修复scalar_one_or_none相关limit

video-gen-api/app/services/credits.py

@@ -16,7 +16,7 @@ from app.utils.exceptions import InsufficientCreditsError
 async def calc_text_credits(db: AsyncSession, input_tokens: int, output_tokens: int) -> float:
     """Calculate text credits based on actual token usage and configurable rate."""
     result = await db.execute(
-        select(SystemConfig).where(SystemConfig.key == "text_credits_per_1000_tokens")
+        select(SystemConfig).where(SystemConfig.key == "text_credits_per_1000_tokens").limit(1)
     )
     config = result.scalar_one_or_none()
     rate = float(config.value) if config else 1.0
@@ -78,6 +78,7 @@ async def calc_video_credits(
             select(VideoEngine.id)
             .where(VideoEngine.is_active == True)
             .order_by(VideoEngine.priority.desc())
+            .limit(1)
         )
         engine_id = video_engines_result.scalar_one_or_none()
     ratio = await _get_credit_ratio(
@@ -122,6 +123,7 @@ async def calc_image_credits(
             select(ImageEngine.id)
             .where(ImageEngine.is_active == True)
             .order_by(ImageEngine.priority.desc())
+            .limit(1)
         )
         engine_id = image_engines_result.scalar_one_or_none()
     ratio = await _get_credit_ratio(
@@ -148,7 +150,7 @@ async def deduct_credits(
 ) -> User:
     """Atomically deduct credits from user. Raises InsufficientCreditsError."""
     result = await db.execute(
-        select(User).where(User.id == user_id)
+        select(User).where(User.id == user_id).limit(1)
     )
     user = result.scalar_one_or_none()
     if not user or user.credits < amount:
@@ -178,7 +180,7 @@ async def add_credits(
 ) -> User:
     """Add credits to user."""
     result = await db.execute(
-        select(User).where(User.id == user_id)
+        select(User).where(User.id == user_id).limit(1)
     )
     user = result.scalar_one_or_none()
     if not user: