# Concealing records

When [policy](policy.md) hides a record from a caller, saying
"forbidden" would reveal that it exists. So a hidden record fails with the
same `not_found` failure your code already maps, and the client can't
tell hidden from absent.

Say policy lets only a todo's owner read it. Then this read of someone
else's todo fails with `TodoNotFound`, exactly like a todo that doesn't
exist:

```jadpo
var todo: Todo = attempt Todo.get(todo_id)
```

The log adds `concealed_by: policy`, so you can still tell the two apart
([When policy says no](when-policy-says-no.md)).