fix(rules): apply maneuver AoO damage as a penalty to the maneuver

PF1e (CRB Combat Maneuvers): "If you are hit by the target, you take the
damage normally and apply that amount as a penalty to the attack roll to
perform the maneuver." Capture the provoked AoO's damage in
_execute_maneuver and subtract it from the check total (floored at 0;
natural 20 still succeeds, natural 1 still fails; dropping below 0 hp
still forfeits). Escape and the Improved-feat exemption are untouched.

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

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

README.md

@@ -946,8 +946,12 @@ Règles modélisées :
   (conformance P2). Conformance P2 : tenter une manœuvre (sauf `escape`)
   **provoque une attaque d'opportunité** de la cible, résolue **avant** le jet
   de CMB ; le don « Improved <Maneuver> » correspondant (Improved Trip, …)
-  annule cette provocation ; si l'AoO fait passer l'attaquant sous 0 pv, la
+  annule cette provocation ; les dégâts infligés par cette AoO sont appliqués
-  manœuvre est perdue. L'AoO de manœuvre consomme le budget d'AoO du round de
+  comme **pénalité au jet de manœuvre** (conformance A2 — CRB « Combat
+  Maneuvers » : « apply that amount as a penalty to the attack roll to perform
+  the maneuver », total planché à 0, 20 naturel réussit / 1 naturel échoue
+  toujours) ; si l'AoO fait passer l'attaquant sous 0 pv, la manœuvre est
+  perdue. L'AoO de manœuvre consomme le budget d'AoO du round de
   la cible (Combat Reflexes inclus). Conformance B16 (CRB « Power Attack ») :
   la pénalité −X de Power Attack actif s'applique **au jet de CMB** de la
   manœuvre (X = BAB//4 + 1) — la pénalité couvre « les jets d'attaque de mêlée

src/pf1e_simulator/combat.py

@@ -3839,10 +3839,16 @@ class CombatEngine:
 
         # PF1e (CRB, Combat Maneuver): attempting the maneuver provokes an
         # attack of opportunity from the target — resolved BEFORE the CMB
-        # check — unless the attacker holds the Improved feat for it. Being
+        # check — unless the attacker holds the Improved feat for it. Damage
-        # knocked below 0 hp by that AoO forfeits the maneuver.
+        # taken from that AoO is applied as a penalty to the maneuver check
+        # (CRB: "apply that amount as a penalty to the attack roll to perform
+        # the maneuver"); being knocked below 0 hp by it forfeits the
+        # maneuver.
+        aoo_damage = 0
         if not self._has_feat(state, _IMPROVED_MANEUVER_FEATS[maneuver]):
+            hp_before = state.hp
             self._maneuver_provoked_aoo(state, target)
+            aoo_damage = max(0, hp_before - state.hp)
             if not state.active:
                 return
 
@@ -3855,7 +3861,15 @@ class CombatEngine:
         attacker_cmb = self._maneuver_cmb(state) - pa_amt
         target_cmd = self._maneuver_cmd(target)
         roll = self._rng.d20()
-        total = roll + attacker_cmb
+        # PF1e (CRB Combat Maneuvers): the provoked-AoO damage rides the
+        # check total (floored at 0); natural 20/1 keep their rules below.
+        total = max(0, roll + attacker_cmb - aoo_damage)
+        if aoo_damage:
+            self._log(
+                f"round {self._current_round} {state.combatant.id}: "
+                f"maneuver AoO dealt {aoo_damage} damage "
+                f"(-{aoo_damage} on the check)"
+            )
         m = _ManeuverRoll(
             roll=roll, attacker_cmb=attacker_cmb, total=total,
             target_cmd=target_cmd,

tests/test_conformance_p2.py

@@ -441,6 +441,30 @@ def test_maneuver_aoo_can_drop_attacker_and_forfeit_trip() -> None:
     )
 
 
+def test_maneuver_aoo_damage_penalizes_the_check() -> None:
+    """A provoked AoO that deals N damage turns a would-be hit into a miss.
+
+    PF1e (CRB Combat Maneuvers): "If you are hit by the target, you take the
+    damage normally and apply that amount as a penalty to the attack roll to
+    perform the maneuver." b's AoO deals 6; the trip roll 15 + CMB 1 = 16
+    would beat CMD 11 by 5 — under the -6 penalty the total is 10 and the
+    trip fails.
+    """
+    a = _combatant("a", bab=1)
+    b = _combatant("b", bab=1, attacks=(_sword("b", bonus=5),))
+    # b's AoO: d20 15 + 5 = 20 vs AC 10 -> HIT 6 damage (a survives at 94).
+    eng = _engine([a, b], [(1, 1), (1, 2)], ["players", "monsters"], [15, 6, 15])
+    eng._execute_maneuver(eng._states[0], eng._states[1], "trip")
+    assert eng._states[0].hp == 94
+    assert eng._states[0].active is True
+    assert not any(
+        ac.condition.name == "prone" for ac in eng._states[1].active_conditions
+    )
+    assert any("maneuver AoO dealt 6 damage" in line for line in eng._transcript)
+    trip_line = next(line for line in eng._transcript if "trip vs b" in line)
+    assert "d20=15+1=10 CMD 11 -> FAIL" in trip_line
+
+
 def test_improved_trip_skips_the_provoking_aoo() -> None:
     a = _combatant("a", features=("Improved Trip",))
     b = _combatant("b")