fix(rules): cover grants a Reflex-save bonus against area effects (SRD cover.md 'Cover and Reflex Saves': +2 vs standard cover - half the AC value, so +1 partial/+2 standard/+4 improved; soft cover grants none) - _area_save adds terrain cover//2 from the effect's point of origin (burst center, caster square for cone/line) to Reflex rolls; resolve_save gains an explicit flat_bonus

tests/test_area_shapes.py

@@ -91,10 +91,31 @@ _BURST_SPARKS = SpellSpec(
     ),
 )
 
+_BURST_GUST = SpellSpec(
+    name="Burst Gust",
+    level=3,
+    school="evocation",
+    range="long",
+    save="ref",
+    base_dc=10,
+    effects=(
+        AreaEffect(
+            radius_ft=20,
+            effects=(
+                DamageEffect(
+                    formula=parse_dice("1d6"), types=("fire",), half_on_save=True
+                ),
+            ),
+            save_for_half=True,
+        ),
+    ),
+)
+
 _REGISTRY = {
     "Cone Sparks": _CONE_SPARKS,
     "Line Sparks": _LINE_SPARKS,
     "Burst Sparks": _BURST_SPARKS,
+    "Burst Gust": _BURST_GUST,
 }
 
 
@@ -129,7 +150,7 @@ def _caster(hp: int = 100) -> CombatantState:
         make_combatant(
             "caster",
             hp=hp,
-            spells=["Cone Sparks", "Line Sparks", "Burst Sparks"],
+            spells=["Cone Sparks", "Line Sparks", "Burst Sparks", "Burst Gust"],
             spell_slots={1: 9, 2: 9, 3: 9},
         ),
         "players",
@@ -137,6 +158,24 @@ def _caster(hp: int = 100) -> CombatantState:
     )
 
 
+def _cover_grid(cover_cells: dict[Pos, int], side: int = 12) -> Grid:
+    """Open floor with terrain-only cover cells; the char encodes the bonus."""
+    legend = {".": TerrainType(type="floor", move_cost=1)}
+    for bonus in cover_cells.values():
+        legend[str(bonus)] = TerrainType(
+            type=f"cover_{bonus}", move_cost=1, cover_bonus=bonus
+        )
+    rows = tuple(
+        "".join(
+            str(cover_cells[(r, c)]) if (r, c) in cover_cells else "."
+            for c in range(side)
+        )
+        for r in range(side)
+    )
+    spec = MapSpec(name="cover", terrain=rows, legend=legend)
+    return Grid.from_spec(spec)
+
+
 # ---------------------------------------------------------------------------
 # cone: 15 ft in front of the caster, ±45° wide, origin cell excluded
 # ---------------------------------------------------------------------------
@@ -393,6 +432,60 @@ def test_burst_still_centers_on_the_target_and_ignores_the_caster_side() -> None
     assert foe_out.hp == 100
 
 
+# ---------------------------------------------------------------------------
+# cover and Reflex saves (CRB "Cover and Reflex Saves")
+# ---------------------------------------------------------------------------
+
+
+def test_improved_cover_grants_reflex_bonus_against_a_burst() -> None:
+    """Given: a Reflex-for-half burst point-cast at (6,6); an improved-cover
+    cell (+8, cover_bonus 8, no LoS block) at (6,7) between the center and
+    foe_cover (6,8); foe_open (4,6) inside the radius with no cover; both
+    roll d20=10 with a +0 Reflex bonus against DC 13
+    When: the burst resolves
+    Then: foe_cover's Reflex total is 10+4=14 (the +8 cover grants +2 on
+    Reflex, half the AC bonus) -> saves -> half of 4 = 2 damage; foe_open
+    totals 10 -> fails -> full 4 damage."""
+    caster = _caster()
+    caster.pos = (6, 0)
+    foe_cover = make_state(make_combatant("foe_cover", hp=100), "monsters", (6, 8))
+    foe_open = make_state(make_combatant("foe_open", hp=100), "monsters", (4, 6))
+    grid = _cover_grid({(6, 7): 8})
+    eng = CombatEngine(
+        ScriptedRng([10, 4, 10, 4]), grid, [caster, foe_cover, foe_open],
+        spell_registry=_REGISTRY,
+    )
+    result = eng._execute(
+        caster, Action(kind="cast_spell", spell_name="Burst Gust", target_pos=(6, 6))
+    )
+    assert result.ok
+    assert foe_cover.hp == 100 - 2
+    assert foe_open.hp == 100 - 4
+    assert caster.hp == 100  # distance 6 > 20 ft: outside the burst
+
+
+def test_partial_cover_grants_plus_one_reflex_against_a_burst() -> None:
+    """Given: the same Reflex-for-half burst, but the sheltering cell grants
+    partial cover (+2 AC) and foe_partial rolls d20=12 against DC 13 with a
+    +0 Reflex bonus
+    When: the burst resolves
+    Then: 12 + 1 (half of the +2 partial cover) = 13 meets the DC -> saves
+    -> half damage; the +2 Reflex a full-value bonus would grant is NOT
+    applied (CRB: partial cover is +2 AC / +1 Reflex)."""
+    caster = _caster()
+    caster.pos = (6, 0)
+    foe_partial = make_state(make_combatant("foe_partial", hp=100), "monsters", (6, 8))
+    grid = _cover_grid({(6, 7): 2})
+    eng = CombatEngine(
+        ScriptedRng([12, 4]), grid, [caster, foe_partial], spell_registry=_REGISTRY
+    )
+    result = eng._execute(
+        caster, Action(kind="cast_spell", spell_name="Burst Gust", target_pos=(6, 6))
+    )
+    assert result.ok
+    assert foe_partial.hp == 100 - 2
+
+
 # ---------------------------------------------------------------------------
 # loader: shape parsing
 # ---------------------------------------------------------------------------