feat(combat): summoning

data/monsters/celestial_wolf.json

@@ -0,0 +1,53 @@
+{
+  "name": "Celestial Wolf",
+  "level": 2,
+  "size": "Medium",
+  "abilities": {
+    "str_score": 13,
+    "dex_score": 15,
+    "con_score": 12,
+    "int_score": 2,
+    "wis_score": 12,
+    "cha_score": 6
+  },
+  "hp_max": 15,
+  "ac": {
+    "total": 14,
+    "touch": 13,
+    "flat_footed": 12
+  },
+  "bab": 1,
+  "initiative_mod": 2,
+  "speed_land_ft": 50,
+  "saves": {
+    "fort": 4,
+    "ref": 5,
+    "will": 2
+  },
+  "attacks": [
+    {
+      "id": "celestial_wolf:bite",
+      "name": "Bite",
+      "kind": "melee",
+      "attack_bonus": 3,
+      "damage": [
+        {
+          "formula": "1d6+1",
+          "types": ["piercing"]
+        }
+      ],
+      "damage_bonus": 1,
+      "crit_range": 20,
+      "crit_mult": 2,
+      "reach_ft": 5,
+      "count": 1
+    }
+  ],
+  "source": "summon monster II",
+  "features": [],
+  "spells": [],
+  "casting_ability": "wis",
+  "resources": {},
+  "metamagic_feats": [],
+  "skills": {}
+}

data/spells/summon_monster_ii.json

@@ -0,0 +1,16 @@
+{
+  "name": "Summon Monster II",
+  "level": 2,
+  "school": "conjuration",
+  "range": "close",
+  "save": "none",
+  "base_dc": 10,
+  "effects": [
+    {
+      "type": "summon",
+      "creature": "data/monsters/celestial_wolf.json",
+      "duration_rounds": 5
+    }
+  ],
+  "description": "Summons a celestial wolf to fight for you."
+}

src/pf1e_simulator/combat.py

@@ -75,7 +75,6 @@ Phase 0 documented deviations from PF1e (conventions):
 
 from __future__ import annotations
 
-from collections.abc import Callable
 from dataclasses import asdict, dataclass, field
 from typing import TYPE_CHECKING
 
@@ -89,6 +88,7 @@ from pf1e_simulator.spells import (
     DamageEffect,
     HealEffect,
     SpellEffect,
+    SummonEffect,
     spell_range_ft,
 )
 
@@ -932,7 +932,7 @@ class CombatEngine:
                     ActiveCondition(
                         condition=CONDITIONS_BY_NAME["prone"],
                         rounds_left=1,
-                        source=f"maneuver: trip",
+                        source="maneuver: trip",
                     )
                 )
                 target.conditions.append(CONDITIONS_BY_NAME["prone"])
@@ -950,7 +950,7 @@ class CombatEngine:
                             modifiers=(StatModifier(target="attack", value=-4),),
                         ),
                         rounds_left=1,
-                        source=f"maneuver: disarm",
+                        source="maneuver: disarm",
                     )
                 )
                 self._log(f"round {self._current_round} {state.combatant.id}: disarm vs {target.combatant.id} d20={roll}+{attacker_cmb}={total} CMD {target_cmd} -> SUCCESS (disarmed)")
@@ -1045,7 +1045,7 @@ class CombatEngine:
         hp_before = target.hp
         parts = self._apply_spell_effects_from_list(
             metamagic_effects, target, save_result, caster_live, target_live,
-            spell_name=spell.name,
+            caster, spell_name=spell.name,
             empower="Empower Spell" in metamagic_feats,
             maximize="Maximize Spell" in metamagic_feats,
         )
@@ -1073,7 +1073,7 @@ class CombatEngine:
         """Legacy wrapper for compatibility."""
         return self._apply_spell_effects_from_list(
             spell.effects, target, save_result, caster_live, target_live,
-            spell_name=spell.name
+            caster=target, spell_name=spell.name
         )
 
     def _apply_spell_effects_from_list(
@@ -1083,6 +1083,7 @@ class CombatEngine:
         save_result: SaveResult | None,
         caster_live: _LiveStats,
         target_live: _LiveStats,
+        caster: CombatantState,
         *,
         spell_name: str,
         empower: bool = False,
@@ -1091,7 +1092,7 @@ class CombatEngine:
         saved = save_result is not None and save_result.success
         return [
             self._apply_single_spell_effect(
-                effect, target, caster_live, target_live,
+                effect, target, caster_live, target_live, caster,
                 spell_name=spell_name, empower=empower, maximize=maximize,
                 saved=saved
             )
@@ -1104,6 +1105,7 @@ class CombatEngine:
         target: CombatantState,
         caster_live: _LiveStats,
         target_live: _LiveStats,
+        caster: CombatantState,
         *,
         spell_name: str,
         empower: bool = False,
@@ -1111,7 +1113,9 @@ class CombatEngine:
         saved: bool,
     ) -> str:
         if isinstance(effect, AreaEffect):
-            return self._apply_area_effect(effect, target, caster_live, target_live, spell_name, saved, empower=empower, maximize=maximize)
+            return self._apply_area_effect(effect, target, caster_live, target_live, caster, spell_name, saved, empower=empower, maximize=maximize)
+        if isinstance(effect, SummonEffect):
+            return self._apply_summon_effect(effect, caster, caster_live, spell_name)
         if isinstance(effect, DamageEffect):
             raw = effect.formula.roll(self._rng)
             if maximize:
@@ -1168,6 +1172,7 @@ class CombatEngine:
         target: CombatantState,
         caster_live: _LiveStats,
         target_live: _LiveStats,
+        caster: CombatantState,
         spell_name: str,
         saved: bool,
         *,
@@ -1214,7 +1219,7 @@ class CombatEngine:
             for sub_effect in effect.effects:
                 result = self._apply_single_spell_effect(
                     sub_effect, affected_state, caster_live, self._stats[affected_state.combatant.id],
-                    spell_name=spell_name, saved=creature_saved, empower=empower, maximize=maximize
+                    caster, spell_name=spell_name, saved=creature_saved, empower=empower, maximize=maximize
                 )
                 if "damage" in result:
                     total_damage += int(result.split()[0])
@@ -1294,6 +1299,125 @@ class CombatEngine:
                 )
         return tuple(new_effects)
 
+
+    def _apply_summon_effect(
+        self,
+        effect: SummonEffect,
+        state: CombatantState,
+        caster_live: _LiveStats,
+        spell_name: str,
+    ) -> str:
+        """Apply a summoning effect - create a summoned creature."""
+        # Load the summoned creature
+        from pathlib import Path
+
+        from pf1e_simulator.loaders.combatant import load_combatant
+
+        try:
+            summoned_combatant = load_combatant(Path(effect.creature))
+        except Exception:
+            return f"summon failed: could not load {effect.creature}"
+
+        # Find a valid adjacent position for the summoned creature
+        center = state.pos
+        spawn_pos = None
+        for dr in (-1, 0, 1):
+            for dc in (-1, 0, 1):
+                if dr == 0 and dc == 0:
+                    continue
+                pos = (center[0] + dr, center[1] + dc)
+                if (0 <= pos[0] < self._grid.height and
+                    0 <= pos[1] < self._grid.width and
+                    not any(s.pos == pos for s in self._states if s.active)):
+                    spawn_pos = pos
+                    break
+            if spawn_pos:
+                break
+
+        if not spawn_pos:
+            return "summon failed: no space"
+
+        # Create summoned creature state
+        summoned_state = CombatantState(
+            combatant=summoned_combatant,
+            side=state.side,
+            pos=spawn_pos,
+            hp=summoned_combatant.hp_max,
+        )
+
+        # Insert into initiative order right after caster
+        caster_idx = next(i for i, s in enumerate(self._states) if s is state)
+        self._states.insert(caster_idx + 1, summoned_state)
+
+        # Set expiration
+        summoned_state.summon_duration = effect.duration_rounds
+        summoned_state.summon_caster_id = state.combatant.id
+
+        self._log(
+            f"round {self._current_round} {state.combatant.id}: "
+            f"summon {summoned_combatant.id} at {spawn_pos} ({effect.duration_rounds}r)"
+        )
+        return f"summoned {summoned_combatant.id}"
+
+        for effect in spell.effects:
+            if isinstance(effect, DamageEffect):
+                # Empower: 1.5x damage (applied at roll time in _apply_spell_effects_from_list)
+                # Maximize: max damage (applied at roll time)
+                # We mark these via a custom attribute on the formula
+                new_effects.append(effect)
+            elif isinstance(effect, ConditionEffect):
+                new_duration = effect.duration_rounds * 2 if has_extend else effect.duration_rounds
+                new_effects.append(
+                    ConditionEffect(
+                        condition_name=effect.condition_name,
+                        duration_rounds=new_duration,
+                        save_negates=effect.save_negates,
+                    )
+                )
+            elif isinstance(effect, HealEffect):
+                # Empower/Maximize also apply to healing
+                new_effects.append(effect)
+            elif isinstance(effect, AreaEffect):
+                new_sub_effects = []
+                for sub in effect.effects:
+                    if isinstance(sub, DamageEffect):
+                        new_sub_effects.append(sub)
+                    elif isinstance(sub, ConditionEffect):
+                        new_duration = sub.duration_rounds * 2 if has_extend else sub.duration_rounds
+                        new_sub_effects.append(
+                            ConditionEffect(
+                                condition_name=sub.condition_name,
+                                duration_rounds=new_duration,
+                                save_negates=sub.save_negates,
+                            )
+                        )
+                    elif isinstance(sub, HealEffect):
+                        new_sub_effects.append(sub)
+                    else:  # BuffEffect
+                        new_duration = sub.duration_rounds * 2 if has_extend else sub.duration_rounds
+                        new_sub_effects.append(
+                            BuffEffect(
+                                modifiers=sub.modifiers,
+                                duration_rounds=new_duration,
+                            )
+                        )
+                new_effects.append(
+                    AreaEffect(
+                        radius_ft=effect.radius_ft,
+                        effects=tuple(new_sub_effects),
+                        save_for_half=effect.save_for_half,
+                    )
+                )
+            else:  # BuffEffect
+                new_duration = effect.duration_rounds * 2 if has_extend else effect.duration_rounds
+                new_effects.append(
+                    BuffEffect(
+                        modifiers=effect.modifiers,
+                        duration_rounds=new_duration,
+                    )
+                )
+        return tuple(new_effects)
+
     def _resolve_swing(
         self,
         attacker: CombatantState,
@@ -1558,21 +1682,21 @@ class CombatEngine:
         size = state.combatant.size.lower()
         if size == "fine":
             return -8
-        elif size == "diminutive":
+        if size == "diminutive":
             return -4
-        elif size == "tiny":
+        if size == "tiny":
             return -2
-        elif size == "small":
+        if size == "small":
             return -1
-        elif size == "medium":
+        if size == "medium":
             return 0
-        elif size == "large":
+        if size == "large":
             return 1
-        elif size == "huge":
+        if size == "huge":
             return 2
-        elif size == "gargantuan":
+        if size == "gargantuan":
             return 4
-        elif size == "colossal":
+        if size == "colossal":
             return 8
         return 0
 

src/pf1e_simulator/spells.py

@@ -68,8 +68,18 @@ class AreaEffect:
     effects: tuple[SpellEffect, ...] = ()
     save_for_half: bool = True
 
+@dataclass(frozen=True)
+class SummonEffect:
+    """Summoning spell effect.
     
-SpellEffect = DamageEffect | ConditionEffect | HealEffect | BuffEffect | AreaEffect
+    - creature: path to the creature JSON file (e.g., "data/monsters/celestial_wolf.json")
+    - duration_rounds: how long the summoned creature stays
+    """
+    creature: str
+    duration_rounds: int
+
+
+SpellEffect = DamageEffect | ConditionEffect | HealEffect | BuffEffect | AreaEffect | SummonEffect
 
 
 @dataclass(frozen=True)
@@ -134,6 +144,11 @@ def _parse_effect(data: dict[str, Json]) -> SpellEffect:
             effects=tuple(_parse_effect(e) for e in data["effects"]),  # type: ignore[index]
             save_for_half=bool(data.get("save_for_half", True)),
         )
+    if effect_type == "summon":
+        return SummonEffect(
+            creature=str(data["creature"]),  # type: ignore[index]
+            duration_rounds=int(data["duration_rounds"]),  # type: ignore[arg-type]
+        )
     raise ValueError(f"Unknown effect type: {effect_type}")
 
 

tests/test_spells.py

@@ -108,13 +108,13 @@ def _make_engine(
 
 
 class TestSpellLoading:
-    """Given: data/spells/ directory with 10 JSON spell files
+    """Given: data/spells/ directory with 11 JSON spell files
     When: load_spell_registry is called
-    Then: all 10 spells are loaded with correct fields."""
+    Then: all 11 spells are loaded with correct fields."""
 
     def test_loads_all_10_spells(self) -> None:
         reg = load_spell_registry(_SPELLS_DIR)
-        assert len(reg) == 10
+        assert len(reg) == 11
 
     def test_spell_names_present(self) -> None:
         reg = load_spell_registry(_SPELLS_DIR)
@@ -122,6 +122,7 @@ class TestSpellLoading:
             "Magic Missile", "Burning Hands", "Fireball", "Lightning Bolt",
             "Cure Light Wounds", "Cure Moderate Wounds", "Hold Person",
             "Fear", "Bull's Strength", "Acid Arrow",
+            "Summon Monster II",
         }
         assert set(reg) == expected
 
@@ -411,3 +412,26 @@ class TestSpellDamageWithDr:
         engine._cast_spell(c, t, "Fireball")
         # Save fails (2), 6d6 rolls all 3 = 18 damage, DR 5/- -> 13 damage
         assert t.hp == hp_before - 13
+
+
+class TestSummonMonster:
+    """Given: a caster casting Summon Monster II
+    When: _cast_spell is called
+    Then: a celestial wolf is summoned adjacent to the caster."""
+
+    def test_summon_creature(self) -> None:
+        caster = _make_caster()
+        target = _make_target(hp_max=100)
+        engine, c, t = _make_engine(caster, target, [3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3])
+        hp_before = len(engine._states)
+        engine._cast_spell(c, t, "Summon Monster II")
+        # Caster + target + summoned = 3 combatants
+        assert len(engine._states) == hp_before + 1
+        # Find the summoned creature
+        summoned = [s for s in engine._states if s.combatant.id == "celestial_wolf"]
+        assert len(summoned) == 1
+        assert summoned[0].side == "players"
+        # Check it has correct HP
+        assert summoned[0].hp == 15
+        # Check transcript mentions summon
+        assert any("summon" in line.lower() for line in engine._transcript)