fix(rules): restricted charge - a creature limited to a standard action (staggered/disabled, surprise round) can still charge at 1x speed

src/pf1e_simulator/combat.py

@@ -3759,6 +3759,18 @@ class CombatEngine:
         state.pos = orig
         return weapon is not None
 
+    def _charge_speed_mult(self, state: CombatantState) -> int:
+        """Charge speed multiplier: 2x normally; 1x for a creature restricted
+        to a single standard action — PF1e (SRD "Charge"): "If you are able to
+        take only a standard action on your turn, you can still charge, but
+        you are only allowed to move up to your speed (instead of up to double
+        your speed)" — staggered/disabled creatures and the surprise round
+        (mirrors the Restricted Withdraw exception).
+        """
+        if self._surprise_round or self._is_staggered_limited(state):
+            return 1
+        return 2
+
     def can_charge(self, state: CombatantState, target: CombatantState) -> ChargeResult | None:
         """Return a ``ChargeResult`` if ``state`` can charge ``target`` this turn, else None.
 
@@ -3782,7 +3794,7 @@ class CombatEngine:
         ):
             return ChargeResult(weapon=None, distance_ft=0, reason="no_line_of_effect")
         speed_cells = _speed_ft(state) // _SQUARE_FT
-        max_cells = 2 * speed_cells
+        max_cells = self._charge_speed_mult(state) * speed_cells
         blocked = self._blocked(state, target)
         melee_weapons = [w for w in state.usable_attacks() if w.kind == "melee"]
         if not melee_weapons:
@@ -3905,7 +3917,7 @@ class CombatEngine:
             return
         inner_cells, reach_cells = _melee_reach_zone_cells(attacker, weapon)
         speed_cells = _speed_ft(attacker) // _SQUARE_FT
-        max_cells = 2 * speed_cells
+        max_cells = self._charge_speed_mult(attacker) * speed_cells
         blocked = self._blocked(attacker, target)
         end = self._charge_end(
             attacker, target, reach_cells, max_cells, blocked, min_reach_cells=inner_cells
@@ -8003,11 +8015,14 @@ def _staggered_filter(
     ``full_attack`` (already in range) is downgraded to a single standard
     ``attack`` that consumes the one move-or-standard slot; a further
     full-round action (charge, run, a full-round/one-round cast,
-    spell_combat) is dropped. Exception (SRD "Full-Round Actions — Restricted
-    Withdraw"): "If you are limited to taking only a standard action each
-    round you can withdraw as a standard action. In this case, you may move
-    up to your speed" — a ``withdraw`` is kept as the one standard action and
-    ``_flee_path`` halves its budget to single speed.
+    spell_combat) is dropped. Exceptions (SRD "Full-Round Actions — Restricted
+    Withdraw", SRD "Charge — restricted"): "If you are limited to taking only
+    a standard action each round you can withdraw as a standard action. In
+    this case, you may move up to your speed" / "If you are able to take only
+    a standard action on your turn, you can still charge, but you are only
+    allowed to move up to your speed" — ``withdraw`` and ``charge`` are kept
+    as the one standard action and their movement budgets halve to single
+    speed (``_flee_path``, ``_charge_speed_mult``).
     """
     kept: list[Action] = []
     slot_used = False  # the single move-OR-standard slot is spent
@@ -8021,8 +8036,8 @@ def _staggered_filter(
             continue
         slot = _effective_slot(action, cast_time, free_draw=free_draw)
         if slot == "full_round":
-            if action.kind == "withdraw" and not slot_used:
-                # Restricted Withdraw: standard action, move up to speed.
+            if action.kind in ("withdraw", "charge") and not slot_used:
+                # Restricted Withdraw / Restricted Charge: standard action.
                 kept.append(action)
                 slot_used = True
             continue
@@ -8050,9 +8065,10 @@ def _surprise_filter(
     grants neither a swift action nor a full-round action, so swift and
     full-round kinds are dropped — with the same conventions as
     ``_staggered_filter``: a ``full_attack`` collapses to a single standard
-    ``attack``, and ``withdraw`` survives as the standard-action Restricted
-    Withdraw (SRD "Full-Round Actions": legal "if you are limited to taking
-    only a standard action each round").
+    ``attack``, and ``withdraw`` / ``charge`` survive as the standard-action
+    Restricted Withdraw / Restricted Charge (SRD "Full-Round Actions",
+    "Charge": legal "if you are able to take only a standard action on your
+    turn", at single speed).
     """
     kept: list[Action] = []
     slot_used = False  # the single standard-or-move slot is spent
@@ -8064,7 +8080,7 @@ def _surprise_filter(
             continue
         slot = _effective_slot(action, cast_time, free_draw=free_draw)
         if slot == "full_round":
-            if action.kind == "withdraw" and not slot_used:
+            if action.kind in ("withdraw", "charge") and not slot_used:
                 kept.append(action)
                 slot_used = True
             continue

tests/test_charge_result.py

@@ -205,6 +205,31 @@ def test_charge_result_no_charge_path_too_far() -> None:
     assert result.distance_ft == 0
 
 
+def test_restricted_charge_halves_the_budget() -> None:
+    """SRD "Charge": a creature able to take only a standard action (here a
+    disabled one at 0 hp) can still charge, but only up to its speed (1x,
+    6 cells at 30 ft) instead of double speed — a target 6 cells away stays
+    chargeable, one 10 cells away is not."""
+    a = make_state(make_combatant("a"), "players", (0, 0))
+    near = make_state(make_combatant("near"), "monsters", (0, 6))
+    engine = make_engine([a, near], make_grid(12))
+    a.hp = 0  # disabled -> staggered -> restricted charge
+    result = engine.can_charge(a, near)
+    assert isinstance(result, ChargeResult)
+    assert result.weapon is not None  # end cell 5 steps away <= 1x budget
+    a2 = make_state(make_combatant("a2"), "players", (0, 0))
+    far = make_state(make_combatant("far"), "monsters", (0, 10))
+    engine2 = make_engine([a2, far], make_grid(12))
+    a2.hp = 0
+    res2 = engine2.can_charge(a2, far)
+    assert isinstance(res2, ChargeResult)
+    assert res2.weapon is None  # 9 steps to the closest attack cell needs 2x
+    a2.hp = 20  # standing again: full 2x charge is legal
+    res3 = engine2.can_charge(a2, far)
+    assert isinstance(res3, ChargeResult)
+    assert res3.weapon is not None
+
+
 # --- Test 5: no melee weapon -------------------------------------------------
 
 

tests/test_conformance_action_economy.py

@@ -291,7 +291,9 @@ def _add_condition(state: CombatantState, name: str) -> None:
 
 def test_staggered_after_budget_keeps_single_legal_action() -> None:
     # (charge, attack): the budget keeps the charge and drops the attack as
-    # surplus standard; the staggered filter then drops the full-round charge.
+    # surplus standard; the staggered filter then keeps the charge as the
+    # Restricted Charge standard action (SRD "Charge": able to take only a
+    # standard action -> charge at up to 1x speed).
     def policy(_e: CombatEngine, s: CombatantState) -> tuple[Action, ...]:
         if s.combatant.id == "hero":
             return (
@@ -307,7 +309,8 @@ def test_staggered_after_budget_keeps_single_legal_action() -> None:
     eng._take_turn(hero)
     reasons = [(r.kind, r.reason) for r in hero.last_action_results]
     assert ("attack", "downgraded:action_economy") in reasons
-    assert ("charge", "downgraded:staggered") in reasons
+    assert ("charge", "downgraded:staggered") not in reasons
+    assert ("charge", "ok") in reasons
 
 
 # ── (d2) the staggered filter keeps swift + free, one move-OR-standard ─────────
@@ -344,8 +347,11 @@ def test_staggered_filter_keeps_only_one_move_or_standard() -> None:
 def test_staggered_filter_drops_full_round_and_downgrades_full_attack() -> None:
     # A leading full_attack collapses to a single standard attack (kept).
     assert _staggered_filter((_foe("full_attack"),)) == (_foe("attack"),)
-    # A full-round charge is dropped; a following standard fills the slot.
-    assert _staggered_filter((_foe("charge"), _foe("attack"))) == (_foe("attack"),)
+    # SRD "Charge": restricted to a standard action, charge survives as the
+    # Restricted Charge (standard, 1x speed) and spends the slot; run and
+    # other full-round kinds stay dropped.
+    assert _staggered_filter((_foe("charge"), _foe("attack"))) == (_foe("charge"),)
+    assert _staggered_filter((_foe("run"), _foe("attack"))) == (_foe("attack"),)
     # full_attack after a spent slot is dropped (the slot is already used).
     assert _staggered_filter((_foe("move"), _foe("full_attack"))) == (_foe("move"),)
 

tests/test_surprise_round.py

@@ -153,14 +153,21 @@ def test_surprise_filter_keeps_one_standard_or_move_plus_free() -> None:
 
 def test_surprise_filter_collapses_full_attack_and_drops_full_rounds() -> None:
     # full_attack collapses to a single standard attack (same convention as
-    # the staggered filter); charge/run and a one-round cast are full-round
-    # and illegal; withdraw survives as the Restricted Withdraw standard.
+    # the staggered filter); run and a one-round cast are full-round and
+    # illegal; withdraw survives as the Restricted Withdraw standard, and
+    # charge as the Restricted Charge (SRD "Charge": "If you are able to take
+    # only a standard action on your turn, you can still charge, but you are
+    # only allowed to move up to your speed").
     full = Action(kind="full_attack", target_id="foe")
     assert _surprise_filter((full,)) == (Action(kind="attack", target_id="foe"),)
-    assert _surprise_filter((Action(kind="charge", target_id="foe"),)) == ()
+    charge = Action(kind="charge", target_id="foe")
+    assert _surprise_filter((charge,)) == (charge,)
     assert _surprise_filter((Action(kind="run", target_id="foe"),)) == ()
     withdraw = Action(kind="withdraw", target_id="foe")
     assert _surprise_filter((withdraw,)) == (withdraw,)
+    attack = Action(kind="attack", target_id="foe")
+    assert _surprise_filter((charge, attack)) == (charge,)
+    assert _surprise_filter((attack, charge)) == (attack,)
     summon = Action(kind="cast_spell", target_id="foe", spell_name="Summon")
     assert _surprise_filter((summon,), cast_time=lambda _a: "one_round") == ()
     bolt = Action(kind="cast_spell", target_id="foe", spell_name="Bolt")