diff --git a/src/renderer/src/components/browser-pane/markup/useMarkupEditor.test.ts b/src/renderer/src/components/browser-pane/markup/useMarkupEditor.test.ts
new file mode 100644
index 00000000000..6e6ba294028
--- /dev/null
+++ b/src/renderer/src/components/browser-pane/markup/useMarkupEditor.test.ts
@@ -0,0 +1,47 @@
+// @vitest-environment happy-dom
+
+import { act, renderHook } from '@testing-library/react'
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import { useMarkupEditor } from './useMarkupEditor'
+
+const realCrypto = globalThis.crypto
+
+function pointerDownEvent(clientX: number, clientY: number): React.PointerEvent<HTMLCanvasElement> {
+  return {
+    button: 0,
+    clientX,
+    clientY,
+    currentTarget: { setPointerCapture: vi.fn() },
+    pointerId: 1,
+    preventDefault: vi.fn()
+  } as unknown as React.PointerEvent<HTMLCanvasElement>
+}
+
+describe('useMarkupEditor.commitPendingText in a non-secure browser context', () => {
+  beforeEach(() => {
+    // Match a non-secure browser context (LAN web client over plain HTTP):
+    // getRandomValues stays, randomUUID is undefined.
+    Object.defineProperty(globalThis, 'crypto', {
+      configurable: true,
+      value: { getRandomValues: realCrypto.getRandomValues.bind(realCrypto) }
+    })
+  })
+
+  afterEach(() => {
+    Object.defineProperty(globalThis, 'crypto', { configurable: true, value: realCrypto })
+  })
+
+  it('commits a text shape with a valid id instead of throwing', () => {
+    const { result } = renderHook(() => useMarkupEditor(false, vi.fn()))
+
+    act(() => result.current.setTool('text'))
+    act(() => result.current.onPointerDown(pointerDownEvent(5, 5)))
+    expect(result.current.pendingText).not.toBeNull()
+
+    expect(() => act(() => result.current.commitPendingText('hello'))).not.toThrow()
+
+    const shape = result.current.shapes.at(-1)
+    expect(shape?.kind).toBe('text')
+    expect(shape?.id).toMatch(/^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[0-9a-f]{4}-[0-9a-f]{12}$/)
+  })
+})
diff --git a/src/renderer/src/components/browser-pane/markup/useMarkupPointerHandlers.test.ts b/src/renderer/src/components/browser-pane/markup/useMarkupPointerHandlers.test.ts
new file mode 100644
index 00000000000..3792a0f0b7b
--- /dev/null
+++ b/src/renderer/src/components/browser-pane/markup/useMarkupPointerHandlers.test.ts
@@ -0,0 +1,63 @@
+// @vitest-environment happy-dom
+
+import { act, renderHook } from '@testing-library/react'
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import { useMarkupPointerHandlers, type MarkupPointerParams } from './useMarkupPointerHandlers'
+import type { MarkupShape } from './markup-drawing-model'
+
+const realCrypto = globalThis.crypto
+
+function pointerDownEvent(clientX: number, clientY: number): React.PointerEvent<HTMLCanvasElement> {
+  return {
+    button: 0,
+    clientX,
+    clientY,
+    currentTarget: { setPointerCapture: vi.fn() },
+    pointerId: 1
+  } as unknown as React.PointerEvent<HTMLCanvasElement>
+}
+
+function baseParams(overrides: Partial<MarkupPointerParams> = {}): MarkupPointerParams {
+  return {
+    busy: false,
+    tool: 'pen',
+    color: '#ef4444',
+    width: 4,
+    pendingText: null,
+    canvasRef: {
+      current: {
+        getBoundingClientRect: () => ({ left: 0, top: 0 })
+      } as unknown as HTMLCanvasElement
+    },
+    setInProgress: vi.fn(),
+    setPendingText: vi.fn(),
+    setDoc: vi.fn(),
+    ...overrides
+  }
+}
+
+describe('useMarkupPointerHandlers in a non-secure browser context', () => {
+  beforeEach(() => {
+    // Match a non-secure browser context (LAN web client over plain HTTP):
+    // getRandomValues stays, randomUUID is undefined.
+    Object.defineProperty(globalThis, 'crypto', {
+      configurable: true,
+      value: { getRandomValues: realCrypto.getRandomValues.bind(realCrypto) }
+    })
+  })
+
+  afterEach(() => {
+    Object.defineProperty(globalThis, 'crypto', { configurable: true, value: realCrypto })
+  })
+
+  it('starts a pen stroke with a valid id instead of throwing', () => {
+    const setInProgress = vi.fn()
+    const { result } = renderHook(() => useMarkupPointerHandlers(baseParams({ setInProgress })))
+
+    expect(() => act(() => result.current.onPointerDown(pointerDownEvent(10, 10)))).not.toThrow()
+
+    expect(setInProgress).toHaveBeenCalledTimes(1)
+    const shape = setInProgress.mock.calls[0][0] as MarkupShape
+    expect(shape.id).toMatch(/^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[0-9a-f]{4}-[0-9a-f]{12}$/)
+  })
+})