fix(combat): channel energy targets living vs undead

tests/test_class_abilities.py

@@ -7,6 +7,8 @@ tammara (deeds), misty (spell_combat + inspire_courage). Each class has an
 
 from __future__ import annotations
 
+from typing import Literal
+
 from pf1e_simulator.combat import Action, CombatantState, CombatEngine, default_policy
 from pf1e_simulator.dice import parse_dice
 from pf1e_simulator.grid import Grid
@@ -29,6 +31,7 @@ def _combatant(
     resources: dict[str, int] | None = None,
     spells: list[str] | None = None,
     hp_max: int = 20,
+    creature_type: Literal["living", "undead", "construct"] = "living",
 ) -> Combatant:
     attack = AttackSpec(
         id=f"{cid}-w",
@@ -55,6 +58,7 @@ def _combatant(
         attacks=[attack],
         resources=resources or {},
         spells=spells or [],
+        creature_type=creature_type,
     )
 
 
@@ -134,6 +138,69 @@ def test_oni_channel_energy_spends_resource() -> None:
     assert me.resources_left["channel_energy"] == 5
 
 
+def test_oni_channel_harm_does_not_damage_living_enemy() -> None:
+    """Regression: positive energy must not damage living creatures (reported bug:
+    oni harmed a Giant Belostomatid — living vermin). Harm mode only hits undead."""
+    oni = _combatant("oni", resources={"channel_energy": 6}, hp_max=30)
+    vermin = _combatant("belostomatid", hp_max=30)
+    engine, me, enemy = _engine(oni, [vermin], rng_queue=[11])
+
+    action = Action(
+        kind="channel_energy", target_id=vermin.id, channel_mode="harm"
+    )
+    engine._execute(me, action)
+
+    assert me.hp == 30  # living caster unaffected by harm mode
+    assert enemy[0].hp == 30  # living vermin unaffected by harm mode
+
+
+def test_oni_channel_harm_damages_undead() -> None:
+    """Harm mode damages undead creatures in the burst regardless of side."""
+    oni = _combatant("oni", resources={"channel_energy": 6}, hp_max=30)
+    lich = _combatant("lich", hp_max=100, creature_type="undead")
+    engine, me, enemy = _engine(oni, [lich], rng_queue=[11])
+
+    action = Action(kind="channel_energy", target_id=lich.id, channel_mode="harm")
+    engine._execute(me, action)
+
+    assert enemy[0].hp == 100 - (1 + 11)  # 2d6 = 1 + roll_die(11)
+
+
+def test_oni_channel_heal_heals_living_enemies_in_range() -> None:
+    """Heal mode heals all living creatures in the burst — including enemies
+    (Selective Channeling, which would exclude them, is not modeled)."""
+    oni = _combatant("oni", resources={"channel_energy": 6}, hp_max=30)
+    goblin = _combatant("goblin", hp_max=6)
+    engine, me, enemy = _engine(oni, [goblin], rng_queue=[5])
+    enemy[0].hp = 2
+
+    action = Action(
+        kind="channel_energy", target_id=me.combatant.id, channel_mode="heal"
+    )
+    engine._execute(me, action)
+
+    assert enemy[0].hp == min(2 + (1 + 5), 6)  # healed, capped at hp_max
+
+
+def test_oni_emits_channel_harm_only_for_grouped_undead() -> None:
+    """Channel harm is emitted only when at least 2 undead enemies are grouped at 30ft
+    — living enemies are never harmed by positive energy."""
+    oni = _combatant("oni", resources={"channel_energy": 6}, hp_max=30)
+    lich1 = _combatant("lich1", hp_max=100, creature_type="undead")
+
+    engine, me, _ = _engine(oni, [lich1])
+    assert not any(a.kind == "channel_energy" for a in default_policy(engine, me))
+
+    lich2 = _combatant("lich2", hp_max=100, creature_type="undead")
+    engine, me, _ = _engine(oni, [lich1, lich2])
+    actions = default_policy(engine, me)
+
+    assert any(
+        a.kind == "channel_energy" and a.channel_mode == "harm"
+        for a in actions
+    )
+
+
 # --- nairda: hex ---