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.

README.md

@@ -417,6 +417,15 @@ Règles modélisées :
    coût Dijkstra depuis la cible, diagonales 5-10-5), en s'arrêtant adjacent à
    l'ennemi le plus proche — les combattants contournent les murs au lieu
    d'osciller contre eux.
+   Vitesse de déplacement (V4) : le budget de tout mouvement (déplacement,
+   charge 2×, retraite 2×, course 4×) est le **meilleur entre la vitesse au
+   sol (`speed_land_ft`) et la vitesse de vol (`speed_fly_ft`)** — une créature
+   dotée d'une vitesse de vol (harvie : vol 80 vs sol 30, ierlieth : vol 40)
+   se déplace donc à sa vitesse de vol. Simplification documentée : voler
+   PAR-DESSUS les obstacles ou le terrain difficile n'est PAS modélisé — la
+   praticabilité et les coûts de terrain de la grille s'appliquent à tout le
+   budget (pas de vol 3D ni de maniabilité) ; le snapshot expose ce budget
+   sous la clé additive `speed_effective_ft`.
   Destination explicite : `Action(kind="move", destination=(r, c))` et
   `Action(kind="5foot_step", destination=(r, c))` déplacent le combattant vers
   la case `(r, c)` désignée (monter au couvert, quitter un défilé, se
@@ -686,7 +695,9 @@ Règles modélisées :
     metamagic_feats (tuple trié), weapon_damage {weapon_id: dégâts courants},
     summon_duration (int ou None), immediate_used, deed_up_close_and_deadly
     (flags actuels), active_buffs {source, rounds_left, mods: tuple de
-    {target, value, bonus_type}} (E5), speed_land_ft, speed_fly_ft, ac {total,
+    {target, value, bonus_type}} (E5), speed_land_ft, speed_fly_ft,
+    speed_effective_ft (V4 : budget de déplacement effectif = max(land, fly),
+    en pieds), ac {total,
     touch, flat_footed}, saves {fort, ref, will}, cmb, cmd, attacks
     (référentiel complet : id, name, kind, attack_bonus, damage, damage_bonus,
     crit_range, crit_mult, reach_ft, range_increment_ft, count, firearm —
@@ -759,7 +770,7 @@ Règles modélisées :
   `channel_energy`, `hexes`, `grit`, `arcane_pool`, `bardic_rounds`, plus
    `spell_slot_{level}` ajouté par le snapshot). Limites documentées : pas de
    grille `reachable_ft` budget=speed (délibérément rejetée —
-   `movement_cost_ft` par paire + `terrain_semantics` + `speed_land_ft`
+    `movement_cost_ft` par paire + `terrain_semantics` + `speed_effective_ft`
     suffisent). Le couvert par paire est exposé via la clé `cover_bonus`
    (calcul identique à `resolve_attack`, couvert mou des créatures inclus).
    Les API de décision exposées (items L1-L8)

src/pf1e_simulator/combat.py

@@ -34,6 +34,8 @@ Phase 0 documented deviations from PF1e (conventions):
 - 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.
+  The speed budget is the best of land and fly speed (V4); flying over
+  obstacles or difficult terrain is NOT modeled (grid costs still apply).
 - 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
@@ -158,7 +160,7 @@ _FIGHT_DEFENSIVELY_AC_BONUS = 2  # PF1e: fighting defensively grants +2 dodge AC
 _FIGHT_DEFENSIVELY_ATTACK_PENALTY = -4  # PF1e: and -4 on attacks / crit confirms
 _AID_ANOTHER_DC = 10  # PF1e: aid another is an attack roll against AC 10
 _AID_ANOTHER_BONUS = 2  # PF1e: a successful aid grants +2 (next attack or AC)
-_RUN_SPEED_FACTOR = 4  # PF1e: running is a full-round action at 4x land speed
+_RUN_SPEED_FACTOR = 4  # PF1e: running is a full-round action at 4x speed
 _SAVE_DESCRIPTOR_CONDITIONS = frozenset({
     "fear", "cold", "electricity", "fey", "divination", "poison", "disease",
     "mind_affecting",
@@ -312,6 +314,18 @@ def _effective_reach_ft(state: CombatantState, weapon: AttackSpec) -> int:
     return max(_SIZE_NATURAL_REACH_FT.get(state.combatant.size, 5), weapon.reach_ft)
 
 
+def _speed_ft(state: CombatantState) -> int:
+    """Movement budget in feet: the best of the combatant's land and fly speed.
+
+    Simplification (V4): a creature that has a fly speed is assumed to use it;
+    flying OVER obstacles or difficult terrain is NOT modeled — the grid's
+    passability and terrain costs still apply to the whole budget. No
+    fly maneuverability, no 3D flight. Swim/climb/burrow speeds do not exist
+    in the model (fly only).
+    """
+    return max(state.combatant.speed_land_ft, state.combatant.speed_fly_ft or 0)
+
+
 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
@@ -1081,6 +1095,7 @@ class CombatEngine:
             ),
             "speed_land_ft": state.combatant.speed_land_ft,
             "speed_fly_ft": state.combatant.speed_fly_ft,
+            "speed_effective_ft": _speed_ft(state),
             "ac": {
                 "total": state.combatant.ac.total,
                 "touch": state.combatant.ac.touch,
@@ -2336,15 +2351,15 @@ class CombatEngine:
         (API publique, lecture pour politique LLM.) Uses the same cost model as
         ``_move_path``: a full Dijkstra field from the target's anchor (other
         active states' cells blocked), then the cheapest field value over
-        ``state``'s footprint, compared against the combatant's land speed.
-        Read-only: never mutates state nor consumes RNG.
+        ``state``'s footprint, compared against the combatant's effective
+        (land-or-fly) speed. Read-only: never mutates state nor consumes RNG.
         """
         blocked = self._blocked(state, target)
         field = self._grid.reachable(target.pos, None, blocked)
         cost_cells = self._footprint_cost(state.occupied_cells(), field)
         if cost_cells is None:
             return None
-        speed_cells = state.combatant.speed_land_ft // _SQUARE_FT
+        speed_cells = _speed_ft(state) // _SQUARE_FT
         if cost_cells > speed_cells:
             return None
         return cost_cells * _SQUARE_FT
@@ -2495,7 +2510,7 @@ class CombatEngine:
             self._grid, state.occupied_cells(), target.occupied_cells()
         ):
             return ChargeResult(weapon=None, distance_ft=0, reason="no_line_of_effect")
-        speed_cells = state.combatant.speed_land_ft // _SQUARE_FT
+        speed_cells = _speed_ft(state) // _SQUARE_FT
         max_cells = 2 * speed_cells
         blocked = self._blocked(state, target)
         melee_weapons = [w for w in state.usable_attacks() if w.kind == "melee"]
@@ -2603,7 +2618,7 @@ class CombatEngine:
         """
         reach_cells = _effective_reach_ft(attacker, weapon) // _SQUARE_FT
         min_reach_cells = weapon.reach_ft // _SQUARE_FT if weapon.reach_ft > _SQUARE_FT else 0
-        speed_cells = attacker.combatant.speed_land_ft // _SQUARE_FT
+        speed_cells = _speed_ft(attacker) // _SQUARE_FT
         max_cells = 2 * speed_cells
         blocked = self._blocked(attacker, target)
         end = self._charge_end(
@@ -4804,7 +4819,7 @@ class CombatEngine:
         ``speed_factor`` widens the budget (run: 4x speed, U5e).
         """
         speed_cells = int(
-            state.combatant.speed_land_ft
+            _speed_ft(state)
             // _SQUARE_FT
             * self._get_speed_mult(state)
             * speed_factor
@@ -4850,7 +4865,7 @@ class CombatEngine:
         """
         speed_mult = self._get_speed_mult(state)
         speed_cells = int(
-            state.combatant.speed_land_ft
+            _speed_ft(state)
             // _SQUARE_FT
             * speed_mult
             * speed_factor
@@ -4910,7 +4925,7 @@ class CombatEngine:
         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)
+        max_cells = int(2 * (_speed_ft(state) // _SQUARE_FT) * speed_mult)
         if max_cells <= 0:
             return []
         blocked = self._blocked(state)

tests/test_fly_speed.py

@@ -0,0 +1,222 @@
+"""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)

tests/test_pc_combat_golden.py

@@ -157,9 +157,14 @@ class TestGoldenCombats:
         self._assert_deterministic_goblin("oni")
 
     def test_harvie_vs_goblin(self):
-        """Harvie (Animal Companion) vs Goblin - the goblin wins."""
+        """Harvie (Animal Companion, flying) vs Goblin - Harvie wins.
+
+        Updated (V4): Harvie has speed_land_ft 10 / speed_fly_ft 80; movement now
+        uses the best of land/fly speed, so Harvie flies at 80 ft and wins (the
+        previous expectation pinned him crawling at 10 ft).
+        """
         result, transcript = run_golden("harvie")
-        assert result.winner == "monsters"
+        assert result.winner == "players"
         assert result.rounds >= 1
         self._assert_deterministic_goblin("harvie")