fix(channel): member delete acts as leave; add coverage and docs

app/chats/router.py

@@ -20,7 +20,7 @@ from app.chats.schemas import (
     ChatTitleUpdateRequest,
 )
 from app.chats import repository as chats_repository
-from app.chats.models import ChatType
+from app.chats.models import ChatMemberRole, ChatType
 from app.chats.service import (
     add_chat_member_for_user,
     ban_chat_member_for_user,
@@ -253,11 +253,19 @@ async def delete_chat(
     current_user: User = Depends(get_current_user),
 ) -> None:
     chat_before_delete = await chats_repository.get_chat_by_id(db, chat_id)
+    membership_before_delete = (
+        await chats_repository.get_chat_member(db, chat_id=chat_id, user_id=current_user.id) if chat_before_delete else None
+    )
     delete_for_all = bool(
         chat_before_delete
         and (
             (for_all and not chat_before_delete.is_saved)
-            or (chat_before_delete.type == ChatType.CHANNEL and not chat_before_delete.is_saved)
+            or (
+                chat_before_delete.type == ChatType.CHANNEL
+                and not chat_before_delete.is_saved
+                and membership_before_delete is not None
+                and membership_before_delete.role in {ChatMemberRole.OWNER, ChatMemberRole.ADMIN}
+            )
         )
     )
     await delete_chat_for_user(db, chat_id=chat_id, user_id=current_user.id, payload=ChatDeleteRequest(for_all=for_all))