fix(inference): restore unofficial overlay tooltips

Pass the portaled tooltip element through the shared D3 render context so unofficial-run points can render and pin the same tooltip as official points.

中文：通过共享 D3 渲染上下文传递 Portal 中的提示卡节点，使非正式运行数据点能够与正式运行数据点一样显示并固定提示卡。

Author: cquil11

packages/app/cypress/e2e/unofficial-watermark.cy.ts

@@ -19,6 +19,14 @@ describe('Unofficial-run watermark', () => {
           ],
           benchmarks: benchmarks.map((row: Record<string, unknown>) => ({
             ...row,
+            is_multinode: true,
+            metrics: {
+              ...(row.metrics as Record<string, unknown> | undefined),
+              kv_offloading: 'dram',
+              kv_offload_backend: 'hicache',
+              kv_p2p_transfer: 'nixl',
+              server_gpu_cache_hit_rate: 0.875,
+            },
             run_url: runUrl,
           })),
           evaluations: [],
@@ -58,6 +66,19 @@ describe('Unofficial-run watermark', () => {
         cy.wrap($image).parent('svg').find('.unofficial-watermark-image').should('have.length', 1);
       });
 
+    cy.get('[data-testid="scatter-graph"] .unofficial-overlay-pt')
+      .first()
+      .then(($point) => {
+        $point[0].dispatchEvent(new MouseEvent('mouseenter'));
+        const tooltip = $point[0].ownerDocument.querySelector<HTMLElement>('[data-chart-tooltip]');
+        expect(tooltip).not.to.equal(null);
+        expect(tooltip!.style.display).to.equal('block');
+        expect(tooltip).to.contain.text('Offload Type: DRAM');
+        expect(tooltip).to.contain.text('Offload Backend: HiCache');
+        expect(tooltip).to.contain.text('KV Cache Transfer Engine: NIXL');
+        expect(tooltip).to.contain.text('GPU Cache Hit Rate: 87.5%');
+      });
+
     cy.get('[data-testid="scatter-graph"]').first().scrollIntoView();
     cy.screenshot('unofficial-watermark', { capture: 'viewport' });
 

packages/app/src/components/inference/ui/ScatterGraph.tsx

@@ -1999,8 +1999,7 @@ const ScatterGraph = React.memo(
               // Overlay tooltip handlers
               const svgNode = ctx.layout.svg.node()!;
               const container = svgNode.parentElement as HTMLDivElement;
-              const tooltipDiv = svgNode.nextElementSibling as HTMLDivElement;
-              const tooltip = d3.select(tooltipDiv);
+              const tooltip = d3.select(ctx.tooltipElement);
 
               const createOverlayConfig = (d: InferenceData, pinned: boolean) => ({
                 data: d,

packages/app/src/lib/d3-chart/D3Chart/types.ts

@@ -197,6 +197,8 @@ export interface TooltipConfig<T = any> {
 
 export interface RenderContext {
   layout: ChartLayout;
+  /** Portaled tooltip node owned by the chart wrapper. */
+  tooltipElement: HTMLDivElement;
   xScale: AnyScale | d3.ScaleTime<number, number>;
   yScale: AnyScale | d3.ScaleTime<number, number>;
   width: number;

packages/app/src/lib/d3-chart/D3Chart/useD3ChartRenderer.ts

@@ -182,6 +182,7 @@ export function useD3ChartRenderer<T>(props: D3ChartProps<T>, deps: RendererDeps
       // ── Render context ──
       const ctx: RenderContext = {
         layout,
+        tooltipElement: tooltipRef.current,
         xScale,
         yScale,
         width,