fix(rules): aid another bonuses expire at the beginning of the aider's next turn, not the beneficiary's (SRD Aid Another)

src/pf1e_simulator/combat.py

@@ -753,10 +753,14 @@ class CombatantState:
     # Aid another & run (not in the frozen data model): aid bonuses granted to
     # this combatant by an ally's aid another — aid_attack_bonus is consumed by
     # its next attack roll, aid_ac_bonus applies against the next attack that
-    # targets it. Both (and the running flag, which denies the Dex bonus to AC
-    # until the runner's next turn) reset at the start of the combatant's turn.
+    # targets it. PF1e (SRD "Aid Another"): the +2 lasts "as long as that
+    # attack comes before the beginning of your next turn" — YOUR = the AIDER,
+    # so each grant is tracked on the aider (target id, mode) and expires at
+    # the start of the aider's next turn. The running flag denies the Dex
+    # bonus to AC until the runner's next turn.
     aid_attack_bonus: int = 0
     aid_ac_bonus: int = 0
+    aid_grants: list[tuple[str, str]] = field(default_factory=list)
     running: bool = False
     # Bleeding (V5b, not in the frozen data model): damage taken at the start
     # of each turn; any effect that restores hit points clears it.
@@ -1780,8 +1784,7 @@ class CombatEngine:
             state.defensive_ac_bonus = 0
             state.fight_defensively = False
             state.total_defense = False
-            state.aid_attack_bonus = 0
-            state.aid_ac_bonus = 0
+            self._expire_aid_grants(state)
             state.running = False
             state.swift_used_this_turn = False
         original = self._policy(self, state)
@@ -4221,6 +4224,7 @@ class CombatEngine:
                 target.aid_ac_bonus += _AID_ANOTHER_BONUS
             else:
                 target.aid_attack_bonus += _AID_ANOTHER_BONUS
+            state.aid_grants.append((target.combatant.id, mode))
         self._log(
             f"round {self._current_round} {state.combatant.id}: "
             f"aid another {target.combatant.id} ({mode}) "
@@ -4229,6 +4233,29 @@ class CombatEngine:
         )
         return ActionResult(kind=kind, ok=True, reason=_REASON_OK)
 
+    def _expire_aid_grants(self, aider: CombatantState) -> None:
+        """Remove this aider's unspent aid bonuses from its beneficiaries.
+
+        PF1e (SRD "Aid Another"): the +2 lasts "as long as that attack comes
+        before the beginning of your next turn" — your = the AIDER's turn, so
+        expiry is tracked on the aider. Each grant subtracts its +2 from the
+        beneficiary's pool (floor 0 — a bonus already consumed by an attack
+        is untouched). Simplification: an aider removed before its next turn
+        never expires its grants (the engine has no death hook for them).
+        """
+        for target_id, mode in aider.aid_grants:
+            for state in self._states:
+                if state.combatant.id != target_id:
+                    continue
+                if mode == "ac":
+                    state.aid_ac_bonus = max(0, state.aid_ac_bonus - _AID_ANOTHER_BONUS)
+                else:
+                    state.aid_attack_bonus = max(
+                        0, state.aid_attack_bonus - _AID_ANOTHER_BONUS
+                    )
+                break
+        aider.aid_grants = []
+
     def _execute_run(
         self, state: CombatantState, target: CombatantState | None, action: Action
     ) -> ActionResult: