diff --git a/backend/app/services/ai_service.py b/backend/app/services/ai_service.py
index 33e6a9e..d6ca471 100644
--- a/backend/app/services/ai_service.py
+++ b/backend/app/services/ai_service.py
@@ -129,10 +129,14 @@ async def _execute_tool(
         return json.dumps({"entries": items, "count": len(items)})
 
     elif tool_name == "schedule_notification":
-        from datetime import datetime
+        from datetime import datetime, timezone as tz
         scheduled_at = None
         if tool_input.get("scheduled_at"):
             scheduled_at = datetime.fromisoformat(tool_input["scheduled_at"])
+            if scheduled_at.tzinfo is None:
+                scheduled_at = scheduled_at.replace(tzinfo=tz.utc)
+            if scheduled_at <= datetime.now(tz.utc):
+                scheduled_at = None  # Past date → send immediately
 
         notif = await create_notification(
             db, user_id,
@@ -145,15 +149,10 @@ async def _execute_tool(
 
         # Push immediately if not scheduled
         if not scheduled_at:
+            from app.workers.notification_sender import _serialize_notification
             await manager.send_to_user(user_id, {
                 "type": "new_notification",
-                "notification": {
-                    "id": str(notif.id),
-                    "title": notif.title,
-                    "body": notif.body,
-                    "type": notif.type,
-                    "created_at": notif.created_at.isoformat(),
-                },
+                "notification": _serialize_notification(notif),
             })
 
         return json.dumps({
diff --git a/backend/app/services/notification_service.py b/backend/app/services/notification_service.py
index 742894e..6cc4203 100644
--- a/backend/app/services/notification_service.py
+++ b/backend/app/services/notification_service.py
@@ -76,6 +76,7 @@ async def mark_all_read(db: AsyncSession, user_id: uuid.UUID) -> int:
         .where(
             Notification.user_id == user_id,
             Notification.read_at.is_(None),
+            Notification.status.in_(["sent", "delivered"]),
         )
         .values(status="read", read_at=datetime.now(timezone.utc))
     )
diff --git a/backend/app/workers/health_review.py b/backend/app/workers/health_review.py
index a219dbd..b8cbb3a 100644
--- a/backend/app/workers/health_review.py
+++ b/backend/app/workers/health_review.py
@@ -1,5 +1,6 @@
 """Daily job: proactive health review for all users with health data."""
 import asyncio
+import json
 import logging
 
 from anthropic import AsyncAnthropic
@@ -48,7 +49,6 @@ async def _review_user(user: User):
             messages=[{"role": "user", "content": f"User health profile:\n{memory_text}"}],
         )
 
-        import json
         try:
             text = response.content[0].text.strip()
             # Extract JSON from response
@@ -71,13 +71,8 @@ async def _review_user(user: User):
                 )
                 await db.commit()
 
+                from app.workers.notification_sender import _serialize_notification
                 await manager.send_to_user(user.id, {
                     "type": "new_notification",
-                    "notification": {
-                        "id": str(notif.id),
-                        "title": notif.title,
-                        "body": notif.body,
-                        "type": notif.type,
-                        "created_at": notif.created_at.isoformat(),
-                    },
+                    "notification": _serialize_notification(notif),
                 })
diff --git a/backend/app/workers/notification_sender.py b/backend/app/workers/notification_sender.py
index aebe7d3..5d836c3 100644
--- a/backend/app/workers/notification_sender.py
+++ b/backend/app/workers/notification_sender.py
@@ -1,24 +1,44 @@
 """Periodic job: send pending scheduled notifications via WebSocket."""
+import logging
+
 from app.database import async_session_factory
 from app.services.notification_service import get_pending_scheduled, mark_as_sent
 from app.services.ws_manager import manager
 
+logger = logging.getLogger(__name__)
+
+
+def _serialize_notification(notif) -> dict:
+    return {
+        "id": str(notif.id),
+        "user_id": str(notif.user_id),
+        "title": notif.title,
+        "body": notif.body,
+        "type": notif.type,
+        "channel": notif.channel,
+        "status": "sent",
+        "scheduled_at": notif.scheduled_at.isoformat() if notif.scheduled_at else None,
+        "sent_at": notif.sent_at.isoformat() if notif.sent_at else None,
+        "read_at": None,
+        "metadata": notif.metadata_,
+        "created_at": notif.created_at.isoformat(),
+    }
+
 
 async def send_pending_notifications():
     async with async_session_factory() as db:
         pending = await get_pending_scheduled(db)
         for notif in pending:
-            await mark_as_sent(db, notif.id)
-            await db.commit()
+            try:
+                notif.status = "sent"
+                from datetime import datetime, timezone
+                notif.sent_at = datetime.now(timezone.utc)
+                await db.commit()
 
-            # Push via WebSocket
-            await manager.send_to_user(notif.user_id, {
-                "type": "new_notification",
-                "notification": {
-                    "id": str(notif.id),
-                    "title": notif.title,
-                    "body": notif.body,
-                    "type": notif.type,
-                    "created_at": notif.created_at.isoformat(),
-                },
-            })
+                await manager.send_to_user(notif.user_id, {
+                    "type": "new_notification",
+                    "notification": _serialize_notification(notif),
+                })
+            except Exception:
+                logger.exception(f"Failed to send notification {notif.id}")
+                await db.rollback()