Replace deprecated datetime.utcnow() with datetime.now(UTC) throughout

Python 3.12 deprecates datetime.utcnow() with a DeprecationWarning and
it will be removed in a future release. Replace all call-site usages in
services, routes, and utils with datetime.now(UTC), and replace the
SQLAlchemy ORM column defaults (which used the bare function reference
datetime.utcnow) with lambda: datetime.now(UTC) so that the returned
objects are timezone-aware and consistent with Python best practice.

Affected: database/models.py, services/{stories,history,profiles,
channels,export_import}.py, routes/{profiles,tasks}.py, utils/tasks.py

backend/services/channels.py

@@ -3,7 +3,7 @@ Audio channel management module.
 """
 
 from typing import List, Optional
-from datetime import datetime
+from datetime import UTC, datetime
 import uuid
 from sqlalchemy.orm import Session
 
@@ -81,7 +81,7 @@ async def create_channel(
         id=str(uuid.uuid4()),
         name=data.name,
         is_default=False,
-        created_at=datetime.utcnow(),
+        created_at=datetime.now(UTC),
     )
     db.add(channel)
     db.flush()

backend/services/export_import.py

@@ -432,7 +432,7 @@ async def import_generation_from_zip(file_bytes: bytes, db: Session) -> dict:
                     duration=generation_data["duration"],
                     seed=generation_data.get("seed"),
                     instruct=generation_data.get("instruct"),
-                    created_at=datetime.utcnow(),
+                    created_at=datetime.now(UTC),
                 )
                 
                 db.add(db_generation)

backend/services/history.py

@@ -3,7 +3,7 @@ Generation history management module.
 """
 
 from typing import List, Optional, Tuple
-from datetime import datetime
+from datetime import UTC, datetime
 import uuid
 import shutil
 from pathlib import Path
@@ -104,7 +104,7 @@ async def create_generation(
         model_size=model_size,
         status=status,
         source=source,
-        created_at=datetime.utcnow(),
+        created_at=datetime.now(UTC),
     )
 
     db.add(db_generation)

backend/services/profiles.py

@@ -4,7 +4,7 @@ import json as _json
 import logging
 import shutil
 import uuid
-from datetime import datetime
+from datetime import UTC, datetime
 from pathlib import Path
 
 from sqlalchemy import func
@@ -183,8 +183,8 @@ async def create_profile(
         design_prompt=data.design_prompt,
         default_engine=default_engine,
         personality=data.personality,
-        created_at=datetime.utcnow(),
-        updated_at=datetime.utcnow(),
+        created_at=datetime.now(UTC),
+        updated_at=datetime.now(UTC),
     )
 
     db.add(db_profile)
@@ -244,7 +244,7 @@ async def add_profile_sample(
 
     db.add(db_sample)
 
-    profile.updated_at = datetime.utcnow()
+    profile.updated_at = datetime.now(UTC)
 
     db.commit()
     db.refresh(db_sample)
@@ -403,7 +403,7 @@ async def update_profile(
     profile.personality = data.personality
     if data.default_engine is not None:
         profile.default_engine = data.default_engine or None  # empty string → NULL
-    profile.updated_at = datetime.utcnow()
+    profile.updated_at = datetime.now(UTC)
 
     db.commit()
     db.refresh(profile)
@@ -672,7 +672,7 @@ async def upload_avatar(
     process_avatar(image_path, str(output_path))
 
     profile.avatar_path = config.to_storage_path(output_path)
-    profile.updated_at = datetime.utcnow()
+    profile.updated_at = datetime.now(UTC)
 
     db.commit()
     db.refresh(profile)
@@ -703,7 +703,7 @@ async def delete_avatar(
         avatar_path.unlink()
 
     profile.avatar_path = None
-    profile.updated_at = datetime.utcnow()
+    profile.updated_at = datetime.now(UTC)
 
     db.commit()
 

backend/services/stories.py

@@ -3,7 +3,7 @@ Story management module.
 """
 
 from typing import List, Optional
-from datetime import datetime
+from datetime import UTC, datetime
 import uuid
 import tempfile
 from pathlib import Path
@@ -96,8 +96,8 @@ async def create_story(
         id=str(uuid.uuid4()),
         name=data.name,
         description=data.description,
-        created_at=datetime.utcnow(),
-        updated_at=datetime.utcnow(),
+        created_at=datetime.now(UTC),
+        updated_at=datetime.now(UTC),
     )
 
     db.add(db_story)
@@ -206,7 +206,7 @@ async def update_story(
 
     story.name = data.name
     story.description = data.description
-    story.updated_at = datetime.utcnow()
+    story.updated_at = datetime.now(UTC)
 
     db.commit()
     db.refresh(story)
@@ -314,13 +314,13 @@ async def add_item_to_story(
         generation_id=data.generation_id,
         start_time_ms=start_time_ms,
         track=track,
-        created_at=datetime.utcnow(),
+        created_at=datetime.now(UTC),
     )
 
     db.add(item)
 
     # Update story updated_at
-    story.updated_at = datetime.utcnow()
+    story.updated_at = datetime.now(UTC)
 
     db.commit()
     db.refresh(item)
@@ -373,7 +373,7 @@ async def move_story_item(
     # Update story updated_at
     story = db.query(DBStory).filter_by(id=story_id).first()
     if story:
-        story.updated_at = datetime.utcnow()
+        story.updated_at = datetime.now(UTC)
 
     db.commit()
     db.refresh(item)
@@ -417,7 +417,7 @@ async def remove_item_from_story(
     # Update story updated_at
     story = db.query(DBStory).filter_by(id=story_id).first()
     if story:
-        story.updated_at = datetime.utcnow()
+        story.updated_at = datetime.now(UTC)
 
     db.commit()
     return True
@@ -470,7 +470,7 @@ async def trim_story_item(
     # Update story updated_at
     story = db.query(DBStory).filter_by(id=story_id).first()
     if story:
-        story.updated_at = datetime.utcnow()
+        story.updated_at = datetime.now(UTC)
 
     db.commit()
     db.refresh(item)
@@ -503,7 +503,7 @@ async def update_story_item_volume(
 
     story = db.query(DBStory).filter_by(id=story_id).first()
     if story:
-        story.updated_at = datetime.utcnow()
+        story.updated_at = datetime.now(UTC)
 
     db.commit()
     db.refresh(item)
@@ -576,7 +576,7 @@ async def split_story_item(
         trim_start_ms=absolute_split_ms,
         trim_end_ms=current_trim_end,
         volume=getattr(item, "volume", 1.0),
-        created_at=datetime.utcnow(),
+        created_at=datetime.now(UTC),
     )
 
     db.add(new_item)
@@ -584,7 +584,7 @@ async def split_story_item(
     # Update story updated_at
     story = db.query(DBStory).filter_by(id=story_id).first()
     if story:
-        story.updated_at = datetime.utcnow()
+        story.updated_at = datetime.now(UTC)
 
     db.commit()
     db.refresh(item)
@@ -650,7 +650,7 @@ async def duplicate_story_item(
         trim_start_ms=current_trim_start,
         trim_end_ms=current_trim_end,
         volume=getattr(original_item, "volume", 1.0),
-        created_at=datetime.utcnow(),
+        created_at=datetime.now(UTC),
     )
 
     db.add(new_item)
@@ -658,7 +658,7 @@ async def duplicate_story_item(
     # Update story updated_at
     story = db.query(DBStory).filter_by(id=story_id).first()
     if story:
-        story.updated_at = datetime.utcnow()
+        story.updated_at = datetime.now(UTC)
 
     db.commit()
     db.refresh(new_item)
@@ -700,7 +700,7 @@ async def update_story_item_times(
         item_map[update.generation_id].start_time_ms = update.start_time_ms
 
     # Update story updated_at
-    story.updated_at = datetime.utcnow()
+    story.updated_at = datetime.now(UTC)
 
     db.commit()
     return True
@@ -764,7 +764,7 @@ async def reorder_story_items(
         updated_items.append(_build_item_detail(item, generation, profile_name, db))
 
     # Update story updated_at
-    story.updated_at = datetime.utcnow()
+    story.updated_at = datetime.now(UTC)
 
     db.commit()
     return updated_items
@@ -823,7 +823,7 @@ async def set_story_item_version(
     # Update story updated_at
     story = db.query(DBStory).filter_by(id=story_id).first()
     if story:
-        story.updated_at = datetime.utcnow()
+        story.updated_at = datetime.now(UTC)
 
     db.commit()
     db.refresh(item)