fix(engine): keep the cast-time face choice per cast, not per object (#7565)

crates/engine/src/ai_support/candidates.rs

@@ -5803,6 +5803,7 @@ mod tests {
         let mut card_types = crate::types::card_type::CardType::default();
         card_types.core_types.push(CoreType::Sorcery);
         crate::game::game_object::BackFaceData {
+            is_swap_snapshot: false,
             name: "Prepared Spell Face".to_string(),
             power: None,
             toughness: None,

crates/engine/src/game/casting.rs

@@ -3107,11 +3107,10 @@ fn simulate_chosen_split_spell_back_face(obj: &mut crate::game::game_object::Gam
     swap_to_alternative_spell_face(obj);
     // Mirror `ChooseModalFace { back_face: true }` so affordability preview and
     // alt-cost resolution use the chosen face without re-prompting or swapping
-    // back to the front half (#3987).
+    // back to the front half (#3987). #7565: the mirror is the transient
+    // choice flag, not a layout_kind erasure.
     obj.modal_back_face = true;
-    if let Some(ref mut bf) = obj.back_face {
-        bf.layout_kind = None;
-    }
+    obj.cast_face_committed = true;
 }
 
 pub(super) fn exile_alt_cost_permission_supports_cast(
@@ -8942,13 +8941,8 @@ pub(super) fn consume_pending_spell_cost_reduction(
 /// spell face for casting. Saves the normal face in `back_face` for later
 /// restoration.
 fn swap_to_alternative_spell_face(obj: &mut crate::game::game_object::GameObject) {
-    let alternative = match obj.back_face.take() {
-        Some(b) => b,
-        None => return,
-    };
-    let normal_snapshot = super::printed_cards::snapshot_object_face(obj);
-    super::printed_cards::apply_back_face_to_object(obj, alternative);
-    obj.back_face = Some(normal_snapshot);
+    // #7565: the shared swap preserves the stored slot's layout_kind.
+    super::printed_cards::swap_object_faces(obj);
 }
 
 /// CR 715 / CR 720: Returns the Adventure-family spell layout if this object
@@ -9038,7 +9032,11 @@ fn is_castable_split_face(types: &crate::types::card_type::CardType) -> bool {
 /// CR 712.11b + CR 709.3: Cast-time face choice for spell//spell MDFCs and
 /// spell//spell split cards.
 fn cast_spell_face_choice_available(obj: &crate::game::game_object::GameObject) -> bool {
-    modal_spell_face_choice_available(obj) || split_spell_face_choice_available(obj)
+    // CR 601.2b (#7565): a choice already made for the CURRENT cast is not
+    // offered again on pipeline re-entry; the transient flag clears once the
+    // cast conversation ends, so a later recast prompts afresh.
+    !obj.cast_face_committed
+        && (modal_spell_face_choice_available(obj) || split_spell_face_choice_available(obj))
 }
 
 /// CR 712.11b: Returns true if `obj` is a Modal double-faced card whose two
@@ -13970,8 +13968,10 @@ pub fn can_cast_modal_face_now(
     };
     if back_face {
         simulate_chosen_split_spell_back_face(obj);
-    } else if let Some(back) = obj.back_face.as_mut() {
-        back.layout_kind = None;
+    } else {
+        // #7565: mirror the front-face choice on the simulation clone the same
+        // way the real handler records it.
+        obj.cast_face_committed = true;
     }
     if obj
         .card_types
@@ -20004,6 +20004,12 @@ pub fn handle_cancel_cast(
             obj.modal_back_face = false;
         }
     }
+    // #7565: a cancelled cast releases its face choice — the object may never
+    // move zones (it stays in hand), so the zone-change clear cannot cover
+    // this path. Unconditional: harmless when no choice was made.
+    if let Some(obj) = state.objects.get_mut(&pending.object_id) {
+        obj.cast_face_committed = false;
+    }
 
     if pending.casting_variant == CastingVariant::Prototype {
         // CR 601.2i + CR 702.160a: backing out of a prototyped cast before

crates/engine/src/game/casting_tests.rs

@@ -10817,6 +10817,7 @@ fn hearth_elemental_self_cost_reduction_counts_adventures() {
         obj.card_types.core_types.push(ty);
         if i == 2 {
             obj.back_face = Some(crate::game::game_object::BackFaceData {
+                is_swap_snapshot: false,
                 name: "Adventure".to_string(),
                 power: None,
                 toughness: None,
@@ -26918,6 +26919,7 @@ fn create_adventure_in_hand(state: &mut GameState, player: PlayerId) -> ObjectId
 
     // Adventure face stored in back_face (Stomp - instant, {1}{R})
     obj.back_face = Some(crate::game::game_object::BackFaceData {
+        is_swap_snapshot: false,
         name: "Stomp".to_string(),
         power: None,
         toughness: None,
@@ -27010,6 +27012,7 @@ fn create_enchantment_adventure_in_hand(state: &mut GameState, player: PlayerId)
     };
 
     obj.back_face = Some(crate::game::game_object::BackFaceData {
+        is_swap_snapshot: false,
         name: "Embereth Blaze".to_string(),
         power: None,
         toughness: None,
@@ -27098,6 +27101,7 @@ fn create_omen_in_hand(state: &mut GameState, player: PlayerId) -> ObjectId {
     obj.mana_cost = ManaCost::generic(5);
 
     obj.back_face = Some(crate::game::game_object::BackFaceData {
+        is_swap_snapshot: false,
         name: "Good Omen".to_string(),
         power: None,
         toughness: None,
@@ -30923,6 +30927,7 @@ fn add_disturb_creature_to_graveyard(
         .push(Keyword::Disturb(disturb_cost.clone()));
     obj.keywords = obj.base_keywords.clone();
     obj.back_face = Some(crate::game::game_object::BackFaceData {
+        is_swap_snapshot: false,
         name: "Luminous Phantom".to_string(),
         power: Some(1),
         toughness: Some(1),
@@ -37215,6 +37220,7 @@ mod mtmte_cast_flow {
         let mut card_types = CardType::default();
         card_types.core_types.push(CoreType::Creature);
         BackFaceData {
+            is_swap_snapshot: false,
             name: "Streetwise Operative".to_string(),
             power: Some(7),
             toughness: Some(7),
@@ -51432,6 +51438,7 @@ fn exact_resolution_offer_does_not_inherit_sibling_cast_transformed() {
         obj.card_types.core_types.push(CoreType::Creature);
         obj.mana_cost = ManaCost::zero();
         obj.back_face = Some(crate::game::game_object::BackFaceData {
+            is_swap_snapshot: false,
             name: "Back Face".to_string(),
             power: Some(3),
             toughness: Some(3),

crates/engine/src/game/day_night.rs

@@ -153,6 +153,7 @@ mod tests {
         obj.color = vec![ManaColor::Green];
         obj.base_color = vec![ManaColor::Green];
         obj.back_face = Some(BackFaceData {
+            is_swap_snapshot: false,
             name: "Nightbound Werewolf".to_string(),
             power: Some(4),
             toughness: Some(4),

crates/engine/src/game/effects/become_copy.rs

@@ -1142,6 +1142,7 @@ mod tests {
             obj.color = vec![ManaColor::Green];
             obj.base_color = vec![ManaColor::Green];
             obj.back_face = Some(BackFaceData {
+                is_swap_snapshot: false,
                 name: "Back Face".to_string(),
                 power: Some(5),
                 toughness: Some(4),

crates/engine/src/game/effects/change_zone.rs

@@ -9711,6 +9711,7 @@ mod tests {
             obj.base_characteristics_initialized = true;
             // Back face: Sorin, Ravenous Neonate — planeswalker with loyalty 3
             obj.back_face = Some(BackFaceData {
+                is_swap_snapshot: false,
                 name: "Sorin, Ravenous Neonate".to_string(),
                 power: None,
                 toughness: None,

crates/engine/src/game/effects/flip_coin.rs

@@ -909,6 +909,7 @@ mod tests {
         obj.base_power = Some(1);
         obj.base_toughness = Some(3);
         obj.back_face = Some(BackFaceData {
+            is_swap_snapshot: false,
             name: "Ral, Leyline Prodigy".to_string(),
             power: None,
             toughness: None,

crates/engine/src/game/effects/flip_permanent.rs

@@ -123,6 +123,7 @@ mod tests {
         obj.color = vec![ManaColor::Black];
         obj.base_color = obj.color.clone();
         obj.back_face = Some(BackFaceData {
+            is_swap_snapshot: false,
             name: "Stabwhisker the Odious".to_string(),
             power: Some(3),
             toughness: Some(3),

crates/engine/src/game/effects/prepare.rs

@@ -1234,6 +1234,7 @@ mod tests {
             let mut card_types = crate::types::card_type::CardType::default();
             card_types.core_types.push(CoreType::Sorcery);
             crate::game::game_object::BackFaceData {
+                is_swap_snapshot: false,
                 name: "Test Prepare Face".to_string(),
                 power: None,
                 toughness: None,

crates/engine/src/game/effects/set_room_door_lock.rs

@@ -118,6 +118,7 @@ mod tests {
     /// presence of `back_face` is read by `existing_doors`.
     fn room_back_face() -> BackFaceData {
         BackFaceData {
+            is_swap_snapshot: false,
             name: "Right Door".to_string(),
             power: None,
             toughness: None,

crates/engine/src/game/effects/token.rs

@@ -3859,6 +3859,7 @@ fn incubator_phyrexian_back_face() -> BackFaceData {
         // no parse to have gone wrong.
         parse_warnings: vec![],
         layout_kind: None,
+        is_swap_snapshot: false,
     }
 }
 

crates/engine/src/game/effects/transform_effect.rs

@@ -194,6 +194,7 @@ mod tests {
         obj.color = vec![ManaColor::Green];
         obj.base_color = vec![ManaColor::Green];
         obj.back_face = Some(crate::game::game_object::BackFaceData {
+            is_swap_snapshot: false,
             name: "Back Face".to_string(),
             power: Some(4),
             toughness: Some(4),

crates/engine/src/game/engine.rs

@@ -8643,28 +8643,22 @@ fn apply_action(
             }
             if let Some(obj) = state.objects.get_mut(object_id) {
                 if back_face {
-                    // Swap to back face using existing primitives
-                    let back = obj.back_face.take().expect("dual-faced card has back face");
-                    let front_snapshot = super::printed_cards::snapshot_object_face(obj);
-                    super::printed_cards::apply_back_face_to_object(obj, back);
-                    obj.back_face = Some(front_snapshot);
+                    // Swap to back face — the shared swap preserves the stored
+                    // slot's layout_kind (#7565).
+                    super::printed_cards::swap_object_faces(obj);
                     // CR 712.8a (MDFC) / CR 709.3 (split): non-front face showing;
                     // `apply_zone_exit_cleanup` reverts when leaving the stack.
                     obj.modal_back_face = true;
-                } else {
-                    // Front face chosen — clear layout_kind so the intercept
-                    // won't re-fire on re-entry into handle_play_land / handle_cast_spell.
-                    if let Some(ref mut bf) = obj.back_face {
-                        bf.layout_kind = None;
-                    }
-                }
-                // After choosing either face, clear layout on the stashed other
-                // half so cast/play re-entry does not re-prompt.
-                if back_face {
-                    if let Some(ref mut bf) = obj.back_face {
-                        bf.layout_kind = None;
-                    }
                 }
+                // CR 601.2b (#7565): remember that THIS cast's face choice is
+                // made so the handle_play_land / handle_cast_spell re-entry
+                // does not re-prompt. A transient flag, NOT
+                // `back_face.layout_kind = None`: that erasure was permanent,
+                // so a recast from hand (Rescue, bounce) silently auto-picked
+                // the front face and every other layout_kind consumer went
+                // blind. Cleared on any zone change off the stack and on
+                // cancel.
+                obj.cast_face_committed = true;
             }
             // CR 712.12 / CR 712.11b: Route the re-entry by the now-active face's
             // type. A land face is put onto the battlefield via the play-land
@@ -13606,10 +13600,14 @@ fn handle_play_land(
 
     // CR 712.12: MDFC land face selection
     if let Some(obj) = state.objects.get(&object_id) {
-        let is_modal = obj
-            .back_face
-            .as_ref()
-            .is_some_and(|bf| bf.layout_kind == Some(crate::types::card::LayoutKind::Modal));
+        // CR 712.12 + CR 601.2b (#7565): the face prompt is offered only while
+        // this cast's choice is still open — `cast_face_committed` suppresses
+        // the re-entry re-prompt (layout_kind itself stays untouched).
+        let is_modal = !obj.cast_face_committed
+            && obj
+                .back_face
+                .as_ref()
+                .is_some_and(|bf| bf.layout_kind == Some(crate::types::card::LayoutKind::Modal));
         let front_is_land = obj
             .card_types
             .core_types
@@ -13635,10 +13633,7 @@ fn handle_play_land(
         if is_modal && !front_is_land && back_is_land {
             // CR 712.12: Only back face is a land — auto-swap (player already chose "play as land")
             let obj = state.objects.get_mut(&object_id).unwrap();
-            let back = obj.back_face.take().expect("MDFC has back face");
-            let front_snapshot = super::printed_cards::snapshot_object_face(obj);
-            super::printed_cards::apply_back_face_to_object(obj, back);
-            obj.back_face = Some(front_snapshot);
+            super::printed_cards::swap_object_faces(obj);
             // CR 712.8a: Mark back-face so apply_zone_exit_cleanup reverts to front face
             // when this land leaves the battlefield. Do NOT set obj.transformed — MDFC
             // face selection is not transformation.
@@ -15624,6 +15619,7 @@ mod priority_principal_tests {
             .get_mut(&object_id)
             .unwrap()
             .back_face = Some(BackFaceData {
+            is_swap_snapshot: false,
             name: "Blow Off Steam".to_string(),
             power: None,
             toughness: None,
@@ -20104,7 +20100,7 @@ mod stage2_injector_tests {
                 //   `:13210 ⇒ :13130`. It creates no CR 603.5 prompt either — a special
                 //   action does not use the stack (CR 116.1) — and the pinned line is again
                 //   the same `OptionalEffectChoice` construction, moved wholesale.
-                "game/engine.rs:13130".to_string(),
+                "game/engine.rs:13124".to_string(),
             ],
             "the five production producers, NAMED: the CR 603.5 gate in `resolve_chain_body` \
              plus the two repeated-optional-payment drivers, the per-player acceptance cursor \

crates/engine/src/game/engine_debug.rs

@@ -1605,6 +1605,7 @@ mod tests {
         let mut card_types = crate::types::card_type::CardType::default();
         card_types.core_types.push(CoreType::Sorcery);
         BackFaceData {
+            is_swap_snapshot: false,
             name: "Test Prepare Face".to_string(),
             power: None,
             toughness: None,

crates/engine/src/game/engine_mdfc_land_tests.rs

@@ -41,6 +41,7 @@ fn make_back_face(
     layout_kind: Option<LayoutKind>,
 ) -> BackFaceData {
     BackFaceData {
+        is_swap_snapshot: false,
         name: name.to_string(),
         power: None,
         toughness: None,