fix(engine): Winter Soldier attack trigger and Hero counter rider (#4560)

[kiannidev]

Summary

• Fix misclassification of Winter Soldier, Reborn Avenger's oracle text as an enters-with replacement; trigger lines with reflexive "enters this way" counter riders now route through trigger dispatch.
• Parse present-tense "enters this way" zone-change gates and the "it enters with an additional +1/+1 counter" rider on graveyard reanimation.
• Add parser and integration tests covering parse output and in-game Hero reanimation with an extra counter.

Fixes #4560

Test plan

• cargo test -p engine --lib winter_soldier_reborn_avenger
• cargo test -p engine --test integration issue_4560

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[gemini-code-assist]

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[github-actions]

Parse changes introduced by this PR · 23 card(s), 28 signature(s) (baseline: main 315c1235db94)

5 card(s) · ability/ApplyPerpetual · added: ApplyPerpetual

Examples: Blooming Cactusfolk, Charged Conjuration, Fearsome Whelp (+2 more)

3 card(s) · static/Continuous · field conditional: unrecognized → cards in hand (you) > cards in hand (max of opponents)

Examples: Descendant of Kiyomaro, Okina Nightwatch, Secretkeeper

3 card(s) · trigger/Phase · field condition: ∅ → cards in hand (you) > cards in hand (max of opponents)

Examples: Akuta, Born of Ash, Death of a Thousand Stings, Exile into Darkness

2 card(s) · ability/Attach · added: Attach (conditional=Equipment changed zones this way, target=you control creature)

Examples: Adaptive Armorer, Masterpiece Vault

2 card(s) · ability/CreateDelayedTrigger · removed: CreateDelayedTrigger (when=when any target enters)

Examples: Adaptive Armorer, Masterpiece Vault

1 card(s) · ability/ApplyPerpetual · added: ApplyPerpetual (conditional=additional cost was paid)

Examples: Talion's Throneguard

1 card(s) · trigger/Attacks · added: Attacks (active in=battlefield, watches=self)

Examples: Winter Soldier, Reborn Avenger

1 card(s) · static/Continuous · added: Continuous (affects=you control creature Human, mods=add chosen keyword)

Examples: Greymond, Avacyn's Stalwart

1 card(s) · static/Continuous · field conditional: unrecognized → not (in battlefield opponent controls creature is present)

Examples: Erebos's Titan

1 card(s) · replacement/CreateToken · added: CreateToken

Examples: Jinnie Fay, Jetmir's Second

1 card(s) · replacement/Moved · added: Moved

Examples: Greymond, Avacyn's Stalwart

1 card(s) · replacement/Moved · removed: Moved

Examples: Winter Soldier, Reborn Avenger

1 card(s) · trigger/Phase · field condition: ∅ → # of 1+ bounty counters in battlefield opponent controls permanent = 0

Examples: Chevill, Bane of Monsters

1 card(s) · trigger/Phase · field condition: ∅ → # of in battlefield opponent controls creature = 0

Examples: Kezzerdrix

1 card(s) · trigger/Phase · field condition: ∅ → life lost this turn (you) ≥ 2

Examples: The Book of Vile Darkness

1 card(s) · ability/PutCounter · added: PutCounter (conditional=revealed is creature, counter=2 P1P1, target=parent target)

Examples: What Must Be Done

1 card(s) · ability/RaiseCost · removed: RaiseCost (affects=any target, conditional=additional cost was paid, duration=until end of turn, grants=RaiseCost, target=parent target)

Examples: Talion's Throneguard

1 card(s) · ability/RaiseCost · removed: RaiseCost (affects=any target, duration=until end of turn, grants=RaiseCost, target=parent target)

Examples: Paths of Tuinvale

1 card(s) · ability/ReduceCost · removed: ReduceCost (affects=any target, duration=until end of turn, grants=ReduceCost, target=parent target)

Examples: Paths of Tuinvale

1 card(s) · ability/ReduceCost · removed: ReduceCost (affects=in hand you control Dragon, grants=ReduceCost)

Examples: Fearsome Whelp

1 card(s) · ability/creature · removed: creature

Examples: Fountainport Charmer

1 card(s) · ability/instant · removed: instant

Examples: Charged Conjuration

1 card(s) · ability/it · field conditional: ∅ → land changed zones this way

Examples: Silver Surfer, Cosmic Voyager

1 card(s) · ability/it · removed: it (conditional=revealed is creature)

Examples: What Must Be Done

1 card(s) · ability/nonland · removed: nonland

Examples: Blooming Cactusfolk

… 3 more signature(s) (3 card-changes) — see parse-diff.json

• 1 card(s) · ability/replacement_structure · removed: replacement_structure
• 1 card(s) · ability/static_structure · removed: static_structure
• 1 card(s) · ability/unknown · removed: unknown

[matthewevans]

[MED] The Hero "enters with" rider is modeled as a later counter effect instead of an entry-time counter. Evidence: crates/engine/src/parser/oracle_effect/mod.rs:884 emits Effect::PutCounter, which resolves through the normal counter effect path (crates/engine/src/game/effects/counters.rs:1021) after the zone move, while actual "enters with" counters are applied inside the zone-change entry pipeline (crates/engine/src/game/zone_pipeline.rs:1758). Why it matters: "it enters with an additional +1/+1 counter" is an entry replacement-style property of the battlefield entry, so entry-time observers/replacements can differ even though the final counter count test passes. Suggested fix: carry the conditional Hero rider into the ChangeZone/entry pipeline as conditional enter_with_counters (or an equivalent entry-time structure), and add a test with an entry-time observer that distinguishes entering with the counter from receiving it afterward.

[matthewevans]

[MED] The Hero "enters with" rider is still modeled as a post-entry counter effect. Evidence: crates/engine/src/parser/oracle_effect/mod.rs:884 still emits Effect::PutCounter { target: TargetFilter::ParentTarget } for "it enters with an additional +1/+1 counter on it; that runs after the parent ChangeZonehas already moved the object, instead of carrying the counter into the entry pipeline viaChangeZone.enter_with_counters. Why it matters: entry-time observers/replacements can distinguish entering with the counter from receiving the counter afterward, so the final counter-count integration test does not prove the rules behavior. Suggested fix: carry the conditional Hero rider into the ChangeZone/entry pipeline as conditional entry counters, and add a regression that distinguishes entry-time counters from a later PutCounter`.

[matthewevans]

[MED] The regression coverage still does not distinguish entry-time counters from a post-entry counter effect. Evidence: crates/engine/tests/integration/issue_4560_winter_soldier.rs:183 only asserts the returned Hero's final battlefield zone and final +1/+1 counter count, while the prior failure mode could produce the same final state with a later PutCounter; the parse assertion at crates/engine/tests/integration/issue_4560_winter_soldier.rs:112 proves the AST shape but does not exercise an entry-time observer/replacement through the runtime pipeline. Why it matters: the original bug class was timing-sensitive: "enters with" must be visible during battlefield entry, not merely after resolution. Suggested fix: add a runtime regression with an entry-time observer/replacement/counter-modifier interaction that fails if the Hero counter is applied after the zone move rather than inside the entry pipeline.

[kiannidev]

Merged latest main, resolved main.rs conflict. Hero counter rider uses conditional_enter_with_counters on ChangeZone (not post-entry PutCounter); parse + integration tests updated accordingly. CI re-running — ready for re-review.

[matthewevans]

[MED] Resolution-choice ChangeZone paths drop the new conditional entry counters. Evidence: crates/engine/src/game/effects/change_zone.rs:587 creates WaitingFor::EffectZoneChoice without carrying conditional_enter_with_counters, and crates/engine/src/game/engine_resolution_choices.rs:2795 resumes with enter_with_counters: vec![] / conditional_enter_with_counters: vec![]. Why it matters: any resolution-time "return/put a card ... If a [type] enters this way, it enters with ..." shape can parse into the new field but enter without the rider when it goes through the choice path. Suggested fix: carry the conditional specs or resolved per-object counters through EffectZoneChoice, then compute/merge per-object counters before process_one_zone_move.

[MED] The prior timing-test blocker is still not fixed. Evidence: crates/engine/tests/integration/issue_4560_winter_soldier.rs:183 only asserts the final battlefield zone, and crates/engine/tests/integration/issue_4560_winter_soldier.rs:188 only asserts the final counter count. Why it matters: a post-entry PutCounter implementation can satisfy the same final-state assertion, so the regression still does not prove the Hero counter is applied as an entry-time counter rather than after the zone move. Suggested fix: add a runtime test with an ETB counter replacement/observer that fails if the Hero counter is applied after the object enters.

[matthewevans]

[MED] The EffectZoneChoice conditional-entry-counter path still has no discriminating regression. Evidence: crates/engine/src/game/engine_resolution_choices.rs:2648 now carries conditional_enter_with_counters through WaitingFor::EffectZoneChoice, and crates/engine/src/game/engine_resolution_choices.rs:2806-2816 applies it when a selected card is moved, but the new Winter Soldier regression drives the normal targeted ChangeZone trigger path (crates/engine/tests/integration/issue_4560_winter_soldier.rs:249) and the existing change_zone.rs test fixtures still construct EffectZoneChoice/ChangeZone cases with conditional_enter_with_counters: vec![]. Why it matters: the last blocker was specifically that resolution-choice ChangeZone paths dropped this rider; without a choice-path fixture, a future regression can erase the newly threaded field while the Winter Soldier tests still pass. Suggested fix: add a focused regression that reaches the EffectZoneChoice SelectCards branch with a non-empty conditional_enter_with_counters rider and verifies the selected matching card enters with the counter while a non-matching card does not.

[matthewevans]

[MED] Missing regression for the previously blocked EffectZoneChoice conditional-counter path.

The production path now carries conditional_enter_with_counters into WaitingFor::EffectZoneChoice (crates/engine/src/game/effects/change_zone.rs) and applies it in the SelectCards branch (crates/engine/src/game/engine_resolution_choices.rs), but the new EffectZoneChoice regression still initializes conditional_enter_with_counters: vec![]. The Winter Soldier integration tests cover the targeted attack-trigger path and final Hero counter result, but they do not discriminate the specific interactive EffectZoneChoice SelectCards branch that previously dropped this field.

Please add a focused regression that parks or reaches WaitingFor::EffectZoneChoice with a non-empty conditional_enter_with_counters rider, selects at least one matching Hero and one non-matching creature/card through GameAction::SelectCards, and asserts only the matching selected object enters with the extra counter. That would fail if the field were dropped during the EffectZoneChoice round trip.

[matthewevans]

Holding this head. CI is failing in the PR's own Winter Soldier parser coverage: panics at with . Because that failure is directly in the touched behavior, I can't treat it as merge-when-ready noise. Please update the parser/test path so the current Winter Soldier representation is internally consistent and the new entry-time counter modeling remains covered.

[matthewevans]

Holding this head. CI is failing in the PR Winter Soldier parser coverage: parser::oracle_trigger::tests::winter_soldier_reborn_avenger_attack_reanimation_trigger panics at crates/engine/src/parser/oracle_trigger.rs:14474 with Hero counter rider. Because that failure is directly in the touched behavior, I cannot treat it as merge-when-ready noise. Please update the parser/test path so the current Winter Soldier representation is internally consistent and the new entry-time counter modeling remains covered.

[matthewevans]

[HIGH] The EffectZoneChoice resume path still drops conditional entry counters in production. Evidence: crates/engine/src/game/engine_resolution_choices.rs:2797 looks up the resolving ability only by scanning state.stack, but resolve_top pops the entry before resolving and stores it in state.resolving_stack_entry (crates/engine/src/game/stack.rs:192, crates/engine/src/game/stack.rs:460). The new regression masks this by manually pushing a fake stack entry before SelectCards (crates/engine/src/game/effects/change_zone.rs:4457), so it exercises a state shape production resolution does not have. Why it matters: when a real resolving ChangeZone pauses for EffectZoneChoice, stack_ability is None, so the branch falls back to enter_with_counters.clone() and silently ignores conditional_enter_with_counters; the Hero selected through this path will not get the entry-time counter. Suggested fix: resolve the ability from the active resolving entry as well as the live stack, and change the regression to model production by using state.resolving_stack_entry rather than pushing a fake live stack entry.

[matthewevans]

[MED] Conditional entry counters are lost or copied incorrectly after a selected zone move pauses. Evidence: crates/engine/src/game/engine_resolution_choices.rs:2812 computes per_obj_enter_counters for the current selected card, but the pause stashes only that resolved vector into PendingChangeZoneIteration.enter_with_counters (crates/engine/src/game/engine_resolution_choices.rs:2863, crates/engine/src/game/engine_resolution_choices.rs:2895); the drain path then reconstructs ChangeZoneIterationCtx with conditional_enter_with_counters: vec![] (crates/engine/src/game/effects/mod.rs:744) and reuses the same enter_with_counters for every remaining object. Why it matters: if the first selected object pauses for an Aura attachment or replacement/as-enters choice, later selected objects no longer get per-object conditional evaluation, so later Heroes can miss the counter or non-Heroes can inherit the paused object's counter. Suggested fix: carry the conditional counter specs plus resolving ability provenance through PendingChangeZoneIteration and recompute enter_with_counters_for_object for each remaining object during drain, or store per-object resolved counters for the remaining queue.

[matthewevans]

[MED] Conditional "enters this way" counters are skipped on the single-pick fast paths. Evidence: crates/engine/src/game/effects/change_zone.rs:460 and crates/engine/src/game/effects/change_zone.rs:525 both call execute_zone_move with only &effect_enter_with_counters; unlike the main multi-object loop and the EffectZoneChoice path, neither branch evaluates effect_conditional_enter_with_counters with enter_with_counters_for_object. Why it matters: a ChangeZone effect that resolves to one eligible/random object can enter a matching Hero without the entry-time counter even though the multi-object/choice path is now correct. Suggested fix: compute the per-object counter vector in both single-pick branches before moving the object, or route those branches through process_one_zone_move with ChangeZoneIterationCtx, and add a single-eligible conditional-counter regression.

[matthewevans]

Reviewed current head. The Winter Soldier entry-time counter modeling now carries conditional entry-counter specs through the normal, EffectZoneChoice, pause/resume, and single-pick ChangeZone paths with discriminating engine coverage. Merge when ready.