fix: persist message delivery status across server restarts

app/messages/repository.py

@@ -180,6 +180,11 @@ async def create_message_receipt(
     return receipt
 
 
+async def list_chat_receipts(db: AsyncSession, *, chat_id: int) -> list[MessageReceipt]:
+    result = await db.execute(select(MessageReceipt).where(MessageReceipt.chat_id == chat_id))
+    return list(result.scalars().all())
+
+
 async def get_message_reaction(db: AsyncSession, *, message_id: int, user_id: int) -> MessageReaction | None:
     result = await db.execute(
         select(MessageReaction)

app/messages/schemas.py

@@ -16,6 +16,7 @@ class MessageRead(BaseModel):
     forwarded_from_message_id: int | None
     type: MessageType
     text: str | None
+    delivery_status: Literal["sending", "sent", "delivered", "read"] | None = None
     created_at: datetime
     updated_at: datetime
 

app/messages/service.py

@@ -107,7 +107,26 @@ async def get_messages(
 ) -> list[Message]:
     await ensure_chat_membership(db, chat_id=chat_id, user_id=user_id)
     safe_limit = max(1, min(limit, 100))
-    return await repository.list_chat_messages(db, chat_id, user_id=user_id, limit=safe_limit, before_id=before_id)
+    messages = await repository.list_chat_messages(db, chat_id, user_id=user_id, limit=safe_limit, before_id=before_id)
+    if not messages:
+        return messages
+    receipts = await repository.list_chat_receipts(db, chat_id=chat_id)
+    other_receipts = [receipt for receipt in receipts if receipt.user_id != user_id]
+    if not other_receipts:
+        return messages
+    for message in messages:
+        if message.sender_id != user_id:
+            continue
+        is_read = any((receipt.last_read_message_id or 0) >= message.id for receipt in other_receipts)
+        if is_read:
+            setattr(message, "delivery_status", "read")
+            continue
+        is_delivered = any((receipt.last_delivered_message_id or 0) >= message.id for receipt in other_receipts)
+        if is_delivered:
+            setattr(message, "delivery_status", "delivered")
+            continue
+        setattr(message, "delivery_status", "sent")
+    return messages
 
 
 async def search_messages(

docs/api-reference.md

@@ -254,6 +254,7 @@ Rules:
   "forwarded_from_message_id": null,
   "type": "text",
   "text": "Hello",
+  "delivery_status": "read",
   "created_at": "2026-03-08T10:02:00Z",
   "updated_at": "2026-03-08T10:02:00Z"
 }