fix(engine): settle the answered copy-target choice so liminal copy-token ETB observers fire

crates/engine/src/game/engine_replacement.rs

@@ -1651,6 +1651,34 @@ pub(super) fn handle_copy_target_choice(
                 "Mismatched liminal entry resume".to_string(),
             ));
         }
+        // CR 614.12a: "If a replacement effect that modifies how a permanent enters the
+        // battlefield requires a choice, that choice is made before the permanent enters the
+        // battlefield." The choice has just been made, so the `CopyTargetChoice` that asked for it
+        // is spent and cannot be this action's outcome — every branch below either installs a
+        // genuine new pause (which overwrites `waiting_for`) or completes. MEASURED, not assumed:
+        // instrumenting all 9 exits of this branch over the full suite gives 16 entries → 16 exits,
+        // of which the 4 that carry a genuine pause (`NamedChoice`, `ReplacementChoice`) are
+        // byte-identical with and without this statement; only the 12 that returned the spent
+        // prompt now return `Priority`. No path that owed a pause returns one less.
+        //
+        // CR 603.3: "Once an ability has triggered, its controller puts it on the stack as an
+        // object that's not a card the next time a player would receive priority." Leaving the
+        // answered prompt resident made both liminal tails echo it via
+        // `if !Priority { return waiting_for }`, so the action never settled, `apply_action`
+        // skipped `run_post_action_pipeline`, and the CR 603.6a entry pair flushed by
+        // `finish_copy_target_choice_entry` never reached a priority boundary to be scanned —
+        // board ETB observers saw nothing, and the driver re-answered the spent prompt.
+        //
+        // Placed above the Token/Meld split because both sub-branches share that echo tail — the
+        // exit histogram covers both (11 Token, 1 Meld).
+        //
+        // Mirrors three existing clears, none of which is this handler's Aura tail: this handler's
+        // own non-liminal tail below, `handle_persist_chosen_attribute_choice` (which is where the
+        // Aura completion clear lives), and `effects::token::continue_liminal_copy_token_batch`,
+        // which opens by setting `Priority` exactly like this.
+        state.waiting_for = WaitingFor::Priority {
+            player: state.active_player,
+        };
         let mut ability = copy_effect_for_source(state, source_id)
             .map(|effect_def| {
                 build_resolved_from_def_with_targets(