fix(rules): Extend Spell doubles SummonEffect duration (SRD extend-spell: lasts twice as long; summon's 1 round/level is neither instantaneous, concentration nor permanent)

2026-09-19 11:55:30 +02:00
parent 65a5e24609
commit 22724f583f
2 changed files with 84 additions and 2 deletions
@@ -335,3 +335,70 @@ class TestSummonDurationScalesWithCasterLevel:
            effect = spell.effects[0]
            assert isinstance(effect, SummonEffect)
            assert effect.duration_rounds_per_level == 1
+
+
+class TestExtendSpellOnSummon:
+    """SRD feats/extend-spell.md: "An extended spell lasts twice as long as
+    normal. A spell with a duration of concentration, instantaneous, or
+    permanent is not affected" - summon monster's "1 round/level (D)" is
+    none of those, so Extend must double it."""
+
+    def test_extend_doubles_the_per_level_summon_duration(self) -> None:
+        # Given: a level 5 caster who knows Extend Spell
+        # When: summoning with Extend Spell (1 round/level -> 2 rounds/level)
+        # Then: the wolf is bound for 10 rounds, and the level-3 slot burns.
+        caster = _make_caster().model_copy(
+            update={
+                "metamagic_feats": ["Extend Spell"],
+                "spell_slots": {1: 3, 2: 3, 3: 3},
+            }
+        )
+        enemy = _make_enemy()
+        c = CombatantState(combatant=caster, side="players", pos=(0, 0), hp=caster.hp_max)
+        e = CombatantState(combatant=enemy, side="monsters", pos=(5, 0), hp=enemy.hp_max)
+        spell = SpellSpec(
+            name="Summon Monster II",
+            level=2,
+            school="conjuration",
+            range="close",
+            effects=(
+                SummonEffect(
+                    creature="data/monsters/celestial_wolf.json",
+                    duration_rounds=1,
+                    duration_rounds_per_level=1,
+                ),
+            ),
+        )
+        legend = {".": TerrainType(type="floor", move_cost=1)}
+        spec = MapSpec(name="test", terrain=tuple(["." * 12] * 12), legend=legend)
+        engine = CombatEngine(
+            SeededRng(1), Grid.from_spec(spec), [c, e],
+            spell_registry={"Summon Monster II": spell},
+        )
+        engine._cast_spell(c, e, "Summon Monster II", metamagic=("Extend Spell",))
+        wolf = next(s for s in engine._states if s.combatant.id == "celestial_wolf")
+        assert wolf.summon_duration == 10
+        assert c.spell_slots_left[3] == 2  # extended: level-3 slot
+
+    def test_extend_doubles_a_fixed_summon_duration(self) -> None:
+        # Given: a summon with only a fixed duration (per_level = 0)
+        # When: the summon is cast extended (feat applied to this cast)
+        # Then: the fixed rounds double (2 -> 4).
+        caster = _make_caster().model_copy(
+            update={
+                "metamagic_feats": ["Extend Spell"],
+                "spell_slots": {1: 3, 2: 3, 3: 3},
+            }
+        )
+        enemy = _make_enemy()
+        c = CombatantState(combatant=caster, side="players", pos=(0, 0), hp=caster.hp_max)
+        e = CombatantState(combatant=enemy, side="monsters", pos=(5, 0), hp=enemy.hp_max)
+        reg = {"Summon Monster II": _make_summon_spell(duration_rounds=2)}
+        legend = {".": TerrainType(type="floor", move_cost=1)}
+        spec = MapSpec(name="test", terrain=tuple(["." * 12] * 12), legend=legend)
+        engine = CombatEngine(
+            SeededRng(1), Grid.from_spec(spec), [c, e], spell_registry=reg
+        )
+        engine._cast_spell(c, e, "Summon Monster II", metamagic=("Extend Spell",))
+        wolf = next(s for s in engine._states if s.combatant.id == "celestial_wolf")
+        assert wolf.summon_duration == 4