Implement/fact or fiction

client/src/adapter/types.ts

@@ -1560,6 +1560,12 @@ export type WaitingFor =
   | { type: "CopyRetarget"; data: { player: PlayerId; copy_id: ObjectId; target_slots: CopyTargetSlot[]; current_slot?: number } }
   // CR 700.3 + CR 700.3a: Subject is partitioning their own eligible objects
   // into two piles for an `Effect::SeparateIntoPiles`. `player` is the
+  // CR 608.2d + CR 700.3: Controller chooses which opponent separates piles (multiplayer).
+  | { type: "SeparatePilesChooseOpponent"; data: {
+      player: PlayerId;
+      candidates: PlayerId[];
+      source_id: ObjectId;
+    } }
   // partitioner (subject); pile B is derived engine-side as
   // `eligible \ pile_a`. `chosen_pile_effect` is opaque to the frontend.
   | { type: "SeparatePilesPartition"; data: {
@@ -1871,6 +1877,7 @@ export type GameAction =
   // CR 702.99a: answer to CipherEncodeChoice — a creature to encode on, or null to decline.
   | { type: "CipherEncode"; data: { creature: ObjectId | null } }
   | { type: "ChooseClashOpponent"; data: { opponent: PlayerId } }
+  | { type: "ChoosePileOpponent"; data: { opponent: PlayerId } }
   | { type: "ChooseAssistPlayer"; data: { player: PlayerId | null } }
   | { type: "CommitAssistPayment"; data: { generic: number } }
   | {

client/src/components/modal/PileOpponentModal.tsx

@@ -0,0 +1,70 @@
+import { useTranslation } from "react-i18next";
+import type { GameAction, PlayerId, WaitingFor } from "../../adapter/types.ts";
+import { useGameDispatch } from "../../hooks/useGameDispatch.ts";
+import { useCanActForWaitingState } from "../../hooks/usePlayerId.ts";
+import { useGameStore } from "../../stores/gameStore.ts";
+import { getOpponentDisplayName } from "../../stores/multiplayerStore.ts";
+import { ChoiceModal } from "./ChoiceModal.tsx";
+
+type PileOpponentWaitingFor = Extract<
+  WaitingFor,
+  { type: "SeparatePilesChooseOpponent" }
+>;
+
+interface PileOpponentModalContentProps {
+  waitingFor: PileOpponentWaitingFor;
+  seatOrder?: PlayerId[];
+  dispatch: (action: GameAction) => void | Promise<void>;
+}
+
+/**
+ * CR 700.3: When a spell or ability instructs "an opponent" to separate cards
+ * into piles, the controller chooses which opponent performs the separation.
+ */
+export function PileOpponentModalContent({
+  waitingFor,
+  seatOrder,
+  dispatch,
+}: PileOpponentModalContentProps) {
+  const { t } = useTranslation("game");
+  const candidates = [...waitingFor.data.candidates].sort((a, b) => {
+    const aIdx = seatOrder?.indexOf(a) ?? a;
+    const bIdx = seatOrder?.indexOf(b) ?? b;
+    return aIdx - bIdx;
+  });
+  return (
+    <ChoiceModal
+      title={t("pileOpponent.title", "Choose Opponent")}
+      subtitle={t(
+        "pileOpponent.subtitle",
+        "Choose which opponent separates the cards into piles.",
+      )}
+      options={candidates.map((opponent) => ({
+        id: String(opponent),
+        label: getOpponentDisplayName(opponent),
+      }))}
+      onChoose={(id) => {
+        dispatch({
+          type: "ChoosePileOpponent",
+          data: { opponent: Number(id) },
+        });
+      }}
+    />
+  );
+}
+
+export function PileOpponentModal() {
+  const canActForWaitingState = useCanActForWaitingState();
+  const dispatch = useGameDispatch();
+  const waitingFor = useGameStore((s) => s.waitingFor);
+  const seatOrder = useGameStore((s) => s.gameState?.seat_order);
+  if (waitingFor?.type !== "SeparatePilesChooseOpponent") return null;
+  if (!canActForWaitingState) return null;
+  return (
+    <PileOpponentModalContent
+      waitingFor={waitingFor}
+      seatOrder={seatOrder}
+      dispatch={dispatch}
+    />
+  );
+}

client/src/game/waitingForRegistry.ts

@@ -150,6 +150,7 @@ export const HANDLED_WAITING_FOR_TYPES: ReadonlySet<WaitingFor["type"]> =
     "RevealUntilKeptChoice",
     "RepeatDecision",
     "VoteChoice",
+    "SeparatePilesChooseOpponent",
     "SeparatePilesPartition",
     "SeparatePilesChoice",
     "ChooseRingBearer",

client/src/i18n/locales/de/game.json

@@ -1608,6 +1608,10 @@
     "title": "Kampf-Gegner wählen",
     "subtitle": "Wähle, welcher Gegner mit dir kämpft."
   },
+  "pileOpponent": {
+    "title": "Choose Opponent",
+    "subtitle": "Choose which opponent separates the cards into piles."
+  },
   "assist": {
     "choose": {
       "title": "Choose a Player to Assist",

client/src/i18n/locales/en/game.json

@@ -1645,6 +1645,10 @@
     "title": "Choose Clash Opponent",
     "subtitle": "Choose which opponent will clash with you."
   },
+  "pileOpponent": {
+    "title": "Choose Opponent",
+    "subtitle": "Choose which opponent separates the cards into piles."
+  },
   "assist": {
     "choose": {
       "title": "Choose a Player to Assist",

client/src/i18n/locales/es/game.json

@@ -1608,6 +1608,10 @@
     "title": "Elegir oponente para chocar",
     "subtitle": "Elige qué oponente chocará contigo."
   },
+  "pileOpponent": {
+    "title": "Choose Opponent",
+    "subtitle": "Choose which opponent separates the cards into piles."
+  },
   "assist": {
     "choose": {
       "title": "Choose a Player to Assist",

client/src/i18n/locales/fr/game.json

@@ -1608,6 +1608,10 @@
     "title": "Choisir l'adversaire pour la confrontation",
     "subtitle": "Choisissez quel adversaire fera la confrontation avec vous."
   },
+  "pileOpponent": {
+    "title": "Choose Opponent",
+    "subtitle": "Choose which opponent separates the cards into piles."
+  },
   "assist": {
     "choose": {
       "title": "Choose a Player to Assist",

client/src/i18n/locales/it/game.json

@@ -1608,6 +1608,10 @@
     "title": "Scegli l'avversario per lo scontro",
     "subtitle": "Scegli quale avversario si scontrerà con te."
   },
+  "pileOpponent": {
+    "title": "Choose Opponent",
+    "subtitle": "Choose which opponent separates the cards into piles."
+  },
   "assist": {
     "choose": {
       "title": "Choose a Player to Assist",

client/src/i18n/locales/pl/game.json

@@ -1608,6 +1608,10 @@
     "title": "Wybierz przeciwnika do starcia",
     "subtitle": "Wybierz, który przeciwnik stoczy z tobą starcie."
   },
+  "pileOpponent": {
+    "title": "Choose Opponent",
+    "subtitle": "Choose which opponent separates the cards into piles."
+  },
   "assist": {
     "choose": {
       "title": "Choose a Player to Assist",

client/src/i18n/locales/pt/game.json

@@ -1608,6 +1608,10 @@
     "title": "Escolher oponente para confronto",
     "subtitle": "Escolha qual oponente fará confronto com você."
   },
+  "pileOpponent": {
+    "title": "Choose Opponent",
+    "subtitle": "Choose which opponent separates the cards into piles."
+  },
   "assist": {
     "choose": {
       "title": "Choose a Player to Assist",

client/src/pages/GamePage.tsx

@@ -84,6 +84,7 @@ import { useModalPeek } from "../components/modal/useModalPeek.ts";
 import { BattleProtectorModal } from "../components/modal/BattleProtectorModal.tsx";
 import { AssistChoosePlayerModal } from "../components/modal/AssistChoosePlayerModal.tsx";
 import { ClashOpponentModal } from "../components/modal/ClashOpponentModal.tsx";
+import { PileOpponentModal } from "../components/modal/PileOpponentModal.tsx";
 import { TributeModal } from "../components/modal/TributeModal.tsx";
 import { CombatTaxModal } from "../components/modal/CombatTaxModal.tsx";
 import { TopOrBottomChoiceModalContent } from "../components/modal/TopOrBottomChoiceModal.tsx";
@@ -1694,6 +1695,7 @@ function GamePageContent({
         <BattleProtectorModal />
         <AssistChoosePlayerModal />
         <ClashOpponentModal />
+        <PileOpponentModal />
         <TributeModal />
         <CombatTaxModal />
         <AlternativeCostModal />

crates/engine/src/ai_support/candidates.rs

@@ -1460,6 +1460,20 @@ pub fn candidate_actions_broad_with_probe(
         // with the player who is authorized to submit it; otherwise the
         // action gets routed to the wrong AI seat in multiplayer. The
         // `actor` field is always set to the authorized submitter.
+        // CR 608.2d + CR 700.3: AI opponent choice for pile separation — offer each
+        // candidate opponent as a legal action.
+        WaitingFor::SeparatePilesChooseOpponent {
+            player, candidates, ..
+        } => candidates
+            .iter()
+            .map(|&opp| {
+                candidate(
+                    GameAction::ChoosePileOpponent { opponent: opp },
+                    TacticalClass::Selection,
+                    Some(*player),
+                )
+            })
+            .collect(),
         // CR 700.3 + CR 700.3a: AI partition candidates. Full powerset is
         // exponential, so we cap at three heuristics: all-in-A (chooser
         // sees an empty pile B), all-in-B (chooser sees a full pile A),

crates/engine/src/analysis/ability_graph.rs

@@ -1276,8 +1276,15 @@ fn collect_effects_in_effect<'a>(effect: &'a Effect, out: &mut Vec<&'a Effect>)
             }
         }
         Effect::SeparateIntoPiles {
-            chosen_pile_effect, ..
-        } => collect_effects(chosen_pile_effect, out),
+            chosen_pile_effect,
+            unchosen_pile_effect,
+            ..
+        } => {
+            collect_effects(chosen_pile_effect, out);
+            if let Some(unchosen) = unchosen_pile_effect {
+                collect_effects(unchosen, out);
+            }
+        }
         Effect::RevealFromHand {
             on_decline: Some(d),
             ..

crates/engine/src/game/ability_rw.rs

@@ -3186,8 +3186,15 @@ fn legacy_effect(x: &Effect) -> bool {
         Effect::SeparateIntoPiles {
             object_filter,
             chosen_pile_effect,
+            unchosen_pile_effect,
             ..
-        } => legacy_target_filter(object_filter) || legacy_definition(chosen_pile_effect),
+        } => {
+            legacy_target_filter(object_filter)
+                || legacy_definition(chosen_pile_effect)
+                || unchosen_pile_effect
+                    .as_ref()
+                    .is_some_and(|d| legacy_definition(d))
+        }
         Effect::EpicCopy { spell } => contains_legacy_event_ref(spell),
         Effect::CreateDelayedTrigger { effect, .. } => legacy_definition(effect),
         Effect::CreateDrawReplacement { replacement_effect } => legacy_effect(replacement_effect),