feat(combat): grant soft cover (+4 AC) to ranged attacks through creatures

src/pf1e_simulator/los.py

@@ -75,10 +75,12 @@ class _LineGrid:
         a: Pos,
         b: Pos,
         blocking: Callable[[TerrainType], bool],
+        occupied: frozenset[Pos] = frozenset(),
     ) -> None:
         self._grid = grid
         self._exclude = frozenset({a, b})
         self._blocking = blocking
+        self._occupied = occupied
 
     def blocked(self, p1: Pt, p2: Pt) -> bool:
         min_x = min(p1[0], p2[0])
@@ -90,9 +92,9 @@ class _LineGrid:
                 pos = (row, col)
                 if pos in self._exclude or not self._grid.in_bounds(pos):
                     continue
-                if self._blocking(self._grid.terrain_at(pos)) and _segment_hits_cell(
-                    p1, p2, row, col
-                ):
+                if (
+                    pos in self._occupied or self._blocking(self._grid.terrain_at(pos))
+                ) and _segment_hits_cell(p1, p2, row, col):
                     return True
         return False
 
@@ -113,16 +115,30 @@ def has_line_of_effect(grid: Grid, a: Pos, b: Pos) -> bool:
     )
 
 
-def has_cover(grid: Grid, attacker: Pos, target: Pos, *, ranged: bool) -> bool:
+def has_cover(
+    grid: Grid,
+    attacker: Pos,
+    target: Pos,
+    *,
+    ranged: bool,
+    occupied: frozenset[Pos] = frozenset(),
+) -> bool:
     """Cover iff every attacker corner has at least one blocked target corner.
 
     The attacker picks their single best corner (PF1e ranged cover rule);
-    Phase 0 documented deviation: melee reuses the same corner rule.
+    Phase 0 documented deviation: melee reuses the same corner rule. For
+    ranged attacks, squares occupied by other creatures also block the
+    lines (soft cover, CRB); melee ignores creatures.
     """
     if attacker == target:
         return False
-    _ = ranged
-    lines = _LineGrid(grid, attacker, target, _grants_cover)
+    lines = _LineGrid(
+        grid,
+        attacker,
+        target,
+        _grants_cover,
+        occupied if ranged else frozenset(),
+    )
     return not any(
         all(not lines.blocked(corner_a, corner_t) for corner_t in _corners(target))
         for corner_a in _corners(attacker)