fix(rules): total defense and fighting defensively cannot be combined (SRD Total Defense) - no stacking, second declaration rejected

tests/test_defensive_actions.py

@@ -256,3 +256,48 @@ def test_control_moving_foe_does_provoke_aoo() -> None:
     eng = _duel(moving_foe, [10, 5, 8, 3], round_cap=1)
     t = eng.run().transcript
     assert any("AoO vs foe" in line for line in t)
+
+
+# ── (g) total defense and fighting defensively do not stack ────────────────────
+
+
+def test_fight_defensively_rejected_while_total_defense_active() -> None:
+    # SRD "Total Defense": "You can't combine total defense with fighting
+    # defensively." Declaring it after total defense is rejected; the AC
+    # bonus stays exactly +4.
+    def policy(_engine: CombatEngine, state: CombatantState) -> tuple[Action, ...]:
+        if state.combatant.id == "hero":
+            return (
+                Action(kind="total_defense"),
+                Action(kind="fight_defensively"),
+            )
+        return _WAIT
+
+    eng = _duel(policy, [10, 5], round_cap=1)
+    t = eng.run().transcript
+    hero = eng._states[0]
+    assert "round 1 hero: fight_defensively rejected (cannot_combine)" in t
+    assert hero.defensive_ac_bonus == 4
+    assert hero.fight_defensively is False
+    assert ("fight_defensively", False, "cannot_combine") in tuple(
+        (r.kind, r.ok, r.reason) for r in hero.last_action_results
+    )
+
+
+def test_total_defense_supersedes_a_fighting_defensively_declaration() -> None:
+    # The reverse order: the +2 declaration is voided by the later total
+    # defense — the bonus is set to +4 (not +6) and the -4 attack flag clears.
+    def policy(_engine: CombatEngine, state: CombatantState) -> tuple[Action, ...]:
+        if state.combatant.id == "hero":
+            return (
+                Action(kind="fight_defensively"),
+                Action(kind="total_defense"),
+            )
+        return _WAIT
+
+    eng = _duel(policy, [10, 5], round_cap=1)
+    eng.run()
+    hero = eng._states[0]
+    assert hero.defensive_ac_bonus == 4
+    assert hero.fight_defensively is False
+    assert hero.total_defense is True