test(chart): guard the tooltip effect against the render-loop regression

The unit test for computeTooltipPosition covers the flip/clamp math, but the
math was never broken — the crash came from the effect re-running on its own
setPos. Add a component test (both review agents' top request) that renders
ChartTooltipPortal and asserts the positioning effect does NOT re-run when the
component re-renders with an unchanged coordinate, and DOES re-run when the
coordinate changes. Verified it fails against the pre-fix dependency-less
effect. ChartTooltipPortal is exported for this, matching how StackedBarShape
is exported for its test.

resources/js/components/ui/chart-tooltip-portal.test.tsx

@@ -0,0 +1,58 @@
+import { fireEvent, render } from '@testing-library/react';
+import * as React from 'react';
+import { afterEach, describe, expect, it, vi } from 'vitest';
+
+import { ChartTooltipPortal } from './chart';
+
+/**
+ * Renders the portal inside a `.recharts-wrapper` (the ancestor its layout
+ * effect looks up) and exposes a button that bumps unrelated state to force a
+ * re-render without touching `coordinate`.
+ */
+function Harness({ coordinate }: { coordinate: { x: number; y: number } }) {
+    const [, setTick] = React.useState(0);
+
+    return (
+        <div className="recharts-wrapper">
+            <button onClick={() => setTick((t) => t + 1)}>rerender</button>
+            <ChartTooltipPortal coordinate={coordinate}>
+                <span>tooltip</span>
+            </ChartTooltipPortal>
+        </div>
+    );
+}
+
+describe('ChartTooltipPortal', () => {
+    afterEach(() => {
+        vi.restoreAllMocks();
+    });
+
+    // The positioning effect reads the wrapper's rect, so a call to
+    // getBoundingClientRect is a proxy for "the effect ran".
+    it('does not recompute its position on a re-render with an unchanged coordinate (regression: PHP-LARAVEL-3B render loop)', () => {
+        const rectSpy = vi.spyOn(Element.prototype, 'getBoundingClientRect');
+        const { getByText } = render(<Harness coordinate={{ x: 10, y: 20 }} />);
+
+        const afterMount = rectSpy.mock.calls.length;
+        expect(afterMount).toBeGreaterThan(0);
+
+        fireEvent.click(getByText('rerender'));
+        fireEvent.click(getByText('rerender'));
+
+        // With the pre-fix dependency-less effect this count would climb on
+        // every render and the setPos feedback loop would eventually throw
+        // "Maximum update depth exceeded".
+        expect(rectSpy.mock.calls.length).toBe(afterMount);
+    });
+
+    it('recomputes its position when the coordinate changes', () => {
+        const rectSpy = vi.spyOn(Element.prototype, 'getBoundingClientRect');
+        const { rerender } = render(<Harness coordinate={{ x: 10, y: 20 }} />);
+
+        const afterMount = rectSpy.mock.calls.length;
+
+        rerender(<Harness coordinate={{ x: 200, y: 300 }} />);
+
+        expect(rectSpy.mock.calls.length).toBeGreaterThan(afterMount);
+    });
+});

resources/js/components/ui/chart.tsx

@@ -686,6 +686,7 @@ export {
     ChartContainer,
     ChartTooltip,
     ChartTooltipContent,
+    ChartTooltipPortal,
     ChartLegend,
     ChartLegendContent,
     ChartStyle,