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

tests/test_combat.py

@@ -664,3 +664,58 @@ def test_ranged_weapon_unusable_beyond_maximum_range() -> None:
     assert engine.weapon_for(states[0], states[1]) is None
     result = engine.run()
     assert result.transcript[2] == "round 1 archer: move (0,0)->(0,1)"
+
+
+def test_ranged_soft_cover_from_creature_between() -> None:
+    """A creature between shooter and target grants soft cover (+4 AC)."""
+    archer = make_combatant("archer", attack_bonus=4, kind="ranged", range_increment_ft=60)
+    blocker = make_combatant("blocker", speed=0)
+    target = make_combatant("target", ac=13)
+    states = [
+        make_state(archer, "players", (1, 1)),
+        make_state(blocker, "players", (1, 2)),
+        make_state(target, "monsters", (1, 4)),
+    ]
+    engine = CombatEngine(ScriptedRng([12, 3]), make_grid(), states)
+    result = engine.resolve_attack(states[0], states[2], archer.attacks[0])
+    assert result.ac == 17  # 13 + 4 soft cover
+    assert result.hit is False  # 12 + 4 = 16 < 17
+
+
+def test_melee_soft_cover_ignored_in_resolution() -> None:
+    """Melee attacks ignore creatures for soft cover (CRB: ranged only)."""
+    attacker = make_combatant("attacker", attack_bonus=2)
+    blocker = make_combatant("blocker", speed=0)
+    target = make_combatant("target", ac=13)
+    states = [
+        make_state(attacker, "players", (1, 1)),
+        make_state(blocker, "players", (1, 2)),
+        make_state(target, "monsters", (1, 4)),
+    ]
+    engine = CombatEngine(ScriptedRng([12, 3]), make_grid(), states)
+    result = engine.resolve_attack(states[0], states[2], attacker.attacks[0])
+    assert result.ac == 13  # melee ignores soft cover
+    assert result.hit is True  # 12 + 2 = 14 >= 13
+
+
+def test_ranged_soft_cover_shown_in_transcript() -> None:
+    """Soft cover raises the AC displayed in the attack log line."""
+    archer = make_combatant("archer", attack_bonus=4, kind="ranged", range_increment_ft=60)
+    blocker = make_combatant("blocker", speed=0)
+    target = make_combatant("target", speed=0)
+    states = [
+        make_state(archer, "players", (0, 0)),
+        make_state(blocker, "players", (0, 2)),
+        make_state(target, "monsters", (0, 4)),
+    ]
+    engine = CombatEngine(ScriptedRng([10, 9, 8, 12]), make_grid(), states, round_cap=1)
+    result = engine.run()
+    assert result.transcript == (
+        "initiative: archer d20=10+0=10",
+        "initiative: blocker d20=9+0=9",
+        "initiative: target d20=8+0=8",
+        "round 1 archer: short bow vs target d20=12+4=16 AC 17 -> MISS",
+        "round 1 blocker: wait",
+        "round 1 target: wait",
+        "battle over: draw after 1 rounds",
+    )

tests/test_los.py

@@ -88,3 +88,31 @@ def test_cover_melee_uses_same_corner_rule_in_phase0() -> None:
 def test_cover_same_square_is_false() -> None:
     grid = make_grid(["."])
     assert has_cover(grid, (0, 0), (0, 0), ranged=True) is False
+
+
+def test_soft_cover_creature_between_grants_cover() -> None:
+    """A creature between shooter and target grants cover on ranged attacks."""
+    grid = make_grid([".....", ".....", "....."])
+    occupied = frozenset({(1, 2)})
+    assert has_cover(grid, (1, 0), (1, 4), ranged=True, occupied=occupied) is True
+
+
+def test_soft_cover_melee_ignores_creatures() -> None:
+    """Melee attacks ignore creatures for soft cover (CRB: ranged only)."""
+    grid = make_grid([".....", ".....", "....."])
+    occupied = frozenset({(1, 2)})
+    assert has_cover(grid, (1, 0), (1, 4), ranged=False, occupied=occupied) is False
+
+
+def test_soft_cover_creature_behind_target_ignored() -> None:
+    """A creature behind the target does not grant cover."""
+    grid = make_grid(["......", "......"])
+    occupied = frozenset({(1, 5)})
+    assert has_cover(grid, (1, 0), (1, 4), ranged=True, occupied=occupied) is False
+
+
+def test_soft_cover_creature_off_axis_ignored() -> None:
+    """A creature off the attack line does not grant cover."""
+    grid = make_grid([".....", "....."])
+    occupied = frozenset({(0, 2)})
+    assert has_cover(grid, (1, 0), (1, 4), ranged=True, occupied=occupied) is False