feat: add optional cover generation toggle

tests/test_ai.py

@@ -247,6 +247,7 @@ class AITests(TempDirMixin, unittest.TestCase):
             cfg["image_dir"] = os.path.join(temp_dir, "images")
             cfg["ai"]["title_concurrency"] = 2
             cfg["ai"]["image_concurrency"] = 2
+            cfg["ai"]["generate_cover"] = True
             batch_id, tasks = self._collected_tasks(temp_dir, cfg)
             cover_prompts = []
             progress = []
@@ -306,11 +307,65 @@ class AITests(TempDirMixin, unittest.TestCase):
 
         self.assert_removed(temp_dir)
 
+    def test_generate_batch_can_skip_cover_generation(self):
+        with self.make_temp_dir() as temp_dir:
+            cfg = self._config()
+            cfg["db_path"] = os.path.join(temp_dir, "cmshopee.db")
+            cfg["image_dir"] = os.path.join(temp_dir, "images")
+            batch_id, tasks = self._collected_tasks(temp_dir, cfg)
+            events = []
+            progress = []
+
+            def fake_title(title_prompt, old_title, **kwargs):
+                self.assertEqual("标题提示", title_prompt)
+                return "新" + old_title
+
+            with mock.patch("app.ai.gen_title", side_effect=fake_title), \
+                    mock.patch("app.ai.gen_cover") as gen_cover:
+                summary = ai.generate_batch(
+                    tasks,
+                    {"title": "标题提示", "cover": "封面 {新标题}"},
+                    ai_cfg={
+                        "config": cfg,
+                        "db_path": cfg["db_path"],
+                        "on_event": events.append,
+                    },
+                    on_progress=progress.append,
+                )
+
+            self.assertTrue(summary["ok"])
+            self.assertFalse(summary["generate_cover"])
+            self.assertEqual(2, summary["title_done"])
+            self.assertEqual(0, summary["cover_done"])
+            self.assertEqual(0, summary["cover_total"])
+            self.assertEqual(2, summary["generated_done"])
+            self.assertEqual(0, summary["failed"])
+            gen_cover.assert_not_called()
+            updated = db.list_tasks(batch_id=batch_id, path=cfg["db_path"])
+            self.assertTrue(all(task.stage == "generated" for task in updated))
+            self.assertTrue(all(task.status == "success" for task in updated))
+            self.assertEqual({"新旧标题A", "新旧标题B"}, {task.new_title for task in updated})
+            self.assertTrue(all(task.new_cover_path is None for task in updated))
+            self.assertEqual(0, progress[-1]["cover_total"])
+            self.assertEqual(2, progress[-1]["generated_done"])
+            self.assertTrue(
+                any(
+                    event.get("phase") == "title"
+                    and event.get("step") == "db_write"
+                    and event.get("result") == "success"
+                    and event.get("detail") == "仅生成标题"
+                    for event in events
+                )
+            )
+
+        self.assert_removed(temp_dir)
+
     def test_generate_batch_marks_failed_task_without_blocking_others(self):
         with self.make_temp_dir() as temp_dir:
             cfg = self._config()
             cfg["db_path"] = os.path.join(temp_dir, "cmshopee.db")
             cfg["image_dir"] = os.path.join(temp_dir, "images")
+            cfg["ai"]["generate_cover"] = True
             batch_id, tasks = self._collected_tasks(temp_dir, cfg, ["好标题", "坏标题"])
 
             def fake_title(title_prompt, old_title, **kwargs):