fix(combat): _find_ally_needing_heal counts only living allies (SRD Channel Energy: heal mode heals living creatures, positive energy never heals undead) - an undead ally below half triggered heal mode, spending the channel to heal nobody; + trigger regression test

tests/test_class_abilities.py

@@ -156,6 +156,24 @@ def test_oni_silent_when_channel_energy_exhausted() -> None:
     assert not any(a.kind == "channel_energy" for a in actions)
 
 
+def test_oni_no_channel_heal_trigger_for_undead_ally() -> None:
+    """SRD Channel Energy: heal mode heals living creatures. An undead ally
+    below half cannot benefit (positive energy harms undead), so it must not
+    trigger the heal mode - the channel would be spent healing nobody."""
+    oni = _combatant("oni", resources={"channel_energy": 6}, hp_max=30)
+    goblin = _combatant("goblin", hp_max=6)
+    engine, me, _ = _engine(oni, [goblin])
+    undead_ally = _state(
+        _combatant("ghoul", hp_max=20, creature_type="undead"),
+        "players", (5, 5), hp=5,
+    )
+    engine.states.append(undead_ally)
+
+    actions = default_policy(engine, me)
+
+    assert not any(a.kind == "channel_energy" for a in actions)
+
+
 def test_oni_channel_energy_spends_resource() -> None:
     oni = _combatant("oni", resources={"channel_energy": 6}, hp_max=30)
     goblin = _combatant("goblin", hp_max=6)