fix(rules): bursts cannot affect creatures in total cover from the point of origin (SRD aiming-a-spell.md: a burst "can't affect creatures with total cover from its point of origin (in other words, its effects don't extend around corners)"; Line of Effect: a burst affects only what it has LoE to from its origin) - _area_creatures skips creatures whose occupied cells have no line of effect from the burst center

tests/test_area_shapes.py

@@ -327,10 +327,54 @@ def test_line_behind_a_wall_does_not_hit_sheltered_creatures() -> None:
 
 
 # ---------------------------------------------------------------------------
-# burst: unchanged circle around the resolved center
+# burst: circle around the center, minus creatures in total cover of it
 # ---------------------------------------------------------------------------
 
 
+def test_burst_does_not_extend_around_a_solid_barrier() -> None:
+    """Given: a 20-ft burst point-cast at center (6,3); wall cells at col 5
+    (rows 5-7); foe_open (4,3) inside the radius with clear LoE, foe_behind
+    (6,7) inside the radius but behind the wall (total cover from the
+    center)
+    When: the burst resolves (caster at (6,2) is in the radius too)
+    Then: the caster and foe_open take damage (two 1d6 consumed); foe_behind
+    is untouched - a burst "can't affect creatures with total cover from its
+    point of origin" (its effects don't extend around corners)."""
+    caster = _caster()
+    walls = frozenset({(5, 5), (6, 5), (7, 5)})
+    foe_open = make_state(make_combatant("foe_open", hp=100), "monsters", (4, 3))
+    foe_behind = make_state(make_combatant("foe_behind", hp=100), "monsters", (6, 7))
+    eng = CombatEngine(
+        ScriptedRng([4, 4]), _walled_grid(walls), [caster, foe_open, foe_behind],
+        spell_registry=_REGISTRY,
+    )
+    result = eng._execute(
+        caster, Action(kind="cast_spell", spell_name="Burst Sparks", target_pos=(6, 3))
+    )
+    assert result.ok
+    assert caster.hp == 100 - 4
+    assert foe_open.hp == 100 - 4
+    assert foe_behind.hp == 100
+
+
+def test_burst_open_field_control_hits_creatures_behind_the_center() -> None:
+    """Given: the same layout on an OPEN grid (no walls)
+    When: the 20-ft burst point-cast at (6,3) resolves
+    Then: all three creatures (caster, foe_open, foe_behind at distance 4)
+    are inside the radius and affected - the LoE filter drops nothing when
+    there is no barrier."""
+    caster = _caster()
+    foe_open = make_state(make_combatant("foe_open", hp=100), "monsters", (4, 3))
+    foe_behind = make_state(make_combatant("foe_behind", hp=100), "monsters", (6, 7))
+    eng = _engine([caster, foe_open, foe_behind], [4, 4, 4])
+    eng._execute(
+        caster, Action(kind="cast_spell", spell_name="Burst Sparks", target_pos=(6, 3))
+    )
+    assert caster.hp == 100 - 4
+    assert foe_open.hp == 100 - 4
+    assert foe_behind.hp == 100 - 4
+
+
 def test_burst_still_centers_on_the_target_and_ignores_the_caster_side() -> None:
     """Given: caster (6,2); foe_in (4,4) and foe_out (2,0) around a burst
     centered on target_id=foe_in (radius 20 ft = 4 cells)