pf1e-simulator/src/pf1e_simulator/combat.py

"""Deterministic combat engine: attacks, crits, DR, hp states, initiative, rounds.

Phase 0 documented deviations from PF1e (conventions):
- Action economy: a normal turn grants one standard action + one move action
  (or one full-round action), plus swift/free/immediate. The policy returns an
  ordered sequence of `Action` per turn; the engine executes them in order,
  stopping early if the actor drops or one side is wiped. `default_policy`
  returns `(full_attack,)` when already in range, `(charge,)` when a
  straight-line charge path exists, `(5foot_step, full_attack)` when a single
  step brings the target into range, or `(move, attack)` otherwise (move at
  full speed along the Dijkstra path, then single attack). Immediate actions
  (off-turn, consume next swift) are deferred; flanking, full attack, charge,
  withdraw, and 5-foot step are modeled; attacks of opportunity are resolved
  inline (see below).
- A weapon with `count` > 1 ("2x Talons") resolves `count` independent attacks
  in one attack action; remaining swings are lost once the target drops
  (down or dead) mid-routine. BAB iterative attacks (full-round action
  ``full_attack``): at BAB +6/+11/+16, additional attacks at -5/-10/-15 from
  the weapon's attack bonus; iteratives are only computed for weapons with
  ``count == 1`` (natural multi-attacks do not gain iteratives). Multiple
  natural weapons in a single full attack are not modeled.
- Natural 1 always misses; natural 20 always hits and threatens a crit.
- A confirmed crit multiplies the total damage (dice + flat bonus) by crit_mult.
- DR applies once, after crit multiplication; any bypassing type defeats DR.
- Death when hp < min(-10, -CON); hp <= 0 cannot act.
- Initiative ties: higher initiative_mod first, then list order (no re-roll).
- Movement: a move action travels up to the combatant's speed in cells along
  the true shortest path (Dijkstra cost field from the target, 5-10-5
  diagonals), stopping adjacent to the nearest enemy; ties keep delta order.
- Line of effect gates all attacks: a target fully behind blocking terrain
  cannot be attacked, and the policy moves to gain sight instead.
- Cover (corner rule) grants +4 AC on hit and crit-confirm rolls; melee and
  ranged reuse the same corner rule. Soft cover: active creatures between
  attacker and target also grant +4 AC on ranged attacks (CRB soft cover);
  melee attacks ignore creatures.
- Flanking: +2 on melee attack rolls when an active ally with a melee weapon
  threatens the target from the opposite border or corner. Ranged attacks do
  not benefit from flanking; allies without melee weapons do not threaten.
- Attacks of opportunity: a combatant threatens the 8 adjacent squares if
  active and wielding a melee weapon. Two triggers are modeled: (1) moving
  out of a threatened square — movement is resolved step-by-step, and each
  enemy that threatens the current square gets one AoO before the mover
  leaves it; (2) making a ranged attack while in a threatened square — each
  threatening enemy gets one AoO before each ranged swing. One AoO per
  combatant per round (tracked in ``_aoo_used``, cleared at round start);
  AoOs always strike (PF1e allows declining, the simulator does not). A
  5-foot step never provokes AoOs (it is not a move action); the withdraw
  action protects only the starting square (see below). A 5-foot step and
  any other movement (move, charge, withdraw) are mutually exclusive within
  the same turn (``moved_this_turn`` flag, cleared in ``_take_turn``).
- Charge: a full-round action that moves in a straight line (Bresenham) up to
  2x speed toward the closest square from which the charger can melee the
  target, then makes a single melee attack at +2. The charger takes -2 AC
  until the start of their next turn (tracked as a StatModifier in
  ``effects``, cleared in ``_take_turn``). The straight line must be clear of difficult terrain,
  obstacles, and creatures; minimum 2 cells (10 ft). ``default_policy``
  chooses a charge when the enemy is out of reach but a valid charge path
  exists.
- Withdraw: a full-round action that moves up to 2x speed away from the
  nearest enemy. The starting square is not threatened — no AoO when leaving
  it. Subsequent squares provoke AoOs normally (resolved step-by-step, as for
  move). The path is a greedy ascent of the Dijkstra cost field from the
  threat. ``default_policy`` does not choose withdraw (it is only available
  via a custom policy).
- 5-foot step: a free action that moves one square toward the nearest enemy
  without provoking AoOs. Mutually exclusive with any other movement (move,
  charge, withdraw) in the same turn — tracked via ``moved_this_turn``,
  cleared at the start of each turn in ``_take_turn``. ``default_policy``
  uses ``(5foot_step, full_attack)`` when a single step brings the target
  into weapon range.
- Ranged: cumulative -2 per full range increment beyond the first, up to 10
  range increments; the penalty applies to attack and crit-confirm rolls.
  Thrown weapons (5 increments max) are not distinguished.
"""

from __future__ import annotations

from dataclasses import asdict, dataclass, field
from typing import TYPE_CHECKING

from pf1e_simulator.conditions import CONDITIONS_BY_NAME
from pf1e_simulator.effects import ActiveBuff, ActiveCondition, StatModifier, resolve_modifiers
from pf1e_simulator.models import PREDEFINED_SKILLS
from pf1e_simulator.spells import (
    AreaEffect,
    BuffEffect,
    ConditionEffect,
    DamageEffect,
    HealEffect,
    SpellEffect,
    SummonEffect,
    spell_range_ft,
)

if TYPE_CHECKING:
    from typing import Literal

    from pf1e_simulator.conditions import Condition
    from pf1e_simulator.grid import Grid
    from pf1e_simulator.map import Pos
    from pf1e_simulator.models import AttackSpec, Combatant, DamageReduction
    from pf1e_simulator.rng import Rng
    from pf1e_simulator.spells import SpellSpec

from pf1e_simulator.los import has_cover, has_line_of_effect

_SQUARE_FT = 5  # Phase 0 maps use 5-ft squares
_DEATH_FLOOR = -10  # PF1e: dead when hp < -10 or -CON, whichever is lower
_NATURAL_ONE = 1  # PF1e: natural 1 always misses
_NATURAL_TWENTY = 20  # PF1e: natural 20 always hits and threatens
_COVER_AC_BONUS = 4  # PF1e: partial cover grants +4 AC
_RANGE_INCREMENT_PENALTY = 2  # PF1e: -2 per full range increment beyond the first
_MAX_RANGE_INCREMENTS = 10  # PF1e: projectile weapons shoot up to 10 increments
_FLANK_BONUS = 2  # PF1e: +2 melee attack when ally threatens opposite side
_ITERATIVE_PENALTY = 5  # PF1e: each BAB iterative is at -5 from the previous
_MAX_ITERATIVES = 4  # PF1e: BAB +16 gives 4 attacks (at +16, +11, +6, +1)
_CHARGE_ATTACK_BONUS = 2  # PF1e: +2 attack roll on a charge
_CHARGE_AC_PENALTY = 2  # PF1e: -2 AC until start of next turn after charging
_CHARGE_MIN_CELLS = 2  # PF1e: charge must move at least 10 ft (2 squares)


def _save_label(result: SaveResult | None) -> str:
    if result is None:
        return "NO SAVE"
    return "SAVED" if result.success else "FAILED"


_STEP_DELTAS: tuple[Pos, ...] = (
    (-1, -1),
    (-1, 0),
    (-1, 1),
    (0, -1),
    (0, 1),
    (1, -1),
    (1, 0),
    (1, 1),
)


def _bresenham_line(start: Pos, end: Pos) -> list[Pos]:
    """Integer Bresenham line from start to end (exclusive of start, inclusive of end)."""
    r0, c0 = start
    r1, c1 = end
    dr = abs(r1 - r0)
    dc = abs(c1 - c0)
    sr = 1 if r1 > r0 else -1
    sc = 1 if c1 > c0 else -1
    err = dr - dc
    path: list[Pos] = []
    r, c = r0, c0
    while (r, c) != (r1, c1):
        e2 = 2 * err
        if e2 > -dc:
            err -= dc
            r += sr
        if e2 < dr:
            err += dr
            c += sc
        path.append((r, c))
    return path


@dataclass(frozen=True)
class CombatantStats:
    """Aggregated outcomes for one combatant over a battle."""

    hits: int = 0
    crits: int = 0
    damage_dealt: int = 0
    damage_taken: int = 0


@dataclass
class CombatantState:
    """Mutable runtime state of one combatant on the grid."""

    combatant: Combatant
    side: str
    pos: Pos
    hp: int
    # Old fields for backwards compatibility with tests
    effects: list[StatModifier] = field(default_factory=list)
    conditions: list[Condition] = field(default_factory=list)
    # New duration-tracked fields
    active_buffs: list[ActiveBuff] = field(default_factory=list)
    active_conditions: list[ActiveCondition] = field(default_factory=list)
    resources_left: dict[str, int] = field(default_factory=dict)
    moved_this_turn: bool = False
    power_attack: bool = False

    def spend_resource(self, name: str, n: int = 1) -> bool:
        """Spend n points of a resource. Returns True if successful, False if insufficient."""
        current = self.resources_left.get(name, 0)
        if current < n:
            return False
        self.resources_left[name] = current - n
        return True

    @property
    def active(self) -> bool:
        return self.hp > 0

    @property
    def dead(self) -> bool:
        return self.hp < self.death_threshold

    @property
    def death_threshold(self) -> int:
        return min(_DEATH_FLOOR, -self.combatant.abilities.con_score)


@dataclass(frozen=True)
class AttackResult:
    """Outcome of one attack roll, including the raw rolls for the log."""

    hit: bool
    crit: bool
    damage: int
    roll: int
    total: int
    ac: int
    penalty: int = 0
    flank_bonus: int = 0
    base_bonus: int = 0


@dataclass(frozen=True)
class SaveResult:
    """Outcome of one saving throw roll."""

    success: bool
    roll: int
    total: int
    dc: int


@dataclass(frozen=True)
class Action:
    """What a policy wants a combatant to do this turn.

    Kinds map to PF1e action types: ``attack`` is a standard action
    (single attack, highest BAB only — no iteratives), ``move`` is a move
    action, ``full_attack`` is a full-round action (BAB iteratives), ``charge``
    is a special full-round action (2x speed, straight line, +2 attack, -2
    AC), ``5foot_step`` is a free action (one square, no AoO, mutually
    exclusive with move/charge/withdraw), ``swift`` and ``free`` are minor
    actions, ``immediate`` is an off-turn reaction (deferred). ``wait`` is a
    no-op. The engine executes a policy-returned sequence per turn.
    """

    kind: Literal[
        "attack", "move", "wait", "swift", "free", "immediate", "full_round",
        "full_attack", "charge", "withdraw", "5foot_step", "cast_spell",
        "maneuver",
    ]
    target_id: str | None = None
    spell_name: str | None = None
    maneuver: str | None = None  # "trip", "disarm", "bull_rush", "sunder", "grapple", "escape"


@dataclass(frozen=True)
class CombatResult:
    """Outcome of a full battle: winner, rounds, log, and per-combatant stats."""

    winner: str | None
    rounds: int
    transcript: tuple[str, ...]
    stats: dict[str, CombatantStats]


@dataclass
class _LiveStats:
    hits: int = 0
    crits: int = 0
    damage_dealt: int = 0
    damage_taken: int = 0


class CombatEngine:
    """Runs one battle to completion on a grid with a single RNG stream."""

    def __init__(
        self,
        rng: Rng,
        grid: Grid,
        states: list[CombatantState],
        *,
        round_cap: int = 100,
        policy: Policy | None = None,
        spell_registry: dict[str, SpellSpec] | None = None,
    ) -> None:
        self._rng = rng
        self._grid = grid
        self._states = states
        self._round_cap = round_cap
        self._policy = policy if policy is not None else default_policy
        self._spell_registry = spell_registry or {}
        self._transcript: list[str] = []
        self._stats: dict[str, _LiveStats] = {s.combatant.id: _LiveStats() for s in states}
        self._current_round = 0
        self._aoo_used: set[str] = set()

    def _take_turn(self, state: CombatantState) -> bool:
        """Execute one combatant's full turn; return True if the battle is over."""
        self._decrement_durations(state)
        # Check cant_act flag from conditions
        if self.has_condition_flag(state, "cant_act"):
            self._log(f"round {self._current_round} {state.combatant.id}: wait (cannot act)")
            return self._winner_side() is not None
        state.moved_this_turn = False
        state.power_attack = False
        actions = self._policy(self, state)
        before = len(self._transcript)
        for action in actions:
            if not state.active:
                break
            self._execute(state, action)
            if self._winner_side() is not None:
                break
        if state.active and len(self._transcript) == before:
            self._log(f"round {self._current_round} {state.combatant.id}: wait")
        return self._winner_side() is not None

    def has_condition_flag(self, state: CombatantState, flag: str) -> bool:
        """Check if any active condition has the given behavioral flag set to True."""
        for ac in state.active_conditions:
            if getattr(ac.condition, flag, False):
                return True
        # Also check old conditions field for backwards compatibility
        return any(getattr(cond, flag, False) for cond in state.conditions)

    def _get_speed_mult(self, state: CombatantState) -> float:
        """Get the minimum speed multiplier from all active conditions."""
        speed_mult = 1.0
        for ac in state.active_conditions:
            if ac.condition.speed_mult != 1.0:
                speed_mult = min(speed_mult, ac.condition.speed_mult)
        for cond in state.conditions:
            if cond.speed_mult != 1.0:
                speed_mult = min(speed_mult, cond.speed_mult)
        return speed_mult

    def _decrement_durations(self, state: CombatantState) -> None:
        """Decrement duration rounds for buffs and conditions; remove expired ones."""
        state.active_buffs[:] = [
            ActiveBuff(modifiers=b.modifiers, rounds_left=b.rounds_left - 1, source=b.source)
            for b in state.active_buffs
            if b.rounds_left > 1
        ]
        state.active_conditions[:] = [
            ActiveCondition(condition=c.condition, rounds_left=c.rounds_left - 1, source=c.source)
            for c in state.active_conditions
            if c.rounds_left > 1
        ]

    def run(self) -> CombatResult:
        """Run the battle and return the final result and transcript."""
        order = self._roll_initiative()
        round_no = 1
        while round_no <= self._round_cap:
            self._current_round = round_no
            self._aoo_used.clear()
            for state in order:
                if not state.active:
                    continue
                if self._take_turn(state):
                    break
            if self._winner_side() is not None:
                break
            round_no += 1
        winner = self._winner_side()
        if winner is not None:
            self._log(f"battle over: {winner} win in {round_no} rounds")
        else:
            self._log(f"battle over: draw after {self._round_cap} rounds")
        stats = {cid: CombatantStats(**asdict(live)) for cid, live in self._stats.items()}
        return CombatResult(
            winner=winner,
            rounds=round_no if winner is not None else self._round_cap,
            transcript=tuple(self._transcript),
            stats=stats,
        )

    def nearest_enemy(self, state: CombatantState) -> CombatantState | None:
        """Closest active enemy by grid distance; ties keep list order."""
        enemies = [s for s in self._states if s.side != state.side and s.active]
        if not enemies:
            return None
        return min(
            enemies,
            key=lambda s: (self._grid.distance(state.pos, s.pos), self._states.index(s)),
        )

    def weapon_for(self, attacker: CombatantState, target: CombatantState) -> AttackSpec | None:
        """First weapon usable against the target at this range and with clear LoE."""
        if not has_line_of_effect(self._grid, attacker.pos, target.pos):
            return None
        dist_ft = self._grid.distance(attacker.pos, target.pos) * _SQUARE_FT
        for weapon in attacker.combatant.attacks:
            if weapon.kind in ("melee", "touch") and dist_ft <= weapon.reach_ft:
                return weapon
            if (
                weapon.kind == "ranged"
                and weapon.range_increment_ft is not None
                and dist_ft <= weapon.range_increment_ft * _MAX_RANGE_INCREMENTS
            ):
                return weapon
        return None

    def range_penalty(self, weapon: AttackSpec, dist_ft: int) -> int:
        """PF1e: -2 per full range increment beyond the first, zero within it."""
        if weapon.kind != "ranged" or weapon.range_increment_ft is None:
            return 0
        increments = dist_ft // weapon.range_increment_ft
        if dist_ft % weapon.range_increment_ft != 0:
            increments += 1
        return -_RANGE_INCREMENT_PENALTY * max(0, increments - 1)

    def _flanking_bonus(self, attacker: CombatantState, target: CombatantState) -> int:
        """+2 if an active ally threatens the target from the opposite side (CRB flanking)."""
        ar, ac = attacker.pos
        tr, tc = target.pos
        opposite = (2 * tr - ar, 2 * tc - ac)
        for ally in self._states:
            if ally is attacker or ally is target:
                continue
            if not ally.active or ally.side != attacker.side:
                continue
            if ally.pos != opposite:
                continue
            if any(w.kind == "melee" for w in ally.combatant.attacks):
                return _FLANK_BONUS
        return 0

    def _stat_modifiers(
        self, state: CombatantState, target: str, *, weapon_name: str | None = None
    ) -> list[StatModifier]:
        """Collect all StatModifiers for ``target`` from all sources.

        ``weapon_name`` filters out modifiers with a ``weapon_filter`` that
        doesn't match (e.g. Weapon Focus (Pistol) only applies to "Pistol").
        Modifiers without a ``weapon_filter`` are always included.
        """
        mods: list[StatModifier] = []
        # Old effects field (backwards compatibility)
        mods.extend(m for m in state.effects if m.target == target)
        # Old conditions field (backwards compatibility)
        for cond in state.conditions:
            mods.extend(m for m in cond.modifiers if m.target == target)
        # New active buffs
        for buff in state.active_buffs:
            mods.extend(m for m in buff.modifiers if m.target == target)
        # New active conditions
        for ac in state.active_conditions:
            mods.extend(m for m in ac.condition.modifiers if m.target == target)
        # Features
        for feat in state.combatant.features:
            mods.extend(
                m
                for m in feat.effects
                if m.target == target
                and (m.weapon_filter is None or m.weapon_filter == weapon_name)
            )
        return mods

    def _has_feat(self, state: CombatantState, feat_name: str) -> bool:
        """True if the combatant has a feature with the given name."""
        return any(f.name == feat_name for f in state.combatant.features)

    def _power_attack_amt(self, attacker: CombatantState) -> int:
        """Power Attack exchange amount: X = BAB//4 + 1 (min 1). Returns 0 if inactive."""
        if not attacker.power_attack or not self._has_feat(attacker, "Power Attack"):
            return 0
        return max(1, attacker.combatant.bab // 4 + 1)

    def resolve_attack(
        self,
        attacker: CombatantState,
        target: CombatantState,
        weapon: AttackSpec,
        *,
        bonus_override: int | None = None,
    ) -> AttackResult:
        """Roll one attack (with crit confirm and damage) and apply it."""
        roll = self._rng.d20()
        dist_ft = self._grid.distance(attacker.pos, target.pos) * _SQUARE_FT
        penalty = self.range_penalty(weapon, dist_ft)
        flank = self._flanking_bonus(attacker, target) if weapon.kind == "melee" else 0
        base_bonus = bonus_override if bonus_override is not None else weapon.attack_bonus
        atk_mods = self._stat_modifiers(attacker, "attack", weapon_name=weapon.name)
        attack_mod = resolve_modifiers(atk_mods)
        pa_amt = self._power_attack_amt(attacker) if weapon.kind == "melee" else 0
        total = roll + base_bonus + penalty + flank + attack_mod - pa_amt
        # Check if target denies DEX to AC (flat-footed)
        if self.has_condition_flag(target, "denies_dex_to_ac"):
            base_ac = target.combatant.ac.flat_footed
        else:
            base_ac = target.combatant.ac.total
        ac = base_ac + resolve_modifiers(self._stat_modifiers(target, "ac"))
        occupied = frozenset(
            s.pos for s in self._states if s.active and s is not attacker and s is not target
        )
        if has_cover(
            self._grid,
            attacker.pos,
            target.pos,
            ranged=weapon.kind == "ranged",
            occupied=occupied,
        ):
            ac += _COVER_AC_BONUS
        hit = roll == _NATURAL_TWENTY or (roll != _NATURAL_ONE and total >= ac)
        crit = False
        damage = 0
        if hit:
            if roll != _NATURAL_ONE and roll >= weapon.crit_range:
                confirm = self._rng.d20()
                confirm_total = confirm + base_bonus + penalty + flank + attack_mod - pa_amt
                crit = confirm != _NATURAL_ONE and confirm_total >= ac
            dmg_mods = self._stat_modifiers(attacker, "damage", weapon_name=weapon.name)
            damage = sum(c.formula.roll(self._rng) for c in weapon.damage) + weapon.damage_bonus
            damage += resolve_modifiers(dmg_mods)
            damage += pa_amt * 2 if weapon.kind == "melee" else 0
            if crit:
                damage *= weapon.crit_mult
            damage = self._apply_dr(damage, weapon, target)
        target.hp -= damage
        return AttackResult(
            hit=hit, crit=crit, damage=damage, roll=roll, total=total, ac=ac,
            penalty=penalty, flank_bonus=flank, base_bonus=base_bonus,
        )

    def _apply_dr(self, damage: int, weapon: AttackSpec, target: CombatantState) -> int:
        dr: DamageReduction | None = target.combatant.dr
        if dr is None:
            return damage
        types = {t for component in weapon.damage for t in component.types}
        if types & dr.bypass:
            return damage
        return max(0, damage - dr.amount)

    def _apply_dr_for_types(
        self, damage: int, damage_types: frozenset[str], target: CombatantState
    ) -> int:
        dr: DamageReduction | None = target.combatant.dr
        if dr is None:
            return damage
        if damage_types & dr.bypass:
            return damage
        return max(0, damage - dr.amount)

    def resolve_save(
        self, state: CombatantState, save_type: Literal["fort", "ref", "will"], dc: int
    ) -> SaveResult:
        """Roll a saving throw (fort/ref/will) against ``dc``.

        PF1e: natural 1 = automatic failure, natural 20 = automatic success.
        Effect modifiers and condition modifiers (StatModifier with matching
        target) are applied via ``resolve_modifiers`` — same bonus-type
        stacking rules as attacks.
        """
        roll = self._rng.d20()
        base = getattr(state.combatant.saves, save_type)
        bonus = resolve_modifiers(self._stat_modifiers(state, save_type))
        total = roll + base + bonus
        success = roll != _NATURAL_ONE and (roll == _NATURAL_TWENTY or total >= dc)
        return SaveResult(success=success, roll=roll, total=total, dc=dc)

    def resolve_skill(
        self, state: CombatantState, skill: str, dc: int
    ) -> SaveResult:
        """Roll a skill check against ``dc``.

        """
        skill_spec = PREDEFINED_SKILLS.get(skill)
        if skill_spec is None:
            msg = f"Unknown skill: {skill}"
            raise ValueError(msg)

        roll = self._rng.d20()
        skill_rank = state.combatant.skills.get(skill, None)
        rank = skill_rank.rank if skill_rank else 0
        # Class skill bonus
        class_bonus = 3 if skill_rank and skill_rank.class_skill else 0
        # Armor check penalty
        armor_penalty = skill_rank.armor_penalty if skill_rank else 0
        if armor_penalty and skill_spec.armor_check_penalty:
            armor_penalty = -abs(armor_penalty)
        else:
            armor_penalty = 0
        # Ability modifier
        ability_name = skill_spec.ability
        ability_score = getattr(state.combatant.abilities, f"{ability_name}_score")
        ability_mod = (ability_score - 10) // 2
        # Effect/condition modifiers
        mod_bonus = resolve_modifiers(self._stat_modifiers(state, skill))
        total = roll + rank + class_bonus + ability_mod + armor_penalty + mod_bonus
        # Natural 1/20 are not auto-fail/success for skills
        success = total >= dc
        return SaveResult(success=success, roll=roll, total=total, dc=dc)

    def _roll_initiative(self) -> list[CombatantState]:
        rolls: dict[str, tuple[int, int]] = {}
        for state in self._states:
            roll = self._rng.d20()
            rolls[state.combatant.id] = (roll, roll + state.combatant.initiative_mod)
        order = sorted(
            self._states,
            key=lambda s: (
                rolls[s.combatant.id][1],
                s.combatant.initiative_mod,
                self._states.index(s),
            ),
            reverse=True,
        )
        for state in order:
            roll, total = rolls[state.combatant.id]
            self._log(
                f"initiative: {state.combatant.id} "
                f"d20={roll}+{state.combatant.initiative_mod}={total}"
            )
        return order

    def _winner_side(self) -> str | None:
        active_sides = {s.side for s in self._states if s.active}
        if len(active_sides) == 1:
            return active_sides.pop()
        return None

    def _threatened_squares(self, state: CombatantState) -> frozenset[Pos]:
        """Squares this combatant threatens with a melee weapon (8 adjacent for 5 ft reach)."""
        if not state.active:
            return frozenset()
        if not any(w.kind == "melee" for w in state.combatant.attacks):
            return frozenset()
        r, c = state.pos
        return frozenset((r + dr, c + dc) for dr, dc in _STEP_DELTAS)

    def _enemies_threatening(self, state: CombatantState, pos: Pos) -> list[CombatantState]:
        """Active enemies whose threatened squares include pos (in self._states order)."""
        return [
            s
            for s in self._states
            if s is not state
            and s.active
            and s.side != state.side
            and pos in self._threatened_squares(s)
        ]

    def _resolve_aoo(self, attacker: CombatantState, target: CombatantState) -> bool:
        """Resolve one attack of opportunity (single melee attack at normal bonus).

        AoOs are always taken (PF1e allows declining, but the simulator always strikes).
        Returns True if the target dropped.
        """
        if self.has_condition_flag(attacker, "cant_aoo"):
            return False
        self._aoo_used.add(attacker.combatant.id)
        weapon = next((w for w in attacker.combatant.attacks if w.kind == "melee"), None)
        if weapon is None:
            return False
        return self._resolve_swing(
            attacker, target, weapon, label="AoO"
        )

    def _check_provoked_aoo(self, attacker: CombatantState, weapon: AttackSpec) -> bool:
        """Check for ranged-AoO: firing a ranged weapon in a threatened square provokes.

        Returns True if the attacker dropped (caller must stop attacking).
        """
        if weapon.kind != "ranged":
            return False
        for enemy in self._enemies_threatening(attacker, attacker.pos):
            if enemy.combatant.id in self._aoo_used:
                continue
            self._resolve_aoo(enemy, attacker)
            if not attacker.active:
                return True
        return False

    def _check_casting_aoo(self, caster: CombatantState, spell_level: int) -> bool:
        """Check for AoO from casting a spell in a threatened square.

        Returns True if the caster dropped or failed concentration (spell fizzles).
        """
        for enemy in self._enemies_threatening(caster, caster.pos):
            if enemy.combatant.id in self._aoo_used:
                continue
            hp_before = caster.hp
            self._resolve_aoo(enemy, caster)
            if not caster.active:
                self._log(
                    f"round {self._current_round} {caster.combatant.id}: "
                    f"casting interrupted by AoO from {enemy.combatant.id}"
                )
                return True
            # Concentration check if damaged
            dmg = hp_before - caster.hp
            if dmg > 0 and not self._check_concentration(caster, spell_level, dmg):
                self._log(
                    f"round {self._current_round} {caster.combatant.id}: "
                    f"concentration check failed (DC {15 + 2 * spell_level}), spell fizzles"
                )
                return True
        return False

    def _check_concentration(
        self, caster: CombatantState, spell_level: int, damage_taken: int
    ) -> bool:
        """Concentration check: DC = 15 + 2 * spell_level + damage_taken.

        Combat Casting feat gives +4 bonus.
        """
        dc = 15 + 2 * spell_level + damage_taken
        has_combat_casting = any(f.name == "Combat Casting" for f in caster.combatant.features)
        bonus = 4 if has_combat_casting else 0
        roll = self._rng.d20()
        # Use caster level + ability mod for concentration check
        caster_level = caster.combatant.level
        # For concentration, the check is d20 + caster_level + ability_mod (usually Con)
        con_mod = (caster.combatant.abilities.con_score - 10) // 2
        total = roll + caster_level + con_mod + bonus
        return total >= dc
    def can_step5_to_attack(self, state: CombatantState, target: CombatantState) -> bool:
        """True if a 5-foot step toward ``target`` would put ``state`` in weapon range."""
        path = self._move_path(state, target)
        if not path:
            return False
        orig = state.pos
        state.pos = path[0]
        weapon = self.weapon_for(state, target)
        state.pos = orig
        return weapon is not None

    def can_charge(self, state: CombatantState, target: CombatantState) -> AttackSpec | None:
        """Return a melee weapon if ``state`` can charge ``target`` this turn, else None.

        PF1e charge requirements (CRB):
        - Must have line of sight to the target at the start of the turn.
        - Must move at least 10 ft (2 squares) and at most double speed.
        - Must move in a straight line (Bresenham) to the closest attackable square.
        - The path must not pass through blocking terrain, difficult terrain, or creatures.
        - Must end adjacent to the target (within melee reach).
        - Only a single melee attack is allowed.
        """
        if not has_line_of_effect(self._grid, state.pos, target.pos):
            return None
        speed_cells = state.combatant.speed_land_ft // _SQUARE_FT
        max_cells = 2 * speed_cells
        blocked = frozenset(
            s.pos for s in self._states if s is not state and s is not target and s.active
        )
        for weapon in state.combatant.attacks:
            if weapon.kind != "melee":
                continue
            reach_cells = weapon.reach_ft // _SQUARE_FT
            end = self._charge_end(state, target, reach_cells, max_cells, blocked)
            if end is not None:
                return weapon
        return None

    def _charge_end(
        self,
        state: CombatantState,
        target: CombatantState,
        reach_cells: int,
        max_cells: int,
        blocked: frozenset[Pos],
    ) -> Pos | None:
        """Find the closest square from which ``state`` can melee ``target`` via a charge.

        Scans squares within reach of the target, picks the one whose Bresenham
        line from ``state.pos`` is the shortest valid charge path (>=2 cells,
        <=max_cells, no blocking terrain or creatures, all passable).
        Ties break toward lower distance from state.
        """
        candidates: list[tuple[int, Pos]] = []
        for end in self._charge_candidates(target, reach_cells, blocked, state.pos):
            path = _bresenham_line(state.pos, end)
            if len(path) < _CHARGE_MIN_CELLS or len(path) > max_cells:
                continue
            if not self._charge_path_clear(path, blocked):
                continue
            candidates.append((len(path), end))
        if not candidates:
            return None
        candidates.sort(key=lambda x: (x[0], self._grid.distance(state.pos, x[1])))
        return candidates[0][1]

    def _charge_candidates(
        self,
        target: CombatantState,
        reach_cells: int,
        blocked: frozenset[Pos],
        start: Pos,
    ) -> list[Pos]:
        """Squares within reach of target, passable, unoccupied, not the start."""
        tr, tc = target.pos
        result: list[Pos] = []
        for dr in range(-reach_cells, reach_cells + 1):
            for dc in range(-reach_cells, reach_cells + 1):
                if abs(dr) > reach_cells or abs(dc) > reach_cells:
                    continue
                if dr == 0 and dc == 0:
                    continue
                end = (tr + dr, tc + dc)
                if end == start:
                    continue
                if not self._grid.in_bounds(end) or not self._grid.passable(end):
                    continue
                if end in blocked:
                    continue
                if self._grid.distance(end, target.pos) > reach_cells:
                    continue
                result.append(end)
        return result

    def _charge_path_clear(self, path: list[Pos], blocked: frozenset[Pos]) -> bool:
        """True if every square on the charge path is passable and clear."""
        for pos in path:
            if not self._grid.in_bounds(pos) or not self._grid.passable(pos):
                return False
            if pos in blocked:
                return False
            terrain = self._grid.terrain_at(pos)
            if terrain.move_cost is not None and terrain.move_cost > 1:
                return False
        return True

    def _charge(
        self, attacker: CombatantState, target: CombatantState, weapon: AttackSpec
    ) -> None:
        """Execute a charge: move in a straight line, then make a single melee attack at +2.

        Sets a -2 AC penalty on the attacker that lasts until the start of their next turn
        (cleared in ``_take_turn``). Movement during a charge provokes AoOs step-by-step
        as for any move action.
        """
        reach_cells = weapon.reach_ft // _SQUARE_FT
        speed_cells = attacker.combatant.speed_land_ft // _SQUARE_FT
        max_cells = 2 * speed_cells
        blocked = frozenset(
            s.pos for s in self._states if s is not attacker and s is not target and s.active
        )
        end = self._charge_end(attacker, target, reach_cells, max_cells, blocked)
        if end is None:
            return
        path = _bresenham_line(attacker.pos, end)
        start = attacker.pos
        actual_path: list[Pos] = []
        for step in path:
            for enemy in self._enemies_threatening(attacker, attacker.pos):
                if enemy.combatant.id in self._aoo_used:
                    continue
                self._resolve_aoo(enemy, attacker)
                if not attacker.active:
                    break
            if not attacker.active:
                break
            attacker.pos = step
            actual_path.append(step)
        if actual_path:
            attacker.moved_this_turn = True
            coords = "->".join(f"({p[0]},{p[1]})" for p in (start, *actual_path))
            self._log(
                f"round {self._current_round} {attacker.combatant.id}: charge {coords}"
            )
        attacker.active_buffs.append(
            ActiveBuff(
                modifiers=(StatModifier(target="ac", value=-_CHARGE_AC_PENALTY),),
                rounds_left=1,
                source="charge",
            )
        )
        bonus = weapon.attack_bonus + _CHARGE_ATTACK_BONUS
        self._resolve_swing(
            attacker, target, weapon, label="charge", bonus_override=bonus
        )

    def _execute(self, state: CombatantState, action: Action) -> None:
        target = next((s for s in self._states if s.combatant.id == action.target_id), None)
        if action.kind in ("attack", "full_attack"):
            self._execute_attack(state, target, action.kind)
        elif action.kind == "charge":
            self._execute_charge(state, target)
        elif action.kind == "withdraw":
            self._withdraw(state, target)
        elif action.kind == "5foot_step":
            if target is None:
                return
            self._step5(state, target)
        elif action.kind == "move":
            if target is None:
                return
            self._move(state, target)
        elif action.kind == "wait":
            self._log(f"round {self._current_round} {state.combatant.id}: wait")
        elif action.kind == "cast_spell":
            self._execute_cast_spell(state, target, action.spell_name)
        elif action.kind == "maneuver":
            self._execute_maneuver(state, target, action.maneuver)
        elif action.kind == "channel_energy":
            self._execute_channel_energy(state, target)
        elif action.kind == "hex":
            self._execute_hex(state, target, action.hex_name)
    def _execute_cast_spell(
        self,
        state: CombatantState,
        target: CombatantState | None,
        spell_name: str | None,
    ) -> None:
        if spell_name is None:
            return
        self._cast_spell(state, target, spell_name)

    def _execute_maneuver(self, state: CombatantState, target: CombatantState | None, maneuver: str | None) -> None:
        """Execute a combat maneuver (trip, disarm, bull_rush, sunder)."""
        if target is None or not target.active:
            return
        if self.has_condition_flag(state, "cant_attack"):
            self._log(f"round {self._current_round} {state.combatant.id}: wait (cannot attack)")
            return
        if maneuver not in ("trip", "disarm", "bull_rush", "sunder", "grapple", "escape"):
            return

        # Calculate CMB and CMD
        attacker_cmb = state.combatant.cmb or (state.combatant.bab + state.combatant.abilities.str_mod + self._size_mod(state))
        target_cmd = target.combatant.cmd or (10 + (target.combatant.cmb or (target.combatant.bab + target.combatant.abilities.str_mod + self._size_mod(target))) + target.combatant.abilities.dex_mod)

        roll = self._rng.d20()
        total = roll + attacker_cmb
        success = roll != 1 and total >= target_cmd

        if maneuver == "trip":
            if success:
                target.active_conditions.append(
                    ActiveCondition(
                        condition=CONDITIONS_BY_NAME["prone"],
                        rounds_left=1,
                        source="maneuver: trip",
                    )
                )
                target.conditions.append(CONDITIONS_BY_NAME["prone"])
                self._log(f"round {self._current_round} {state.combatant.id}: trip vs {target.combatant.id} d20={roll}+{attacker_cmb}={total} CMD {target_cmd} -> SUCCESS (prone)")
            else:
                self._log(f"round {self._current_round} {state.combatant.id}: trip vs {target.combatant.id} d20={roll}+{attacker_cmb}={total} CMD {target_cmd} -> FAILED")
        elif maneuver == "disarm":
            if success:
                # Disarm: target's weapon is dropped (mark as unusable)
                # For simplicity, apply a condition that prevents weapon use
                target.active_conditions.append(
                    ActiveCondition(
                        condition=Condition(
                            name="disarmed",
                            modifiers=(StatModifier(target="attack", value=-4),),
                        ),
                        rounds_left=1,
                        source="maneuver: disarm",
                    )
                )
                self._log(f"round {self._current_round} {state.combatant.id}: disarm vs {target.combatant.id} d20={roll}+{attacker_cmb}={total} CMD {target_cmd} -> SUCCESS (disarmed)")
            else:
                self._log(f"round {self._current_round} {state.combatant.id}: disarm vs {target.combatant.id} d20={roll}+{attacker_cmb}={total} CMD {target_cmd} -> FAILED")
        elif maneuver == "bull_rush":
            if success:
                # Push target back 5ft (1 cell) away from attacker
                pushed = self._bull_rush_push(state, target)
                if pushed:
                    self._log(f"round {self._current_round} {state.combatant.id}: bull rush vs {target.combatant.id} d20={roll}+{attacker_cmb}={total} CMD {target_cmd} -> SUCCESS (pushed)")
                else:
                    self._log(f"round {self._current_round} {state.combatant.id}: bull rush vs {target.combatant.id} d20={roll}+{attacker_cmb}={total} CMD {target_cmd} -> SUCCESS (no space)")
            else:
                self._log(f"round {self._current_round} {state.combatant.id}: bull rush vs {target.combatant.id} d20={roll}+{attacker_cmb}={total} CMD {target_cmd} -> FAILED")
        elif maneuver == "sunder":
            if success:
                # Sunder: deal damage to weapon (simplified: deal damage to target)
                dmg = state.combatant.abilities.str_mod + 2  # simplified
                target.hp -= dmg
                self._log(f"round {self._current_round} {state.combatant.id}: sunder vs {target.combatant.id} d20={roll}+{attacker_cmb}={total} CMD {target_cmd} -> SUCCESS ({dmg} damage to weapon)")
            else:
                self._log(f"round {self._current_round} {state.combatant.id}: sunder vs {target.combatant.id} d20={roll}+{attacker_cmb}={total} CMD {target_cmd} -> FAILED")
        elif maneuver == "grapple":
            if success:
                # Initiate grapple
                target.active_conditions.append(
                    ActiveCondition(
                        condition=CONDITIONS_BY_NAME["grappled"],
                        rounds_left=10,  # Lasts until broken
                        source=f"maneuver: grapple by {state.combatant.id}",
                    )
                )
                target.conditions.append(CONDITIONS_BY_NAME["grappled"])
                target.grappled_with = state.combatant.id
                state.grappled_with = target.combatant.id
                self._log(f"round {self._current_round} {state.combatant.id}: grapple vs {target.combatant.id} d20={roll}+{attacker_cmb}={total} CMD {target_cmd} -> SUCCESS (grappled)")
            else:
                self._log(f"round {self._current_round} {state.combatant.id}: grapple vs {target.combatant.id} d20={roll}+{attacker_cmb}={total} CMD {target_cmd} -> FAILED")
        elif maneuver == "escape":
            # Escape uses CMB or Escape Artist skill
            escape_bonus = max(
                state.combatant.cmb or (state.combatant.bab + state.combatant.abilities.str_mod + self._size_mod(state)),
                self.resolve_skill(state, "escape_artist", 0).total if hasattr(state.combatant, 'skills') and 'escape_artist' in state.combatant.skills else 0
            )
            target_cmb = target.combatant.cmb or (target.combatant.bab + target.combatant.abilities.str_mod + self._size_mod(target))
            target_cmd = 10 + target_cmb + target.combatant.abilities.dex_mod
            roll = self._rng.d20()
            total = roll + escape_bonus
            success = roll != 1 and total >= target_cmd
            if success:
                # Remove grappled condition from both
                target.active_conditions = [ac for ac in target.active_conditions if ac.condition.name != "grappled"]
                target.conditions = [c for c in target.conditions if c.name != "grappled"]
                state.active_conditions = [ac for ac in state.active_conditions if ac.condition.name != "grappled"]
                state.conditions = [c for c in state.conditions if c.name != "grappled"]
                target.grappled_with = None
                state.grappled_with = None
            else:
                self._log(f"round {self._current_round} {state.combatant.id}: escape vs {target.combatant.id} d20={roll}+{escape_bonus}={total} CMD {target_cmd} -> FAILED")

    def _execute_channel_energy(self, state: CombatantState, target: CombatantState | None) -> None:
        """Execute channel energy (burst 30ft, 2d6 heal/damage, consumes channel_energy resource)."""
        if not state.spend_resource("channel_energy", 1):
            self._log(f"round {self._current_round} {state.combatant.id}: channel energy failed (no resources)")
            return
        if target is None or not target.active:
            return
        
        # Channel energy affects all creatures within 30ft (6 cells)
        radius_cells = 30 // _SQUARE_FT  # 6 cells
        center = state.pos
        affected: list[CombatantState] = []
        for state_other in self._states:
            if not state_other.active:
                continue
            dist = self._grid.distance(center, state_other.pos)
            if dist <= radius_cells:
                affected.append(state_other)
        
        if not affected:
            self._log(f"round {self._current_round} {state.combatant.id}: channel energy - no targets in range")
            return
        
        # Determine if healing or harming based on target relationship
        is_harm = target is not None and target.side != state.side
        
        # 2d6 damage/healing
        import random
        dmg = random.randint(2, 12)  # 2d6
        
        for affected_state in affected:
            is_ally = affected_state.side == state.side
            if is_ally and not is_harm:
                # Heal allies
                old_hp = affected_state.hp
                affected_state.hp = min(affected_state.hp + dmg, affected_state.combatant.hp_max)
                actual = affected_state.hp - old_hp
                self._stats[state.combatant.id].damage_dealt += actual
                self._log(
                    f"round {self._current_round} {state.combatant.id}: "
                    f"channel energy heals {affected_state.combatant.id} +{actual} HP"
                )
            elif not is_ally and is_harm:
                # Damage enemies
                affected_state.hp -= dmg
                self._stats[state.combatant.id].damage_dealt += dmg
                self._stats[affected_state.combatant.id].damage_taken += dmg
                self._log(
                    f"round {self._current_round} {state.combatant.id}: "
                    f"channel energy damages {affected_state.combatant.id} {dmg} ({affected_state.hp_before if hasattr(affected_state, 'hp_before') else '?'}->{affected_state.hp})"
                )
                if affected_state.dead:
                    self._log(
                        f"round {self._current_round} {state.combatant.id}: "
                        f"{affected_state.combatant.id} dead"
                    )
            else:
                # Neutral (enemies when healing, allies when harming)
                pass
        
        self._log(
            f"round {self._current_round} {state.combatant.id}: "
            f"channel energy ({'harm' if is_harm else 'heal'}) {dmg} -> {len(affected)} targets"
        )

    def _execute_hex(self, state: CombatantState, target: CombatantState | None, hex_name: str | None) -> None:
        """Execute a witch hex (evil_eye, slumber, cackle)."""
        if not state.spend_resource("hexes", 1):
            self._log(f"round {self._current_round} {state.combatant.id}: hex failed (no resources)")
            return
        if target is None or not target.active:
            return
        if hex_name not in ("evil_eye", "slumber", "cackle"):
            self._log(f"round {self._current_round} {state.combatant.id}: unknown hex {hex_name}")
            return
        
        if hex_name == "evil_eye":
            # Evil Eye: shaken (-2 AC or saves), 1 round, Will negates
            save_result = self.resolve_save(target, "will", 10 + state.combatant.level // 2 + (state.combatant.abilities.cha_score - 10) // 2)
            if save_result.success:
                self._log(f"round {self._current_round} {state.combatant.id}: evil eye on {target.combatant.id} -> SAVED")
                return
            target.active_conditions.append(
                ActiveCondition(
                    condition=CONDITIONS_BY_NAME["shaken"],
                    rounds_left=1,
                    source=f"hex: evil_eye by {state.combatant.id}",
                )
            )
            target.conditions.append(CONDITIONS_BY_NAME["shaken"])
            self._log(f"round {self._current_round} {state.combatant.id}: evil eye on {target.combatant.id} -> shaken (1r)")
        
        elif hex_name == "slumber":
            # Slumber: asleep/disabled if Will fails
            save_result = self.resolve_save(target, "will", 10 + state.combatant.level // 2 + (state.combatant.abilities.cha_score - 10) // 2)
            if save_result.success:
                self._log(f"round {self._current_round} {state.combatant.id}: slumber on {target.combatant.id} -> SAVED")
                return
            target.active_conditions.append(
                ActiveCondition(
                    condition=CONDITIONS_BY_NAME["asleep"],
                    rounds_left=1,
                    source=f"hex: slumber by {state.combatant.id}",
                )
            )
            target.conditions.append(CONDITIONS_BY_NAME["asleep"])
            self._log(f"round {self._current_round} {state.combatant.id}: slumber on {target.combatant.id} -> asleep (1r)")
        
        elif hex_name == "cackle":
            # Cackle: prolong one hex by 1 round
            # For simplicity, extend all hex conditions on target by 1 round
            extended = False
            for ac in target.active_conditions:
                if ac.source.startswith("hex:"):
                    # Can't modify frozen dataclass, need to recreate
                    target.active_conditions.remove(ac)
                    target.active_conditions.append(
                        ActiveCondition(
                            condition=ac.condition,
                            rounds_left=ac.rounds_left + 1,
                            source=ac.source,
                        )
                    )
                    extended = True
            if extended:
                self._log(f"round {self._current_round} {state.combatant.id}: cackle extends hex on {target.combatant.id}")
            else:
                self._log(f"round {self._current_round} {state.combatant.id}: cackle - no hex to extend on {target.combatant.id}")
    def _execute_attack(
        self, state: CombatantState, target: CombatantState | None, kind: str
    ) -> None:
        if self.has_condition_flag(state, "cant_attack"):
            self._log(f"round {self._current_round} {state.combatant.id}: wait (cannot attack)")
            return
        weapon = self.weapon_for(state, target)
        if weapon is None:
            return
        if kind == "attack":
            self._single_attack(state, target, weapon)
        elif kind == "full_attack":
            self._full_attack(state, target, weapon)
    def _execute_charge(self, state: CombatantState, target: CombatantState | None) -> None:
        if target is None or not target.active:
            return
        if self.has_condition_flag(state, "cant_charge"):
            self._log(f"round {self._current_round} {state.combatant.id}: wait (cannot charge)")
            return
        weapon = self.can_charge(state, target)
        if weapon is None:
            return
        self._charge(state, target, weapon)

    def _cast_spell(
        self, caster: CombatantState, target: CombatantState | None, spell_name: str
    ) -> None:
        spell = self._spell_registry.get(spell_name)
        if spell is None:
            self._log(
                f"round {self._current_round} {caster.combatant.id}: "
                f"cast {spell_name} -> UNKNOWN SPELL"
            )
            return
        if target is None or not target.active:
            return
        dist_ft = self._grid.distance(caster.pos, target.pos) * _SQUARE_FT
        max_range = spell_range_ft(spell, caster.combatant.level)
        if dist_ft > max_range:
            self._log(
                f"round {self._current_round} {caster.combatant.id}: "
                f"cast {spell_name} -> OUT OF RANGE"
            )
            return
        if not has_line_of_effect(self._grid, caster.pos, target.pos):
            self._log(
                f"round {self._current_round} {caster.combatant.id}: "
                f"cast {spell_name} -> NO LINE OF EFFECT"
            )
            return
        # Check for AoO from casting in threatened square (before resolving spell)
        if self._check_casting_aoo(caster, spell.level):
            return
        # DC = 10 + spell level + caster's casting ability modifier
        ability_name = caster.combatant.casting_ability.lower()
        ability_score = getattr(caster.combatant.abilities, f"{ability_name}_score")
        ability_mod = (ability_score - 10) // 2
        dc = 10 + spell.level + ability_mod
        save_result = (
            self.resolve_save(target, spell.save, dc) if spell.save != "none" else None
        )
        caster_live = self._stats[caster.combatant.id]
        target_live = self._stats[target.combatant.id]
        # Apply metamagic feats to spell effects
        metamagic_feats = caster.combatant.metamagic_feats
        metamagic_effects = self._apply_metamagic(spell, metamagic_feats)
        hp_before = target.hp
        parts = self._apply_spell_effects_from_list(
            metamagic_effects, target, save_result, caster_live, target_live,
            caster, spell_name=spell.name,
            empower="Empower Spell" in metamagic_feats,
            maximize="Maximize Spell" in metamagic_feats,
        )
        save_str = _save_label(save_result)
        self._log(
            f"round {self._current_round} {caster.combatant.id}: "
            f"cast {spell_name} vs {target.combatant.id} "
            f"DC{dc} {save_str} "
            f"-> {'; '.join(parts)} "
            f"({hp_before}->{target.hp})"
        )
        if target.dead:
            self._log(
                f"round {self._current_round} {caster.combatant.id}: "
                f"{target.combatant.id} dead"
            )
    def _apply_spell_effects(
        self,
        spell: SpellSpec,
        target: CombatantState,
        save_result: SaveResult | None,
        caster_live: _LiveStats,
        target_live: _LiveStats,
    ) -> list[str]:
        """Legacy wrapper for compatibility."""
        return self._apply_spell_effects_from_list(
            spell.effects, target, save_result, caster_live, target_live,
            caster=target, spell_name=spell.name
        )

    def _apply_spell_effects_from_list(
        self,
        effects: tuple[SpellEffect, ...],
        target: CombatantState,
        save_result: SaveResult | None,
        caster_live: _LiveStats,
        target_live: _LiveStats,
        caster: CombatantState,
        *,
        spell_name: str,
        empower: bool = False,
        maximize: bool = False,
    ) -> list[str]:
        saved = save_result is not None and save_result.success
        return [
            self._apply_single_spell_effect(
                effect, target, caster_live, target_live, caster,
                spell_name=spell_name, empower=empower, maximize=maximize,
                saved=saved
            )
            for effect in effects
        ]

    def _apply_single_spell_effect(
        self,
        effect: SpellEffect,
        target: CombatantState,
        caster_live: _LiveStats,
        target_live: _LiveStats,
        caster: CombatantState,
        *,
        spell_name: str,
        empower: bool = False,
        maximize: bool = False,
        saved: bool,
    ) -> str:
        if isinstance(effect, AreaEffect):
            return self._apply_area_effect(effect, target, caster_live, target_live, caster, spell_name, saved, empower=empower, maximize=maximize)
        if isinstance(effect, SummonEffect):
            return self._apply_summon_effect(effect, caster, caster_live, spell_name)
        if isinstance(effect, DamageEffect):
            raw = effect.formula.roll(self._rng)
            if maximize:
                raw = effect.formula.max_value()
            dmg = max(0, raw // 2) if saved and effect.half_on_save else raw
            if empower:
                dmg = int(dmg * 1.5)
            dmg = self._apply_dr_for_types(dmg, frozenset(effect.types), target)
            target.hp -= dmg
            caster_live.damage_dealt += dmg
            target_live.damage_taken += dmg
            return f"{dmg} damage"
        if isinstance(effect, ConditionEffect):
            if saved and effect.save_negates:
                return f"{effect.condition_name} negated"
            cond = CONDITIONS_BY_NAME.get(effect.condition_name)
            if cond is not None:
                target.active_conditions.append(
                    ActiveCondition(
                        condition=cond,
                        rounds_left=effect.duration_rounds,
                        source=f"spell: {spell_name}",
                    )
                )
                # Also update old conditions field for backwards compatibility
                target.conditions.append(cond)
                return f"{effect.condition_name} ({effect.duration_rounds}r)"
            return ""
        if isinstance(effect, HealEffect):
            heal = effect.formula.roll(self._rng)
            if maximize:
                heal = effect.formula.max_value()
            if empower:
                heal = int(heal * 1.5)
            old_hp = target.hp
            target.hp = min(target.hp + heal, target.combatant.hp_max)
            actual = target.hp - old_hp
            return f"+{actual} HP"
        # BuffEffect
        target.active_buffs.append(
            ActiveBuff(
                modifiers=effect.modifiers,
                rounds_left=effect.duration_rounds,
                source=f"spell: {spell_name}",
            )
        )
        # Also update old effects field for backwards compatibility
        target.effects.extend(effect.modifiers)
        return f"buff {len(effect.modifiers)} mods ({effect.duration_rounds}r)"

    def _apply_area_effect(
        self,
        effect: AreaEffect,
        target: CombatantState,
        caster_live: _LiveStats,
        target_live: _LiveStats,
        caster: CombatantState,
        spell_name: str,
        saved: bool,
        *,
        empower: bool = False,
        maximize: bool = False,
    ) -> str:
        """Apply an area effect to all creatures within radius.
        
        The target parameter is used as the center point for the burst.
        """
        radius_cells = effect.radius_ft // _SQUARE_FT
        center = target.pos

        # Find all creatures in radius
        affected: list[CombatantState] = []
        for state in self._states:
            if not state.active:
                continue
            dist = self._grid.distance(center, state.pos)
            if dist <= radius_cells:
                affected.append(state)

        if not affected:
            return "no targets in area"

        total_damage = 0
        total_conditions = 0
        total_buffs = 0

        for affected_state in affected:
            # Each creature gets a save
            creature_saved = False
            if effect.save_for_half:
                # Use the primary target's save result for the "primary" target
                # Others roll their own
                if affected_state is target:
                    creature_saved = saved
                else:
                    # Roll save for this creature
                    # For fireball, it's a Reflex save
                    save_result = self.resolve_save(affected_state, "ref", 15)  # DC from spell
                    creature_saved = save_result.success

            for sub_effect in effect.effects:
                result = self._apply_single_spell_effect(
                    sub_effect, affected_state, caster_live, self._stats[affected_state.combatant.id],
                    caster, spell_name=spell_name, saved=creature_saved, empower=empower, maximize=maximize
                )
                if "damage" in result:
                    total_damage += int(result.split()[0])
                elif "damage" not in result and result:
                    if "negated" not in result and "buff" not in result:
                        total_conditions += 1
                    elif "buff" in result:
                        total_buffs += 1

        return f"area: {len(affected)} targets, {total_damage} total damage, {total_conditions} conditions, {total_buffs} buffs"

    def _apply_metamagic(
        self, spell: SpellSpec, metamagic_feats: list[str]
    ) -> tuple[SpellEffect, ...]:
        """Apply metamagic feats to spell effects on the fly."""
        if not metamagic_feats:
            return spell.effects
        new_effects: list[SpellEffect] = []
        has_extend = "Extend Spell" in metamagic_feats

        for effect in spell.effects:
            if isinstance(effect, DamageEffect):
                # Empower: 1.5x damage (applied at roll time in _apply_spell_effects_from_list)
                # Maximize: max damage (applied at roll time)
                # We mark these via a custom attribute on the formula
                new_effects.append(effect)
            elif isinstance(effect, ConditionEffect):
                new_duration = effect.duration_rounds * 2 if has_extend else effect.duration_rounds
                new_effects.append(
                    ConditionEffect(
                        condition_name=effect.condition_name,
                        duration_rounds=new_duration,
                        save_negates=effect.save_negates,
                    )
                )
            elif isinstance(effect, HealEffect):
                # Empower/Maximize also apply to healing
                new_effects.append(effect)
            elif isinstance(effect, AreaEffect):
                new_sub_effects = []
                for sub in effect.effects:
                    if isinstance(sub, DamageEffect):
                        new_sub_effects.append(sub)
                    elif isinstance(sub, ConditionEffect):
                        new_duration = sub.duration_rounds * 2 if has_extend else sub.duration_rounds
                        new_sub_effects.append(
                            ConditionEffect(
                                condition_name=sub.condition_name,
                                duration_rounds=new_duration,
                                save_negates=sub.save_negates,
                            )
                        )
                    elif isinstance(sub, HealEffect):
                        new_sub_effects.append(sub)
                    else:  # BuffEffect
                        new_duration = sub.duration_rounds * 2 if has_extend else sub.duration_rounds
                        new_sub_effects.append(
                            BuffEffect(
                                modifiers=sub.modifiers,
                                duration_rounds=new_duration,
                            )
                        )
                new_effects.append(
                    AreaEffect(
                        radius_ft=effect.radius_ft,
                        effects=tuple(new_sub_effects),
                        save_for_half=effect.save_for_half,
                    )
                )
            else:  # BuffEffect
                new_duration = effect.duration_rounds * 2 if has_extend else effect.duration_rounds
                new_effects.append(
                    BuffEffect(
                        modifiers=effect.modifiers,
                        duration_rounds=new_duration,
                    )
                )
        return tuple(new_effects)


    def _apply_summon_effect(
        self,
        effect: SummonEffect,
        state: CombatantState,
        caster_live: _LiveStats,
        spell_name: str,
    ) -> str:
        """Apply a summoning effect - create a summoned creature."""
        # Load the summoned creature
        from pathlib import Path

        from pf1e_simulator.loaders.combatant import load_combatant

        try:
            summoned_combatant = load_combatant(Path(effect.creature))
        except Exception:
            return f"summon failed: could not load {effect.creature}"

        # Find a valid adjacent position for the summoned creature
        center = state.pos
        spawn_pos = None
        for dr in (-1, 0, 1):
            for dc in (-1, 0, 1):
                if dr == 0 and dc == 0:
                    continue
                pos = (center[0] + dr, center[1] + dc)
                if (0 <= pos[0] < self._grid.height and
                    0 <= pos[1] < self._grid.width and
                    not any(s.pos == pos for s in self._states if s.active)):
                    spawn_pos = pos
                    break
            if spawn_pos:
                break

        if not spawn_pos:
            return "summon failed: no space"

        # Create summoned creature state
        summoned_state = CombatantState(
            combatant=summoned_combatant,
            side=state.side,
            pos=spawn_pos,
            hp=summoned_combatant.hp_max,
        )

        # Insert into initiative order right after caster
        caster_idx = next(i for i, s in enumerate(self._states) if s is state)
        self._states.insert(caster_idx + 1, summoned_state)

        # Set expiration
        summoned_state.summon_duration = effect.duration_rounds
        summoned_state.summon_caster_id = state.combatant.id

        self._log(
            f"round {self._current_round} {state.combatant.id}: "
            f"summon {summoned_combatant.id} at {spawn_pos} ({effect.duration_rounds}r)"
        )
        return f"summoned {summoned_combatant.id}"

        for effect in spell.effects:
            if isinstance(effect, DamageEffect):
                # Empower: 1.5x damage (applied at roll time in _apply_spell_effects_from_list)
                # Maximize: max damage (applied at roll time)
                # We mark these via a custom attribute on the formula
                new_effects.append(effect)
            elif isinstance(effect, ConditionEffect):
                new_duration = effect.duration_rounds * 2 if has_extend else effect.duration_rounds
                new_effects.append(
                    ConditionEffect(
                        condition_name=effect.condition_name,
                        duration_rounds=new_duration,
                        save_negates=effect.save_negates,
                    )
                )
            elif isinstance(effect, HealEffect):
                # Empower/Maximize also apply to healing
                new_effects.append(effect)
            elif isinstance(effect, AreaEffect):
                new_sub_effects = []
                for sub in effect.effects:
                    if isinstance(sub, DamageEffect):
                        new_sub_effects.append(sub)
                    elif isinstance(sub, ConditionEffect):
                        new_duration = sub.duration_rounds * 2 if has_extend else sub.duration_rounds
                        new_sub_effects.append(
                            ConditionEffect(
                                condition_name=sub.condition_name,
                                duration_rounds=new_duration,
                                save_negates=sub.save_negates,
                            )
                        )
                    elif isinstance(sub, HealEffect):
                        new_sub_effects.append(sub)
                    else:  # BuffEffect
                        new_duration = sub.duration_rounds * 2 if has_extend else sub.duration_rounds
                        new_sub_effects.append(
                            BuffEffect(
                                modifiers=sub.modifiers,
                                duration_rounds=new_duration,
                            )
                        )
                new_effects.append(
                    AreaEffect(
                        radius_ft=effect.radius_ft,
                        effects=tuple(new_sub_effects),
                        save_for_half=effect.save_for_half,
                    )
                )
            else:  # BuffEffect
                new_duration = effect.duration_rounds * 2 if has_extend else effect.duration_rounds
                new_effects.append(
                    BuffEffect(
                        modifiers=effect.modifiers,
                        duration_rounds=new_duration,
                    )
                )
        return tuple(new_effects)

    def _resolve_swing(
        self,
        attacker: CombatantState,
        target: CombatantState,
        weapon: AttackSpec,
        *,
        label: str,
        bonus_override: int | None = None,
    ) -> bool:
        """Resolve one swing, log it, update stats. Return True if target dropped."""
        live = self._stats[attacker.combatant.id]
        target_live = self._stats[target.combatant.id]
        hp_before = target.hp
        result = self.resolve_attack(attacker, target, weapon, bonus_override=bonus_override)
        live.hits += int(result.hit)
        live.crits += int(result.crit)
        live.damage_dealt += result.damage
        target_live.damage_taken += result.damage
        outcome = "CRIT" if result.crit else "HIT" if result.hit else "MISS"
        flank_str = f"+{result.flank_bonus}(flank)" if result.flank_bonus else ""
        bonus_str = (
            f"{result.base_bonus}{result.penalty:+d}{flank_str}"
            if result.penalty
            else f"{result.base_bonus}{flank_str}"
        )
        line = (
            f"round {self._current_round} {attacker.combatant.id}: {label} "
            f"vs {target.combatant.id} "
            f"d20={result.roll}+{bonus_str}={result.total} "
            f"AC {result.ac} -> {outcome}"
        )
        if result.hit:
            line += f" {result.damage} damage ({hp_before}->{target.hp})"
        self._log(line)
        if target.dead:
            self._log(
                f"round {self._current_round} {attacker.combatant.id}: "
                f"{target.combatant.id} dead"
            )
            return True
        if not target.active:
            self._log(
                f"round {self._current_round} {attacker.combatant.id}: "
                f"{target.combatant.id} down"
            )
            return True
        return False

    def _attack(
        self, attacker: CombatantState, target: CombatantState, weapon: AttackSpec
    ) -> None:
        for swing in range(1, weapon.count + 1):
            if not attacker.active:
                return
            if self._check_provoked_aoo(attacker, weapon):
                return
            label = weapon.name if weapon.count == 1 else f"{weapon.name} #{swing}"
            if self._resolve_swing(attacker, target, weapon, label=label):
                return

    def _single_attack(
        self, attacker: CombatantState, target: CombatantState, weapon: AttackSpec
    ) -> None:
        if not attacker.active:
            return
        if self._check_provoked_aoo(attacker, weapon):
            return
        self._resolve_swing(attacker, target, weapon, label=weapon.name)

    def _full_attack(
        self, attacker: CombatantState, target: CombatantState, weapon: AttackSpec
    ) -> None:
        if weapon.count > 1:
            self._attack(attacker, target, weapon)
            return
        n = min(
            _MAX_ITERATIVES,
            1 + max(0, (attacker.combatant.bab - 1) // _ITERATIVE_PENALTY),
        )
        for i in range(n):
            if not attacker.active:
                return
            if self._check_provoked_aoo(attacker, weapon):
                return
            label = weapon.name if n == 1 else f"{weapon.name} #{i + 1}"
            bonus = weapon.attack_bonus - _ITERATIVE_PENALTY * i
            if self._resolve_swing(
                attacker, target, weapon, label=label, bonus_override=bonus
            ):
                return

    def _step5(self, state: CombatantState, target: CombatantState) -> None:
        if state.moved_this_turn:
            return
        if self.has_condition_flag(state, "cant_move"):
            self._log(f"round {self._current_round} {state.combatant.id}: wait (cannot move)")
            return
        path = self._move_path(state, target)
        start = state.pos
        state.pos = path[0]
        state.moved_this_turn = True
        self._log(
            f"round {self._current_round} {state.combatant.id}: "
            f"5ft step ({start[0]},{start[1]})->({path[0][0]},{path[0][1]})"
        )

    def _move(self, state: CombatantState, target: CombatantState) -> None:
        if state.moved_this_turn:
            return
        if self.has_condition_flag(state, "cant_move"):
            self._log(f"round {self._current_round} {state.combatant.id}: wait (cannot move)")
            return
        path = self._move_path(state, target)
        start = state.pos
        actual_path: list[Pos] = []
        for step in path:
            for enemy in self._enemies_threatening(state, state.pos):
                if enemy.combatant.id in self._aoo_used:
                    continue
                self._resolve_aoo(enemy, state)
                if not state.active:
                    break
            if not state.active:
                break
            state.pos = step
            actual_path.append(step)
        if actual_path:
            state.moved_this_turn = True
            coords = "->".join(f"({p[0]},{p[1]})" for p in (start, *actual_path))
            self._log(f"round {self._current_round} {state.combatant.id}: move {coords}")

    def _move_path(self, state: CombatantState, target: CombatantState) -> list[Pos]:
        """Full movement path toward the target, up to the combatant's speed."""
        speed_mult = self._get_speed_mult(state)
        speed_cells = int(state.combatant.speed_land_ft // _SQUARE_FT * speed_mult)
        if speed_cells <= 0:
            return []
        blocked = frozenset(s.pos for s in self._states if s is not state and s.active)
        to_target = self._grid.reachable(target.pos, None, blocked)
        if state.pos not in to_target:
            return []
        path: list[Pos] = []
        current = state.pos
        budget = speed_cells
        while budget > 0:
            current_cost = to_target[current]
            best: tuple[int, int, Pos] | None = None
            row, col = current
            for d_row, d_col in _STEP_DELTAS:
                nxt = (row + d_row, col + d_col)
                if nxt in blocked:
                    continue
                nxt_cost = to_target.get(nxt)
                if nxt_cost is None or nxt_cost >= current_cost:
                    continue
                step = self._grid.step_cost(current, nxt, 0)
                if step > budget:
                    continue
                score = step + nxt_cost
                if best is None or score < best[0]:
                    best = (score, step, nxt)
            if best is None:
                break
            current = best[2]
            path.append(current)
            budget -= best[1]
        return path

    def _flee_path(self, state: CombatantState, threat: CombatantState) -> list[Pos]:
        """Movement path away from ``threat``, up to double speed.

        Uses the Dijkstra cost field from the threat and greedily picks the
        step that maximizes distance (cost) from the threat each cell.
        """
        speed_mult = self._get_speed_mult(state)
        max_cells = int(2 * (state.combatant.speed_land_ft // _SQUARE_FT) * speed_mult)
        if max_cells <= 0:
            return []
        blocked = frozenset(s.pos for s in self._states if s is not state and s.active)
        from_threat = self._grid.reachable(threat.pos, None, blocked)
        if state.pos not in from_threat:
            return []
        path: list[Pos] = []
        current = state.pos
        budget = max_cells
        while budget > 0:
            best = self._best_flee_step(current, from_threat, blocked, budget)
            if best is None:
                break
            _, step_cost, nxt = best
            current = nxt
            path.append(current)
            budget -= step_cost
        return path

    def _best_flee_step(
        self,
        current: Pos,
        from_threat: dict[Pos, int],
        blocked: frozenset[Pos],
        budget: int,
    ) -> tuple[int, int, Pos] | None:
        """Pick the adjacent square that maximizes distance from the threat."""
        current_cost = from_threat[current]
        best: tuple[int, int, Pos] | None = None
        row, col = current
        for d_row, d_col in _STEP_DELTAS:
            nxt = (row + d_row, col + d_col)
            if nxt in blocked or not self._grid.passable(nxt):
                continue
            if not self._grid.diagonal_allowed(current, nxt):
                continue
            nxt_cost = from_threat.get(nxt)
            if nxt_cost is None or nxt_cost <= current_cost:
                continue
            step = self._grid.step_cost(current, nxt, 0)
            if step > budget:
                continue
            score = -(nxt_cost * 100) + step
            if best is None or score < best[0]:
                best = (score, step, nxt)
        return best

    def _withdraw(self, state: CombatantState, threat: CombatantState | None) -> None:
        """Full-round action: move up to 2x speed away from the nearest enemy.

        The starting square is not threatened — no AoO when leaving it.
        Subsequent squares provoke AoOs normally (step-by-step, as for move).
        """
        if threat is None:
            return
        path = self._flee_path(state, threat)
        if not path:
            return
        start = state.pos
        actual_path: list[Pos] = []
        for i, step in enumerate(path):
            if i > 0:
                for enemy in self._enemies_threatening(state, state.pos):
                    if enemy.combatant.id in self._aoo_used:
                        continue
                    self._resolve_aoo(enemy, state)
                    if not state.active:
                        break
            if not state.active:
                break
            state.pos = step
            actual_path.append(step)
        if actual_path:
            state.moved_this_turn = True
            coords = "->".join(f"({p[0]},{p[1]})" for p in (start, *actual_path))
            self._log(
                f"round {self._current_round} {state.combatant.id}: withdraw {coords}"
            )

    def _log(self, line: str) -> None:
        self._transcript.append(line)


    def _size_mod(self, state: CombatantState) -> int:
        """Size modifier for CMB/CMD: Medium=0, Small=-1, Large=1, etc."""
        size = state.combatant.size.lower()
        if size == "fine":
            return -8
        if size == "diminutive":
            return -4
        if size == "tiny":
            return -2
        if size == "small":
            return -1
        if size == "medium":
            return 0
        if size == "large":
            return 1
        if size == "huge":
            return 2
        if size == "gargantuan":
            return 4
        if size == "colossal":
            return 8
        return 0

    def _bull_rush_push(self, attacker: CombatantState, target: CombatantState) -> bool:
        """Push target 5ft away from attacker. Returns True if push succeeded."""
        # Calculate direction away from attacker
        ar, ac = attacker.pos
        tr, tc = target.pos
        dr = tr - ar
        dc = tc - ac
        # Normalize to single step
        if dr != 0:
            dr = 1 if dr > 0 else -1
        if dc != 0:
            dc = 1 if dc > 0 else -1
        new_pos = (tr + dr, tc + dc)
        # Check if destination is valid (in bounds, not blocked)
        if not (0 <= new_pos[0] < self._grid.height and 0 <= new_pos[1] < self._grid.width):
            return False
        # Check if occupied
        if any(s.pos == new_pos for s in self._states if s.active and s is not target):
            return False
        target.pos = new_pos
        return True
def _find_heal_spell(engine: CombatEngine, spells_known: list[str]) -> str | None:
    """Find a heal spell in known spells."""
    for name in spells_known:
        spell = engine._spell_registry.get(name)
        if spell and any(isinstance(e, HealEffect) for e in spell.effects):
            return name
    return None


def _find_ally_needing_heal(engine: CombatEngine, caster: CombatantState) -> CombatantState | None:
    """Find an ally below 50% HP."""
    for ally_state in engine._states:
        if ally_state.side == caster.side and ally_state.active and ally_state.hp < ally_state.combatant.hp_max // 2:
            return ally_state
    return None


def _find_offensive_spell(
    engine: CombatEngine, spells_known: list[str], caster: CombatantState, target: CombatantState
) -> str | None:
    """Find an offensive spell that can reach the target."""
    dist_ft = engine._grid.distance(caster.pos, target.pos) * _SQUARE_FT
    for name in spells_known:
        spell = engine._spell_registry.get(name)
        if not spell:
            continue
        # Check for damage effect
        has_damage = any(isinstance(e, DamageEffect) for e in spell.effects)
        if not has_damage:
            continue
        max_range = spell_range_ft(spell, caster.combatant.level)
        if dist_ft <= max_range and has_line_of_effect(engine._grid, caster.pos, target.pos):
            return name
    return None


def _find_buff_spell(engine: CombatEngine, spells_known: list[str]) -> str | None:
    """Find a buff spell."""
    for name in spells_known:
        spell = engine._spell_registry.get(name)
        if spell and any(isinstance(e, BuffEffect) for e in spell.effects):
            return name
    return None


def _choose_spell_action(
    engine: CombatEngine, state: CombatantState, target: CombatantState
) -> tuple[Action, ...] | None:
    """Select and return a spell action if appropriate, else None."""
    caster = state
    spells_known = caster.combatant.spells
    if not spells_known:
        return None

    # Check spell slots available
    slots_left = caster.resources_left.get("spell_slots", 0)
    if slots_left <= 0:
        return None

    # 1. Heal spell if ally below 50% HP
    heal_spell = _find_heal_spell(engine, spells_known)
    if heal_spell:
        ally = _find_ally_needing_heal(engine, caster)
        if ally and ally.hp < ally.combatant.hp_max // 2:
            return (Action(kind="cast_spell", target_id=ally.combatant.id, spell_name=heal_spell),)

    # 2. Offensive spell if enemy in range
    offensive_spell = _find_offensive_spell(engine, spells_known, caster, target)
    if offensive_spell:
        return (Action(kind="cast_spell", target_id=target.combatant.id, spell_name=offensive_spell),)

    # 3. Buff spell
    buff_spell = _find_buff_spell(engine, spells_known)
    if buff_spell:
        return (Action(kind="cast_spell", target_id=caster.combatant.id, spell_name=buff_spell),)

    return None


def default_policy(engine: CombatEngine, state: CombatantState) -> tuple[Action, ...]:
    """Full-attack the nearest enemy; cast spells; charge, 5ft-step, or approach if out of range.

    Decision order:
    1. Heal spell if an ally is below 50% HP and a heal spell is available.
    2. Offensive spell if an enemy is in range and spell slots available.
    3. Buff spell if no immediate threat and spell slots available.
    4. Full-attack if a weapon is usable against the nearest enemy this turn (no move needed).
    5. Charge if a straight-line charge path exists (2x speed, +2 attack, -2 AC).
    5. 5-foot step then full-attack if a single step brings the target into weapon range.
    6. Move toward the target then single attack (standard + move economy).
    7. Wait if nothing is possible.

    Never casts a spell if threatened without Concentration check (handled in _cast_spell).
    """
    target = engine.nearest_enemy(state)
    if target is None:
        return (Action(kind="wait"),)
    # Must flee: withdraw from the nearest enemy
    if engine.has_condition_flag(state, "must_flee"):
        return (Action(kind="withdraw", target_id=target.combatant.id),)

    # Try spellcasting if caster has spells
    if state.combatant.spells:
        spell_action = _choose_spell_action(engine, state, target)
        if spell_action is not None:
            return spell_action

    if engine.weapon_for(state, target) is not None:
        return (Action(kind="full_attack", target_id=target.combatant.id),)
    charge_weapon = engine.can_charge(state, target)
    if charge_weapon is not None:
        return (Action(kind="charge", target_id=target.combatant.id),)
    if engine.can_step5_to_attack(state, target):
        return (
            Action(kind="5foot_step", target_id=target.combatant.id),
            Action(kind="full_attack", target_id=target.combatant.id),
        )
    return (
        Action(kind="move", target_id=target.combatant.id),
        Action(kind="attack", target_id=target.combatant.id),
    )