fix(rules): allow a free weapon draw with a move at BAB +1

SRD 'Move Actions': 'If you have a base attack bonus of +1 or higher, you may draw a weapon as a free action combined with a regular move.' _filter_turn_actions computes free_draw (BAB >= 1 AND a move action in the turn sequence) and threads it through _effective_slot/_action_economy_filter/_staggered_filter: retrieve_weapon then occupies the free slot instead of the move slot. Static classification stays 'move' (repair_weapon and no-move draws unchanged). Filter-level and engine-level (BAB +2 vs BAB 0) tests added.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

README.md

@@ -402,9 +402,15 @@ Règles modélisées :
    par action (conformance D5 — APG « Cackle ») : `hex` avec
    `hex_name="cackle"` occupe le compartiment **libre** (résolu par
    `_effective_slot`, le kind `hex` restant standard pour evil_eye/slumber) ;
-  **mouvement** = `move`, `stand_up`,
+   **mouvement** = `move`, `stand_up`,
-   `retrieve_weapon` (sortir une arme est une action de mouvement),
+    `retrieve_weapon` (sortir une arme est une action de mouvement),
-   `repair_weapon` ; **swift** = `swift`, `deed`,
+    `repair_weapon` ; exception conformance L7 (SRD « Move Actions ») : « If
+    you have a base attack bonus of +1 or higher, you may draw a weapon as a
+    free action combined with a regular move » — quand la séquence du tour
+    contient une action `move` ET que le combattant a un BAB ≥ +1,
+    `retrieve_weapon` occupe le compartiment **libre** (drapeau `free_draw`
+    résolu par `_effective_slot`) et n'entame pas le budget mouvement ;
+    `repair_weapon` reste mouvement (la règle RAW ne couvre que le dégainement) ; **swift** = `swift`, `deed`,
    `inspire_courage` ; **round complet** = `full_attack`, `charge`, `withdraw`,
    `full_round`, `spell_combat` (sort + attaque à outrance dans le même round),
    `run` (round complet en RAW — il consacre le standard ET le mouvement, tout

src/pf1e_simulator/combat.py

@@ -1625,7 +1625,16 @@ class CombatEngine:
             for _ in range(len(actions) - len(schedulable))
         )
         actions = schedulable
-        kept = _action_economy_filter(actions, cast_time=self._cast_time_of)
+        # PF1e (SRD "Move Actions"): "If you have a base attack bonus of +1 or
+        # higher, you may draw a weapon as a free action combined with a
+        # regular move." The draw rides the turn's move action instead of
+        # consuming the move slot.
+        free_draw = state.combatant.bab >= 1 and any(
+            a.kind == "move" for a in actions
+        )
+        kept = _action_economy_filter(
+            actions, cast_time=self._cast_time_of, free_draw=free_draw
+        )
         results.extend(
             ActionResult(
                 kind=kind, ok=False, reason=_REASON_DOWNGRADED_ACTION_ECONOMY
@@ -1642,7 +1651,9 @@ class CombatEngine:
             actions = kept
             state.immediate_used = False
         if self._is_staggered_limited(state):
-            kept = _staggered_filter(actions, cast_time=self._cast_time_of)
+            kept = _staggered_filter(
+                actions, cast_time=self._cast_time_of, free_draw=free_draw
+            )
             results.extend(
                 ActionResult(kind=kind, ok=False, reason=_REASON_DOWNGRADED_STAGGERED)
                 for kind in _dropped_kinds(actions, kept)
@@ -6790,13 +6801,24 @@ def _cast_time_slot(cast_time: CastTime) -> _ActionEconomySlot:
     raise ValueError(msg)
 
 
-def _effective_slot(action: Action, cast_time: CastTimeResolver) -> _ActionEconomySlot:
+def _effective_slot(
+    action: Action, cast_time: CastTimeResolver, *, free_draw: bool = False
+) -> _ActionEconomySlot:
     """The budget slot an action consumes, resolving cast_spell by cast time
-    and the cackle hex by its APG free-action cost."""
+    and the cackle hex by its APG free-action cost.
+
+    ``free_draw`` (SRD "Move Actions": "If you have a base attack bonus of +1
+    or higher, you may draw a weapon as a free action combined with a regular
+    move") makes retrieve_weapon occupy the free slot instead of the move
+    slot — the caller sets it only when the turn's sequence carries a move
+    action and the actor's BAB is at least +1.
+    """
     if action.kind == "cast_spell":
         return _cast_time_slot(cast_time(action))
     if action.kind == "hex" and action.hex_name == "cackle":
         return "free"
+    if action.kind == "retrieve_weapon" and free_draw:
+        return "free"
     return _action_economy_slot(action.kind)
 
 
@@ -6831,6 +6853,7 @@ def _staggered_filter(
     actions: tuple[Action, ...],
     *,
     cast_time: CastTimeResolver = _default_cast_time,
+    free_draw: bool = False,
 ) -> tuple[Action, ...]:
     """Staggered: one move OR one standard action, plus every swift and free.
 
@@ -6859,7 +6882,7 @@ def _staggered_filter(
                 kept.append(Action(kind="attack", target_id=action.target_id))
                 slot_used = True
             continue
-        slot = _effective_slot(action, cast_time)
+        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.
@@ -6950,6 +6973,7 @@ def _action_economy_filter(
     actions: tuple[Action, ...],
     *,
     cast_time: CastTimeResolver = _default_cast_time,
+    free_draw: bool = False,
 ) -> tuple[Action, ...]:
     """Degrade a policy sequence to the legal PF1e action economy.
 
@@ -6964,7 +6988,8 @@ def _action_economy_filter(
     move action converts the standard slot (so (move, stand_up) and
     (move, move) are legal). The kept sequence is therefore the earliest
     order-stable legal prefix-subsequence; every skipped action is
-    deterministic.
+    deterministic. ``free_draw`` makes retrieve_weapon a free action (SRD
+    "Move Actions", BAB +1 combined with a move — see _effective_slot).
     """
     kept: list[Action] = []
     spent: dict[_ActionEconomySlot, bool] = {
@@ -6975,7 +7000,7 @@ def _action_economy_filter(
         "free": False,
     }
     for action in actions:
-        slot = _effective_slot(action, cast_time)
+        slot = _effective_slot(action, cast_time, free_draw=free_draw)
         if slot == "free":
             kept.append(action)
             continue

tests/test_conformance_action_economy.py

@@ -362,6 +362,33 @@ def test_staggered_filter_keeps_withdraw_as_restricted_standard() -> None:
     assert _staggered_filter((_foe("withdraw"), _foe("attack"))) == (_foe("withdraw"),)
 
 
+def test_free_draw_with_a_move_at_bab_plus1() -> None:
+    # SRD "Move Actions": "If you have a base attack bonus of +1 or higher,
+    # you may draw a weapon as a free action combined with a regular move."
+    # With the engine's free_draw flag set (BAB >= 1 AND a move in sequence),
+    # retrieve_weapon does not consume the move slot — the standard stays
+    # available for the attack.
+    actions = (_foe("move"), _foe("retrieve_weapon"), _foe("attack"))
+    assert _action_economy_filter(actions, free_draw=True) == actions
+    # Without the free draw the retrieve spends the move slot, converts the
+    # standard slot (move-slot conversion) and the attack is surplus.
+    kept_no_free = _action_economy_filter(actions, free_draw=False)
+    assert tuple(a.kind for a in kept_no_free) == ("move", "retrieve_weapon")
+    # A second standard after a free draw is surplus: the move slot was
+    # taken by the move, the standard by the first attack.
+    kept = _action_economy_filter(
+        (_foe("move"), _foe("retrieve_weapon"), _foe("attack"), _foe("attack")),
+        free_draw=True,
+    )
+    assert tuple(a.kind for a in kept) == ("move", "retrieve_weapon", "attack")
+    # Without a move in the sequence the engine never sets free_draw; the
+    # retrieve then spends the move slot itself and the attack is surplus.
+    kept_no_move = _action_economy_filter(
+        (_foe("retrieve_weapon"), _foe("attack")), free_draw=False
+    )
+    assert tuple(a.kind for a in kept_no_move) == ("retrieve_weapon", "attack")
+
+
 def test_nauseated_after_budget_keeps_single_move() -> None:
     # (move, attack, move): the budget drops the second move; the nauseated
     # filter then keeps only the first move and drops the standard attack.

tests/test_retrieve_weapon.py

@@ -159,3 +159,59 @@ def _run_with_retrieve() -> tuple[str, ...]:
 
 def test_determinism_same_seed_same_transcript() -> None:
     assert _run_with_retrieve() == _run_with_retrieve()
+
+
+# --- Test 6: free draw combined with a move at BAB +1 ------------------------
+
+
+def _move_retrieve_attack_run(bab: int) -> CombatEngine:
+    a_spec = make_combatant("a", attack_bonus=bab)
+    b_spec = make_combatant("b")
+    a = make_state(a_spec, "players", (1, 1))
+    b = make_state(b_spec, "monsters", (1, 4))
+    a.weapon_stolen.add("a-w")
+
+    def policy(engine: CombatEngine, state: CombatantState) -> tuple[Action, ...]:
+        if state.combatant.id == "a":
+            return (
+                Action(kind="move", target_id="b"),
+                Action(kind="retrieve_weapon", weapon_id="a-w"),
+                Action(kind="attack", target_id="b"),
+            )
+        return (Action(kind="wait"),)
+
+    engine = CombatEngine(
+        ScriptedRng([10, 5, 10, 3]), make_grid(), [a, b], policy=policy, round_cap=1
+    )
+    engine.run()
+    return engine
+
+
+def test_bab_plus1_draws_for_free_and_still_attacks() -> None:
+    # SRD "Move Actions": "If you have a base attack bonus of +1 or higher,
+    # you may draw a weapon as a free action combined with a regular move."
+    # Given: a BAB +2 combatant whose turn sequence is (move, retrieve, attack)
+    # When: the turn runs
+    # Then: all three actions execute — the draw rides the move for free and
+    # the standard attack still happens.
+    engine = _move_retrieve_attack_run(bab=2)
+    a = engine._states[0]
+    assert not a.weapon_stolen
+    kinds = [(r.kind, r.ok) for r in a.last_action_results]
+    assert ("move", True) in kinds
+    assert ("retrieve_weapon", True) in kinds
+    assert ("attack", True) in kinds
+    assert any(" vs b " in line for line in engine._transcript)
+
+
+def test_bab_zero_draw_still_costs_the_standard_slot() -> None:
+    # Given: the same sequence but BAB 0 — the draw is a move action, which
+    # converts the standard slot, leaving nothing for the attack.
+    # Then: the attack is downgraded out.
+    engine = _move_retrieve_attack_run(bab=0)
+    a = engine._states[0]
+    assert not a.weapon_stolen
+    assert any(
+        r.kind == "attack" and r.reason == "downgraded:action_economy"
+        for r in a.last_action_results
+    )