feat(combat): area-of-effect spells

src/pf1e_simulator/spells.py

@@ -54,7 +54,22 @@ class BuffEffect:
     duration_rounds: int
 
 
-SpellEffect = DamageEffect | ConditionEffect | HealEffect | BuffEffect
+@dataclass(frozen=True)
+class AreaEffect:
+    """Area of effect spell (burst only for Phase 0).
+    
+    - shape: only "burst" supported (circle around target point)
+    - radius_ft: radius in feet (e.g., 20 for fireball)
+    - effects: the effects applied to each creature in the area
+    - save_for_half: if True, successful save halves damage
+    """
+    shape: Literal["burst"] = "burst"
+    radius_ft: int = 20
+    effects: tuple[SpellEffect, ...] = ()
+    save_for_half: bool = True
+
+
+SpellEffect = DamageEffect | ConditionEffect | HealEffect | BuffEffect | AreaEffect
 
 
 @dataclass(frozen=True)
@@ -111,10 +126,15 @@ def _parse_effect(data: dict[str, Json]) -> SpellEffect:
                 )
                 for m in cast("list[dict[str, Json]]", data["modifiers"])
             ),
-            duration_rounds=int(data["duration_rounds"]),  # type: ignore[arg-type]
+            duration_rounds=int(data.get("duration_rounds", 0)),  # type: ignore[arg-type]
         )
-    msg = f"Unknown effect type: {effect_type}"
-    raise ValueError(msg)
+    if effect_type == "area":
+        return AreaEffect(
+            radius_ft=int(data.get("radius_ft", 20)),  # type: ignore[arg-type]
+            effects=tuple(_parse_effect(e) for e in data["effects"]),  # type: ignore[index]
+            save_for_half=bool(data.get("save_for_half", True)),
+        )
+    raise ValueError(f"Unknown effect type: {effect_type}")
 
 
 def load_spell(path: str | Path) -> SpellSpec: