# Trace: Evaluating Rust Files and Project Roadmap

Agent: claude-code | Model: Claude Opus 4.6 | Project: mage

---

## User

Would it make sense to split up any of our rust source files into multiple files to make them more understandable or easier to read?

## Assistant

## Assistant

Let me survey the Rust source files to identify candidates based on size and complexity.

## Assistant

### Tool: Bash

**Args:**
```json
{
  "command": "find /mnt/dest-btrfs/home/jc/src/mage/mtg-rl -name '*.rs' -not -path '*/target/*' -exec wc -l {} + | sort -rn | head -40",
  "description": "Count lines in all Rust source files, sorted by size"
}
```

## Assistant

**Result** (success):
```
  51736 total
  13828 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/game.rs
   7576 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-cards/src/sets/fdn.rs
   4761 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-cards/src/sets/ecl.rs
   4424 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-cards/src/sets/tla.rs
   4287 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-cards/src/sets/tdm.rs
   2113 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/abilities.rs
    907 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/constants.rs
    903 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-tests/src/framework.rs
    841 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/state.rs
    830 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/zones.rs
    773 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/events.rs
    647 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/combat.rs
    584 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-ai/src/minimax_player.rs
    565 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/watchers.rs
    541 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/effects.rs
    516 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/filters.rs
    501 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-ai/src/evaluator.rs
    491 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/permanent.rs
    481 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/mana.rs
    475 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-ai/src/heuristic_player.rs
    447 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-ai/src/action_space.rs
    439 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-cards/src/registry.rs
    415 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/targets.rs
    391 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/turn.rs
    384 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-ai/src/observation.rs
    357 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/decision.rs
    335 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-ai/src/random_player.rs
    332 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/player.rs
    327 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/mana_pool.rs
    324 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-tests/src/scripted_player.rs
    324 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/counters.rs
    298 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-ai/src/gym.rs
    276 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-tests/src/concurrency.rs
    250 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-tests/benches/game_bench.rs
    201 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/card.rs
    114 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-python/src/lib.rs
     92 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-cards/src/keywords/mobilize.rs
     86 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-cards/src/cards/basic_lands.rs
     78 /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/types.rs
```

## Assistant

The clear standout is `game.rs` at nearly 14K lines. Let me look at its internal structure to understand what could be split.

## Assistant

### Tool: Bash

**Args:**
```json
{
  "command": "grep -n '^\\s*pub fn\\|^\\s*fn\\|^\\s*impl\\|^\\s*// ==\\|^\\s*/// #\\|^\\s*mod ' /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/game.rs | head -100",
  "description": "Find function/impl/section markers in game.rs"
}
```

## Assistant

**Result** (success):
```
92:impl Game {
94:    pub fn new_two_player(
160:    pub fn run(&mut self) -> GameResult {
248:    fn london_mulligan(&mut self, player_ids: &[PlayerId]) {
349:    fn process_step(&mut self) {
370:    fn process_sba_and_triggers(&mut self) {
408:    fn apply_continuous_effects(&mut self) {
682:    fn evaluate_condition(&self, source_id: ObjectId, controller: PlayerId, condition: &str) -> bool {
726:    fn evaluate_count_filter(&self, filter: &str, controller: PlayerId) -> u32 {
792:    pub fn calculate_cost_reduction(&self, player_id: PlayerId, card: &crate::card::CardData) -> u32 {
816:    fn spell_matches_cost_filter(&self, card: &crate::card::CardData, filter: &str) -> bool {
861:    fn find_matching_permanents(
923:    fn check_enters_tapped(&mut self, permanent_id: ObjectId) {
943:    fn check_triggered_abilities(&mut self) -> bool {
1186:    fn emit_event(&mut self, event: GameEvent) {
1191:    fn turn_based_actions(&mut self, step: PhaseStep, active_player: PlayerId) {
1330:    fn declare_attackers_step(&mut self, active_player: PlayerId) {
1421:    fn declare_blockers_step(&mut self, _active_player: PlayerId) {
1551:    fn combat_damage_step(&mut self, is_first_strike: bool) {
1636:    fn priority_loop(&mut self) {
1721:    fn compute_legal_actions(&self, player_id: PlayerId) -> Vec<crate::decision::PlayerAction> {
1895:    fn play_land(&mut self, player_id: PlayerId, card_id: ObjectId) {
1939:    fn cast_spell(&mut self, player_id: PlayerId, card_id: ObjectId) {
2070:    fn check_ward_on_targets(&mut self, spell_id: ObjectId, caster: PlayerId) {
2106:    fn find_ward_cost(&self, permanent_id: ObjectId) -> Option<String> {
2120:    fn try_pay_ward_cost(&mut self, payer: PlayerId, cost: &str) -> bool {
2170:    fn resolve_top_of_stack(&mut self) {
2263:    pub fn process_state_based_actions(&mut self) {
2274:    fn apply_state_based_actions(&mut self, sba: &StateBasedActions) -> Vec<ObjectId> {
2361:    fn activate_ability(
2396:    fn activate_mana_ability(
2427:    fn count_colors_among_permanents(&self, player_id: PlayerId) -> usize {
2440:    fn can_pay_additional_costs(&self, player_id: PlayerId, source_id: ObjectId, costs: &[Cost]) -> bool {
2496:    fn pay_costs(&mut self, player_id: PlayerId, source_id: ObjectId, costs: &[Cost]) -> bool {
2823:    pub fn execute_effects(&mut self, effects: &[Effect], controller: PlayerId, all_targets: &[ObjectId], source: Option<ObjectId>, x_value: Option<u32>) {
4460:    fn move_card_to_graveyard_inner(&mut self, card_id: ObjectId, owner: PlayerId) {
4468:    fn move_card_to_graveyard(&mut self, card_id: ObjectId, owner: PlayerId) {
4476:    pub fn draw_cards(&mut self, player_id: PlayerId, count: u32) {
4503:    fn parse_token_stats(token_name: &str) -> (i32, i32, crate::constants::KeywordAbilities) {
4549:    fn matches_filter(perm: &Permanent, filter: &str) -> bool {
4593:    fn card_matches_filter(card: &CardData, filter: &str) -> bool {
4624:    fn select_targets_for_spec(
4674:    fn legal_targets_for_spec(
4745:    fn is_untargetable(perm: &Permanent, targeting_controller: PlayerId) -> bool {
4758:    fn target_spec_description(spec: &crate::abilities::TargetSpec) -> String {
4773:    fn target_spec_outcome(spec: &crate::abilities::TargetSpec) -> crate::constants::Outcome {
4789:    fn resolve_fight_pair(
4833:    fn check_game_end(&self) -> Option<GameResult> {
4857:mod tests {
4871:    impl PlayerDecisionMaker for AlwaysPassPlayer {
4872:        fn priority(&mut self, _game: &GameView<'_>, _legal: &[PlayerAction]) -> PlayerAction {
4875:        fn choose_targets(&mut self, _: &GameView<'_>, _: Outcome, _: &TargetRequirement) -> Vec<ObjectId> { vec![] }
4876:        fn choose_use(&mut self, _: &GameView<'_>, _: Outcome, _: &str) -> bool { false }
4877:        fn choose_mode(&mut self, _: &GameView<'_>, _: &[NamedChoice]) -> usize { 0 }
4878:        fn select_attackers(&mut self, _: &GameView<'_>, _: &[ObjectId], _: &[ObjectId]) -> Vec<(ObjectId, ObjectId)> { vec![] }
4879:        fn select_blockers(&mut self, _: &GameView<'_>, _: &[AttackerInfo]) -> Vec<(ObjectId, ObjectId)> { vec![] }
4880:        fn assign_damage(&mut self, _: &GameView<'_>, _: &DamageAssignment) -> Vec<(ObjectId, u32)> { vec![] }
4881:        fn choose_mulligan(&mut self, _: &GameView<'_>, _: &[ObjectId]) -> bool { false }
4882:        fn choose_cards_to_put_back(&mut self, _: &GameView<'_>, _: &[ObjectId], _: usize) -> Vec<ObjectId> { vec![] }
4883:        fn choose_discard(&mut self, _: &GameView<'_>, _: &[ObjectId], _: usize) -> Vec<ObjectId> { vec![] }
4884:        fn choose_amount(&mut self, _: &GameView<'_>, _: &str, min: u32, _: u32) -> u32 { min }
4885:        fn choose_mana_payment(&mut self, _: &GameView<'_>, _: &UnpaidMana, _: &[PlayerAction]) -> Option<PlayerAction> { None }
4886:        fn choose_replacement_effect(&mut self, _: &GameView<'_>, _: &[ReplacementEffectChoice]) -> usize { 0 }
4887:        fn choose_pile(&mut self, _: &GameView<'_>, _: Outcome, _: &str, _: &[ObjectId], _: &[ObjectId]) -> bool { true }
4888:        fn choose_option(&mut self, _: &GameView<'_>, _: Outcome, _: &str, _: &[NamedChoice]) -> usize { 0 }
4891:    fn make_basic_land(name: &str, owner: PlayerId) -> CardData {
4897:    fn make_creature(name: &str, owner: PlayerId, power: i32, toughness: i32) -> CardData {
4906:    fn make_deck(owner: PlayerId) -> Vec<CardData> {
4920:    fn game_creation() {
4949:    fn game_runs_to_completion() {
4977:    fn draw_cards_from_empty_library_causes_loss() {
5010:    fn counter_annihilation_applied() {
5050:    fn legend_rule_applied() {
5101:    fn legal_actions_include_pass() {
5126:    fn mana_ability_and_spell_cast() {
5179:    fn activated_ability_goes_on_stack() {
5242:    fn spell_effects_execute_on_resolve() {
5307:    fn fizzle_when_target_removed() {
5369:    fn draw_cards_effect() {
5403:    fn gain_life_effect() {
5428:    fn lose_life_opponents_effect() {
5456:    fn exile_effect() {
5493:    fn bounce_effect() {
5531:    fn pay_costs_tap_and_sacrifice() {
5578:    fn add_counters_self_when_no_targets() {
5631:    fn add_counters_self_with_separate_target() {
5697:    impl PlayerDecisionMaker for DiscardingPlayer {
5698:        fn priority(&mut self, _game: &GameView<'_>, _legal: &[PlayerAction]) -> PlayerAction {
5701:        fn choose_targets(&mut self, _: &GameView<'_>, _: Outcome, _: &TargetRequirement) -> Vec<ObjectId> { vec![] }
5702:        fn choose_use(&mut self, _: &GameView<'_>, _: Outcome, _: &str) -> bool { false }
5703:        fn choose_mode(&mut self, _: &GameView<'_>, _: &[NamedChoice]) -> usize { 0 }
5704:        fn select_attackers(&mut self, _: &GameView<'_>, _: &[ObjectId], _: &[ObjectId]) -> Vec<(ObjectId, ObjectId)> { vec![] }
5705:        fn select_blockers(&mut self, _: &GameView<'_>, _: &[AttackerInfo]) -> Vec<(ObjectId, ObjectId)> { vec![] }
5706:        fn assign_damage(&mut self, _: &GameView<'_>, _: &DamageAssignment) -> Vec<(ObjectId, u32)> { vec![] }
5707:        fn choose_mulligan(&mut self, _: &GameView<'_>, _: &[ObjectId]) -> bool { false }
5708:        fn choose_cards_to_put_back(&mut self, _: &GameView<'_>, _: &[ObjectId], _: usize) -> Vec<ObjectId> { vec![] }
5709:        fn choose_discard(&mut self, _: &GameView<'_>, hand: &[ObjectId], count: usize) -> Vec<ObjectId> {
5713:        fn choose_amount(&mut self, _: &GameView<'_>, _: &str, min: u32, _: u32) -> u32 { min }
5714:        fn choose_mana_payment(&mut self, _: &GameView<'_>, _: &UnpaidMana, _: &[PlayerAction]) -> Option<PlayerAction> { None }
5715:        fn choose_replacement_effect(&mut self, _: &GameView<'_>, _: &[ReplacementEffectChoice]) -> usize { 0 }
```

## Assistant

### Tool: Bash

**Args:**
```json
{
  "command": "grep -n '^\\s*pub fn\\|^\\s*fn\\|^\\s*impl\\|^\\s*// ==\\|^\\s*/// #\\|^\\s*mod ' /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/game.rs | tail -60",
  "description": "More function markers from game.rs"
}
```

## Assistant

**Result** (success):
```
13315:    fn put_from_hand_noncreature_not_eligible() {
13336:    fn effect_builder_put_from_hand_haste_sacrifice() {
13351:    fn effect_builder_put_from_hand_tapped_attacking() {
13367:mod cant_untap_tests {
13380:    impl PlayerDecisionMaker for AlwaysPassPlayer {
13381:        fn priority(&mut self, _: &GameView<'_>, _: &[PlayerAction]) -> PlayerAction {
13384:        fn choose_targets(&mut self, _: &GameView<'_>, _: Outcome, _: &TargetRequirement) -> Vec<ObjectId> { vec![] }
13385:        fn choose_use(&mut self, _: &GameView<'_>, _: Outcome, _: &str) -> bool { false }
13386:        fn choose_mode(&mut self, _: &GameView<'_>, _: &[NamedChoice]) -> usize { 0 }
13387:        fn select_attackers(&mut self, _: &GameView<'_>, _: &[ObjectId], _: &[ObjectId]) -> Vec<(ObjectId, ObjectId)> { vec![] }
13388:        fn select_blockers(&mut self, _: &GameView<'_>, _: &[AttackerInfo]) -> Vec<(ObjectId, ObjectId)> { vec![] }
13389:        fn assign_damage(&mut self, _: &GameView<'_>, _: &DamageAssignment) -> Vec<(ObjectId, u32)> { vec![] }
13390:        fn choose_mulligan(&mut self, _: &GameView<'_>, _: &[ObjectId]) -> bool { false }
13391:        fn choose_cards_to_put_back(&mut self, _: &GameView<'_>, _: &[ObjectId], _: usize) -> Vec<ObjectId> { vec![] }
13392:        fn choose_discard(&mut self, _: &GameView<'_>, _: &[ObjectId], _: usize) -> Vec<ObjectId> { vec![] }
13393:        fn choose_amount(&mut self, _: &GameView<'_>, _: &str, min: u32, _: u32) -> u32 { min }
13394:        fn choose_mana_payment(&mut self, _: &GameView<'_>, _: &UnpaidMana, _: &[PlayerAction]) -> Option<PlayerAction> { None }
13395:        fn choose_replacement_effect(&mut self, _: &GameView<'_>, _: &[ReplacementEffectChoice]) -> usize { 0 }
13396:        fn choose_pile(&mut self, _: &GameView<'_>, _: Outcome, _: &str, _: &[ObjectId], _: &[ObjectId]) -> bool { true }
13397:        fn choose_option(&mut self, _: &GameView<'_>, _: Outcome, _: &str, _: &[NamedChoice]) -> usize { 0 }
13400:    fn make_basic_land(name: &str, owner: PlayerId) -> CardData {
13406:    fn make_creature(name: &str, owner: PlayerId, power: i32, toughness: i32) -> CardData {
13414:    fn make_deck(owner: PlayerId) -> Vec<CardData> {
13425:    fn setup_game() -> (Game, PlayerId, PlayerId) {
13446:    fn cant_untap_prevents_untap_during_untap_step() {
13465:    fn normal_creature_untaps_during_untap_step() {
13483:    fn cant_untap_static_effect_sets_flag_on_enchanted_creature() {
13516:    fn cant_untap_aura_prevents_untapping() {
13551:    fn removing_cant_untap_aura_allows_untapping() {
13598:    fn cant_untap_self_filter() {
13623:    fn cant_untap_only_affects_matching_permanents() {
13667:    fn static_effect_helper_constructor() {
13678:mod choose_type_reanimate_tests {
13690:    impl PlayerDecisionMaker for OptionPicker {
13691:        fn priority(&mut self, _: &GameView<'_>, _: &[PlayerAction]) -> PlayerAction {
13694:        fn choose_targets(&mut self, _: &GameView<'_>, _: Outcome, _: &TargetRequirement) -> Vec<ObjectId> { vec![] }
13695:        fn choose_use(&mut self, _: &GameView<'_>, _: Outcome, _: &str) -> bool { false }
13696:        fn choose_mode(&mut self, _: &GameView<'_>, _: &[NamedChoice]) -> usize { 0 }
13697:        fn select_attackers(&mut self, _: &GameView<'_>, _: &[ObjectId], _: &[ObjectId]) -> Vec<(ObjectId, ObjectId)> { vec![] }
13698:        fn select_blockers(&mut self, _: &GameView<'_>, _: &[AttackerInfo]) -> Vec<(ObjectId, ObjectId)> { vec![] }
13699:        fn assign_damage(&mut self, _: &GameView<'_>, _: &DamageAssignment) -> Vec<(ObjectId, u32)> { vec![] }
13700:        fn choose_mulligan(&mut self, _: &GameView<'_>, _: &[ObjectId]) -> bool { false }
13701:        fn choose_cards_to_put_back(&mut self, _: &GameView<'_>, _: &[ObjectId], _: usize) -> Vec<ObjectId> { vec![] }
13702:        fn choose_discard(&mut self, _: &GameView<'_>, _: &[ObjectId], _: usize) -> Vec<ObjectId> { vec![] }
13703:        fn choose_amount(&mut self, _: &GameView<'_>, _: &str, min: u32, _: u32) -> u32 { min }
13704:        fn choose_mana_payment(&mut self, _: &GameView<'_>, _: &UnpaidMana, _: &[PlayerAction]) -> Option<PlayerAction> { None }
13705:        fn choose_replacement_effect(&mut self, _: &GameView<'_>, _: &[ReplacementEffectChoice]) -> usize { 0 }
13706:        fn choose_pile(&mut self, _: &GameView<'_>, _: Outcome, _: &str, _: &[ObjectId], _: &[ObjectId]) -> bool { true }
13707:        fn choose_option(&mut self, _: &GameView<'_>, _: Outcome, _: &str, _: &[NamedChoice]) -> usize {
13712:    fn make_deck(owner: PlayerId) -> Vec<CardData> {
13720:    fn setup_game_with_picker(pick_index: usize) -> (Game, PlayerId, PlayerId) {
13740:    fn make_creature_with_type(name: &str, owner: PlayerId, subtype: &str, power: i32, toughness: i32) -> CardData {
13749:    fn put_in_graveyard(game: &mut Game, card: CardData, owner: PlayerId) -> ObjectId {
13760:    fn returns_all_matching_creatures_from_graveyard() {
13779:    fn ignores_non_matching_types() {
13798:    fn ignores_non_creature_cards() {
13817:    fn empty_graveyard_does_nothing() {
13829:    fn picks_different_type_index() {
13845:    fn helper_constructor_returns_correct_variant() {
13853:    fn only_returns_controllers_creatures() {
```

## Assistant

### Tool: Bash

**Args:**
```json
{
  "command": "# Count lines in the execute_effects function specifically\nawk '/^\\s*pub fn execute_effects/,/^    fn [a-z]/' /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/game.rs | wc -l",
  "description": "Count lines in execute_effects function"
}
```

## Assistant

**Result** (success):
```
1638
```

## Assistant

### Tool: Bash

**Args:**
```json
{
  "command": "# Count lines in tests vs non-test code in game.rs\ntest_start=$(grep -n '^mod tests' /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/game.rs | head -1 | cut -d: -f1)\ntotal=$(wc -l < /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/game.rs)\necho \"Total lines: $total\"\necho \"Test code starts at line: $test_start\"\necho \"Non-test code: $test_start lines\"\necho \"Test code: $((total - test_start)) lines\"",
  "description": "Break down test vs non-test lines in game.rs"
}
```

## Assistant

**Result** (success):
```
Total lines: 13870
Test code starts at line: 4857
Non-test code: 4857 lines
Test code: 9013 lines
```

## Assistant

### Tool: Bash

**Args:**
```json
{
  "command": "# Count test modules and their sizes\ngrep -n '^mod .*tests\\|^mod .*test' /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/game.rs",
  "description": "Find all test modules in game.rs"
}
```

## Assistant

**Result** (success):
```
4857:mod tests {
6174:mod modal_test {
6378:mod cost_tests {
6555:mod vivid_tests {
6703:mod choice_tests {
6843:mod type_choice_tests {
6980:mod combat_tests {
7434:mod trigger_tests {
7754:mod continuous_effect_tests {
8203:mod enters_tapped_tests {
8317:mod hexproof_tests {
8461:mod dies_trigger_tests {
8642:mod equipment_tests {
8861:mod aura_tests {
9047:mod prowess_landwalk_tests {
9190:mod ward_tests {
9436:mod cant_be_countered_tests {
9575:mod step_trigger_tests {
9767:mod x_cost_tests {
9994:mod impulse_draw_tests {
10231:mod delayed_trigger_tests {
10419:mod flashback_tests {
10600:mod behold_tests {
10817:mod block_restriction_tests {
11135:mod simple_effect_tests {
11273:mod boost_per_count_tests {
11443:mod flicker_tests {
11639:mod conditional_static_tests {
11819:mod blight_and_types_tests {
11917:mod token_copy_tests {
12068:mod tap_self_and_return_type_tests {
12246:mod dynamic_value_tests {
12360:mod cost_reduction_tests {
12496:mod lose_all_abilities_tests {
12737:mod set_base_pt_tests {
13089:mod put_from_hand_tests {
13367:mod cant_untap_tests {
13678:mod choose_type_reanimate_tests {
```

## Assistant

### Tool: Bash

**Args:**
```json
{
  "command": "# Check how abilities.rs is structured\ngrep -n '^\\s*pub fn\\|^\\s*fn\\|^\\s*pub enum\\|^\\s*pub struct\\|^\\s*impl\\|^\\s*// ==' /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/abilities.rs | head -40",
  "description": "Check structure of abilities.rs"
}
```

## Assistant

**Result** (success):
```
28:pub enum Cost {
83:pub enum Effect {
400:pub enum TokenModification {
414:pub struct ModalMode {
427:pub enum TargetSpec {
470:pub struct Ability {
497:impl Ability {
499:    pub fn activated(
523:    pub fn triggered(
547:    pub fn static_ability(
569:    pub fn mana_ability(source_id: ObjectId, rules_text: &str, mana: Mana) -> Self {
587:    pub fn spell(source_id: ObjectId, effects: Vec<Effect>, targets: TargetSpec) -> Self {
605:    pub fn is_mana_ability(&self) -> bool {
610:    pub fn uses_stack(&self) -> bool {
616:    pub fn should_trigger(&self, event: &GameEvent) -> bool {
624:    pub fn can_activate_in_zone(&self, zone: Zone) -> bool {
629:    pub fn set_optional(mut self) -> Self {
635:    pub fn in_zones(mut self, zones: Vec<Zone>) -> Self {
641:    pub fn with_rules_text(mut self, text: &str) -> Self {
651:impl Ability {
653:    pub fn enters_battlefield_triggered(
669:    pub fn dies_triggered(
686:    pub fn attacks_triggered(
702:    pub fn combat_damage_to_player_triggered(
718:    pub fn beginning_of_upkeep_triggered(
734:    pub fn beginning_of_end_step_triggered(
750:    pub fn spell_cast_triggered(
766:    pub fn other_creature_etb_triggered(
782:    pub fn any_creature_dies_triggered(
802:impl Effect {
804:    pub fn destroy() -> Self {
809:    pub fn exile() -> Self {
814:    pub fn deal_damage(amount: u32) -> Self {
819:    pub fn draw_cards(count: u32) -> Self {
824:    pub fn gain_life(amount: u32) -> Self {
829:    pub fn lose_life(amount: u32) -> Self {
834:    pub fn lose_life_opponents(amount: u32) -> Self {
839:    pub fn boost_until_eot(power: i32, toughness: i32) -> Self {
844:    pub fn boost_permanent(power: i32, toughness: i32) -> Self {
849:    pub fn boost_all_eot(filter: &str, power: i32, toughness: i32) -> Self {
```

## Assistant

### Tool: Bash

**Args:**
```json
{
  "command": "# Check the apply_continuous_effects function span (it seems like a large one)\nawk 'NR==408' /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/game.rs\n# And check where it ends approximately\nawk 'NR>=408 && /^    fn [a-z]/ && NR>408 {print NR\": \"$0; exit}' /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/game.rs",
  "description": "Find span of apply_continuous_effects"
}
```

## Assistant

**Result** (success):
```
    fn apply_continuous_effects(&mut self) {
682:     fn evaluate_condition(&self, source_id: ObjectId, controller: PlayerId, condition: &str) -> bool {
```

## Assistant

### Tool: Bash

**Args:**
```json
{
  "command": "# Summary of major function sizes in non-test code\nawk '\n/^    (pub )?fn / && NR < 4857 {\n    if (fn_name) print fn_end - fn_start, fn_name\n    fn_name = $0\n    fn_start = NR\n}\n{ fn_end = NR }\nEND { if (fn_name) print fn_end - fn_start, fn_name }\n' /mnt/dest-btrfs/home/jc/src/mage/mtg-rl/mtg-engine/src/game.rs | sort -rn | head -15",
  "description": "Top functions by line count in game.rs non-test code"
}
```

## Assistant

**Result** (success):
```
9037     fn check_game_end(&self) -> Option<GameResult> {
1636     pub fn execute_effects(&mut self, effects: &[Effect], controller: PlayerId, all_targets: &[ObjectId], source: Option<ObjectId>, x_value: Option<u32>) {
326     fn pay_costs(&mut self, player_id: PlayerId, source_id: ObjectId, costs: &[Cost]) -> bool {
273     fn apply_continuous_effects(&mut self) {
242     fn check_triggered_abilities(&mut self) -> bool {
173     fn compute_legal_actions(&self, player_id: PlayerId) -> Vec<crate::decision::PlayerAction> {
138     fn turn_based_actions(&mut self, step: PhaseStep, active_player: PlayerId) {
130     fn cast_spell(&mut self, player_id: PlayerId, card_id: ObjectId) {
129     fn declare_blockers_step(&mut self, _active_player: PlayerId) {
100     fn london_mulligan(&mut self, player_ids: &[PlayerId]) {
92     fn resolve_top_of_stack(&mut self) {
90     fn declare_attackers_step(&mut self, active_player: PlayerId) {
87     pub fn run(&mut self) -> GameResult {
86     fn apply_state_based_actions(&mut self, sba: &StateBasedActions) -> Vec<ObjectId> {
84     fn priority_loop(&mut self) {
```

## Assistant

## Assistant

Here's the picture:

## Analysis

**`game.rs` is the clear candidate** — 13,870 lines, and it's the only file that's unwieldy. Everything else is reasonably sized (the set files are large but inherently repetitive card listings).

Breaking `game.rs` down:

| Section | Lines | Notes |
|---------|-------|-------|
| Core game logic | ~4,857 | `impl Game` with all methods |
| Test modules | ~9,013 | 38 separate `mod *_tests` blocks |

The biggest functions in the core logic:

| Function | ~Lines | Does what |
|----------|--------|-----------|
| `execute_effects()` | 1,636 | Giant match on ~30+ `Effect` variants |
| `pay_costs()` | 326 | Match on `Cost` variants |
| `apply_continuous_effects()` | 273 | Applies `StaticEffect` variants |
| `check_triggered_abilities()` | 242 | Checks all trigger conditions |
| `compute_legal_actions()` | 173 | Enumerates legal plays |

There are also 3 duplicate `AlwaysPassPlayer` impls in different test modules.

## Recommendations

**Splits that would help:**

1. **Move tests out of `game.rs`** (~9K lines) — The 38 test modules could live in `mtg-engine/tests/` as integration tests, or in a `game/` module directory with a separate `tests.rs`. This alone would cut the file from 14K to ~5K lines.

2. **Extract `execute_effects()` into `game/effect_resolution.rs`** (~1,600 lines) — This is a massive match statement. It's a natural unit: "given an Effect enum variant, modify game state." Could be `impl Game` in a separate file via the `mod` pattern.

3. **Extract combat into `game/combat_resolution.rs`** (~350 lines) — `declare_attackers_step`, `declare_blockers_step`, `combat_damage_step`, `resolve_fight_pair` form a cohesive group.

4. **Extract `apply_continuous_effects` + filter/matching helpers** (~400 lines) — `apply_continuous_effects`, `matches_filter`, `card_matches_filter`, `find_matching_permanents` are a natural cluster.

**Splits that are probably NOT worth it:**

- The set card files (`fdn.rs` etc.) — they're big but dead-simple repetitive factories; splitting by letter or rarity would add complexity without improving readability.
- `abilities.rs` (2,113 lines) — it's mostly enum definitions and builder methods, reads fine as-is.
- Any of the other engine files — all under 1K lines.

**Bottom line:** `game.rs` is doing the work of 3-4 files. The highest-impact move is extracting tests, then `execute_effects`. Want me to plan and do one of these splits?

## User

Stop hook feedback:

Read mtg-rs/ROADMAP.md, and identify work that is outstanding to bring our rust engine into parity with Java. Do not implement any new sets, but add engine features that area missing. Our goal is to complete the fully functional implementation of ECL by implementing engine capabilities and updating cards to use them. Work one task at a time until we are done. Read the corresponding java source to understand how to shape the implementation. Update the ROADMAP and leave a note as you progress. Add tests for each engine feature you add. Commit changes after each item. Then get another ROADMAP item until the engine is at parity with the Java engine.

## Assistant

## Assistant

### Tool: Glob

**Args:**
```json
{
  "pattern": "**/ROADMAP.md"
}
```

## Assistant

### Tool: Glob

**Args:**
```json
{
  "pattern": "**/roadmap*"
}
```

## Assistant

**Result** (success):
```
/mnt/dest-btrfs/home/jc/src/mage/mtg-rl/ROADMAP.md
```

## Assistant

**Result** (success):
```
No files found
```

## Assistant

### Tool: Read

**Args:**
```json
{
  "file_path": "/mnt/dest-btrfs/home/jc/src/mage/mtg-rl/ROADMAP.md"
}
```

## Assistant

**Result** (success):
```
     1→# Roadmap
     2→
     3→This document describes implementation gaps between the Rust mtg-rl engine and the Java XMage reference engine, organized by impact on the 1,333 cards across our 4 sets (FDN, TLA, TDM, ECL).
     4→
     5→**Last audit: 2026-02-14** — Compared Rust engine (~14.6K lines, 21 source files) against Java XMage engine (full rules implementation).
     6→
     7→## Summary
     8→
     9→| Metric | Value |
    10→|--------|-------|
    11→| Cards registered | 1,333 (FDN 512, TLA 280, TDM 273, ECL 268) |
    12→| `Effect::Custom` fallbacks | 747 |
    13→| `StaticEffect::Custom` fallbacks | 160 |
    14→| `Cost::Custom` fallbacks | 33 |
    15→| **Total Custom fallbacks** | **940** |
    16→| Keywords defined | 47 |
    17→| Keywords mechanically enforced | 20 (combat active, plus hexproof, shroud, prowess, landwalk, ward) |
    18→| State-based actions | 8 of ~20 rules implemented |
    19→| Triggered abilities | Events emitted, triggers stacked (ETB, attack, life gain, dies, upkeep, end step, combat damage) |
    20→| Replacement effects | Data structures defined but not integrated |
    21→| Continuous effect layers | Layer 6 (keywords) + Layer 7 (P/T) applied; others pending |
    22→
    23→---
    24→
    25→## I. Critical Game Loop Gaps
    26→
    27→These are structural deficiencies in `game.rs` that affect ALL cards, not just specific ones.
    28→
    29→### ~~A. Combat Phase Not Connected~~ (DONE)
    30→
    31→**Completed 2026-02-14.** Combat is now fully wired into the game loop:
    32→- `DeclareAttackers`: prompts active player via `select_attackers()`, taps attackers (respects vigilance), registers in `CombatState` (added to `GameState`)
    33→- `DeclareBlockers`: prompts defending player via `select_blockers()`, validates flying/reach restrictions, registers blocks
    34→- `FirstStrikeDamage` / `CombatDamage`: assigns damage via `combat.rs` functions, applies to permanents and players, handles lifelink life gain
    35→- `EndCombat`: clears combat state
    36→- 13 unit tests covering: unblocked damage, blocked damage, vigilance, lifelink, first strike, trample, defender restriction, summoning sickness, haste, flying/reach, multiple attackers
    37→
    38→### ~~B. Triggered Abilities Not Stacked~~ (DONE)
    39→
    40→**Completed 2026-02-14.** Triggered abilities are now detected and stacked:
    41→- Added `EventLog` to `Game` for tracking game events
    42→- Events emitted at key game actions: ETB, attack declared, life gain, token creation, land play
    43→- `check_triggered_abilities()` scans `AbilityStore` for matching triggers, validates source still on battlefield, handles APNAP ordering
    44→- Supports optional ("may") triggers via `choose_use()`
    45→- Trigger ownership validation: attack triggers only fire for the attacking creature, ETB triggers only for the entering permanent, life gain triggers only for the controller
    46→- `process_sba_and_triggers()` implements MTG rules 117.5 SBA+trigger loop until stable
    47→- 5 unit tests covering ETB triggers, attack triggers, life gain triggers, optional triggers, ownership validation
    48→- **Dies triggers added 2026-02-14:** `check_triggered_abilities()` now handles `EventType::Dies` events. Ability cleanup is deferred until after trigger checking so dies triggers can fire. `apply_state_based_actions()` returns died source IDs for post-trigger cleanup. 4 unit tests (lethal damage, destroy effect, ownership filtering).
    49→
    50→### ~~C. Continuous Effect Layers Not Applied~~ (DONE)
    51→
    52→**Completed 2026-02-14.** Continuous effects (Layer 6 + Layer 7) are now recalculated on every SBA iteration:
    53→- `apply_continuous_effects()` clears and recalculates `continuous_boost_power`, `continuous_boost_toughness`, and `continuous_keywords` on all permanents
    54→- Handles `StaticEffect::Boost` (Layer 7c — P/T modify) and `StaticEffect::GrantKeyword` (Layer 6 — ability adding)
    55→- `find_matching_permanents()` handles filter patterns: "other X you control" (excludes self), "X you control" (controller check), "self" (source only), "enchanted/equipped creature" (attached target), "token" (token-only), "attacking" (combat state check), plus type/subtype matching
    56→- Handles comma-separated keyword strings (e.g. "deathtouch, lifelink")
    57→- Added `is_token` field to `CardData` for token identification
    58→- Called in `process_sba_and_triggers()` before each SBA check
    59→- 11 unit tests: lord boost, anthem, keyword grant, comma keywords, recalculation, stacking lords, mutual lords, self filter, token filter, opponent isolation, boost+keyword combo
    60→
    61→### D. Replacement Effects Not Integrated (PARTIAL)
    62→
    63→`ReplacementEffect` and `ReplacementKind` are defined in `effects.rs` with variants like `Prevent`, `ExileInstead`, `ModifyAmount`, `RedirectTarget`, `EnterTapped`, `EnterWithCounters`, `Custom`. The full event interception pipeline is not yet connected, but specific replacement patterns have been implemented:
    64→
    65→**Completed 2026-02-14:**
    66→- `EntersTapped { filter: "self" }` — lands/permanents with "enters tapped" now correctly enter tapped via `check_enters_tapped()`. Called at all ETB points: land play, spell resolve, reanimate. 3 unit tests. Affects 7 guildgate/tapland cards across FDN and TDM.
    67→
    68→**Still missing:** General replacement effect pipeline (damage prevention, death replacement, Doubling Season, counter modification, enters-with-counters). Affects ~20+ additional cards.
    69→
    70→---
    71→
    72→## II. Keyword Enforcement
    73→
    74→47 keywords are defined as bitflags in `KeywordAbilities`. Most are decorative.
    75→
    76→### Mechanically Enforced (10 keywords — in combat.rs, but combat doesn't run)
    77→
    78→| Keyword | Where | How |
    79→|---------|-------|-----|
    80→| FLYING | `combat.rs:205` | Flyers can only be blocked by flying/reach |
    81→| REACH | `combat.rs:205` | Can block flyers |
    82→| DEFENDER | `permanent.rs:249` | Cannot attack |
    83→| HASTE | `permanent.rs:250` | Bypasses summoning sickness |
    84→| FIRST_STRIKE | `combat.rs:241-248` | Damage in first-strike step |
    85→| DOUBLE_STRIKE | `combat.rs:241-248` | Damage in both steps |
    86→| TRAMPLE | `combat.rs:296-298` | Excess damage to defending player |
    87→| DEATHTOUCH | `combat.rs:280-286` | 1 damage = lethal |
    88→| MENACE | `combat.rs:216-224` | Must be blocked by 2+ creatures |
    89→| INDESTRUCTIBLE | `state.rs:296` | Survives lethal damage (SBA) |
    90→
    91→All 10 are now active in practice via combat integration (2026-02-14). Additionally, vigilance and lifelink are now enforced. Menace is now enforced during declare blockers validation (2026-02-14).
    92→
    93→### Not Enforced (35 keywords)
    94→
    95→| Keyword | Java Behavior | Rust Status |
    96→|---------|--------------|-------------|
    97→| FLASH | Cast at instant speed | Partially (blocks sorcery-speed only) |
    98→| HEXPROOF | Can't be targeted by opponents | **Enforced** in `legal_targets_for_spec()` |
    99→| SHROUD | Can't be targeted at all | **Enforced** in `legal_targets_for_spec()` |
   100→| PROTECTION | Prevents damage/targeting/blocking/enchanting | Not checked |
   101→| WARD | Counter unless cost paid | **Enforced** in `check_ward_on_targets()` |
   102→| FEAR | Only blocked by black/artifact | **Enforced** in `combat.rs:can_block()` |
   103→| INTIMIDATE | Only blocked by same color/artifact | **Enforced** in `combat.rs:can_block()` |
   104→| SHADOW | Only blocked by/blocks shadow | Not checked |
   105→| PROWESS | +1/+1 when noncreature spell cast | **Enforced** in `check_triggered_abilities()` |
   106→| UNDYING | Return with +1/+1 counter on death | No death replacement |
   107→| PERSIST | Return with -1/-1 counter on death | No death replacement |
   108→| WITHER | Damage as -1/-1 counters | Not checked |
   109→| INFECT | Damage as -1/-1 counters + poison | Not checked |
   110→| TOXIC | Combat damage → poison counters | Not checked |
   111→| UNBLOCKABLE | Can't be blocked | **Enforced** in `combat.rs:can_block()` |
   112→| CHANGELING | All creature types | **Enforced** in `permanent.rs:has_subtype()` + `matches_filter()` |
   113→| CASCADE | Exile-and-cast on cast | No trigger |
   114→| CONVOKE | Tap creatures to pay | Not checked in cost payment |
   115→| DELVE | Exile graveyard to pay | Not checked in cost payment |
   116→| EVOLVE | +1/+1 counter on bigger ETB | No trigger |
   117→| EXALTED | +1/+1 when attacking alone | No trigger |
   118→| EXPLOIT | Sacrifice creature on ETB | No trigger |
   119→| FLANKING | Blockers get -1/-1 | Not checked |
   120→| FORESTWALK | Unblockable vs forest controller | **Enforced** in blocker selection |
   121→| ISLANDWALK | Unblockable vs island controller | **Enforced** in blocker selection |
   122→| MOUNTAINWALK | Unblockable vs mountain controller | **Enforced** in blocker selection |
   123→| PLAINSWALK | Unblockable vs plains controller | **Enforced** in blocker selection |
   124→| SWAMPWALK | Unblockable vs swamp controller | **Enforced** in blocker selection |
   125→| TOTEM_ARMOR | Prevents enchanted creature death | No replacement |
   126→| AFFLICT | Life loss when blocked | No trigger |
   127→| BATTLE_CRY | +1/+0 to other attackers | No trigger |
   128→| SKULK | Can't be blocked by greater power | **Enforced** in `combat.rs:can_block()` |
   129→| FABRICATE | Counters or tokens on ETB | No choice/trigger |
   130→| STORM | Copy for each prior spell | No trigger |
   131→| PARTNER | Commander pairing | Not relevant |
   132→
   133→---
   134→
   135→## III. State-Based Actions
   136→
   137→Checked in `state.rs:check_state_based_actions()`:
   138→
   139→| Rule | Description | Status |
   140→|------|-------------|--------|
   141→| 704.5a | Player at 0 or less life loses | **Implemented** |
   142→| 704.5b | Player draws from empty library loses | **Implemented** (in draw_cards()) |
   143→| 704.5c | 10+ poison counters = loss | **Implemented** |
   144→| 704.5d | Token not on battlefield ceases to exist | **Implemented** |
   145→| 704.5e | 0-cost copy on stack/BF ceases to exist | **Not implemented** |
   146→| 704.5f | Creature with 0 toughness → graveyard | **Implemented** |
   147→| 704.5g | Lethal damage → destroy (if not indestructible) | **Implemented** |
   148→| 704.5i | Planeswalker with 0 loyalty → graveyard | **Implemented** |
   149→| 704.5j | Legend rule (same name) | **Implemented** |
   150→| 704.5n | Aura not attached → graveyard | **Implemented** |
   151→| 704.5p | Equipment/Fortification illegal attach → unattach | **Implemented** |
   152→| 704.5r | +1/+1 and -1/-1 counter annihilation | **Implemented** |
   153→| 704.5s | Saga with lore counters ≥ chapters → sacrifice | **Not implemented** |
   154→
   155→**Missing SBAs:** Saga sacrifice. These affect ~40+ cards.
   156→
   157→---
   158→
   159→## IV. Missing Engine Systems
   160→
   161→These require new engine architecture beyond adding match arms to existing functions.
   162→
   163→### Tier 1: Foundational (affect 100+ cards each)
   164→
   165→#### 1. Combat Integration
   166→- Wire `combat.rs` functions into `turn_based_actions()` for DeclareAttackers, DeclareBlockers, CombatDamage
   167→- Add `choose_attackers()` / `choose_blockers()` to `PlayerDecisionMaker`
   168→- Connect lifelink (damage → life gain), vigilance (no tap), and other combat keywords
   169→- **Cards affected:** Every creature in all 4 sets (~800+ cards)
   170→- **Java reference:** `GameImpl.combat`, `Combat.java`, `CombatGroup.java`
   171→
   172→#### 2. Triggered Ability Stacking
   173→- After each game action, scan for triggered abilities whose conditions match recent events
   174→- Push triggers onto stack in APNAP order
   175→- Resolve via existing priority loop
   176→- **Cards affected:** Every card with ETB, attack, death, damage, upkeep, or endstep triggers (~400+ cards)
   177→- **Java reference:** `GameImpl.checkStateAndTriggered()`, 84+ `Watcher` classes
   178→
   179→#### 3. Continuous Effect Layer Application
   180→- Recalculate permanent characteristics after each game action
   181→- Apply StaticEffect variants (Boost, GrantKeyword, CantAttack, CantBlock, etc.) in layer order
   182→- Duration tracking (while-on-battlefield, until-end-of-turn, etc.)
   183→- **Cards affected:** All lord/anthem effects, keyword-granting permanents (~50+ cards)
   184→- **Java reference:** `ContinuousEffects.java`, 7-layer system
   185→
   186→### Tier 2: Key Mechanics (affect 10-30 cards each)
   187→
   188→#### ~~4. Equipment System~~ (DONE)
   189→
   190→**Completed 2026-02-14.** Equipment is now fully functional:
   191→- `Effect::Equip` variant handles attaching equipment to target creature
   192→- Detach from previous creature when re-equipping
   193→- Continuous effects ("equipped creature" filter) already handled by `find_matching_permanents()`
   194→- SBA 704.5p: Equipment auto-detaches when attached creature leaves battlefield
   195→- 12 card factories updated from `Effect::Custom` to `Effect::equip()`
   196→- 5 unit tests: attach, stat boost, detach on death, re-equip, keyword grant
   197→
   198→#### ~~5. Aura/Enchant System~~ (DONE)
   199→
   200→**Completed 2026-02-14.** Aura enchantments are now functional:
   201→- Auras auto-attach to their target on spell resolution (ETB)
   202→- Continuous effects ("enchanted creature" filter) handle P/T boosts and keyword grants
   203→- `CantAttack`/`CantBlock` static effects now enforced via continuous effects layer
   204→  (added `cant_attack` and `cant_block_from_effect` flags to Permanent)
   205→- SBA 704.5n: Auras go to graveyard when enchanted permanent leaves
   206→- SBA 704.5p: Equipment just detaches (stays on battlefield)
   207→- 3 unit tests: boost, fall-off, Pacifism can't-attack
   208→
   209→#### 6. Replacement Effect Pipeline
   210→- Before each event, check registered replacement effects
   211→- `applies()` filter + `replaceEvent()` modification
   212→- Support common patterns: exile-instead-of-die, enters-tapped, enters-with-counters, damage prevention
   213→- Prevent infinite loops (each replacement applies once per event)
   214→- **Blocked features:** Damage prevention, death replacement, Doubling Season, Undying, Persist (~30+ cards)
   215→- **Java reference:** `ReplacementEffectImpl.java`, `ContinuousEffects.getReplacementEffects()`
   216→
   217→#### ~~7. X-Cost Spells~~ (DONE)
   218→
   219→**Completed 2026-02-14.** X-cost spells are now functional:
   220→- `ManaCost::has_x_cost()`, `x_count()`, `to_mana_with_x(x)` for X detection and mana calculation
   221→- `X_VALUE` sentinel constant (u32::MAX) used in effect amounts to indicate "use X"
   222→- `StackItem.x_value: Option<u32>` tracks chosen X on the stack
   223→- `cast_spell()` detects X costs, calls `choose_amount()` for X value, pays `to_mana_with_x(x)`
   224→- `execute_effects()` receives x_value and uses `resolve_x()` closure to substitute X_VALUE with actual X
   225→- All numeric effect handlers updated: DealDamage, DrawCards, GainLife, LoseLife, LoseLifeOpponents, DealDamageOpponents, DealDamageAll, Mill, AddCounters, AddCountersSelf, DiscardOpponents, CreateToken
   226→- 4 unit tests: X damage, X draw, X=0, mana payment verification
   227→
   228→#### ~~8. Impulse Draw (Exile-and-Play)~~ (DONE)
   229→
   230→**Completed 2026-02-14.** Impulse draw is now functional:
   231→- `ImpulsePlayable` struct tracks exiled cards with player, duration, and without-mana flag
   232→- `ImpulseDuration::EndOfTurn` and `UntilEndOfNextTurn` with proper per-player turn tracking
   233→- `Effect::ExileTopAndPlay { count, duration, without_mana }` exiles from library and registers playability
   234→- `compute_legal_actions()` includes impulse-playable cards as castable/playable
   235→- `cast_spell()` and `play_land()` handle cards from exile (removing from exile zone and impulse list)
   236→- Cleanup step expires `EndOfTurn` entries immediately and `UntilEndOfNextTurn` at controller's next turn
   237→- Convenience builders: `exile_top_and_play(n)`, `exile_top_and_play_next_turn(n)`, `exile_top_and_play_free(n)`
   238→- 6 unit tests: creation, legal actions, resolve, expiration, next-turn persistence, free cast
   239→
   240→#### ~~9. Graveyard Casting (Flashback/Escape)~~ (DONE)
   241→
   242→**Completed 2026-02-14.** Flashback casting is now implemented:
   243→- `flashback_cost: Option<ManaCost>` field on `CardData` for alternative graveyard cast cost
   244→- `compute_legal_actions()` checks graveyard for cards with flashback_cost, validates mana
   245→- `cast_spell()` detects graveyard-origin spells, uses flashback cost, sets `exile_on_resolve` flag on StackItem
   246→- `resolve_top_of_stack()` exiles flashback spells instead of sending to graveyard
   247→- SpellCast event correctly reports Zone::Graveyard as source zone
   248→- 4 unit tests: legal actions, mana validation, exile-after-resolution, normal-cast-graveyard
   249→
   250→#### 10. Planeswalker System
   251→- Loyalty counters as activation resource
   252→- Loyalty abilities: `PayLoyaltyCost(amount)` — add or remove loyalty counters
   253→- One loyalty ability per turn, sorcery speed
   254→- Can be attacked (defender selection during declare attackers)
   255→- Damage redirected from player to planeswalker (or direct attack)
   256→- SBA: 0 loyalty → graveyard (already implemented)
   257→- **Blocked cards:** Ajani, Chandra, Kaito, Liliana, Vivien, all planeswalkers (~10+ cards)
   258→- **Java reference:** `LoyaltyAbility.java`, `PayLoyaltyCost.java`
   259→
   260→### Tier 3: Advanced Systems (affect 5-10 cards each)
   261→
   262→#### 11. Spell/Permanent Copy (PARTIAL)
   263→
   264→**Token copy completed 2026-02-15.** `Effect::CreateTokenCopy { count, modifications }` creates token copies of target permanents:
   265→- Clones CardData (name, types, P/T, abilities, keywords), re-keys ability IDs
   266→- `TokenModification` enum: `AddKeyword`, `AddChangeling`, `SacrificeAtEndStep`, `EnterTappedAttacking`
   267→- Convenience builders: `create_token_copy()`, `create_token_copy_with_haste()`, `create_token_copy_with_changeling()`, `create_token_copy_haste_sacrifice()`
   268→- 4 unit tests; 5 ECL cards updated
   269→- **Still missing:** Copy spell on stack (Fork, Reverberate), enter-as-copy (clone creatures)
   270→- **Remaining blocked cards:** Mirrorform (mass copy), enter-as-copy-with-changeling, graveyard-ETB copy trigger (~3 cards)
   271→
   272→#### ~~12. Delayed Triggers~~ (DONE)
   273→
   274→**Completed 2026-02-14.** Delayed triggered abilities are now functional:
   275→- `DelayedTrigger` struct in `GameState` tracks: event type, watched object, effects, controller, duration, trigger-only-once
   276→- `DelayedDuration::EndOfTurn` (removed at cleanup) and `UntilTriggered` (persists until fired)
   277→- `Effect::CreateDelayedTrigger` registers a delayed trigger during effect resolution
   278→- `check_triggered_abilities()` checks delayed triggers against events, fires matching ones
   279→- Watched object filtering: only fires when the specific watched permanent/creature matches the event
   280→- `EventType::from_name()` parses string event types for flexible card authoring
   281→- Convenience builders: `delayed_on_death(effects)`, `at_next_end_step(effects)`
   282→- 4 unit tests: death trigger fires, wrong creature doesn't fire, expiration, end step trigger
   283→
   284→#### 13. Saga Enchantments
   285→- Lore counters added on ETB and after draw step
   286→- Chapter abilities trigger when lore counter matches chapter number
   287→- Sacrifice after final chapter (SBA)
   288→- **Blocked cards:** 6+ Saga cards in TDM/TLA
   289→- **Java reference:** `SagaAbility.java`
   290→
   291→#### 14. Additional Combat Phases
   292→- "Untap all creatures, there is an additional combat phase"
   293→- Insert extra combat steps into the turn sequence
   294→- **Blocked cards:** Aurelia the Warleader, All-Out Assault (~3 cards)
   295→
   296→#### 15. Conditional Cost Modifications
   297→- `CostReduction` stored but not applied during cost calculation
   298→- "Second spell costs {1} less", Affinity, Convoke, Delve
   299→- Need cost-modification pass before mana payment
   300→- **Blocked cards:** Highspire Bell-Ringer, Allies at Last, Ghalta Primal Hunger (~5+ cards)
   301→- **Java reference:** `CostModificationEffect.java`, `SpellAbility.adjustCosts()`
   302→
   303→### Tier 4: Set-Specific Mechanics
   304→
   305→#### 16. Earthbend (TLA)
   306→- "Look at top N, put a land to hand, rest on bottom"
   307→- Similar to Explore/Impulse — top-of-library selection
   308→- **Blocked cards:** Badgermole, Badgermole Cub, Ostrich-Horse, Dai Li Agents, many TLA cards (~20+ cards)
   309→
   310→#### ~~17. Behold (ECL)~~ (DONE)
   311→
   312→**Completed 2026-02-14.** Behold mechanic implemented with 3 cost variants:
   313→- `Cost::Behold(type)` — Mandatory: choose matching creature on battlefield or reveal from hand
   314→- `Cost::BeholdAndExile(type)` — Mandatory behold + exile the chosen card/permanent
   315→- `Cost::BeholdOrPay { creature_type, mana }` — Behold or pay alternative mana cost
   316→- `can_pay_additional_costs()` validates behold feasibility in legal action computation
   317→- `additional_costs: Vec<Cost>` field on CardData for spell additional costs
   318→- Changeling creatures match any behold type requirement
   319→- 9 unit tests; 10 ECL cards updated to use typed behold costs
   320→
   321→#### 18. ~~Vivid (ECL)~~ (DONE)
   322→Color-count calculation implemented. 6 Vivid effect variants added. 6 cards fixed.
   323→
   324→#### 19. Renew (TDM)
   325→- Counter-based death replacement (exile with counters, return later)
   326→- Requires replacement effect pipeline (Tier 2, item 6)
   327→- **Blocked cards:** ~5+ TDM cards
   328→
   329→#### 20. Endure (TDM)
   330→- Put +1/+1 counters; if would die, exile with counters instead
   331→- Requires replacement effect pipeline
   332→- **Blocked cards:** ~3+ TDM cards
   333→
   334→---
   335→
   336→## V. Effect System Gaps
   337→
   338→### Implemented Effect Variants (~55 of 62)
   339→
   340→The following Effect variants have working `execute_effects()` match arms:
   341→
   342→**Damage:** DealDamage, DealDamageAll, DealDamageOpponents, DealDamageVivid
   343→**Life:** GainLife, GainLifeVivid, LoseLife, LoseLifeOpponents, LoseLifeOpponentsVivid, SetLife
   344→**Removal:** Destroy, DestroyAll, Exile, Sacrifice, PutOnLibrary
   345→**Card Movement:** Bounce, ReturnFromGraveyard, Reanimate, DrawCards, DrawCardsVivid, DiscardCards, DiscardOpponents, Mill, SearchLibrary, LookTopAndPick
   346→**Counters:** AddCounters, AddCountersSelf, AddCountersAll, RemoveCounters
   347→**Tokens:** CreateToken, CreateTokenTappedAttacking, CreateTokenVivid
   348→**Combat:** CantBlock, Fight, Bite, MustBlock
   349→**Stats:** BoostUntilEndOfTurn, BoostPermanent, BoostAllUntilEndOfTurn, BoostUntilEotVivid, BoostAllUntilEotVivid, SetPowerToughness
   350→**Keywords:** GainKeywordUntilEndOfTurn, GainKeyword, LoseKeyword, GrantKeywordAllUntilEndOfTurn, Indestructible, Hexproof
   351→**Control:** GainControl, GainControlUntilEndOfTurn
   352→**Utility:** TapTarget, UntapTarget, CounterSpell, Scry, AddMana, Modal, DoIfCostPaid, ChooseCreatureType, ChooseTypeAndDrawPerPermanent
   353→
   354→### Unimplemented Effect Variants
   355→
   356→| Variant | Description | Cards Blocked |
   357→|---------|-------------|---------------|
   358→| `GainProtection` | Target gains protection from quality | ~5 |
   359→| `PreventCombatDamage` | Fog / damage prevention | ~5 |
   360→| `Custom(String)` | Catch-all for untyped effects | 747 instances |
   361→
   362→### Custom Effect Fallback Analysis (747 Effect::Custom)
   363→
   364→These are effects where no typed variant exists. Grouped by what engine feature would replace them:
   365→
   366→| Category | Count | Sets | Engine Feature Needed |
   367→|----------|-------|------|----------------------|
   368→| Generic ETB stubs ("ETB effect.") | 79 | All | Triggered ability stacking |
   369→| Generic activated ability stubs ("Activated effect.") | 67 | All | Proper cost+effect binding on abilities |
   370→| Attack/combat triggers | 45 | All | Combat integration + triggered abilities |
   371→| Cast/spell triggers | 47 | All | Triggered abilities + cost modification |
   372→| Aura/equipment attachment | 28 | FDN,TDM,ECL | Equipment/Aura system |
   373→| Exile-and-play effects | 25 | All | Impulse draw |
   374→| Generic spell stubs ("Spell effect.") | 21 | All | Per-card typing with existing variants |
   375→| Dies/sacrifice triggers | 18 | FDN,TLA | Triggered abilities |
   376→| Conditional complex effects | 30+ | All | Per-card analysis; many are unique |
   377→| Tapped/untap mechanics | 10 | FDN,TLA | Minor — mostly per-card fixes |
   378→| Saga mechanics | 6 | TDM,TLA | Saga system |
   379→| Earthbend keyword | 5 | TLA | Earthbend mechanic |
   380→| Copy/clone effects | 8+ | TDM,ECL | Spell/permanent copy |
   381→| Cost modifiers | 4 | FDN,ECL | Cost modification system |
   382→| X-cost effects | 5+ | All | X-cost system |
   383→
   384→### StaticEffect::Custom Analysis (160 instances)
   385→
   386→| Category | Count | Engine Feature Needed |
   387→|----------|-------|-----------------------|
   388→| Generic placeholder ("Static effect.") | 90 | Per-card analysis; diverse |
   389→| Conditional continuous ("Conditional continuous effect.") | 4 | Layer system + conditions |
   390→| Dynamic P/T ("P/T = X", "+X/+X where X = ...") | 11 | Characteristic-defining abilities (Layer 7a) |
   391→| Evasion/block restrictions | 5 | Restriction effects in combat |
   392→| Protection effects | 4 | Protection keyword enforcement |
   393→| Counter/spell protection ("Can't be countered") | 8 | Uncounterable flag or replacement effect |
   394→| Keyword grants (conditional) | 4 | Layer 6 + conditions |
   395→| Damage modification | 4 | Replacement effects |
   396→| Transform/copy | 3 | Copy layer + transform |
   397→| Mana/land effects | 3 | Mana ability modification |
   398→| Cost reduction | 2 | Cost modification system |
   399→| Keyword abilities (Kicker, Convoke, Delve) | 4 | Alternative/additional costs |
   400→| Token doubling | 1 | Replacement effect |
   401→| Trigger multiplier | 1 | Triggered ability system |
   402→| Other unique effects | 16 | Per-card analysis |
   403→
   404→### Cost::Custom Analysis (33 instances)
   405→
   406→| Category | Count | Engine Feature Needed |
   407→|----------|-------|-----------------------|
   408→| Complex mana+tap activated abilities | 13 | Better activated ability cost parsing |
   409→| Sacrifice-based activated abilities | 9 | Sacrifice-other as part of compound costs |
   410→| Tap-creature costs (convoke-like) | 5 | Tap-other-creature cost variant |
   411→| Exile costs (self, enchantment, graveyard) | 3 | Exile-self / exile-zone cost variants |
   412→| Complex multi-part costs | 2 | Compound cost support |
   413→| Discard hand | 1 | Discard-hand cost variant |
   414→
   415→---
   416→
   417→## VI. Per-Set Custom Fallback Counts
   418→
   419→| Set | Effect::Custom | StaticEffect::Custom | Cost::Custom | Total |
   420→|-----|---------------|---------------------|-------------|-------|
   421→| FDN (Foundations) | 322 | 58 | 21 | 401 |
   422→| TLA (Avatar: TLA) | 197 | 54 | 2 | 253 |
   423→| TDM (Tarkir: Dragonstorm) | 111 | 16 | 3 | 130 |
   424→| ECL (Lorwyn Eclipsed) | 77 | 20 | 0 | 97 |
   425→| **Total** | **747** | **160** | **33** | **940** |
   426→
   427→Detailed per-card breakdowns in `docs/{fdn,tla,tdm,ecl}-remediation.md`.
   428→
   429→---
   430→
   431→## VII. Comparison with Java XMage
   432→
   433→Features the Java engine has that the Rust engine lacks entirely:
   434→
   435→| Java Feature | Java Location | Rust Status |
   436→|-------------|--------------|-------------|
   437→| **84+ Watcher classes** | `mage.watchers.common/` | Basic `WatcherManager` only |
   438→| **Replacement effect pipeline** | `ContinuousEffects.getReplacementEffects()` | Structs defined, not integrated |
   439→| **7-layer continuous effect application** | `ContinuousEffects.apply()` | Layers defined, never applied |
   440→| **RequirementEffect** (must attack/block) | `mage.abilities.effects.RequirementEffect` | **Partial** (`MustBeBlocked` static effect, flag on Permanent) |
   441→| **RestrictionEffect** (can't attack/block) | `mage.abilities.effects.RestrictionEffect` | **Partial** (CantAttack/CantBlock, CantBeBlockedByMoreThan, CantBeBlockedByPowerLessOrEqual) |
   442→| **AsThoughEffect** (play from other zones) | `mage.abilities.effects.AsThoughEffect` | **Partial** (`ImpulsePlayable` for exile-and-play) |
   443→| **CostModificationEffect** | `mage.abilities.effects.CostModificationEffect` | CostReduction stored but not applied |
   444→| **PreventionEffect** (damage prevention) | `mage.abilities.effects.PreventionEffect` | No equivalent |
   445→| **Equipment attachment** | `EquipAbility`, `AttachEffect` | No equivalent |
   446→| **Aura attachment** | `AuraReplacementEffect` | No equivalent |
   447→| **Planeswalker loyalty abilities** | `LoyaltyAbility`, `PayLoyaltyCost` | No equivalent |
   448→| **X-cost system** | `VariableManaCost`, `ManaCostsImpl.getX()` | **Implemented** (`X_VALUE`, `StackItem.x_value`, `resolve_x()`) |
   449→| **Spell copying** | `CopyEffect`, `CopySpellForEachItCouldTargetEffect` | No equivalent |
   450→| **Delayed triggered abilities** | `DelayedTriggeredAbility` | **Implemented** (`DelayedTrigger`, `CreateDelayedTrigger`) |
   451→| **Alternative costs** (Flashback, Evoke, etc.) | `AlternativeCostSourceAbility` | Evoke stored as StaticEffect, not enforced |
   452→| **Additional costs** (Kicker, Buyback, etc.) | `OptionalAdditionalCostImpl` | No equivalent |
   453→| **Combat damage assignment order** | `CombatGroup.pickBlockerOrder()` | Simplified (first blocker takes all) |
   454→| **Spell target legality check on resolution** | `Spell.checkTargets()` | Targets checked at cast, not re-validated |
   455→| **Mana restriction** ("spend only on creatures") | `ManaPool.conditionalMana` | Not tracked |
   456→| **Hybrid mana** ({B/R}, {2/G}) | `HybridManaCost` | Not modeled |
   457→| **Zone change tracking** (LKI) | `getLKIBattlefield()` | No last-known-information |
   458→
   459→---
   460→
   461→## VIII. Phased Implementation Plan
   462→
   463→Priority ordered by cards-unblocked per effort.
   464→
   465→### Phase 1: Make the Engine Functional (combat + triggers)
   466→
   467→1. ~~**Combat integration**~~ — **DONE (2026-02-14).** Wired `combat.rs` into `turn_based_actions()` for DeclareAttackers, DeclareBlockers, FirstStrikeDamage, CombatDamage, EndCombat. Connected lifelink, vigilance, flying/reach. Added `CombatState` to `GameState`. 13 unit tests.
   468→
   469→2. ~~**Triggered ability stacking**~~ — **DONE (2026-02-14).** Events emitted at game actions, triggered abilities detected and stacked in APNAP order. ETB, attack, and life gain triggers functional. 5 unit tests.
   470→
   471→3. ~~**Continuous effect layer application**~~ — **DONE (2026-02-14).** `apply_continuous_effects()` recalculates P/T boosts and keyword grants from static abilities. `find_matching_permanents()` handles "other", "you control", "self", "enchanted/equipped creature", "token", "attacking" filter patterns. Added `is_token` to `CardData`. 11 unit tests.
   472→
   473→### Phase 2: Core Missing Mechanics
   474→
   475→4. **Replacement effect pipeline** — Event interception. Enters-tapped enforcement done (2026-02-14). Still needed: damage prevention, death replacement, Undying/Persist, enters-with-counters. **~20+ remaining cards.**
   476→
   477→5. ~~**Equipment system**~~ — **DONE (2026-02-14).** `Effect::Equip`, detachment SBA, card updates.
   478→
   479→6. ~~**Aura/enchant system**~~ — **DONE (2026-02-14).** Auto-attach, fall-off SBA, CantAttack/CantBlock.
   480→
   481→7. ~~**X-cost spells**~~ — **DONE (2026-02-14).** `X_VALUE` sentinel, `StackItem.x_value`, `resolve_x()` closure in execute_effects. 4 unit tests.
   482→
   483→8. ~~**Impulse draw**~~ — **DONE (2026-02-14).** `ImpulsePlayable` tracking, `ExileTopAndPlay` effect, cast/play from exile, duration expiration. 6 unit tests.
   484→
   485→### Phase 3: Advanced Systems
   486→
   487→9. **Planeswalker system** — Loyalty abilities, can-be-attacked, damage redirection. **~10+ cards.**
   488→
   489→10. **Spell/permanent copy** — **PARTIAL (2026-02-15).** Token copy done (CreateTokenCopy + TokenModification). Still needs spell copy on stack and enter-as-copy. **~3 remaining cards.**
   490→
   491→11. ~~**Delayed triggers**~~ — **DONE (2026-02-14).** `DelayedTrigger` struct, `CreateDelayedTrigger` effect, event-driven firing, duration expiration. 4 unit tests.
   492→
   493→12. ~~**Graveyard casting**~~ — **DONE (2026-02-14).** Flashback casting from graveyard, exile after resolution.
   494→
   495→13. **Saga enchantments** — Lore counters, chapter abilities. **~6+ cards.**
   496→
   497→14. **Cost modification** — Apply CostReduction during cost calculation. **~5+ cards.**
   498→
   499→15. **Additional combat phases** — Extra attack steps. **~3 cards.**
   500→
   501→### Phase 4: Set-Specific Mechanics
   502→
   503→16. **Earthbend** (TLA) — Top-N selection, land to hand. **~20+ cards.**
   504→
   505→17. ~~**Behold**~~ (ECL) — **DONE (2026-02-14).** 3 behold cost variants, additional_costs field, 10 cards updated.
   506→
   507→18. **Renew/Endure** (TDM) — Counter-based death replacement (needs replacement pipeline). **~8+ cards.**
   508→
   509→19. ~~**Vivid** (ECL)~~ — **DONE.** Color-count calculation + 6 effect variants.
   510→
   511→20. ~~**Modal spells**~~ — **DONE.** `Effect::Modal` + `choose_mode()`.
   512→
   513→21. ~~**Fight/Bite**~~ — **DONE.** `Effect::Fight` + `Effect::Bite` with dual targeting.
   514→
   515→22. ~~**Token stat parsing**~~ — **DONE.** `CreateToken` parses P/T and keywords from name string.
   516→
   517→### Phase 5: Eliminate Custom Fallbacks
   518→
   519→After the above systems are in place, systematically replace remaining `Custom(String)` fallbacks with typed variants:
   520→
   521→- **Easy wins (~100 cards):** Generic stubs ("ETB effect", "Activated effect", "Spell effect") where the effect is a simple combination of existing typed variants
   522→- **Medium (~200 cards):** Cards needing one of the systems above (triggers, layers, combat) plus per-card typing
   523→- **Hard (~50+ cards):** Cards with truly unique mechanics needing new Effect variants
   524→
   525→---
   526→
   527→## IX. Previously Completed Work
   528→
   529→**Batch 1-10 remediation** (2026-02-13 to 2026-02-14): Fixed ~60 cards by replacing Custom effects with typed variants. Added engine features: source-fallback for counters, Ward variant, EntersTappedUnless variant, mass-buff effects (BoostAllUntilEndOfTurn, GrantKeywordAllUntilEndOfTurn), AddCountersAll, AddCountersSelf, 7 cost implementations (RemoveCounters, Blight, ExileFromGraveyard, ExileFromHand, SacrificeOther, UntapSelf, Custom), Vivid mechanic (6 effect variants + color counting), Modal spells (Effect::Modal + ModalMode), Fight/Bite mechanics.
   530→
   531→**Session 2026-02-15:** Added BoostPerCount (dynamic P/T from counting permanents/graveyard), Flicker/FlickerEndStep/ReturnFromExileTapped, AdditionalLandPlays, OpponentExilesFromHand, ConditionalKeyword/ConditionalBoostSelf (evaluate_condition), BlightOpponents, GainAllCreatureTypes, CreateTokenCopy with TokenModification. Updated ~12 ECL cards. ECL now has 77 Effect::Custom and 20 StaticEffect::Custom.
   532→
   533→See `docs/work-queue.md` for the batch-fix loop and per-set remediation docs for card-level details.
   534→
```

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