fix(combat): correct spell DC formula

src/pf1e_simulator/combat.py

@@ -834,8 +834,11 @@ class CombatEngine:
                 f"round {self._current_round} {caster.combatant.id}: "
                 f"cast {spell_name} -> NO LINE OF EFFECT"
             )
-            return
-        dc = spell.base_dc + caster.combatant.level
+        # DC = 10 + spell level + caster's casting ability modifier
+        ability_name = caster.combatant.casting_ability.lower()
+        ability_score = getattr(caster.combatant.abilities, f"{ability_name}_score")
+        ability_mod = (ability_score - 10) // 2
+        dc = 10 + spell.level + ability_mod
         save_result = (
             self.resolve_save(target, spell.save, dc) if spell.save != "none" else None
         )

src/pf1e_simulator/models.py

@@ -113,3 +113,5 @@ class Combatant(_FrozenModel):
     notes: str = ""
     features: list[AbilitySpec] = []
     spells: list[str] = []
+    casting_ability: str = "wis"  # ability used for spell DCs: str/dex/con/int/wis/cha
+    resources: dict[str, int] = Field(default_factory=dict)  # resource pools per combat