fix: 完善失败重试与跳过边界

tests/integration/test_failure_tolerance.py

@@ -34,6 +34,24 @@ class OneFailedOneSuccessfulItemPlatform:
         return [CommentData(source_comment_id="c1", content="继续成功")]
 
 
+class AllItemsFailPlatform:
+    def fetch_hotspots(self, *, limit):
+        from app.platforms.base import HotspotData
+
+        return [HotspotData(source_hot_id="h1", title="热点一", rank=1)]
+
+    def search_items_by_hotspot(self, keyword, *, limit):
+        from app.platforms.base import ContentItemData
+
+        return [
+            ContentItemData(source_item_id="bad-one", item_type="video", title="失败内容一"),
+            ContentItemData(source_item_id="bad-two", item_type="video", title="失败内容二"),
+        ]
+
+    def fetch_comments(self, source_item_id, *, limit):
+        raise PlatformAPIError("comments exhausted", error_type="rate_limited", status_code=429)
+
+
 def test_hotspot_failure_marks_task_failed(monkeypatch):
     with make_test_client() as (_client, engine):
         monkeypatch.setattr("app.services.task_service.build_platform", lambda _platform: FailingHotspotPlatform())
@@ -102,3 +120,30 @@ def test_failed_content_item_is_recorded_and_following_item_continues(monkeypatc
         assert failed_item.error_stage == "crawl_comments"
         assert failed_item.error_type == "rate_limited"
         assert successful_item.status == "success"
+
+
+def test_task_fails_with_visible_reason_when_all_content_items_fail(monkeypatch):
+    with make_test_client() as (_client, engine):
+        monkeypatch.setattr("app.services.task_service.build_platform", lambda _platform: AllItemsFailPlatform())
+
+        with Session(engine) as session:
+            task = create_task(
+                session,
+                CreateTaskRequest(platform="douyin", hotspot_limit=1, item_limit_per_hotspot=2, comment_limit_per_item=10),
+                submit_background=False,
+            )
+            task_id = task.id
+            run_task(task_id, session_factory=lambda: session)
+
+            persisted = session.get(Task, task_id)
+            failed_items = session.query(ContentItem).filter_by(task_id=task_id, status="failed").all()
+
+        assert persisted.status == "failed"
+        assert persisted.total_items_count == 2
+        assert persisted.processed_items_count == 2
+        assert persisted.successful_items_count == 0
+        assert persisted.failed_items_count == 2
+        assert persisted.error_stage == "crawl_comments"
+        assert persisted.error_type == "rate_limited"
+        assert persisted.error_message == "comments exhausted"
+        assert len(failed_items) == 2