feat(combat): support partial and improved cover levels

src/pf1e_simulator/combat.py

@@ -115,7 +115,7 @@ if TYPE_CHECKING:
     TrickCondition = Literal["dazzled", "blinded", "deafened", "entangled", "nauseated"]
 
 from pf1e_simulator.los import (
-    has_cover_cells,
+    cover_bonus_cells,
     has_line_of_effect_cells,
 )
 
@@ -123,7 +123,6 @@ _SQUARE_FT = 5  # Phase 0 maps use 5-ft squares
 _DEATH_FLOOR = -10  # PF1e: dead when hp < -10 or -CON, whichever is lower
 _NATURAL_ONE = 1  # PF1e: natural 1 always misses
 _NATURAL_TWENTY = 20  # PF1e: natural 20 always hits and threatens
-_COVER_AC_BONUS = 4  # PF1e: partial cover grants +4 AC
 _RANGE_INCREMENT_PENALTY = 2  # PF1e: -2 per full range increment beyond the first
 _MAX_RANGE_INCREMENTS = 10  # PF1e: projectile weapons shoot up to 10 increments
 _MAX_TOUCH_RANGE_INCREMENTS = 5  # PF1e: thrown/firearm touch weapons shoot up to 5 increments
@@ -720,6 +719,7 @@ class CombatEngine:
                 "move_cost": cell.move_cost,
                 "blocks_los": cell.blocks_los,
                 "cover": cell.cover,
+                "cover_bonus": cell.cover_bonus,
             }
             for cell in (seen[name] for name in sorted(seen))
         )
@@ -1418,14 +1418,13 @@ class CombatEngine:
             if s.active and s is not attacker and s is not target
             for cell in s.occupied_cells()
         )
-        if has_cover_cells(
+        ac += cover_bonus_cells(
             self._grid,
             attacker.occupied_cells(),
             target.occupied_cells(),
             ranged=self._is_ranged_attack(weapon),
             occupied=occupied,
-        ):
-            ac += _COVER_AC_BONUS
+        )
         hit = roll == _NATURAL_TWENTY or (roll != _NATURAL_ONE and total >= ac)
         damage = 0
         concealment_miss = False