fix(frontend): keep entity and message deletes in sync

frontend/src/__tests__/pages/EditTaskPage.test.tsx

@@ -294,6 +294,45 @@ describe('EditTaskPage', () => {
     })
   })
 
+  it('should_removeOnlyDeletedGeneratedMessage_when_deleteSucceedsWithoutRefetch', async () => {
+    persistedHistory = [
+      {
+        id: 'message-2',
+        taskId: 'task-1',
+        label: 'Message #2',
+        content: 'SUBJECT: Second\nBODY:\nSecond output',
+        createdAt: '2026-03-27T12:10:00Z',
+      },
+      {
+        id: 'message-1',
+        taskId: 'task-1',
+        label: 'Message #1',
+        content: 'SUBJECT: First\nBODY:\nFirst output',
+        createdAt: '2026-03-27T12:00:00Z',
+      },
+    ]
+    vi.mocked(tasksApi.getTaskGeneratedMessages).mockResolvedValue(persistedHistory)
+    vi.mocked(tasksApi.deleteTaskGeneratedMessage).mockResolvedValue(undefined)
+
+    renderPage()
+
+    const secondMessageHistoryItem = await screen.findByRole('button', { name: /^message #2$/i })
+    expect(await screen.findByRole('button', { name: /^message #1$/i })).toBeInTheDocument()
+
+    fireEvent.click(
+      screen.getByRole('button', {
+        name: /delete message #1/i,
+      })
+    )
+
+    await waitFor(() => {
+      expect(tasksApi.deleteTaskGeneratedMessage).toHaveBeenCalledWith('task-1', 'message-1')
+      expect(screen.queryByRole('button', { name: /^message #1$/i })).not.toBeInTheDocument()
+      expect(secondMessageHistoryItem).toBeInTheDocument()
+      expect(screen.getByText(/Second output/i)).toBeInTheDocument()
+    })
+  })
+
   it('should_loadPersistedGeneratedMessageHistory_when_pageLoads', async () => {
     persistedHistory = [
       {

frontend/src/__tests__/pages/EntitiesPage.test.tsx

@@ -89,6 +89,23 @@ describe('EntitiesPage', () => {
     })
   })
 
+  it('should_removeDeletedEntityFromList_when_deleteSucceeds', async () => {
+    vi.mocked(entitiesApi.getEntities).mockResolvedValue([mockEntity])
+    vi.mocked(entitiesApi.deleteEntity).mockResolvedValue(undefined)
+
+    render(<EntitiesPage />, { wrapper })
+
+    await waitFor(() => {
+      expect(screen.getByText('Test Entity')).toBeInTheDocument()
+    })
+
+    fireEvent.click(screen.getByRole('button', { name: /delete|deactivate/i }))
+
+    await waitFor(() => {
+      expect(screen.queryByText('Test Entity')).not.toBeInTheDocument()
+    })
+  })
+
   it('should_renderDetailLink_when_entitiesLoaded', async () => {
     vi.mocked(entitiesApi.getEntities).mockResolvedValue([mockEntity])
     render(<EntitiesPage />, { wrapper })

frontend/src/pages/EditTaskPage.tsx

@@ -255,8 +255,15 @@ export default function EditTaskPage() {
 
   const deleteGeneratedMessageMutation = useMutation({
     mutationFn: (messageId: string) => deleteTaskGeneratedMessage(taskId, messageId),
-    onSuccess: async () => {
-      await queryClient.invalidateQueries({ queryKey: ['task-generated-messages', taskId] })
+    onSuccess: ( _data, messageId) => {
+      queryClient.setQueryData(
+        ['task-generated-messages', taskId],
+        (
+          currentMessages:
+            | Awaited<ReturnType<typeof getTaskGeneratedMessages>>
+            | undefined
+        ) => currentMessages?.filter((message) => message.id !== messageId) ?? []
+      )
     },
   })
 

frontend/src/pages/EntitiesPage.tsx

@@ -37,7 +37,13 @@ export default function EntitiesPage() {
 
   const deleteMutation = useMutation({
     mutationFn: (id: string) => deleteEntity(id),
-    onSuccess: () => queryClient.invalidateQueries({ queryKey: ['entities'] }),
+    onSuccess: (_data, id) => {
+      queryClient.setQueryData(
+        ['entities'],
+        (currentEntities: Awaited<ReturnType<typeof getEntities>> | undefined) =>
+          currentEntities?.filter((entity) => entity.id !== id) ?? []
+      )
+    },
   })
 
   return (