fix(engine): Gemstone Mine-class conditional sacrifice binds to source, not an unbound ParentTarget

crates/engine/src/game/mana_abilities.rs

@@ -9947,6 +9947,170 @@ mod tests {
         );
     }
 
+    // Issue #6507 integration follow-up: `make_gemstone_mine` above omits the
+    // trailing "If there are no mining counters on this land, sacrifice it."
+    // sub-ability entirely, so it never exercised the reported bug or its fix
+    // through the real activation pipeline — only the parser-level AST shape
+    // is covered by `oracle::tests::gemstone_mine_conditional_sacrifice_binds_to_self_ref`.
+    // This fixture mirrors the actual end-to-end parsed shape (mana effect +
+    // conditional `Sacrifice { target: SelfRef }` sub-ability gated on zero
+    // mining counters) so activation itself proves the fix: mana is produced
+    // regardless, and the land is sacrificed only on the activation that
+    // removes its LAST counter.
+    fn make_gemstone_mine_with_sacrifice_sub_ability(
+        state: &mut GameState,
+        player: PlayerId,
+        initial_mining_counters: u32,
+    ) -> ObjectId {
+        let land = create_object(
+            state,
+            CardId(8003),
+            player,
+            "Gemstone Mine".to_string(),
+            Zone::Battlefield,
+        );
+        let obj = state.objects.get_mut(&land).unwrap();
+        obj.card_types
+            .core_types
+            .push(crate::types::card_type::CoreType::Land);
+        let mining_key = crate::types::counter::parse_counter_type("MINING");
+        obj.counters.insert(mining_key, initial_mining_counters);
+
+        let sacrifice_if_depleted = AbilityDefinition::new(
+            AbilityKind::Spell,
+            Effect::Sacrifice {
+                target: TargetFilter::SelfRef,
+                count: QuantityExpr::Fixed { value: 1 },
+                min_count: 0,
+            },
+        )
+        .condition(AbilityCondition::QuantityCheck {
+            lhs: QuantityExpr::Ref {
+                qty: QuantityRef::CountersOn {
+                    scope: ObjectScope::Source,
+                    counter_type: Some(CounterType::Generic("mining".to_string())),
+                },
+            },
+            comparator: Comparator::EQ,
+            rhs: QuantityExpr::Fixed { value: 0 },
+        });
+
+        let ability = AbilityDefinition::new(
+            AbilityKind::Activated,
+            Effect::Mana {
+                produced: ManaProduction::AnyOneColor {
+                    count: QuantityExpr::Fixed { value: 1 },
+                    color_options: vec![
+                        ManaColor::White,
+                        ManaColor::Blue,
+                        ManaColor::Black,
+                        ManaColor::Red,
+                        ManaColor::Green,
+                    ],
+                    contribution: ManaContribution::Base,
+                },
+                restrictions: Vec::new(),
+                grants: Vec::new(),
+                expiry: None,
+                target: None,
+            },
+        )
+        .cost(AbilityCost::Composite {
+            costs: vec![
+                AbilityCost::Tap,
+                AbilityCost::RemoveCounter {
+                    count: 1,
+                    counter_type: CounterMatch::OfType(CounterType::Generic("mining".to_string())),
+                    target: None,
+                    selection: crate::types::ability::CounterCostSelection::SingleObject,
+                },
+            ],
+        })
+        .sub_ability(sacrifice_if_depleted);
+        Arc::make_mut(&mut obj.abilities).push(ability);
+        land
+    }
+
+    #[test]
+    fn gemstone_mine_survives_activation_with_counters_remaining() {
+        let mut state = GameState::new_two_player(42);
+        let player = PlayerId(0);
+        let land = make_gemstone_mine_with_sacrifice_sub_ability(&mut state, player, 2);
+
+        let def = state
+            .objects
+            .get(&land)
+            .unwrap()
+            .abilities
+            .first()
+            .cloned()
+            .unwrap();
+        let mut events = Vec::new();
+        resolve_mana_ability(
+            &mut state,
+            land,
+            player,
+            &def,
+            &mut events,
+            Some(ProductionOverride::SingleColor(ManaType::Green)),
+        )
+        .expect("Gemstone Mine activation must not fail with counters present");
+
+        assert_eq!(
+            state.players[player.0 as usize]
+                .mana_pool
+                .count_color(ManaType::Green),
+            1,
+            "mana must be produced regardless of the trailing conditional sacrifice"
+        );
+        assert!(
+            state.battlefield.contains(&land),
+            "Gemstone Mine must remain on the battlefield while a mining counter remains after activation"
+        );
+    }
+
+    #[test]
+    fn gemstone_mine_sacrifices_itself_on_last_counter_removed() {
+        let mut state = GameState::new_two_player(42);
+        let player = PlayerId(0);
+        let land = make_gemstone_mine_with_sacrifice_sub_ability(&mut state, player, 1);
+
+        let def = state
+            .objects
+            .get(&land)
+            .unwrap()
+            .abilities
+            .first()
+            .cloned()
+            .unwrap();
+        let mut events = Vec::new();
+        resolve_mana_ability(
+            &mut state,
+            land,
+            player,
+            &def,
+            &mut events,
+            Some(ProductionOverride::SingleColor(ManaType::Green)),
+        )
+        .expect("Gemstone Mine activation must not fail on its last counter");
+
+        assert_eq!(
+            state.players[player.0 as usize]
+                .mana_pool
+                .count_color(ManaType::Green),
+            1,
+            "mana must still be produced on the activation that empties the last counter"
+        );
+        assert!(
+            !state.battlefield.contains(&land),
+            "Gemstone Mine must be sacrificed once its last mining counter is removed (issue #6507)"
+        );
+        assert!(
+            state.players[player.0 as usize].graveyard.contains(&land),
+            "the sacrificed Gemstone Mine must land in its controller's graveyard"
+        );
+    }
+
     #[test]
     fn cabal_coffers_pays_generic_taps_and_counts_swamps() {
         let mut state = GameState::new_two_player(42);

crates/engine/src/parser/oracle_effect/mod.rs

@@ -30668,10 +30668,46 @@ pub(crate) fn parse_effect_chain_ir(
         // which is exactly why a head-only rewrite corrupts the chain.
         let is_distributed_chunk = text_is_compound_subject_distribution(&text);
         // Kicker clauses referencing "that creature"/"it" inherit the parent's target.
+        //
+        // CR 608.2c + CR 122.1 (issue #6507): gated on the immediately preceding
+        // clause actually exposing SOME target concept (`target_filter().is_some()`),
+        // not merely `!builder.is_empty()`. A prior clause can establish a legitimate
+        // antecedent through several different shapes (a chosen typed target — the
+        // kicker_instead_chain_produces_correct_condition DealDamage head; a
+        // self-reference by printed name — Managorger Phoenix's `PutCounter{SelfRef}`;
+        // a cost-paid object — Jhoira of the Ghitu's exiled card), so this deliberately
+        // does not enumerate those shapes — it only excludes the one shape that has NO
+        // target concept at all. A mana ability's `Effect::Mana` has an `Option<target>`
+        // that is `None` for every ordinary mana ability (Gemstone Mine's "Add one mana
+        // of any color" chooses nothing), so `target_filter()` returns `None` and there
+        // is no antecedent for a following "it" to inherit. Previously this rewrite
+        // fired unconditionally whenever the builder was non-empty, clobbering an
+        // unbound sacrifice target into `ParentTarget`, which resolves to nothing at
+        // runtime — see the sibling fixup immediately below for the other half of the
+        // fix (rebinding that unbound default to the ability's own source instead).
+        //
+        // `target_filter().is_none()` alone over-fires on two OTHER legitimate
+        // non-target antecedents, so both must be excluded here too:
+        //   - `Effect::Populate` has no `target` field (`target_filter()` is `None`)
+        //     but DOES publish a created-token referent — the exact "populate anaphor
+        //     chain" class already documented at `parse_targeted_action_ast`'s bare-"it"
+        //     sacrifice binding. `chain_prior_referent_is_created_token` is the single
+        //     authority that already recognizes this (Token/CopyTokenOf are excluded
+        //     for free since both DO have a `target_filter()`).
+        //   - A `GenericEffect` whose referent lives only in a granted static's
+        //     `affected` field (not its own top-level `target`) still has
+        //     `target_filter() == None`, but `if_you_do_object_anchor` — computed just
+        //     above for this exact clause's "if you do" gate — already finds it.
+        let prior_clause_has_no_target_concept = builder
+            .clauses()
+            .last()
+            .is_some_and(|prev| prev.parsed.effect.target_filter().is_none())
+            && !chain_prior_referent_is_created_token(builder.clauses())
+            && if_you_do_anchor.is_none();
         if condition.is_some()
             && !is_distributed_chunk
             && !condition.as_ref().is_some_and(condition_refs_source_object)
-            && !builder.is_empty()
+            && !prior_clause_has_no_target_concept
             && has_anaphoric_reference(&text_lower)
             && !matches!(if_you_do_anchor, Some(TargetFilter::SelfRef))
             && !typed_trigger_subject
@@ -30683,6 +30719,25 @@ pub(crate) fn parse_effect_chain_ir(
         {
             replace_target_with_parent(&mut clause.effect);
         }
+        // CR 608.2c + CR 122.1 (issue #6507): the sacrifice imperative parser
+        // (`parse_targeted_action_ast`) defaults a bare "it"/"them" pronoun with no
+        // trigger subject to `ParentTarget`, on the assumption that SOME earlier
+        // clause in the chain chose a real target for it to inherit — the common case
+        // (`bare_it_without_trigger_subject_preserves_parent_target`). When the
+        // immediately preceding clause has no target concept at all (the Kicker-clause
+        // guard above), that assumption is false: there is nothing for `ParentTarget`
+        // to resolve to, so a conditional "sacrifice it" tail (Gemstone Mine's "{T},
+        // Remove a mining counter: Add one mana of any color. If there are no mining
+        // counters on this land, sacrifice it.") silently never sacrifices anything.
+        // Rebind it to the ability's own source, the only object "it" can plausibly
+        // name here.
+        if condition.is_some() && !is_distributed_chunk && prior_clause_has_no_target_concept {
+            if let Effect::Sacrifice { target, .. } = &mut clause.effect {
+                if matches!(target, TargetFilter::ParentTarget) {
+                    *target = TargetFilter::SelfRef;
+                }
+            }
+        }
         // CR 608.2c: Pronoun clause following a conditional targeted effect.
         if condition.is_none()
             && !is_distributed_chunk

crates/engine/src/parser/oracle_effect/tests.rs

@@ -18715,6 +18715,38 @@ fn kicker_instead_chain_produces_correct_condition() {
     ));
 }
 
+/// Issue #6507 review follow-up: `Effect::Populate` has no `target` field
+/// (`target_filter()` is `None`, just like a mana ability's untargeted `Add`),
+/// but it DOES publish a created-token referent via
+/// `chain_prior_referent_is_created_token` — the same "populate anaphor
+/// chain" class documented at the sacrifice imperative's bare-"it" binding.
+/// A conditional "sacrifice it" tail after Populate must keep inheriting the
+/// populated token (`ParentTarget`, rewritten to `LastCreated` by
+/// `rewrite_parent_target_to_last_created`) — NOT get rebound to `SelfRef`,
+/// which would sacrifice the ability's source instead of the populated copy.
+#[test]
+fn populate_conditional_sacrifice_keeps_created_token_not_self_ref() {
+    let ability = parse_effect_chain(
+        "Populate. If it was kicked, sacrifice it.",
+        AbilityKind::Spell,
+    );
+    assert!(matches!(&*ability.effect, Effect::Populate));
+    let sub = ability.sub_ability.as_ref().expect("expected sub_ability");
+    assert!(
+        sub.condition.is_some(),
+        "expected the 'if it was kicked' gate to survive as a condition"
+    );
+    let Effect::Sacrifice { target, .. } = &*sub.effect else {
+        panic!("expected Effect::Sacrifice, got {:?}", sub.effect);
+    };
+    assert_eq!(
+        *target,
+        TargetFilter::LastCreated,
+        "sacrifice target must bind to the populated token (LastCreated), \
+         not fall back to SelfRef (the ability's own source)"
+    );
+}
+
 #[test]
 fn kicker_leading_instead_produces_correct_condition() {
     // CR 608.2c: "if kicked, instead [effect]" — leading "instead" variant.

crates/engine/src/parser/oracle_tests.rs

@@ -8214,6 +8214,50 @@ fn mox_pearl_mana_ability() {
     assert_eq!(r.abilities[0].kind, AbilityKind::Activated);
 }
 
+/// Issue #6507: Gemstone Mine's mana ability is targetless ("Add one mana of
+/// any color" chooses no target), so the trailing "If there are no mining
+/// counters on this land, sacrifice it" conditional has no parent target to
+/// inherit. The bare "it" pronoun must bind to the ability's own source
+/// (`TargetFilter::SelfRef`), not `ParentTarget` — `ParentTarget` resolves to
+/// nothing here and the land was never sacrificed. This is the
+/// depletion-land class, not a one-off: any targetless activated ability
+/// whose trailing conditional says "sacrifice it" shares the exposure.
+#[test]
+fn gemstone_mine_conditional_sacrifice_binds_to_self_ref() {
+    let r = parse(
+        "This land enters with three mining counters on it.\n\
+         {T}, Remove a mining counter from this land: Add one mana of any color. \
+         If there are no mining counters on this land, sacrifice it.",
+        "Gemstone Mine",
+        &[],
+        &["Land"],
+        &[],
+    );
+    assert_eq!(r.abilities.len(), 1);
+    let ability = &r.abilities[0];
+    assert!(
+        matches!(*ability.effect, Effect::Mana { .. }),
+        "expected Effect::Mana, got {:?}",
+        ability.effect
+    );
+    let sub_ability = ability
+        .sub_ability
+        .as_ref()
+        .expect("expected a conditional sub_ability for the trailing sacrifice sentence");
+    assert!(
+        sub_ability.condition.is_some(),
+        "expected the 'if there are no mining counters' gate to survive as a condition"
+    );
+    let Effect::Sacrifice { target, .. } = &*sub_ability.effect else {
+        panic!("expected Effect::Sacrifice, got {:?}", sub_ability.effect);
+    };
+    assert_eq!(
+        *target,
+        TargetFilter::SelfRef,
+        "sacrifice target must bind to the source land, not an unestablished ParentTarget"
+    );
+}
+
 #[test]
 fn parses_return_forest_cost_untap_activated_ability() {
     let r = parse(