diff --git a/src/store/slices/syncSlice.test.ts b/src/store/slices/syncSlice.test.ts
new file mode 100644
index 0000000..314401a
--- /dev/null
+++ b/src/store/slices/syncSlice.test.ts
@@ -0,0 +1,98 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest'
+
+const {
+  mockFetchAllFromFlask,
+  mockDbPut,
+  mockDbGetAll,
+  mockDbDelete
+} = vi.hoisted(() => {
+  return {
+    mockFetchAllFromFlask: vi.fn<[], Promise<Record<string, any>>>(),
+    mockDbPut: vi.fn<[string, any], Promise<void>>(),
+    mockDbGetAll: vi.fn<[string], Promise<any[]>>(),
+    mockDbDelete: vi.fn<[string, string], Promise<void>>()
+  }
+})
+
+vi.mock('@/store/middleware/flaskSync', () => ({
+  fetchAllFromFlask: mockFetchAllFromFlask
+}))
+
+vi.mock('@/lib/db', () => ({
+  db: {
+    put: mockDbPut,
+    getAll: mockDbGetAll,
+    delete: mockDbDelete
+  }
+}))
+
+import { syncFromFlaskBulk } from './syncSlice'
+
+describe('syncFromFlaskBulk', () => {
+  const dispatch = vi.fn()
+  const getState = vi.fn()
+
+  beforeEach(() => {
+    mockFetchAllFromFlask.mockReset()
+    mockDbPut.mockReset()
+    mockDbGetAll.mockReset()
+    mockDbDelete.mockReset()
+    dispatch.mockReset()
+    getState.mockReset()
+  })
+
+  it('ignores invalid keys from Flask', async () => {
+    mockFetchAllFromFlask.mockResolvedValue({
+      'unknown:1': { id: '1' },
+      'files': { id: 'missing-colon' },
+      'models:': { id: 'empty-id' },
+      'components:abc:extra': { id: 'abc' }
+    })
+    mockDbGetAll.mockResolvedValue([])
+
+    const action = await syncFromFlaskBulk()(dispatch, getState, undefined)
+
+    expect(action.type).toBe('sync/syncFromFlaskBulk/fulfilled')
+    expect(mockDbPut).not.toHaveBeenCalled()
+    expect(mockDbDelete).not.toHaveBeenCalled()
+  })
+
+  it('updates local DB for valid keys', async () => {
+    const file = { id: 'file-1', name: 'File 1' }
+    const model = { id: 'model-1', name: 'Model 1' }
+
+    mockFetchAllFromFlask.mockResolvedValue({
+      'files:file-1': file,
+      'models:model-1': model
+    })
+    mockDbGetAll.mockResolvedValue([])
+
+    const action = await syncFromFlaskBulk()(dispatch, getState, undefined)
+
+    expect(action.type).toBe('sync/syncFromFlaskBulk/fulfilled')
+    expect(mockDbPut).toHaveBeenCalledWith('files', file)
+    expect(mockDbPut).toHaveBeenCalledWith('models', model)
+  })
+
+  it('deletes local entries missing from Flask data', async () => {
+    const file = { id: 'keep', name: 'Keep' }
+
+    mockFetchAllFromFlask.mockResolvedValue({
+      'files:keep': file
+    })
+    mockDbGetAll.mockImplementation((storeName) => {
+      if (storeName === 'files') {
+        return Promise.resolve([file, { id: 'stale', name: 'Stale' }])
+      }
+      return Promise.resolve([])
+    })
+
+    const action = await syncFromFlaskBulk()(dispatch, getState, undefined)
+
+    expect(action.type).toBe('sync/syncFromFlaskBulk/fulfilled')
+    expect(mockDbPut).toHaveBeenCalledWith('files', file)
+    expect(mockDbDelete).toHaveBeenCalledTimes(1)
+    expect(mockDbDelete).toHaveBeenCalledWith('files', 'stale')
+    expect(mockDbDelete).not.toHaveBeenCalledWith('files', 'keep')
+  })
+})