fix: harden memoir image generation flow

api/routers/chapters.py

@@ -14,6 +14,12 @@ from database.models import Chapter as ChapterModel
 from database.models import User as UserModel
 from middleware.auth import get_current_user
 from agents.prompts.memory_prompts import CHAPTER_CATEGORIES, CHAPTER_ORDER, STAGE_TO_ORDER
+from services.memoir_images.schema import (
+    completed_image_assets,
+    IMAGE_STATUS_COMPLETED,
+    normalize_image_assets,
+)
+from services.memoir_images.settings import MemoirImageSettings
 from services.memoir_images.storage import (
     TencentCosStorageService,
     normalize_cos_url,
@@ -29,9 +35,13 @@ def _normalize_image_assets(images: list[dict] | None) -> list[dict]:
     region = os.getenv("TENCENT_COS_REGION", "")
     base_url = os.getenv("TENCENT_COS_BASE_URL", "")
     storage = TencentCosStorageService.from_env()
+    settings = MemoirImageSettings.from_env()
+    source_assets = normalize_image_assets(images)
+    if not settings.enabled:
+        source_assets = completed_image_assets(source_assets)
     normalized_assets: list[dict] = []
 
-    for item in (images or []):
+    for item in source_assets:
         asset = dict(item)
         normalized_url = normalize_cos_url(
             asset.get("url"),
@@ -40,12 +50,13 @@ def _normalize_image_assets(images: list[dict] | None) -> list[dict]:
             base_url=base_url,
         )
         storage_key = resolve_image_storage_key(asset)
-        if asset.get("status") == "completed" and storage_key:
+        if asset.get("status") == IMAGE_STATUS_COMPLETED and storage_key:
             try:
                 asset["url"] = storage.get_download_url(storage_key)
             except Exception as exc:
                 logger.warning("章节图片签名失败: key=%s, error=%s", storage_key, exc)
                 asset["url"] = normalized_url
+                asset["error"] = asset.get("error") or "image delivery unavailable"
         else:
             asset["url"] = normalized_url
         asset.pop("storage_key", None)