diff --git a/packages/web-shell/client/index-html.test.ts b/packages/web-shell/client/index-html.test.ts
index 3db8e8bdce8..3d6d47f856b 100644
--- a/packages/web-shell/client/index-html.test.ts
+++ b/packages/web-shell/client/index-html.test.ts
@@ -2,9 +2,7 @@ import { readFileSync } from 'node:fs';
 import { resolve } from 'node:path';
 import { describe, expect, it, vi } from 'vitest';
 
-function installMeasureGuard(
-  measure: (...args: unknown[]) => unknown,
-): Performance {
+function extractMeasureScript(): string {
   const html = readFileSync(resolve(__dirname, 'index.html'), 'utf8');
   const script = Array.from(
     html.matchAll(/<script(?:\s[^>]*)?>([\s\S]*?)<\/script>/g),
@@ -13,8 +11,15 @@ function installMeasureGuard(
     .find((source) => source.includes('performance.measure ='));
 
   if (!script) throw new Error('Performance measure guard not found');
+  return script;
+}
 
-  const performance = { measure };
+function installMeasureGuard(
+  measure: (...args: unknown[]) => unknown,
+  clearMeasures?: () => void,
+): Performance {
+  const script = extractMeasureScript();
+  const performance = { measure, clearMeasures };
   Function('performance', 'DOMException', script)(performance, DOMException);
   return performance as Performance;
 }
@@ -59,4 +64,178 @@ describe('React performance measure guard', () => {
 
     expect(measure).toHaveBeenCalledWith('custom-measure', options);
   });
+
+  it('strips detail from any React devtools track, not just Components', () => {
+    const measure = vi.fn(() => 'measure');
+    const performance = installMeasureGuard(measure);
+    const options = {
+      start: 1,
+      end: 2,
+      detail: { devtools: { track: 'Blocking', properties: [['k', 'v']] } },
+    };
+
+    performance.measure('React', options);
+
+    expect(
+      (measure.mock.calls[0]?.[1] as PerformanceMeasureOptions).detail,
+    ).toBeNull();
+  });
+
+  it('clears the measure timeline on a budget so entries cannot accumulate', () => {
+    const measureThis: unknown[] = [];
+    const measure = vi.fn(function (this: unknown): string {
+      measureThis.push(this);
+      return 'measure';
+    });
+    const clearThis: unknown[] = [];
+    const clearMeasures = vi.fn(function (this: unknown) {
+      clearThis.push(this);
+    });
+    const fakePerformance = installMeasureGuard(measure, clearMeasures);
+    // The real flood mixes lane/scheduler tracks and measure names, so drive
+    // a mixed flood: the budget must count every React devtools measure
+    // regardless of track or name.
+    const tracks = ['Blocking', 'Transition', 'Suspense', 'Components ⚛'];
+    const names = ['⏱ lane', '⏱ render', '⏱ commit'];
+    const reactName = (index: number): string => names[index % names.length];
+    let reactDriven = 0;
+    const driveReact = (count: number): void => {
+      for (let i = 0; i < count; i += 1) {
+        fakePerformance.measure(reactName(reactDriven), {
+          start: 1,
+          end: 2,
+          detail: { devtools: { track: tracks[reactDriven % tracks.length] } },
+        });
+        reactDriven += 1;
+      }
+    };
+
+    // The clear fires at exactly the budget, not one measure early.
+    driveReact(16383);
+    expect(clearMeasures).not.toHaveBeenCalled();
+    driveReact(1);
+    expect(clearMeasures).toHaveBeenCalledTimes(1);
+    // The timeline is cleared with no name filter (React never names its
+    // measures) and with the performance object as receiver (a detached
+    // brand-checked clearMeasures throws Illegal invocation).
+    expect(clearMeasures).toHaveBeenCalledWith();
+    expect(clearThis).toEqual([fakePerformance]);
+    // Every React measure is still forwarded with its name preserved and its
+    // detail stripped — including the one that triggers the clear.
+    expect(measure).toHaveBeenCalledTimes(16384);
+    expect(measure.mock.calls[16383]).toEqual([
+      reactName(16383),
+      expect.objectContaining({ detail: null }),
+    ]);
+
+    // The clear is not latched: a second full window clears again, and
+    // forwarding + stripping survive past the first clear.
+    driveReact(16384);
+    expect(clearMeasures).toHaveBeenCalledTimes(2);
+    expect(measure).toHaveBeenCalledTimes(32768);
+    expect(measure.mock.calls[32767]).toEqual([
+      reactName(32767),
+      expect.objectContaining({ detail: null }),
+    ]);
+
+    // A full window of non-React measures neither counts toward the budget
+    // nor is dropped or stripped after a clear.
+    const customOptions = { start: 1, end: 2, detail: { source: 'web-shell' } };
+    for (let i = 0; i < 16384 - 1; i += 1) {
+      fakePerformance.measure('custom-measure', customOptions);
+    }
+    // The wrapper's return value passes through like the native call's.
+    const customResult = fakePerformance.measure(
+      'custom-measure',
+      customOptions,
+    );
+    expect(clearMeasures).toHaveBeenCalledTimes(2);
+    expect(customResult).toBe('measure');
+    expect(measure).toHaveBeenCalledTimes(49152);
+    // Identity: the non-React options object is forwarded as-is.
+    expect(measure.mock.calls[49151]?.[0]).toBe('custom-measure');
+    expect(measure.mock.calls[49151]?.[1]).toBe(customOptions);
+    // Value survival, not just reference: an in-place strip of the caller's
+    // options object must fail here.
+    expect(
+      (measure.mock.calls[49151]?.[1] as PerformanceMeasureOptions).detail,
+    ).toEqual({ source: 'web-shell' });
+
+    // Mixed app + React traffic still reaches the budget: interleaved
+    // non-React measures must not reset the counter.
+    for (let i = 0; i < 16384; i += 1) {
+      driveReact(1);
+      fakePerformance.measure('custom-measure', customOptions);
+    }
+    expect(clearMeasures).toHaveBeenCalledTimes(3);
+
+    // A detached wrapper call still reaches the native measure bound to the
+    // performance object (both captures keep their .bind(performance)).
+    const detachedMeasure = fakePerformance.measure as (
+      ...args: unknown[]
+    ) => unknown;
+    detachedMeasure('detached', {
+      start: 1,
+      end: 2,
+      detail: { devtools: { track: 'Blocking' } },
+    });
+    expect(measure).toHaveBeenCalledTimes(81921);
+    expect(measureThis.every((receiver) => receiver === fakePerformance)).toBe(
+      true,
+    );
+  });
+
+  it('keeps measuring when clearMeasures is unavailable', () => {
+    const measure = vi.fn(() => 'measure');
+    const performance = installMeasureGuard(measure);
+    const options = {
+      start: 1,
+      end: 2,
+      detail: { devtools: { track: 'Blocking' } },
+    };
+
+    expect(() => {
+      for (let i = 0; i < 16384 + 1; i += 1) {
+        performance.measure('⏱ lane', options);
+      }
+    }).not.toThrow();
+    expect(measure).toHaveBeenCalledTimes(16384 + 1);
+  });
+
+  it('forwards standard measure shapes untouched', () => {
+    const measure = vi.fn(() => 'measure');
+    const performance = installMeasureGuard(measure);
+    const bareMeasure = performance.measure as (
+      name: string,
+      options?: unknown,
+    ) => unknown;
+    const options = { start: 1, end: 2 };
+
+    expect(() => {
+      bareMeasure('plain');
+      bareMeasure('null-options', null);
+      bareMeasure('string-mark', 'start-mark');
+      bareMeasure('detail-less', options);
+    }).not.toThrow();
+
+    expect(bareMeasure('return-check', options)).toBe('measure');
+    expect(measure.mock.calls[0]).toEqual(['plain']);
+    expect(measure.mock.calls[1]).toEqual(['null-options', null]);
+    expect(measure.mock.calls[2]).toEqual(['string-mark', 'start-mark']);
+    expect(measure.mock.calls[3]).toEqual(['detail-less', options]);
+  });
+
+  it('does not touch environments without performance.measure', () => {
+    const script = extractMeasureScript();
+    const install = (performance: unknown): void => {
+      Function(
+        'performance',
+        'DOMException',
+        script,
+      )(performance, DOMException);
+    };
+
+    expect(() => install(undefined)).not.toThrow();
+    expect(() => install({})).not.toThrow();
+  });
 });
diff --git a/packages/web-shell/client/index.html b/packages/web-shell/client/index.html
index c53ef7011e0..645e78476db 100644
--- a/packages/web-shell/client/index.html
+++ b/packages/web-shell/client/index.html
@@ -51,12 +51,22 @@
       Prevent React 19 dev-mode OOM crashes. React records component prop
       details through performance.measure(), which structured-clones and retains
       those details. Strip the detail before large transcripts reach the native
-      call while preserving the component timing and non-React measures.
+      call while preserving the component timing and non-React measures. The
+      stripped entries themselves still accumulate in the browser's unbounded
+      user-timing buffer — an idle dev page emits ~16k measures/s — so the
+      timeline is also cleared on a budget, or long-lived dev tabs exhaust the
+      renderer's PartitionAlloc address space and die with SIGABRT.
     -->
     <script>
       !(function () {
         if (typeof performance === 'undefined' || !performance.measure) return;
         var m = performance.measure.bind(performance);
+        var clear =
+          typeof performance.clearMeasures === 'function'
+            ? performance.clearMeasures.bind(performance)
+            : null;
+        var reactMeasures = 0;
+        var CLEAR_EVERY = 16384;
         performance.measure = function () {
           var options = arguments[1];
           var devtools =
@@ -64,7 +74,12 @@
             typeof options === 'object' &&
             options.detail &&
             options.detail.devtools;
-          if (devtools && devtools.track === 'Components ⚛') {
+          if (devtools) {
+            reactMeasures += 1;
+            if (clear && reactMeasures >= CLEAR_EVERY) {
+              reactMeasures = 0;
+              clear();
+            }
             var args = Array.prototype.slice.call(arguments);
             args[1] = Object.assign({}, options, { detail: null });
             return m.apply(this, args);