feat(combat): use fly speed for movement

Movement budget is now max(land, fly) speed. Updates the harvie golden: Harvie (land 10 / fly 80) is a flyer and now flies at 80 ft, so he wins vs the goblin instead of being pinned crawling at 10 ft.

tests/test_fly_speed.py

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+"""V4: movement uses the best of land and fly speed.
+
+The engine budgets every movement action (move, 5-foot step toward a target,
+charge at 2x, withdraw at 2x, run at 4x) from ``_speed_ft(state)`` — the
+maximum of the creature's ``speed_land_ft`` and ``speed_fly_ft`` (a missing
+fly speed counts as 0, so a land-only creature is unchanged). Simplification:
+a creature that has a fly speed is assumed to use it, but flying OVER
+obstacles or difficult terrain is NOT modeled — the grid's passability and
+terrain costs still apply to the whole budget. The observation snapshot adds
+an additive ``speed_effective_ft`` key; ``speed_land_ft``/``speed_fly_ft`` are
+kept as-is.
+"""
+from __future__ import annotations
+
+from collections.abc import Callable
+
+from pf1e_simulator.combat import (
+    Action,
+    CombatantState,
+    CombatEngine,
+)
+from pf1e_simulator.dice import parse_dice
+from pf1e_simulator.grid import Grid
+from pf1e_simulator.map import MapSpec, TerrainType
+from pf1e_simulator.models import (
+    AbilityScores,
+    ACProfile,
+    AttackSpec,
+    Combatant,
+    DamageComponent,
+    Saves,
+)
+from pf1e_simulator.rng import ScriptedRng
+from tests.test_observation_enriched import make_state
+
+PolicyFn = Callable[[CombatEngine, CombatantState], tuple[Action, ...]]
+
+_WAIT: tuple[Action, ...] = (Action(kind="wait"),)
+
+
+def _combatant(
+    id_: str, *, land: int, fly: int | None = None, initiative_mod: int = 0
+) -> Combatant:
+    return Combatant(
+        id=id_,
+        name=id_,
+        level=1,
+        abilities=AbilityScores(
+            str_score=10, dex_score=10, con_score=10,
+            int_score=10, wis_score=10, cha_score=10,
+        ),
+        ac=ACProfile(total=10, touch=10, flat_footed=10),
+        bab=1,
+        initiative_mod=initiative_mod,
+        speed_land_ft=land,
+        speed_fly_ft=fly,
+        hp_max=100,
+        saves=Saves(fort=0, ref=0, will=0),
+        attacks=[
+            AttackSpec(
+                id=f"{id_}-sword",
+                name="short sword",
+                kind="melee",
+                attack_bonus=5,
+                damage=[
+                    DamageComponent(formula=parse_dice("1d6"), types=["slashing"])
+                ],
+            )
+        ],
+    )
+
+
+def _corridor(cols: int) -> Grid:
+    """A single-row open floor of ``cols`` cells (all move_cost 1)."""
+    legend = {".": TerrainType(type="floor", move_cost=1)}
+    spec = MapSpec(name="corridor", terrain=("." * cols,), legend=legend)
+    return Grid.from_spec(spec)
+
+
+def _run_move(
+    *, land: int, fly: int | None, destination: tuple[int, int], cols: int,
+) -> CombatantState:
+    """Hero acts first, takes a single ``move`` to ``destination``; foe idles
+    far down the corridor (never threatens). Returns the hero state."""
+    hero = make_state(
+        _combatant("hero", land=land, fly=fly, initiative_mod=2),
+        "players",
+        (0, 0),
+    )
+    foe = make_state(_combatant("foe", land=30), "monsters", (0, cols - 1))
+
+    def policy(_engine: CombatEngine, state: CombatantState) -> tuple[Action, ...]:
+        if state.combatant.id == "hero":
+            return (Action(kind="move", destination=destination),)
+        return _WAIT
+
+    eng = CombatEngine(
+        ScriptedRng([10, 5]), _corridor(cols), [hero, foe],
+        policy=policy, round_cap=1,
+    )
+    eng.run()
+    return eng._states[0]
+
+
+# ── (a) a land-only creature moves at its land speed (unchanged) ──────────────
+
+
+def test_land_only_creature_uses_land_speed() -> None:
+    # speed 30 ft = 6 cells; (0, 6) is exactly reachable, (0, 7) is not.
+    hero = _run_move(land=30, fly=None, destination=(0, 6), cols=12)
+    assert hero.pos == (0, 6)
+
+    hero = _run_move(land=30, fly=None, destination=(0, 7), cols=12)
+    assert hero.pos == (0, 0)
+
+
+# ── (b) a fly 80 / land 30 creature moves up to 80 ft (16 cells) ──────────────
+
+
+def test_flyer_moves_farther_than_land_only() -> None:
+    # fly 80 ft = 16 cells: (0, 16) is within the move budget.
+    flyer = _run_move(land=30, fly=80, destination=(0, 16), cols=20)
+    assert flyer.pos == (0, 16)
+
+    # A land-only creature cannot reach the same cell this turn.
+    crawler = _run_move(land=30, fly=None, destination=(0, 16), cols=20)
+    assert crawler.pos == (0, 0)
+    assert _corridor(20).distance(flyer.pos, (0, 0)) > _corridor(20).distance(
+        crawler.pos, (0, 0)
+    )
+
+
+# ── (c) charge uses 2x the effective speed; run uses 4x ──────────────────────
+
+
+def test_charge_budget_is_double_the_fly_speed() -> None:
+    # fly 80 -> charge up to 2x16 = 32 cells; the foe at (0, 20) is chargeable.
+    flyer = make_state(
+        _combatant("hero", land=30, fly=80), "players", (0, 0)
+    )
+    eng = CombatEngine(
+        ScriptedRng([]), _corridor(24),
+        [flyer, make_state(_combatant("foe", land=30), "monsters", (0, 20))],
+    )
+    result = eng.can_charge(flyer, eng._states[1])
+    assert result is not None
+    assert result.weapon is not None
+    assert result.reason is None
+
+    # A land-only creature (max 2x6 = 12 cells) cannot reach (0, 20).
+    crawler = make_state(_combatant("hero", land=30), "players", (0, 0))
+    foe2 = make_state(_combatant("foe", land=30), "monsters", (0, 20))
+    eng2 = CombatEngine(ScriptedRng([]), _corridor(24), [crawler, foe2])
+    result2 = eng2.can_charge(crawler, foe2)
+    assert result2 is not None
+    assert result2.reason == "no_charge_path"
+
+
+def test_run_budget_is_four_times_the_fly_speed() -> None:
+    # fly 80 -> run 4x16 = 64 cells; (0, 40) is reachable by running.
+    hero = make_state(
+        _combatant("hero", land=30, fly=80, initiative_mod=2), "players", (0, 0)
+    )
+    foe = make_state(_combatant("foe", land=30), "monsters", (0, 63))
+
+    def policy(_engine: CombatEngine, state: CombatantState) -> tuple[Action, ...]:
+        if state.combatant.id == "hero":
+            return (Action(kind="run", destination=(0, 40)),)
+        return _WAIT
+
+    eng = CombatEngine(
+        ScriptedRng([10, 5]), _corridor(64), [hero, foe],
+        policy=policy, round_cap=1,
+    )
+    eng.run()
+    assert eng._states[0].pos == (0, 40)
+
+    # A land-only creature (run 4x6 = 24 cells) cannot reach (0, 40).
+    crawler = make_state(
+        _combatant("hero", land=30, fly=None, initiative_mod=2), "players", (0, 0)
+    )
+    foe2 = make_state(_combatant("foe", land=30), "monsters", (0, 63))
+    eng2 = CombatEngine(
+        ScriptedRng([10, 5]), _corridor(64), [crawler, foe2],
+        policy=policy, round_cap=1,
+    )
+    eng2.run()
+    assert eng2._states[0].pos == (0, 0)
+
+
+# ── (d) the snapshot exposes speed_effective_ft ───────────────────────────────
+
+
+def test_snapshot_exposes_speed_effective_ft() -> None:
+    flyer = make_state(_combatant("flyer", land=30, fly=80), "players", (0, 0))
+    land_only = make_state(_combatant("walker", land=30), "monsters", (0, 3))
+    eng = CombatEngine(ScriptedRng([]), _corridor(8), [flyer, land_only])
+    obs = eng._build_observation(flyer).to_dict()
+    by_id = {c["id"]: c for c in obs["combatants"]}
+    assert by_id["flyer"]["speed_effective_ft"] == 80
+    assert by_id["flyer"]["speed_land_ft"] == 30
+    assert by_id["flyer"]["speed_fly_ft"] == 80
+    assert by_id["walker"]["speed_effective_ft"] == 30
+    assert by_id["walker"]["speed_fly_ft"] is None
+
+
+# ── (e) a fly speed lower than land falls back to land (max) ──────────────────
+
+
+def test_fly_lower_than_land_uses_land() -> None:
+    hero = make_state(_combatant("hero", land=30, fly=10), "players", (0, 0))
+    foe = make_state(_combatant("foe", land=30), "monsters", (0, 7))
+    eng = CombatEngine(ScriptedRng([]), _corridor(8), [hero, foe])
+    obs = eng._build_observation(hero).to_dict()
+    by_id = {c["id"]: c for c in obs["combatants"]}
+    assert by_id["hero"]["speed_effective_ft"] == 30
+
+    # Movement still uses the 30 ft land budget (6 cells), not the 10 ft fly.
+    mover = _run_move(land=30, fly=10, destination=(0, 6), cols=12)
+    assert mover.pos == (0, 6)
+    mover = _run_move(land=30, fly=10, destination=(0, 7), cols=12)
+    assert mover.pos == (0, 0)