = document.querySelector('[role="presentation"]') as HTMLElement;
+			(wrapper as unknown as { setPointerCapture: (id: number) => void }).setPointerCapture =
+				() => {};
+
+			wrapper.dispatchEvent(
+				new PointerEvent('pointerdown', {
+					bubbles: true,
+					clientX: 50,
+					clientY: 50,
+					pointerId: 1
+				})
+			);
+
+			// No preview rect rendered
+			const preview = wrapper.querySelector('div[style*="border: 2px dashed"]');
+			expect(preview).toBeNull();
+		});
+
+		it('does not start a draw when pointerdown lands on an existing annotation', async () => {
+			render(AnnotationLayer, {
+				annotations: [annotation],
+				canDraw: true,
+				color: '#00c7b1',
+				onDraw: () => {}
+			});
+
+			const ann = document.querySelector('[data-testid="annotation-ann-1"]') as HTMLElement;
+			(ann as unknown as { setPointerCapture: (id: number) => void }).setPointerCapture = () => {};
+
+			// pointerdown bubbles to the layer; layer should refuse to draw because
+			// closest('[data-annotation]') matches.
+			ann.dispatchEvent(
+				new PointerEvent('pointerdown', {
+					bubbles: true,
+					clientX: 0,
+					clientY: 0,
+					pointerId: 1
+				})
+			);
+
+			const preview = document.querySelector('div[style*="border: 2px dashed"]');
+			expect(preview).toBeNull();
+		});
+
+		it('renders no preview rect when no draw is in progress', async () => {
+			render(AnnotationLayer, {
+				annotations: [],
+				canDraw: true,
+				color: '#00c7b1',
+				onDraw: () => {}
+			});
+
+			const preview = document.querySelector('div[style*="border: 2px dashed"]');
+			expect(preview).toBeNull();
+		});
+
+		it('handles pointermove without a started draw (early-return)', async () => {
+			render(AnnotationLayer, {
+				annotations: [],
+				canDraw: true,
+				color: '#00c7b1',
+				onDraw: () => {}
+			});
+
+			const wrapper = document.querySelector('[role="presentation"]') as HTMLElement;
+			expect(() =>
+				wrapper.dispatchEvent(
+					new PointerEvent('pointermove', { bubbles: true, clientX: 0, clientY: 0 })
+				)
+			).not.toThrow();
+		});
+
+		it('handles pointerup without a started draw (early-return)', async () => {
+			let drawn = false;
+			render(AnnotationLayer, {
+				annotations: [],
+				canDraw: true,
+				color: '#00c7b1',
+				onDraw: () => {
+					drawn = true;
+				}
+			});
+
+			const wrapper = document.querySelector('[role="presentation"]') as HTMLElement;
+			wrapper.dispatchEvent(
+				new PointerEvent('pointerup', { bubbles: true, clientX: 0, clientY: 0 })
+			);
+
+			expect(drawn).toBe(false);
+		});
+	});
 });