fix(bench): MUI + TanStack comparators publish post-filter row count

apps/bench/src/__tests__/mui-adapter.test.tsx

@@ -2,6 +2,7 @@ import { render, waitFor } from "@testing-library/react";
 import { describe, expect, test } from "vitest";
 
 import { MuiAdapter } from "../mui-adapter";
+import type { BenchInteractionPlan } from "../interaction-plan";
 
 const dataset = {
   columns: [
@@ -14,6 +15,35 @@ const dataset = {
   ],
 };
 
+const statusDataset = {
+  columns: [
+    { id: "id", header: "ID", wrap: false, widthPx: 80 },
+    { id: "status", header: "Status", wrap: false, widthPx: 160 },
+  ],
+  rows: [
+    { id: "1", status: "running" },
+    { id: "2", status: "stopped" },
+    { id: "3", status: "running" },
+    { id: "4", status: "idle" },
+  ],
+};
+
+function filterPlan(
+  mode: "filter-metadata" | "filter-text",
+  filters: Record<string, string>,
+): BenchInteractionPlan {
+  return {
+    focusedRowId: null,
+    filters,
+    mode,
+    probeColumnId: Object.keys(filters)[0] ?? "",
+    resultRowCount: 0,
+    rows: [],
+    selectedRowId: null,
+    sort: null,
+  };
+}
+
 describe("MuiAdapter", () => {
   test("mounts and renders MUI DataGrid public selectors", async () => {
     const { container } = render(
@@ -33,4 +63,34 @@ describe("MuiAdapter", () => {
       expect(container.querySelector(".MuiDataGrid-root")).not.toBeNull();
     });
   });
+
+  test("publishes the post-filter row count, not the full dataset size", async () => {
+    const { container, rerender } = render(
+      <MuiAdapter
+        dataset={statusDataset as never}
+        runKey={0}
+        scriptName="filter-metadata"
+        interactionPlan={null}
+      />,
+    );
+    await waitFor(() => {
+      expect(container.querySelector(".MuiDataGrid-root")).not.toBeNull();
+    });
+
+    rerender(
+      <MuiAdapter
+        dataset={statusDataset as never}
+        runKey={0}
+        scriptName="filter-metadata"
+        interactionPlan={filterPlan("filter-metadata", { status: "running" })}
+      />,
+    );
+
+    // status === "running" matches 2 of 4 rows. The published count is sourced
+    // from the grid's filtered-row selector, not the full dataset size.
+    await waitFor(() => {
+      const section = container.querySelector('[data-benchmark-adapter="mui"]');
+      expect(section?.getAttribute("data-bench-result-row-count")).toBe("2");
+    });
+  });
 });

apps/bench/src/__tests__/tanstack-adapter.test.tsx

@@ -2,6 +2,7 @@ import { render, waitFor } from "@testing-library/react";
 import { beforeAll, describe, expect, test } from "vitest";
 
 import { TanstackAdapter } from "../tanstack-adapter";
+import type { BenchInteractionPlan } from "../interaction-plan";
 
 const dataset = {
   columns: [
@@ -14,6 +15,35 @@ const dataset = {
   ],
 };
 
+const statusDataset = {
+  columns: [
+    { id: "id", header: "ID", wrap: false, widthPx: 80 },
+    { id: "status", header: "Status", wrap: false, widthPx: 160 },
+  ],
+  rows: [
+    { id: "1", status: "running" },
+    { id: "2", status: "stopped" },
+    { id: "3", status: "running" },
+    { id: "4", status: "idle" },
+  ],
+};
+
+function filterPlan(
+  mode: "filter-metadata" | "filter-text",
+  filters: Record<string, string>,
+): BenchInteractionPlan {
+  return {
+    focusedRowId: null,
+    filters,
+    mode,
+    probeColumnId: Object.keys(filters)[0] ?? "",
+    resultRowCount: 0,
+    rows: [],
+    selectedRowId: null,
+    sort: null,
+  };
+}
+
 beforeAll(() => {
   // jsdom doesn't ship ResizeObserver and reports zero offsetWidth /
   // offsetHeight for every element. @tanstack/react-virtual reads
@@ -67,4 +97,38 @@ describe("TanstackAdapter", () => {
       ).toBeGreaterThan(0);
     });
   });
+
+  test("publishes the post-filter row count, not the full dataset size", async () => {
+    const { container, rerender } = render(
+      <TanstackAdapter
+        dataset={statusDataset as never}
+        runKey={0}
+        scriptName="filter-metadata"
+        interactionPlan={null}
+      />,
+    );
+    await waitFor(() => {
+      expect(
+        container.querySelector("[data-pretable-bench-tanstack-viewport]"),
+      ).not.toBeNull();
+    });
+
+    rerender(
+      <TanstackAdapter
+        dataset={statusDataset as never}
+        runKey={0}
+        scriptName="filter-metadata"
+        interactionPlan={filterPlan("filter-metadata", { status: "running" })}
+      />,
+    );
+
+    // status === "running" matches 2 of 4 rows. The published count comes from
+    // table.getRowModel().rows (post-filter), not the full dataset size.
+    await waitFor(() => {
+      const section = container.querySelector(
+        '[data-benchmark-adapter="tanstack"]',
+      );
+      expect(section?.getAttribute("data-bench-result-row-count")).toBe("2");
+    });
+  });
 });

apps/bench/src/mui-adapter.tsx

@@ -1,5 +1,10 @@
 import { useEffect, useMemo, useRef, useState } from "react";
-import { DataGrid, useGridApiRef, type GridColDef } from "@mui/x-data-grid";
+import {
+  DataGrid,
+  gridFilteredTopLevelRowCountSelector,
+  useGridApiRef,
+  type GridColDef,
+} from "@mui/x-data-grid";
 
 import type {
   ScenarioColumn,
@@ -76,12 +81,29 @@ export function MuiAdapter({
   onAutosizeReadyRef.current = onAutosizeReady;
 
   const [rows, setRows] = useState<ScenarioRow[]>(() => dataset.rows.slice());
+  // Post-interaction visible-row count. `rows` above is always the full
+  // dataset (DataGrid filters internally), so the published count is sourced
+  // from the grid's filtered-row selector instead — keeping it in sync with
+  // what the grid actually shows after a filter.
+  const [resultRowCount, setResultRowCount] = useState(dataset.rows.length);
 
   useEffect(() => {
     // eslint-disable-next-line react-hooks/set-state-in-effect -- runKey reset
     setRows(dataset.rows.slice());
   }, [dataset.rows, runKey]);
 
+  useEffect(() => {
+    const api = apiRef.current;
+    if (!api) return;
+    // Seed immediately (covers a filter already applied before subscribe),
+    // then track every filter change. `filteredRowsSet` fires after the grid
+    // recomputes its filtered model.
+    const sync = () =>
+      setResultRowCount(gridFilteredTopLevelRowCountSelector(apiRef));
+    sync();
+    return api.subscribeEvent("filteredRowsSet", sync);
+  }, [apiRef, runKey, dataset.rows.length]);
+
   const columns = useMemo(
     () => dataset.columns.map((c) => toColDef(c, scriptName)),
     [dataset.columns, scriptName],
@@ -146,7 +168,7 @@ export function MuiAdapter({
     <section
       aria-label="MUI X DataGrid adapter"
       data-benchmark-adapter="mui"
-      data-bench-result-row-count={String(rows.length)}
+      data-bench-result-row-count={String(resultRowCount)}
       style={{ display: "grid", gap: 12 }}
     >
       <header>

apps/bench/src/tanstack-adapter.tsx

@@ -188,7 +188,10 @@ export function TanstackAdapter({
     <section
       aria-label="TanStack Table adapter"
       data-benchmark-adapter="tanstack"
-      data-bench-result-row-count={String(data.length)}
+      // `rows` is the post-filter, post-sort row model (table.getRowModel()),
+      // so this reflects the count the grid actually displays after an
+      // interaction. `data` is the full unfiltered dataset (always 3000).
+      data-bench-result-row-count={String(rows.length)}
       style={{ display: "grid", gap: 12 }}
     >
       <header>