Sandbox: "Turn Face Down" only sets the flag, so the permanent keeps its real face (SetFaceState)

[cuinhellcat]

Summary

The sandbox card menu's Turn Face Down entry sets face_down = true and nothing else. The permanent keeps its name, printed P/T and abilities while claiming to be face down, and back_face stays empty — so it can never be turned back up, including by the repaired Turn Face Up from #7539.

This is the face-DOWN half of the same match arm; #7540 deliberately scoped to face-up only.

Cause

game/engine_debug.rs, DebugAction::SetFaceState:

_ => {
    validate_object_mut(state, object_id)?.face_down = fd;
}

CR 708.2a says a permanent turned face down "becomes a 2/2 face-down creature with no text, no name, no subtypes, and no mana cost" — the real characteristics have to be snapshotted and replaced, not shadowed by a flag.

Expected

Route a face_down: Some(true) write on a battlefield permanent through zone_pipeline::apply_face_down_entry_profile, the authority the manifest, cloak and face-down-cast paths all run through, stamped FaceDownCause::TurnedFaceDown. CR 708.2b (an already-face-down permanent is left alone) falls out of the arm order.

Steps to reproduce

1. Sandbox, click mode on.
2. Card menu on any face-up battlefield creature → Turn Face Down.
3. The card still shows its name and printed P/T.
4. Turn Face Up does nothing, because there is no stored face to restore.

Related

#7539 / #7540 (the face-up half), #3284 / #3684 (the same class for the transformed write).