diff --git a/scripts/format-scope.json b/scripts/format-scope.json
index 5fb980b1f..d2cce50af 100644
--- a/scripts/format-scope.json
+++ b/scripts/format-scope.json
@@ -563,6 +563,7 @@
   "src/ui/renderFailureEventRetry.test.mjs",
   "src/app/renderFailureInlineRetry.test.mjs",
   "src/ui/renderFailureSecondLoop.test.mjs",
+  "src/ui/renderLoopFixture.mjs",
   "src/layers/cctv/lifecycle.js",
   "src/layers/cctv/controls.js",
   "src/layers/cctv/geometry.js",
diff --git a/src/app/renderFailureInlineRetry.test.mjs b/src/app/renderFailureInlineRetry.test.mjs
index 2bbc98f1e..fa84e880f 100644
--- a/src/app/renderFailureInlineRetry.test.mjs
+++ b/src/app/renderFailureInlineRetry.test.mjs
@@ -5,10 +5,9 @@ import test from 'node:test';
 import assert from 'node:assert/strict';
 import * as Cesium from 'cesium';
 import { keepPanelRendering } from './embed.js';
-import { installRenderFailureNotice } from '../ui/renderFailure.js';
+import { renderLoopFixture } from '../ui/renderLoopFixture.mjs';
 
 function setup() {
-  const frames = [];
   let tick = null;
   let clock = 0;
   // The host reports the panel hidden: its own animation frames never arrive.
@@ -18,8 +17,6 @@ function setup() {
     setInterval: (fn) => ((tick = fn), 1),
     clearInterval() {},
   };
-  const previousRaf = globalThis.requestAnimationFrame;
-  globalThis.requestAnimationFrame = (fn) => frames.push(fn);
   const previousError = console.error;
   console.error = () => {};
   const state = { failure: null, drawn: 0 };
@@ -40,66 +37,33 @@ function setup() {
       this.postRender.raiseEvent(this);
     },
   };
-  const widget = Object.create(Cesium.CesiumWidget.prototype);
-  Object.assign(widget, {
-    _scene: scene,
-    _clock: { tick() {} },
-    _canRender: true,
-    _useDefaultRenderLoop: false,
-    _renderLoopRunning: false,
-    _showRenderLoopErrors: false,
-    _targetFrameRate: undefined,
-    isDestroyed: () => false,
-    resize() {},
-  });
-  // CesiumWidget's own renderError handler, which marks the loop stopped.
-  scene.renderError.addEventListener(() => {
-    widget._useDefaultRenderLoop = false;
-    widget._renderLoopRunning = false;
-  });
-  const viewer = {
-    scene,
-    cesiumWidget: widget,
-    canvas: { addEventListener() {}, removeEventListener() {} },
-    get useDefaultRenderLoop() {
-      return widget.useDefaultRenderLoop;
-    },
-    set useDefaultRenderLoop(value) {
-      widget.useDefaultRenderLoop = value;
-    },
-    isDestroyed: () => false,
-    render: () => widget.render(),
-    resize: () => widget.resize(),
-  };
-  const store = {
-    renderFailure: null,
-    publishRenderFailure(next) {
-      this.renderFailure = next;
-    },
-  };
-  const uninstall = installRenderFailureNotice(viewer, {
-    store,
-    allowReload: false,
-    locationRef: { href: 'https://gev.example/', reload() {}, assign() {} },
-    logError() {},
-  });
+  const { frames, widget, viewer, store, runFrames, restore } =
+    renderLoopFixture(scene, {
+      viewer: {
+        isDestroyed: () => false,
+        render: () => widget.render(),
+        resize: () => widget.resize(),
+      },
+      notice: { allowReload: false },
+    });
   const stop = keepPanelRendering(viewer, { windowRef, now: () => clock });
   viewer.useDefaultRenderLoop = true;
   const timerFrame = () => {
     clock += 400;
     tick();
   };
-  const animationFrames = (n) => {
-    for (let frame = 1; frame <= n; frame += 1)
-      for (const render of frames.splice(0)) render(frame * 16);
+  return {
+    frames,
+    state,
+    store,
+    timerFrame,
+    animationFrames: runFrames,
+    restore: () => {
+      stop();
+      restore();
+      console.error = previousError;
+    },
   };
-  const restore = () => {
-    stop();
-    uninstall();
-    globalThis.requestAnimationFrame = previousRaf;
-    console.error = previousError;
-  };
-  return { frames, state, store, timerFrame, animationFrames, restore };
 }
 
 for (const failure of ['caught', 'thrown']) {
diff --git a/src/ui/renderFailure.js b/src/ui/renderFailure.js
index 9226a72dd..7600a8dc7 100644
--- a/src/ui/renderFailure.js
+++ b/src/ui/renderFailure.js
@@ -21,7 +21,7 @@ export function installRenderFailureNotice(
   } = {},
 ) {
   const { scene } = viewer;
-  const canvas = viewer.canvas ?? scene.canvas;
+  const { canvas } = viewer;
   let notice = null;
   let contextLost = false;
   // With rethrowRenderErrors, Scene throws the error it has just raised;
@@ -36,7 +36,7 @@ export function installRenderFailureNotice(
       return;
     }
     viewer.useDefaultRenderLoop = true;
-    scene.requestRender?.();
+    scene.requestRender();
   }
 
   function reset() {
@@ -113,11 +113,11 @@ export function installRenderFailureNotice(
       raisedByScene = null;
     }),
   );
-  canvas?.addEventListener?.('webglcontextlost', onContextLost);
+  canvas.addEventListener('webglcontextlost', onContextLost);
   return () => {
     removeRenderError();
     unguard.forEach((restore) => restore());
-    canvas?.removeEventListener?.('webglcontextlost', onContextLost);
+    canvas.removeEventListener('webglcontextlost', onContextLost);
     clear();
   };
 }
@@ -147,7 +147,6 @@ function frameEvents(viewer) {
       tileset?.loadProgress,
       tileset?.allTilesLoaded,
       tileset?.initialTilesLoaded,
-      tileset?.tileLoad,
     );
   }
   return events;
diff --git a/src/ui/renderFailure.test.mjs b/src/ui/renderFailure.test.mjs
index 565422226..43f83dff2 100644
--- a/src/ui/renderFailure.test.mjs
+++ b/src/ui/renderFailure.test.mjs
@@ -1,27 +1,14 @@
 import test from 'node:test';
 import assert from 'node:assert/strict';
+import * as Cesium from 'cesium';
 import { installRenderFailureNotice } from './renderFailure.js';
 
-function event() {
-  const listeners = new Set();
-  return {
-    listeners,
-    addEventListener(listener) {
-      listeners.add(listener);
-      return () => listeners.delete(listener);
-    },
-    raise(...args) {
-      for (const listener of [...listeners]) listener(...args);
-    },
-  };
-}
-
 function fixture(t, options = {}) {
   const canvasListeners = new Map();
   const scene = {
-    renderError: event(),
-    preUpdate: event(),
-    postRender: event(),
+    renderError: new Cesium.Event(),
+    preUpdate: new Cesium.Event(),
+    postRender: new Cesium.Event(),
     requestRender() {
       this.requests = (this.requests ?? 0) + 1;
     },
@@ -62,12 +49,12 @@ function fixture(t, options = {}) {
   // One Cesium frame: preUpdate, an optional render error, then postRender,
   // which Cesium raises after a failed frame too.
   const frame = (error) => {
-    scene.preUpdate.raise(scene);
+    scene.preUpdate.raiseEvent(scene);
     if (error) {
       viewer.useDefaultRenderLoop = false;
-      scene.renderError.raise(scene, error);
+      scene.renderError.raiseEvent(scene, error);
     }
-    scene.postRender.raise(scene);
+    scene.postRender.raiseEvent(scene);
   };
   return {
     viewer,
@@ -105,8 +92,8 @@ test('Retry restarts the render loop and a clean frame clears the notice', (t) =
   f.frame();
   assert.equal(f.store.renderFailure, null);
   // Clearing stops the per-frame listeners.
-  assert.equal(f.scene.preUpdate.listeners.size, 0);
-  assert.equal(f.scene.postRender.listeners.size, 0);
+  assert.equal(f.scene.preUpdate.numberOfListeners, 0);
+  assert.equal(f.scene.postRender.numberOfListeners, 0);
 });
 
 test('a loop restarted into the same error keeps one notice', (t) => {
@@ -137,7 +124,7 @@ test('a new failure after recovery is a new appearance', (t) => {
 test('a render error without a value shows no detail', (t) => {
   const f = fixture(t);
   f.viewer.useDefaultRenderLoop = false;
-  f.scene.renderError.raise(f.scene, undefined);
+  f.scene.renderError.raiseEvent(f.scene, undefined);
   assert.equal(f.store.renderFailure.reason, 'render-error');
   assert.equal(f.store.renderFailure.detail, '');
 });
@@ -179,8 +166,8 @@ test('uninstall removes the listeners and the notice', (t) => {
   f.frame(new Error('boom'));
   f.uninstall();
   assert.equal(f.store.renderFailure, null);
-  assert.equal(f.scene.renderError.listeners.size, 0);
-  assert.equal(f.scene.postRender.listeners.size, 0);
+  assert.equal(f.scene.renderError.numberOfListeners, 0);
+  assert.equal(f.scene.postRender.numberOfListeners, 0);
   assert.equal(f.canvasListeners.size, 0);
   f.frame(new Error('later'));
   assert.equal(f.store.renderFailure, null);
diff --git a/src/ui/renderFailureEventRetry.test.mjs b/src/ui/renderFailureEventRetry.test.mjs
index 8de8944d0..a41697493 100644
--- a/src/ui/renderFailureEventRetry.test.mjs
+++ b/src/ui/renderFailureEventRetry.test.mjs
@@ -5,11 +5,9 @@ import test from 'node:test';
 import assert from 'node:assert/strict';
 import * as Cesium from 'cesium';
 import { installRenderFailureNotice } from './renderFailure.js';
+import { renderLoopFixture } from './renderLoopFixture.mjs';
 
 function setup() {
-  const frames = [];
-  const previousRaf = globalThis.requestAnimationFrame;
-  globalThis.requestAnimationFrame = (fn) => frames.push(fn);
   // Scene.render as in Scene.js:4369: preUpdate always, preRender/postRender
   // only when a frame is rendered (requestRenderMode idle skips them).
   const scene = {
@@ -34,53 +32,7 @@ function setup() {
       this.postRender.raiseEvent(this, time);
     },
   };
-  const widget = Object.create(Cesium.CesiumWidget.prototype);
-  Object.assign(widget, {
-    _scene: scene,
-    _clock: { tick() {} },
-    _canRender: true,
-    _useDefaultRenderLoop: false,
-    _renderLoopRunning: false,
-    _showRenderLoopErrors: false,
-    _targetFrameRate: undefined,
-    isDestroyed: () => false,
-    resize() {},
-  });
-  scene.renderError.addEventListener(() => {
-    widget._useDefaultRenderLoop = false;
-    widget._renderLoopRunning = false;
-  });
-  const viewer = {
-    scene,
-    cesiumWidget: widget,
-    canvas: { addEventListener() {}, removeEventListener() {} },
-    get useDefaultRenderLoop() {
-      return widget.useDefaultRenderLoop;
-    },
-    set useDefaultRenderLoop(value) {
-      widget.useDefaultRenderLoop = value;
-    },
-  };
-  const store = {
-    renderFailure: null,
-    publishRenderFailure(next) {
-      this.renderFailure = next;
-    },
-  };
-  const uninstall = installRenderFailureNotice(viewer, {
-    store,
-    locationRef: { href: 'https://gev.example/', reload() {}, assign() {} },
-    logError() {},
-  });
-  const runFrames = (n) => {
-    for (let i = 0; i < n; i += 1)
-      for (const fn of frames.splice(0)) fn(16 * (i + 1));
-  };
-  const restore = () => {
-    uninstall();
-    globalThis.requestAnimationFrame = previousRaf;
-  };
-  return { frames, scene, widget, viewer, store, runFrames, restore };
+  return { scene, ...renderLoopFixture(scene) };
 }
 
 for (const eventName of ['postRender', 'preUpdate']) {
@@ -200,7 +152,6 @@ const FRAME_EVENTS = {
   'tileset.allTilesLoaded': (v) => v.scene.primitives.get(0).allTilesLoaded,
   'tileset.initialTilesLoaded': (v) =>
     v.scene.primitives.get(0).initialTilesLoaded,
-  'tileset.tileLoad': (v) => v.scene.primitives.get(0).tileLoad,
 };
 
 for (const [name, pick] of Object.entries(FRAME_EVENTS)) {
@@ -214,7 +165,6 @@ for (const [name, pick] of Object.entries(FRAME_EVENTS)) {
       loadProgress: new Cesium.Event(),
       allTilesLoaded: new Cesium.Event(),
       initialTilesLoaded: new Cesium.Event(),
-      tileLoad: new Cesium.Event(),
     };
     const viewer = {
       scene: {
diff --git a/src/ui/renderFailureLoopErrors.test.mjs b/src/ui/renderFailureLoopErrors.test.mjs
index f8f3607c6..1446c149f 100644
--- a/src/ui/renderFailureLoopErrors.test.mjs
+++ b/src/ui/renderFailureLoopErrors.test.mjs
@@ -3,66 +3,21 @@
 import test from 'node:test';
 import assert from 'node:assert/strict';
 import * as Cesium from 'cesium';
-import { installRenderFailureNotice } from './renderFailure.js';
-
-// What src/app/scene.js passes to the viewer (showRenderLoopErrors).
-const SHOW_RENDER_LOOP_ERRORS = false;
+import { renderLoopFixture } from './renderLoopFixture.mjs';
 
 function runLoop(render) {
-  const frames = [];
-  const previousRaf = globalThis.requestAnimationFrame;
-  globalThis.requestAnimationFrame = (fn) => frames.push(fn);
-  try {
-    const scene = {
-      renderError: new Cesium.Event(),
-      preUpdate: new Cesium.Event(),
-      postRender: new Cesium.Event(),
-      requestRender() {},
-      initializeFrame() {},
-      render,
-    };
-    const widget = Object.create(Cesium.CesiumWidget.prototype);
-    Object.assign(widget, {
-      _scene: scene,
-      _clock: { tick() {} },
-      _canRender: true,
-      _useDefaultRenderLoop: false,
-      _renderLoopRunning: false,
-      _showRenderLoopErrors: SHOW_RENDER_LOOP_ERRORS,
-      _targetFrameRate: undefined,
-      isDestroyed: () => false,
-      resize() {},
-      showErrorPanel() {},
-    });
-    const viewer = {
-      scene,
-      cesiumWidget: widget,
-      canvas: { addEventListener() {}, removeEventListener() {} },
-      get useDefaultRenderLoop() {
-        return widget.useDefaultRenderLoop;
-      },
-      set useDefaultRenderLoop(value) {
-        widget.useDefaultRenderLoop = value;
-      },
-    };
-    const store = {
-      renderFailure: null,
-      publishRenderFailure(next) {
-        this.renderFailure = next;
-      },
-    };
-    const logged = [];
-    const uninstall = installRenderFailureNotice(viewer, {
-      store,
-      locationRef: { href: 'https://gev.example/', reload() {}, assign() {} },
-      logError: (error) => logged.push(error),
-    });
-    viewer.useDefaultRenderLoop = true;
-    while (frames.length) frames.shift()(16);
-    return { widget, store, logged, uninstall };
-  } finally {
-    globalThis.requestAnimationFrame = previousRaf;
-  }
+  const scene = {
+    renderError: new Cesium.Event(),
+    preUpdate: new Cesium.Event(),
+    postRender: new Cesium.Event(),
+    requestRender() {},
+    initializeFrame() {},
+    render,
+  };
+  const fixture = renderLoopFixture(scene);
+  fixture.viewer.useDefaultRenderLoop = true;
+  fixture.runFrames(3);
+  return { ...fixture, uninstall: fixture.restore };
 }
 
 test('an error thrown outside tryAndCatchError still shows the notice', () => {
diff --git a/src/ui/renderFailureSecondLoop.test.mjs b/src/ui/renderFailureSecondLoop.test.mjs
index ba36c1817..2b5c6196f 100644
--- a/src/ui/renderFailureSecondLoop.test.mjs
+++ b/src/ui/renderFailureSecondLoop.test.mjs
@@ -4,12 +4,9 @@
 import test from 'node:test';
 import assert from 'node:assert/strict';
 import * as Cesium from 'cesium';
-import { installRenderFailureNotice } from './renderFailure.js';
+import { renderLoopFixture } from './renderLoopFixture.mjs';
 
 function setup({ targetFrameRate } = {}) {
-  const frames = [];
-  const previousRaf = globalThis.requestAnimationFrame;
-  globalThis.requestAnimationFrame = (fn) => frames.push(fn);
   const scene = {
     renderError: new Cesium.Event(),
     preUpdate: new Cesium.Event(),
@@ -29,57 +26,7 @@ function setup({ targetFrameRate } = {}) {
       this.postRender.raiseEvent(this, time);
     },
   };
-  const widget = Object.create(Cesium.CesiumWidget.prototype);
-  Object.assign(widget, {
-    _scene: scene,
-    _clock: { tick() {} },
-    _canRender: true,
-    _useDefaultRenderLoop: false,
-    _renderLoopRunning: false,
-    _showRenderLoopErrors: false,
-    _targetFrameRate: targetFrameRate,
-    isDestroyed: () => false,
-    resize() {},
-  });
-  // CesiumWidget's own renderError handler (CesiumWidget.js:414).
-  scene.renderError.addEventListener(() => {
-    widget._useDefaultRenderLoop = false;
-    widget._renderLoopRunning = false;
-  });
-  const viewer = {
-    scene,
-    cesiumWidget: widget,
-    canvas: { addEventListener() {}, removeEventListener() {} },
-    get useDefaultRenderLoop() {
-      return widget.useDefaultRenderLoop;
-    },
-    set useDefaultRenderLoop(value) {
-      widget.useDefaultRenderLoop = value;
-    },
-  };
-  const store = {
-    renderFailure: null,
-    publishRenderFailure(next) {
-      this.renderFailure = next;
-    },
-  };
-  const uninstall = installRenderFailureNotice(viewer, {
-    store,
-    locationRef: { href: 'https://gev.example/', reload() {}, assign() {} },
-    logError() {},
-  });
-  let time = 0;
-  const runFrames = (n) => {
-    for (let i = 0; i < n; i += 1) {
-      time += 17;
-      for (const fn of frames.splice(0)) fn(time);
-    }
-  };
-  const restore = () => {
-    uninstall();
-    globalThis.requestAnimationFrame = previousRaf;
-  };
-  return { frames, scene, viewer, store, runFrames, restore };
+  return { scene, ...renderLoopFixture(scene, { targetFrameRate }) };
 }
 
 for (const targetFrameRate of [undefined, 60]) {
diff --git a/src/ui/renderLoopFixture.mjs b/src/ui/renderLoopFixture.mjs
new file mode 100644
index 000000000..562e2d3f7
--- /dev/null
+++ b/src/ui/renderLoopFixture.mjs
@@ -0,0 +1,72 @@
+// A widget on Cesium's real CesiumWidget.prototype (startRenderLoop, the
+// useDefaultRenderLoop setter, render) around a scene double, with animation
+// frames queued by hand and the render failure notice installed.
+import * as Cesium from 'cesium';
+import { installRenderFailureNotice } from './renderFailure.js';
+
+export function renderLoopFixture(
+  scene,
+  { targetFrameRate, viewer: viewerExtras = {}, notice = {} } = {},
+) {
+  const frames = [];
+  const previousRaf = globalThis.requestAnimationFrame;
+  globalThis.requestAnimationFrame = (fn) => frames.push(fn);
+  const widget = Object.create(Cesium.CesiumWidget.prototype);
+  Object.assign(widget, {
+    _scene: scene,
+    _clock: { tick() {} },
+    _canRender: true,
+    _useDefaultRenderLoop: false,
+    _renderLoopRunning: false,
+    // What src/app/scene.js passes to the viewer.
+    _showRenderLoopErrors: false,
+    _targetFrameRate: targetFrameRate,
+    isDestroyed: () => false,
+    resize() {},
+  });
+  // CesiumWidget's own renderError handler, which marks the loop stopped.
+  scene.renderError.addEventListener(() => {
+    widget._useDefaultRenderLoop = false;
+    widget._renderLoopRunning = false;
+  });
+  const viewer = Object.assign(
+    {
+      scene,
+      cesiumWidget: widget,
+      canvas: { addEventListener() {}, removeEventListener() {} },
+      get useDefaultRenderLoop() {
+        return widget.useDefaultRenderLoop;
+      },
+      set useDefaultRenderLoop(value) {
+        widget.useDefaultRenderLoop = value;
+      },
+    },
+    viewerExtras,
+  );
+  const store = {
+    renderFailure: null,
+    publishRenderFailure(next) {
+      this.renderFailure = next;
+    },
+  };
+  const logged = [];
+  const uninstall = installRenderFailureNotice(viewer, {
+    store,
+    locationRef: { href: 'https://gev.example/', reload() {}, assign() {} },
+    logError: (error) => logged.push(error),
+    ...notice,
+  });
+  let time = 0;
+  const runFrames = (n) => {
+    for (let i = 0; i < n; i += 1) {
+      // Above a 60 fps target's interval, so every frame draws.
+      time += 17;
+      for (const fn of frames.splice(0)) fn(time);
+    }
+  };
+  const restore = () => {
+    uninstall();
+    globalThis.requestAnimationFrame = previousRaf;
+  };
+  return { frames, widget, viewer, store, logged, runFrames, restore };
+}