feat: log cmhub download diagnostics in GenerateWorker

GUI 半边配合 ai.py 的 cmhub 下载诊断：格式化「图片下载较慢」warning、
`cover_image_url` 调试行（脱敏 token、debug_only 不写入 SQLite run_log）；
`_log_run_event` 增加 persist 开关。tests/test_gui.py 覆盖脱敏与不持久化。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app/gui/workers.py

@@ -159,7 +159,12 @@ class GenerateWorker(BaseWorker):
         message = self._format_generation_event(payload)
         if not message:
             return
-        self._log_run_event(message, task=task, level=payload.get("level") or "info")
+        self._log_run_event(
+            message,
+            task=task,
+            level=payload.get("level") or "info",
+            persist=not bool(payload.get("debug_only")),
+        )
 
     def _remember_cmhub_metadata(self, payload):
         metadata = payload.get("metadata")
@@ -195,10 +200,15 @@ class GenerateWorker(BaseWorker):
                 return f"[停止] {self._task_plain_label(task)} 标题生成已取消"
             return None
         if phase == "cover":
+            if result == "debug" and step == "cover_image_url":
+                debug_detail = self._debug_detail(payload.get("detail"))
+                return f"[调试] {self._task_progress_label(task)} {debug_detail}"
             if result == "start" and step == "cover_submit":
                 return f"[图片] {self._task_progress_label(task)} 开始生成"
             if result == "success" and step == "cover_request":
                 return f"[图片] {self._task_progress_label(task)} {detail or 'cmhub 已返回，耗时未知'}"
+            if result == "warning" and step == "cover_download":
+                return f"[图片] {self._task_progress_label(task)} {detail or '图片下载较慢'}"
             if result == "success" and step == "cover_download":
                 return f"[图片] {self._task_progress_label(task)} {detail or '图片下载完成，耗时未知'}"
             if result == "success" and step == "cover_save":
@@ -267,6 +277,14 @@ class GenerateWorker(BaseWorker):
             return text[:177] + "..."
         return text
 
+    def _debug_detail(self, detail):
+        if detail is None:
+            return ""
+        text = diagnostics.redact_log_text(str(detail)).replace("\r", " ").replace("\n", " ").strip()
+        if len(text) > 2000:
+            return text[:1997] + "..."
+        return text
+
     def _format_generate_completion(self, summary):
         progress = self._summary_text(summary)
         billing_error = summary.get("billing_error") or {}
@@ -382,10 +400,10 @@ class GenerateWorker(BaseWorker):
         except Exception:
             return
 
-    def _log_run_event(self, message, task=None, level="info"):
+    def _log_run_event(self, message, task=None, level="info", persist=True):
         safe_message = diagnostics.redact_log_text(message)
         self.log.emit(str(safe_message))
-        if self._run_id is None:
+        if self._run_id is None or not persist:
             return
         try:
             db.add_run_log_event(

tests/test_gui.py

@@ -2008,6 +2008,27 @@ class GuiTests(TempDirMixin, unittest.TestCase):
                         "detail": "下载完成，1.3MB，耗时 12.4秒",
                     }
                 )
+                ai_cfg["on_event"](
+                    {
+                        "task": tasks[0],
+                        "phase": "cover",
+                        "step": "cover_download",
+                        "result": "warning",
+                        "detail": "图片下载较慢，已用 24.0秒，大小 1.3MB",
+                        "level": "warning",
+                    }
+                )
+                ai_cfg["on_event"](
+                    {
+                        "task": tasks[0],
+                        "phase": "cover",
+                        "step": "cover_image_url",
+                        "result": "debug",
+                        "detail": "cmhub 图片 URL：https://cdn.example.com/generated.png?token=SECRET-TOKEN",
+                        "level": "warning",
+                        "debug_only": True,
+                    }
+                )
                 ai_cfg["on_event"](
                     {
                         "task": tasks[0],
@@ -2046,6 +2067,8 @@ class GuiTests(TempDirMixin, unittest.TestCase):
             self.assertIn("准备重试 1/2", joined_logs)
             self.assertIn("cmhub 已返回 image_url，耗时 91.2秒", joined_logs)
             self.assertIn("下载完成，1.3MB，耗时 12.4秒", joined_logs)
+            self.assertIn("图片下载较慢，已用 24.0秒，大小 1.3MB", joined_logs)
+            self.assertIn("cmhub 图片 URL：https://cdn.example.com/generated.png?token=***", joined_logs)
             self.assertIn("本地保存完成，JPEG 已保存，耗时 1.1秒，文件 220.0KB", joined_logs)
             self.assertIn("token=***", joined_logs)
             self.assertNotIn("SECRET-TOKEN", joined_logs)
@@ -2055,6 +2078,8 @@ class GuiTests(TempDirMixin, unittest.TestCase):
             self.assertIn("[图片] 1/1 商品 51100639510", event_messages)
             self.assertIn("准备重试 1/2", event_messages)
             self.assertIn("下载完成，1.3MB，耗时 12.4秒", event_messages)
+            self.assertIn("图片下载较慢，已用 24.0秒，大小 1.3MB", event_messages)
+            self.assertNotIn("cmhub 图片 URL", event_messages)
 
         self.assert_removed(temp_dir)