diff --git a/packages/studio/src/components/editor/PropertyPanel.test.ts b/packages/studio/src/components/editor/PropertyPanel.test.ts
index cb22bd97a..9b470316e 100644
--- a/packages/studio/src/components/editor/PropertyPanel.test.ts
+++ b/packages/studio/src/components/editor/PropertyPanel.test.ts
@@ -8,11 +8,11 @@ import {
   getCssFilterFunctionPx,
   inferBoxShadowPreset,
   inferClipPathPreset,
+  isSelectedElementHidden,
   normalizePanelPxValue,
   parseInsetClipPathSides,
   setCssFilterFunctionPx,
-} from "./PropertyPanel";
-import { isSelectedElementHidden } from "./propertyPanelHelpers";
+} from "./propertyPanelHelpers";
 
 describe("PropertyPanel style helpers", () => {
   it("normalizes bounded pixel values without accepting incompatible units", () => {
diff --git a/packages/studio/src/components/editor/PropertyPanelEmptyState.test.tsx b/packages/studio/src/components/editor/PropertyPanelEmptyState.test.tsx
index ed2059bfc..445f1838c 100644
--- a/packages/studio/src/components/editor/PropertyPanelEmptyState.test.tsx
+++ b/packages/studio/src/components/editor/PropertyPanelEmptyState.test.tsx
@@ -1,26 +1,12 @@
 // @vitest-environment happy-dom
 
-import React, { act } from "react";
-import { createRoot } from "react-dom/client";
-import { afterEach, describe, expect, it, vi } from "vitest";
+import { act } from "react";
+import { describe, expect, it, vi } from "vitest";
 import { PropertyPanelEmptyState } from "./PropertyPanelEmptyState";
 import type { DomEditSelection } from "./domEditingTypes";
+import { renderInto, setupReactActEnvironment } from "./testRenderUtils";
 
-(globalThis as unknown as { IS_REACT_ACT_ENVIRONMENT: boolean }).IS_REACT_ACT_ENVIRONMENT = true;
-
-afterEach(() => {
-  document.body.innerHTML = "";
-});
-
-function renderInto(node: React.ReactElement) {
-  const host = document.createElement("div");
-  document.body.append(host);
-  const root = createRoot(host);
-  act(() => {
-    root.render(node);
-  });
-  return { host, root };
-}
+setupReactActEnvironment();
 
 describe("PropertyPanelEmptyState — flat empty", () => {
   it("shows the cursor glyph, headline, and the two shortcut rows", () => {
diff --git a/packages/studio/src/components/editor/propertyPanelFlatColorGradingSection.test.tsx b/packages/studio/src/components/editor/propertyPanelFlatColorGradingSection.test.tsx
index 987bd4ee7..1e12ce41b 100644
--- a/packages/studio/src/components/editor/propertyPanelFlatColorGradingSection.test.tsx
+++ b/packages/studio/src/components/editor/propertyPanelFlatColorGradingSection.test.tsx
@@ -1,8 +1,7 @@
 // @vitest-environment happy-dom
 
-import React, { act } from "react";
-import { createRoot } from "react-dom/client";
-import { afterEach, describe, expect, it, vi } from "vitest";
+import { act } from "react";
+import { describe, expect, it, vi } from "vitest";
 import {
   FlatColorGradingAccessory,
   FlatColorGradingSection,
@@ -11,22 +10,9 @@ import {
   normalizeHfColorGrading,
   type NormalizedHfColorGrading,
 } from "@hyperframes/core/color-grading";
+import { renderInto, setupReactActEnvironment } from "./testRenderUtils";
 
-(globalThis as unknown as { IS_REACT_ACT_ENVIRONMENT: boolean }).IS_REACT_ACT_ENVIRONMENT = true;
-
-afterEach(() => {
-  document.body.innerHTML = "";
-});
-
-function renderInto(node: React.ReactElement) {
-  const host = document.createElement("div");
-  document.body.append(host);
-  const root = createRoot(host);
-  act(() => {
-    root.render(node);
-  });
-  return { host, root };
-}
+setupReactActEnvironment();
 
 function neutralGrading() {
   const grading = normalizeHfColorGrading("neutral");
diff --git a/packages/studio/src/components/editor/propertyPanelFlatLayoutSection.test.tsx b/packages/studio/src/components/editor/propertyPanelFlatLayoutSection.test.tsx
index ece488c96..176eff612 100644
--- a/packages/studio/src/components/editor/propertyPanelFlatLayoutSection.test.tsx
+++ b/packages/studio/src/components/editor/propertyPanelFlatLayoutSection.test.tsx
@@ -1,8 +1,7 @@
 // @vitest-environment happy-dom
 
-import React, { act } from "react";
-import { createRoot } from "react-dom/client";
-import { afterEach, describe, expect, it, vi } from "vitest";
+import { act } from "react";
+import { describe, expect, it, vi } from "vitest";
 import {
   FlatLayoutSection,
   LayoutFlexBlock,
@@ -10,22 +9,9 @@ import {
   LayoutTransform3DBlock,
   LayoutZIndexRow,
 } from "./propertyPanelFlatLayoutSection";
+import { renderInto, setupReactActEnvironment } from "./testRenderUtils";
 
-(globalThis as unknown as { IS_REACT_ACT_ENVIRONMENT: boolean }).IS_REACT_ACT_ENVIRONMENT = true;
-
-afterEach(() => {
-  document.body.innerHTML = "";
-});
-
-function renderInto(node: React.ReactElement) {
-  const host = document.createElement("div");
-  document.body.append(host);
-  const root = createRoot(host);
-  act(() => {
-    root.render(node);
-  });
-  return { host, root };
-}
+setupReactActEnvironment();
 
 function getFlatRowInput(host: HTMLElement, label: string): HTMLInputElement {
   const rows = Array.from(host.querySelectorAll<HTMLElement>(".group"));
diff --git a/packages/studio/src/components/editor/propertyPanelFlatMotionSection.test.tsx b/packages/studio/src/components/editor/propertyPanelFlatMotionSection.test.tsx
index ac24d4b37..dec9281e2 100644
--- a/packages/studio/src/components/editor/propertyPanelFlatMotionSection.test.tsx
+++ b/packages/studio/src/components/editor/propertyPanelFlatMotionSection.test.tsx
@@ -1,16 +1,15 @@
 // @vitest-environment happy-dom
 
-import React, { act } from "react";
-import { createRoot } from "react-dom/client";
+import { act } from "react";
 import { afterEach, describe, expect, it, vi } from "vitest";
 import { FlatMotionSection, FlatTimingRow } from "./propertyPanelFlatMotionSection";
 import type { DomEditSelection } from "./domEditing";
 import { usePlayerStore } from "../../player";
+import { renderInto, setupReactActEnvironment } from "./testRenderUtils";
 
-(globalThis as unknown as { IS_REACT_ACT_ENVIRONMENT: boolean }).IS_REACT_ACT_ENVIRONMENT = true;
+setupReactActEnvironment();
 
 afterEach(() => {
-  document.body.innerHTML = "";
   // The store is module-global, so a test that parks a focused ease segment
   // would otherwise leak it into every test that runs after it.
   usePlayerStore.getState().reset();
@@ -47,16 +46,6 @@ function baseElement(overrides: Partial<DomEditSelection> = {}): DomEditSelectio
   } as DomEditSelection;
 }
 
-function renderInto(node: React.ReactElement) {
-  const host = document.createElement("div");
-  document.body.append(host);
-  const root = createRoot(host);
-  act(() => {
-    root.render(node);
-  });
-  return { host, root };
-}
-
 describe("FlatTimingRow", () => {
   it("renders Start, End, and Duration from the element's data attributes", () => {
     const { host, root } = renderInto(
diff --git a/packages/studio/src/components/editor/propertyPanelFlatPrimitives.test.tsx b/packages/studio/src/components/editor/propertyPanelFlatPrimitives.test.tsx
index 831c80467..54677f2d3 100644
--- a/packages/studio/src/components/editor/propertyPanelFlatPrimitives.test.tsx
+++ b/packages/studio/src/components/editor/propertyPanelFlatPrimitives.test.tsx
@@ -1,8 +1,7 @@
 // @vitest-environment happy-dom
 
 import React, { act } from "react";
-import { createRoot } from "react-dom/client";
-import { afterEach, describe, expect, it, vi } from "vitest";
+import { describe, expect, it, vi } from "vitest";
 import {
   FlatGroupHeader,
   FlatRow,
@@ -10,22 +9,9 @@ import {
   FlatSelectRow,
   FlatSlider,
 } from "./propertyPanelFlatPrimitives";
+import { renderInto, setupReactActEnvironment } from "./testRenderUtils";
 
-(globalThis as unknown as { IS_REACT_ACT_ENVIRONMENT: boolean }).IS_REACT_ACT_ENVIRONMENT = true;
-
-afterEach(() => {
-  document.body.innerHTML = "";
-});
-
-function renderInto(node: React.ReactElement) {
-  const host = document.createElement("div");
-  document.body.append(host);
-  const root = createRoot(host);
-  act(() => {
-    root.render(node);
-  });
-  return { host, root };
-}
+setupReactActEnvironment();
 
 describe("FlatRow", () => {
   it("renders the default tier with no reset button", () => {
diff --git a/packages/studio/src/components/editor/propertyPanelFlatTextSection.test.tsx b/packages/studio/src/components/editor/propertyPanelFlatTextSection.test.tsx
index 4dbe02cc0..4c52de210 100644
--- a/packages/studio/src/components/editor/propertyPanelFlatTextSection.test.tsx
+++ b/packages/studio/src/components/editor/propertyPanelFlatTextSection.test.tsx
@@ -1,28 +1,14 @@
 // @vitest-environment happy-dom
 
-import React, { act, useState } from "react";
-import { createRoot } from "react-dom/client";
+import { act, useState } from "react";
 import postcss from "postcss";
 import tailwindcss from "tailwindcss";
-import { afterEach, describe, expect, it, vi } from "vitest";
+import { describe, expect, it, vi } from "vitest";
 import { FlatTextLayerList, FlatTextSection } from "./propertyPanelFlatTextSection";
 import type { DomEditSelection, DomEditTextField } from "./domEditingTypes";
+import { renderInto, setupReactActEnvironment } from "./testRenderUtils";
 
-(globalThis as unknown as { IS_REACT_ACT_ENVIRONMENT: boolean }).IS_REACT_ACT_ENVIRONMENT = true;
-
-afterEach(() => {
-  document.body.innerHTML = "";
-});
-
-function renderInto(node: React.ReactElement) {
-  const host = document.createElement("div");
-  document.body.append(host);
-  const root = createRoot(host);
-  act(() => {
-    root.render(node);
-  });
-  return { host, root };
-}
+setupReactActEnvironment();
 
 const FIELDS = [
   {
@@ -365,12 +351,7 @@ describe("FlatTextSection — multi-field", () => {
       );
     }
 
-    const host = document.createElement("div");
-    document.body.append(host);
-    const root = createRoot(host);
-    act(() => {
-      root.render(<Harness />);
-    });
+    const { host, root } = renderInto(<Harness />);
 
     let rows = host.querySelectorAll('[data-flat-text-layer-row="true"]');
     expect(rows).toHaveLength(2);
@@ -461,12 +442,7 @@ describe("FlatTextSection — multi-field", () => {
       );
     }
 
-    const host = document.createElement("div");
-    document.body.append(host);
-    const root = createRoot(host);
-    act(() => {
-      root.render(<Harness />);
-    });
+    const { host, root } = renderInto(<Harness />);
 
     const addButton = host.querySelector<HTMLButtonElement>('[data-flat-text-layer-add="true"]');
     // Wait for onAddTextField's promise to resolve (adds field "c" and makes it
@@ -489,22 +465,17 @@ describe("FlatTextSection — multi-field", () => {
     const element = makeMultiFieldElement();
     element.textFields[0].value = "First line\nSecond line\nThird line";
 
-    const host = document.createElement("div");
-    document.body.append(host);
-    const root = createRoot(host);
-    act(() => {
-      root.render(
-        <FlatTextSection
-          element={element}
-          styles={{}}
-          fontAssets={[]}
-          onSetText={vi.fn()}
-          onSetTextFieldStyle={vi.fn()}
-          onAddTextField={vi.fn()}
-          onRemoveTextField={vi.fn()}
-        />,
-      );
-    });
+    const { host, root } = renderInto(
+      <FlatTextSection
+        element={element}
+        styles={{}}
+        fontAssets={[]}
+        onSetText={vi.fn()}
+        onSetTextFieldStyle={vi.fn()}
+        onAddTextField={vi.fn()}
+        onRemoveTextField={vi.fn()}
+      />,
+    );
 
     const contentTextarea = host.querySelector<HTMLTextAreaElement>("textarea");
     expect(contentTextarea?.value).toBe("First line\nSecond line\nThird line");
diff --git a/packages/studio/src/components/editor/propertyPanelFlatToggle.test.tsx b/packages/studio/src/components/editor/propertyPanelFlatToggle.test.tsx
index e16956937..ee4ff774d 100644
--- a/packages/studio/src/components/editor/propertyPanelFlatToggle.test.tsx
+++ b/packages/studio/src/components/editor/propertyPanelFlatToggle.test.tsx
@@ -1,25 +1,11 @@
 // @vitest-environment happy-dom
 
-import React, { act } from "react";
-import { createRoot } from "react-dom/client";
-import { afterEach, describe, expect, it, vi } from "vitest";
+import { act } from "react";
+import { describe, expect, it, vi } from "vitest";
 import { FlatToggle } from "./propertyPanelFlatToggle";
+import { renderInto, setupReactActEnvironment } from "./testRenderUtils";
 
-(globalThis as unknown as { IS_REACT_ACT_ENVIRONMENT: boolean }).IS_REACT_ACT_ENVIRONMENT = true;
-
-afterEach(() => {
-  document.body.innerHTML = "";
-});
-
-function renderInto(node: React.ReactElement) {
-  const host = document.createElement("div");
-  document.body.append(host);
-  const root = createRoot(host);
-  act(() => {
-    root.render(node);
-  });
-  return { host, root };
-}
+setupReactActEnvironment();
 
 describe("FlatToggle", () => {
   it("renders the off state with a dim label and dim knob, and fires onChange(true) on click", () => {
diff --git a/packages/studio/src/components/editor/testRenderUtils.tsx b/packages/studio/src/components/editor/testRenderUtils.tsx
new file mode 100644
index 000000000..bc0632162
--- /dev/null
+++ b/packages/studio/src/components/editor/testRenderUtils.tsx
@@ -0,0 +1,26 @@
+import React, { act } from "react";
+import { createRoot } from "react-dom/client";
+import { afterEach } from "vitest";
+
+/**
+ * Marks the current environment as React-act-aware and registers the shared
+ * per-test DOM cleanup. Call once per test file, at module scope, before any
+ * `describe`/`it` blocks run.
+ */
+export function setupReactActEnvironment(): void {
+  (globalThis as unknown as { IS_REACT_ACT_ENVIRONMENT: boolean }).IS_REACT_ACT_ENVIRONMENT = true;
+
+  afterEach(() => {
+    document.body.innerHTML = "";
+  });
+}
+
+export function renderInto(node: React.ReactElement) {
+  const host = document.createElement("div");
+  document.body.append(host);
+  const root = createRoot(host);
+  act(() => {
+    root.render(node);
+  });
+  return { host, root };
+}