## Hidden Objects

Objects with `hidden: true` don't appear in the room's object listing. Players discover them by reading room descriptions or trying commands. The object is still fully interactable — `push gate`, `look gate`, etc.

```yaml
# data/objects/secret_lever.yaml
id: secret_lever
name: stone lever
hidden: true
description: "A cleverly concealed lever behind a loose stone."
use_interactions:
  - condition:
      flag: secret_passage_open
      value: true
      not: true
    message: "You pull the lever. A grinding sound echoes from the east."
    action:
      set_flags:
        secret_passage_open: true
```

Room description hints at it:
```yaml
description: "A dusty corridor. One of the wall stones looks slightly out of place."
```

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