diff --git a/src/main/ipc/pet.test.ts b/src/main/ipc/pet.test.ts
new file mode 100644
index 000000000..59311df56
--- /dev/null
+++ b/src/main/ipc/pet.test.ts
@@ -0,0 +1,112 @@
+import { mkdtemp, mkdir, readFile, rm, writeFile } from 'node:fs/promises'
+import { join } from 'node:path'
+import { tmpdir } from 'node:os'
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+
+const {
+  appGetPathMock,
+  browserWindowFromWebContentsMock,
+  browserWindowGetFocusedWindowMock,
+  handleMock,
+  nativeImageCreateFromBufferMock,
+  showOpenDialogMock
+} = vi.hoisted(() => ({
+  appGetPathMock: vi.fn(),
+  browserWindowFromWebContentsMock: vi.fn(),
+  browserWindowGetFocusedWindowMock: vi.fn(),
+  handleMock: vi.fn(),
+  nativeImageCreateFromBufferMock: vi.fn(),
+  showOpenDialogMock: vi.fn()
+}))
+
+vi.mock('electron', () => ({
+  app: {
+    getPath: appGetPathMock
+  },
+  BrowserWindow: {
+    fromWebContents: browserWindowFromWebContentsMock,
+    getFocusedWindow: browserWindowGetFocusedWindowMock
+  },
+  dialog: {
+    showOpenDialog: showOpenDialogMock
+  },
+  ipcMain: {
+    handle: handleMock
+  },
+  nativeImage: {
+    createFromBuffer: nativeImageCreateFromBufferMock
+  }
+}))
+
+import { registerPetHandlers } from './pet'
+import type { CustomPet } from '../../shared/types'
+
+describe('registerPetHandlers', () => {
+  let tempDir: string
+  let userDataDir: string
+  const handlers = new Map<string, (event: unknown, ...args: unknown[]) => Promise<unknown>>()
+
+  beforeEach(async () => {
+    tempDir = await mkdtemp(join(tmpdir(), 'orca-pet-test-'))
+    userDataDir = join(tempDir, 'user-data')
+    handlers.clear()
+    appGetPathMock.mockReset()
+    browserWindowFromWebContentsMock.mockReset()
+    browserWindowGetFocusedWindowMock.mockReset()
+    handleMock.mockReset()
+    nativeImageCreateFromBufferMock.mockReset()
+    showOpenDialogMock.mockReset()
+
+    appGetPathMock.mockReturnValue(userDataDir)
+    browserWindowFromWebContentsMock.mockReturnValue(null)
+    browserWindowGetFocusedWindowMock.mockReturnValue(null)
+    handleMock.mockImplementation((channel, handler) => {
+      handlers.set(channel, handler)
+    })
+    nativeImageCreateFromBufferMock.mockReturnValue({
+      isEmpty: () => true,
+      getSize: () => ({ width: 0, height: 0 })
+    })
+  })
+
+  afterEach(async () => {
+    await rm(tempDir, { recursive: true, force: true })
+  })
+
+  function getHandler(channel: string): (event: unknown, ...args: unknown[]) => Promise<unknown> {
+    registerPetHandlers()
+    const handler = handlers.get(channel)
+    if (!handler) {
+      throw new Error(`${channel} handler not registered`)
+    }
+    return handler
+  }
+
+  it('imports a pet bundle whose manifest uses Windows separators', async () => {
+    const bundleDir = join(tempDir, 'windows-export.codex-pet')
+    const sheetBytes = Buffer.from('not decoded without frame metadata')
+    await mkdir(join(bundleDir, 'assets'), { recursive: true })
+    await writeFile(
+      join(bundleDir, 'pet.json'),
+      JSON.stringify({
+        id: 'windows-export',
+        displayName: 'Windows export',
+        spritesheetPath: String.raw`assets\spritesheet.png`
+      })
+    )
+    await writeFile(join(bundleDir, 'assets', 'spritesheet.png'), sheetBytes)
+    showOpenDialogMock.mockResolvedValue({ canceled: false, filePaths: [bundleDir] })
+
+    const result = (await getHandler('pet:importPetBundle')({ sender: {} })) as CustomPet
+
+    expect(result).toMatchObject({
+      label: 'Windows export',
+      fileName: 'spritesheet.png',
+      mimeType: 'image/png',
+      kind: 'bundle'
+    })
+    await expect(
+      readFile(join(userDataDir, 'sidekicks', 'custom', result.id, 'spritesheet.png'))
+    ).resolves.toEqual(sheetBytes)
+  })
+})
diff --git a/src/main/ipc/pet.ts b/src/main/ipc/pet.ts
index de3d11b59..2a6c0e13c 100644
--- a/src/main/ipc/pet.ts
+++ b/src/main/ipc/pet.ts
@@ -315,10 +315,17 @@ export function registerPetHandlers(): void {
     // that shape before path validation. Reject absolute paths and any resolved
     // path that escapes the bundle directory. Also reject symlinks so a
     // malicious bundle can't reach outside via a sibling link.
-    if (isAbsolute(manifest.spritesheetPath)) {
+    const normalizedSpritePath = manifest.spritesheetPath.replace(/[\\/]+/g, sep)
+    if (
+      isAbsolute(manifest.spritesheetPath) ||
+      isAbsolute(normalizedSpritePath) ||
+      /^[a-zA-Z]:/.test(manifest.spritesheetPath)
+    ) {
       throw new Error('spritesheetPath must be relative to the bundle.')
     }
-    const sheetSrc = resolve(bundleDir, manifest.spritesheetPath)
+    // Why: pet bundles may be exported on Windows and imported on macOS/Linux;
+    // normalize manifest separators before Node resolves the bundle-relative path.
+    const sheetSrc = resolve(bundleDir, normalizedSpritePath)
     const bundleResolved = resolve(bundleDir)
     if (sheetSrc === bundleResolved) {
       throw new Error('spritesheetPath must point to a file, not the bundle root.')