fix(rules): natural weapons get no BAB iteratives, secondary attacks at -5

PF1e (CRB "Natural Attacks"):
- Natural weapons (natural=true) get exactly one swing per full attack,
  regardless of BAB (no BAB iteratives for natural attacks).
- Secondary natural attacks (secondary=true) attack at BAB -5; the
  Multiattack feat reduces this to -2.
- Manifested in combat.py (_full_attack_weapon, _resolve_swing),
  models.py (AttackSpec.natural/secondary), 6 data JSONs, 4 new tests,
  and README documentation.

1461 passed, ruff clean, basedpyright 0 errors.

README.md

@@ -647,9 +647,16 @@ Règles modélisées :
   résout `count` balayages indépendants dans la même action ; les balayages
   restants sont perdus si la cible tombe (inconsciente ou morte) en cours de
   rafale. Attaque à outrance (action à round complet) : à BAB +6/+11/+16, des
-  attaques supplémentaires à -5/-10/-15 ; les armes naturelles (`count` > 1)
-  ne gagnent pas d'itératifs. Plusieurs armes naturelles en une seule attaque
-  à outrance ne sont pas modélisées.
+  attaques supplémentaires à -5/-10/-15 pour les armes manufacturées. Les
+  armes naturelles (`natural: true` dans le JSON — morsures, griffes, sabots,
+  talons…) ne gagnent **jamais** d'itératifs : une attaque à outrance avec une
+  arme naturelle résout **un seul** balayage quel que soit le BAB (CRB
+  « Natural Attacks » : « You do not receive additional natural attacks for a
+  high base attack bonus »). Une attaque naturelle marquée `secondary: true`
+  (les attaques secondaires du bestiaire) frappe à **BAB −5** ; le don
+  Multiattack réduit cette pénalité à **−2** (CRB « Natural Attacks » /
+  « Multiattack »). Plusieurs armes naturelles en une seule attaque à outrance
+  ne sont pas modélisées.
   Choix de l'arme : `Action(kind="attack", weapon_id=...)` et
   `Action(kind="full_attack", weapon_id=...)` frappent avec l'arme désignée
   (l'arc plutôt que l'épée, l'arme principale plutôt que la secondaire) au

data/monsters/celestial_wolf.json

@@ -33,14 +33,17 @@
    "damage": [
     {
      "formula": "1d6+1",
-          "types": ["piercing"]
+     "types": [
+      "piercing"
+     ]
     }
    ],
    "damage_bonus": 1,
    "crit_range": 20,
    "crit_mult": 2,
    "reach_ft": 5,
-      "count": 1
+   "count": 1,
+   "natural": true
   }
  ],
  "source": "summon monster II",

data/monsters/giant_belostomatid.json

@@ -15,30 +15,54 @@
   "cha_score": 2
  },
  "hp_max": 30,
-  "ac": { "total": 15, "touch": 10, "flat_footed": 14 },
+ "ac": {
+  "total": 15,
+  "touch": 10,
+  "flat_footed": 14
+ },
  "bab": 3,
  "initiative_mod": 1,
  "speed_land_ft": 20,
-  "saves": { "fort": 7, "ref": 2, "will": 1 },
+ "saves": {
+  "fort": 7,
+  "ref": 2,
+  "will": 1
+ },
  "attacks": [
   {
    "name": "bite",
    "kind": "melee",
    "attack_bonus": 4,
-      "damage": [{ "formula": "1d6", "types": ["piercing"] }],
+   "damage": [
+    {
+     "formula": "1d6",
+     "types": [
+      "piercing"
+     ]
+    }
+   ],
    "damage_bonus": 2,
    "crit_mult": 2,
-      "reach_ft": 10
+   "reach_ft": 10,
+   "natural": true
   },
   {
    "name": "claw",
    "kind": "melee",
    "attack_bonus": 4,
-      "damage": [{ "formula": "1d4", "types": ["slashing"] }],
+   "damage": [
+    {
+     "formula": "1d4",
+     "types": [
+      "slashing"
+     ]
+    }
+   ],
    "damage_bonus": 2,
    "crit_mult": 2,
    "count": 2,
-      "reach_ft": 10
+   "reach_ft": 10,
+   "natural": true
   }
  ],
  "cmb": 6,

data/pcs/harvie.json

@@ -34,14 +34,17 @@
    "damage": [
     {
      "formula": "1d4",
-          "types": ["piercing"]
+     "types": [
+      "piercing"
+     ]
     }
    ],
    "damage_bonus": 0,
    "crit_range": 20,
    "crit_mult": 2,
    "reach_ft": 5,
-      "count": 1
+   "count": 1,
+   "natural": true
   },
   {
    "id": "harvie:claw",
@@ -51,14 +54,17 @@
    "damage": [
     {
      "formula": "1d3",
-          "types": ["slashing"]
+     "types": [
+      "slashing"
+     ]
     }
    ],
    "damage_bonus": 0,
    "crit_range": 20,
    "crit_mult": 2,
    "reach_ft": 5,
-      "count": 1
+   "count": 1,
+   "natural": true
   }
  ],
  "source": "fiches_personnages/harvie_sheet.json",

data/pcs/ierlieth.json

@@ -34,14 +34,17 @@
    "damage": [
     {
      "formula": "1d4",
-          "types": ["piercing"]
+     "types": [
+      "piercing"
+     ]
     }
    ],
    "damage_bonus": 1,
    "crit_range": 20,
    "crit_mult": 2,
    "reach_ft": 5,
-      "count": 1
+   "count": 1,
+   "natural": true
   }
  ],
  "source": "fiches_personnages/ierlieth_sheet.json",

data/pcs/misty.json

@@ -86,7 +86,8 @@
    "crit_range": 20,
    "crit_mult": 2,
    "reach_ft": 5,
-      "count": 1
+   "count": 1,
+   "natural": true
   },
   {
    "name": "Bite (attaque naturelle)",
@@ -104,7 +105,8 @@
    "crit_range": 20,
    "crit_mult": 2,
    "reach_ft": 5,
-      "count": 1
+   "count": 1,
+   "natural": true
   },
   {
    "name": "Unarmed Strike",

data/pcs/oni.json

@@ -87,7 +87,8 @@
    "crit_range": 20,
    "crit_mult": 2,
    "reach_ft": 5,
-      "count": 1
+   "count": 1,
+   "natural": true
   }
  ],
  "source": "fiches_personnages/oni_sheet.json",

src/pf1e_simulator/combat.py

@@ -6699,6 +6699,12 @@ class CombatEngine:
         target_live = self._stats[target.combatant.id]
         hp_before = target.hp
         override = bonus_override
+        if weapon.secondary:
+            # PF1e (CRB "Natural Attacks"): secondary natural attacks are at
+            # base attack bonus -5; the Multiattack feat reduces this to -2.
+            penalty = 2 if self._has_feat(attacker, "Multiattack") else 5
+            base = weapon.attack_bonus if override is None else override
+            override = base - penalty
         if attack_penalty:
             base = weapon.attack_bonus if override is None else override
             override = base + attack_penalty
@@ -6829,6 +6835,12 @@ class CombatEngine:
         if weapon.count > 1:
             self._attack(attacker, target, weapon, attack_penalty=attack_penalty)
             return
+        if weapon.natural:
+            # PF1e (CRB "Natural Attacks"): "You do not receive additional
+            # natural attacks for a high base attack bonus." One swing per
+            # natural weapon, at its own attack bonus.
+            self._attack(attacker, target, weapon, attack_penalty=attack_penalty)
+            return
         n = min(
             _MAX_ITERATIVES,
             1 + max(0, (attacker.combatant.bab - 1) // _ITERATIVE_PENALTY),

src/pf1e_simulator/models.py

@@ -249,7 +249,11 @@ class AttackSpec(_FrozenModel):
     reach). Without the flag a melee attack follows the creature's natural
     reach, which is a DISK: a Large creature's natural attack (its JSON
     `reach_ft` IS its natural reach, 10 ft) still strikes and threatens
-    adjacent squares.
+    adjacent squares. `natural` marks a natural weapon (bite, claw, etc.):
+    PF1e (CRB "Natural Attacks") grants no BAB iteratives for natural
+    weapons. `secondary` marks a secondary natural attack (tail, wing, etc.):
+    the engine applies -5 to the attack bonus (reduced to -2 with the
+    Multiattack feat).
     """
 
     id: str
@@ -266,6 +270,8 @@ class AttackSpec(_FrozenModel):
     count: int = Field(default=1, ge=1)
     firearm: bool = False
     two_handed: bool = False
+    natural: bool = False
+    secondary: bool = False
 
 
 class DamageReduction(_FrozenModel):

tests/test_natural_attacks.py

@@ -0,0 +1,167 @@
+"""Natural weapon attack rules (CRB "Natural Attacks").
+
+Given an attacker with natural weapons and high BAB
+When a full attack is resolved
+Then natural weapons make exactly one swing each (no BAB iteratives)
+
+Given a secondary natural attack
+When a swing is resolved
+Then the attack bonus is reduced by 5
+
+Given a secondary natural attack and the attacker has the Multiattack feat
+When a swing is resolved
+Then the attack bonus is reduced by 2 (instead of 5)
+"""
+
+from __future__ import annotations
+
+from pf1e_simulator.combat import CombatantState, CombatEngine
+from pf1e_simulator.dice import parse_dice
+from pf1e_simulator.grid import Grid
+from pf1e_simulator.map import MapSpec, TerrainType
+from pf1e_simulator.models import (
+    AbilityScores,
+    AbilitySpec,
+    ACProfile,
+    AttackSpec,
+    Combatant,
+    DamageComponent,
+    Saves,
+)
+from pf1e_simulator.rng import ScriptedRng
+
+
+def _make_combatant(
+    cid: str,
+    *,
+    side: str,
+    bab: int = 1,
+    attack_bonus: int = 0,
+    natural: bool = False,
+    secondary: bool = False,
+    features: tuple[str, ...] = (),
+) -> Combatant:
+    """Build a minimal Combatant with one attack."""
+    attack = AttackSpec(
+        id=f"{cid}-w",
+        name="weapon",
+        kind="melee",
+        attack_bonus=attack_bonus,
+        damage=[DamageComponent(formula=parse_dice("1d6"), types=["slashing"])],
+        natural=natural,
+        secondary=secondary,
+    )
+    return Combatant(
+        id=cid,
+        name=cid,
+        level=1,
+        size="Medium",
+        bab=bab,
+        abilities=AbilityScores(
+            str_score=10, dex_score=10, con_score=10,
+            int_score=10, wis_score=10, cha_score=10,
+        ),
+        hp_max=20,
+        ac=ACProfile(total=15, touch=10, flat_footed=10),
+        initiative_mod=0,
+        speed_land_ft=30,
+        saves=Saves(fort=0, ref=0, will=0),
+        attacks=[attack],
+        features=[AbilitySpec(name=f, category="feat") for f in features],
+    )
+
+
+def _make_grid() -> Grid:
+    """8x8 floor grid."""
+    legend = {".": TerrainType(type="floor", move_cost=1)}
+    spec = MapSpec(name="test", terrain=tuple(["." * 8] * 8), legend=legend)
+    return Grid.from_spec(spec)
+
+
+def _make_engine(
+    queue: list[int],
+    attacker: Combatant,
+    target: Combatant,
+    attacker_pos: tuple[int, int] = (1, 1),
+    target_pos: tuple[int, int] = (1, 2),
+) -> tuple[CombatEngine, CombatantState, CombatantState]:
+    """Create engine with two adjacent combatants and return (engine, atk_state, tgt_state)."""
+    a = CombatantState(combatant=attacker, side="players", pos=attacker_pos,
+                       hp=attacker.hp_max)
+    t = CombatantState(combatant=target, side="monsters", pos=target_pos,
+                       hp=target.hp_max)
+    engine = CombatEngine(ScriptedRng(queue), _make_grid(), [a, t])
+    return engine, a, t
+
+
+def _swing_lines(engine: CombatEngine, target_id: str) -> list[str]:
+    """Transcript lines that resolved a swing against the target."""
+    return [line for line in engine._transcript if f"vs {target_id}" in line]
+
+
+# BAB iteratives
+
+
+def test_natural_weapon_no_bab_iteratives() -> None:
+    """Natural weapon with BAB 16 produces exactly 1 swing, not 4.
+
+    PF1e (CRB "Natural Attacks"): you do not receive additional natural
+    attacks for a high base attack bonus.
+    """
+    atk = _make_combatant("a1", side="players", bab=16, attack_bonus=18, natural=True)
+    tgt = _make_combatant("t1", side="monsters", bab=1)
+    # RNG: [d20=15] attack roll; on hit -> damage dice (1d6=4)
+    engine, a, t = _make_engine([15, 4], atk, tgt)
+    engine._full_attack(a, t)
+    swings = _swing_lines(engine, "t1")
+    assert len(swings) == 1, f"natural weapon should swing once, got {len(swings)}: {swings}"
+
+
+def test_manufactured_weapon_gets_iteratives() -> None:
+    """Non-natural weapon with BAB 16 produces 4 iterative swings (16/11/6/1)."""
+    atk = _make_combatant("a2", side="players", bab=16, attack_bonus=18)
+    tgt = _make_combatant("t2", side="monsters", bab=1)
+    # RNG: 4 swings, each = 1 attack d20 (15) + 1 damage roll (3); target
+    # survives 4 x 3 = 12 damage (hp_max 20) so all iteratives resolve.
+    queue = [15, 3] * 4
+    engine, a, t = _make_engine(queue, atk, tgt)
+    engine._full_attack(a, t)
+    swings = _swing_lines(engine, "t2")
+    assert len(swings) == 4, f"manufactured weapon should swing 4x, got {len(swings)}: {swings}"
+
+
+def test_secondary_natural_attack_penalty() -> None:
+    """Secondary natural attack has -5 penalty on attack bonus.
+
+    PF1e (CRB "Natural Attacks"): secondary natural attacks are at
+    base attack bonus -5.
+    """
+    atk = _make_combatant("a3", side="players", bab=1, attack_bonus=10,
+                          natural=True, secondary=True)
+    tgt = _make_combatant("t3", side="monsters", bab=1)
+    # RNG: [d20=15] attack -> 10 - 5 = 5; total = 15 + 5 = 20 >= AC 15 -> hit; damage 1d6=4
+    engine, a, t = _make_engine([15, 4], atk, tgt)
+    engine._full_attack(a, t)
+    swings = _swing_lines(engine, "t3")
+    assert len(swings) == 1
+    # base_bonus is 5 (10 - 5 secondary penalty)
+    assert "d20=15+5=20" in swings[0]
+
+
+def test_multiattack_feat_reduces_secondary_penalty() -> None:
+    """Multiattack feat reduces secondary natural penalty from -5 to -2.
+
+    PF1e (CRB "Multiattack"): secondary natural attacks are at
+    base attack bonus -2 (instead of -5).
+    """
+    atk = _make_combatant("a4", side="players", bab=1, attack_bonus=10,
+                          natural=True, secondary=True,
+                          features=("Multiattack",))
+    tgt = _make_combatant("t4", side="monsters", bab=1)
+    # RNG: [d20=15] attack -> 10 - 2 = 8; total = 15 + 8 = 23 >= AC 15 -> hit; damage 1d6=4
+    engine, a, t = _make_engine([15, 4], atk, tgt)
+    engine._full_attack(a, t)
+    swings = _swing_lines(engine, "t4")
+    assert len(swings) == 1
+    # base_bonus is 8 (10 - 2 Multiattack)
+    assert "d20=15+8=23" in swings[0]