fix(rules): exclude weapon special ability dice from critical multiplication

PF1e (CRB Critical Hits): "additional damage dice from weapon special
abilities (such as flaming) are not multiplied when you score a critical
hit". _resolve_hit_damage now multiplies only the physical dice plus flat
bonuses by crit_mult; energy-typed component dice are added at 1x (the
energy share on the DR path and the per-component resistance step drop
their crit factor). Sneak precision dice were already excluded. README
and the module convention list updated.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

README.md

@@ -303,7 +303,10 @@ vers la fiche Foundry d'origine.
 Règles modélisées :
 
 - 1 naturel = échec automatique ; 20 naturel = touche + menace de critique.
-- Critique : (dés + bonus) × multiplicateur ; le 20 naturel au jet de
+- Critique : (dés physiques + bonus plat) × multiplicateur ; les dés
+  énergétiques des spécificités d'arme (flaming, etc.) et les dés de précision
+  ne sont PAS multipliés (exception CRB « Critical Hits ») ; le 20 naturel au
+  jet de
   confirmation confirme automatiquement la critique (conformance P2 — le jet
   de confirmation est un jet d'attaque) ; la RD s'applique après
   multiplication, un type de contournement annule la RD — une RD à plusieurs

src/pf1e_simulator/combat.py

@@ -35,7 +35,9 @@ Phase 0 documented deviations from PF1e (conventions):
   ``count == 1`` (natural multi-attacks do not gain iteratives). Multiple
   natural weapons in a single full attack are not modeled.
 - Natural 1 always misses; natural 20 always hits and threatens a crit.
-- A confirmed crit multiplies the total damage (dice + flat bonus) by crit_mult.
+- A confirmed crit multiplies the base damage (physical dice + flat bonus)
+  by crit_mult; energy weapon-special-ability dice (flaming etc.) and
+  precision dice are NOT multiplied (CRB Critical Hits exception).
 - DR applies once, after crit multiplication, to the PHYSICAL portion of the
   damage only (bludgeoning/piercing/slashing dice, flat bonuses and precision
   dice) — energy damage dealt along with an attack is never reduced by DR
@@ -2532,7 +2534,18 @@ class CombatEngine:
             attacker, "damage", weapon_name=weapon.name, weapon=weapon, dist_ft=dist_ft
         )
         rolls = [c.formula.roll(self._rng) for c in weapon.damage]
-        damage = sum(rolls) + weapon.damage_bonus
+        # PF1e (CRB, Critical Hits): "Precision damage ... and additional
+        # damage dice from weapon special abilities (such as flaming) are not
+        # multiplied when you score a critical hit." Only the base physical
+        # dice ride the multiplier with the flat bonuses; energy-typed
+        # component dice (flaming/frost/shock/...) are added at 1x.
+        physical_dice = sum(
+            roll
+            for comp, roll in zip(weapon.damage, rolls, strict=True)
+            if _PHYSICAL_DAMAGE_TYPES.issuperset(comp.types)
+        )
+        energy_dice = sum(rolls) - physical_dice
+        damage = physical_dice + weapon.damage_bonus
         damage += resolve_modifiers(dmg_mods)
         # PF1e (CRB Power Attack): +2X damage with a melee weapon, +3X (the
         # bonus increased by half) with a two-handed weapon, a one-handed
@@ -2547,22 +2560,23 @@ class CombatEngine:
             damage += pa_amt * (3 if weapon.two_handed else 2)
         if crit:
             damage *= weapon.crit_mult
-        damage += sneak_total
+        damage += sneak_total + energy_dice
         # PF1e (CRB Damage Reduction): "Damage reduction does not negate ...
         # energy damage dealt along with an attack" — DR reduces only the
         # non-energy share of the damage (physical dice, flat bonuses and
         # precision dice); energy components are cut solely by energy
-        # resistance/immunity in the per-component step below.
-        mult = weapon.crit_mult if crit else 1
+        # resistance/immunity in the per-component step below. The energy
+        # share is its 1x dice: special-ability dice never ride the crit
+        # multiplier (CRB Critical Hits exception).
         energy_share = sum(
-            roll * mult
+            roll
             for comp, roll in zip(weapon.damage, rolls, strict=True)
             if not _PHYSICAL_DAMAGE_TYPES.issuperset(comp.types)
         )
         physical = max(0, damage - energy_share)
         damage = self._apply_dr(physical, weapon, target) + energy_share
         return crit, False, self._apply_energy_resistance_per_component(
-            damage, weapon, rolls, crit=crit, target=target
+            damage, weapon, rolls, target=target
         )
 
     def _concealment_chance(self, target: CombatantState) -> int:
@@ -2739,7 +2753,6 @@ class CombatEngine:
         weapon: AttackSpec,
         rolls: list[int],
         *,
-        crit: bool,
         target: CombatantState,
     ) -> int:
         """Energy resistance / immunity applied PER DAMAGE COMPONENT (B21).
@@ -2750,9 +2763,9 @@ class CombatEngine:
         loses only its fire portion; the slashing dice, the flat bonuses
         (damage_bonus, ability/damage modifiers, Power Attack) and the
         untyped sneak precision dice are never eaten by energy resistance.
-        Each component's share of the final damage is its own roll times
-        the crit multiplier (engine convention: every damage die is
-        multiplied on a crit) and its reduction is capped at that share.
+        Each component's share of the final damage is its own roll at 1x:
+        energy (weapon special ability) dice are never multiplied on a crit
+        (CRB Critical Hits exception), so no crit factor rides this step.
         A component carrying several energy types uses the largest matching
         resistance (documented simplification: one die roll cannot be split
         across the listed types). Physical-only components match nothing in
@@ -2762,9 +2775,8 @@ class CombatEngine:
         attack); single-component weapons keep the exact arithmetic of the
         old lumped-total path.
         """
-        mult = weapon.crit_mult if crit else 1
         for comp, roll in zip(weapon.damage, rolls, strict=True):
-            damage -= self._energy_reduction(roll * mult, frozenset(comp.types), target)
+            damage -= self._energy_reduction(roll, frozenset(comp.types), target)
         return max(0, damage)
 
     def _energy_reduction(

tests/test_conformance_energy.py

@@ -125,6 +125,23 @@ def test_fire_immunity_negates_only_fire_component() -> None:
     assert eng._states[1].hp == 94
 
 
+def test_crit_does_not_multiply_flaming_dice() -> None:
+    """CRB Critical Hits: "additional damage dice from weapon special
+    abilities (such as flaming) are not multiplied when you score a critical
+    hit" — the slashing die rides the x2, the fire die stays at 1x."""
+    weapon = _attack("fiery-blade", _MIXED)
+    hero = _combatant("hero", attacks=(weapon,))
+    foe = _combatant("foe")
+    # d20=20 threatens, confirm 20 auto-crits, slashing 1d6=6, fire 1d6=4.
+    eng = _engine([hero, foe], [(0, 0), (0, 1)], ["players", "monsters"],
+                  [20, 20, 6, 4])
+    result = eng.resolve_attack(eng._states[0], eng._states[1], weapon)
+    assert result.crit is True
+    # 6x2 + 4 = 16 — NOT (6+4)x2 = 20 (the old multiply-everything convention).
+    assert result.damage == 16
+    assert eng._states[1].hp == 84
+
+
 def test_physical_only_weapon_ignores_energy_resistance() -> None:
     """(c) a physical-only weapon vs fire resistance is untouched."""
     weapon = _attack("sword", (("1d6", ("slashing",)),))