fix(rules): harmless spells on willing targets forgo the save roll - SpellSpec gains a data-driven 'harmless' flag set on the 29 SRD '(harmless)' spells (verified one by one against the KB); a same-side/self target consumes NO save die (SRD saving-throw.md: '(harmless) ... can attempt a saving throw if it desires' + 'Voluntarily Giving up a Saving Throw'), while hostile targets and undead receiving a cure (harmful to them, Will half for undead damage) keep the roll; snapshot spell summaries expose 'harmless'; golden transcript unchanged (no harmless-save cast in it); +8 tests, 3 fixtures re-pinned for the removed die

src/pf1e_simulator/combat.py

@@ -6240,6 +6240,7 @@ class CombatEngine:
                 "summary": "",
                 "half_on_save": False,
                 "save_negates": False,
+                "harmless": False,
                 "area": None,
                 "cast_time": "standard",
             }
@@ -6254,6 +6255,7 @@ class CombatEngine:
             "summary": _spell_summary(spell),
             "half_on_save": half_on_save,
             "save_negates": spell.save != "none" and not half_on_save,
+            "harmless": spell.harmless,
             "area": _spell_area_dict(spell),
             "cast_time": spell.cast_time,
         }
@@ -6710,6 +6712,35 @@ class CombatEngine:
             return False
         return True
 
+    def _save_forgone(
+        self, caster: CombatantState, target: CombatantState, spell: SpellSpec
+    ) -> bool:
+        """True when a willing target forgoes the save of a harmless spell.
+
+        PF1e (SRD "Spell Descriptions — Saving Throw",
+        rules/prpg-core-rulebook/saving-throw.md): "(harmless): The spell is
+        usually beneficial, not harmful, but a targeted creature can attempt
+        a saving throw if it desires" and "Voluntarily Giving up a Saving
+        Throw: A creature can voluntarily forego a saving throw and willingly
+        accept a spell's result". The engine's willingness proxy is the side:
+        self and same-side creatures are willing, so a spell flagged
+        ``harmless`` rolled on them consumes NO save die. Two faithful
+        exceptions keep the roll: a hostile target is not willing (it may
+        attempt the save), and a cure spell is HARMFUL to an undead target
+        (SRD cure-light-wounds.md: it "deals damage to them instead of
+        curing their wounds [...] can attempt a Will save to take half
+        damage"), so an undead never forgoes that save.
+        """
+        if not spell.harmless:
+            return False
+        if target is not caster and target.side != caster.side:
+            return False
+        return not any(
+            isinstance(effect, HealEffect)
+            and target.combatant.creature_type == "undead"
+            for effect in spell.effects
+        )
+
     def _apply_and_log_cast(
         self,
         caster: CombatantState,
@@ -6744,6 +6775,7 @@ class CombatEngine:
                 target, spell.save, dc, save_descriptors=spell_save_descriptors(spell)
             )
             if spell.save != "none" and target is not None
+            and not self._save_forgone(caster, target, spell)
             else None
         )
         caster_live = self._stats[caster.combatant.id]

src/pf1e_simulator/spells.py

@@ -364,6 +364,14 @@ class SpellSpec:
     # no" (Acid Arrow, Flurry of Snowballs, ...). False = skip the SR check
     # entirely (targeted and per-creature in areas). Default True.
     spell_resistance: bool = True
+    # PF1e (SRD, Magic — Spell Descriptions, saving throw notation):
+    # "(harmless): The spell is usually beneficial, not harmful, but a
+    # targeted creature can attempt a saving throw if it desires"
+    # (rules/prpg-core-rulebook/saving-throw.md). A willing target forgoes
+    # the save ("Voluntarily Giving up a Saving Throw: A creature can
+    # voluntarily forego a saving throw and willingly accept a spell's
+    # result"), so the engine skips the save roll on same-side targets.
+    harmless: bool = False
     effects: tuple[SpellEffect, ...] = ()
     description: str = ""
 
@@ -803,6 +811,7 @@ def load_spell(path: str | Path) -> SpellSpec:
         requires_ranged_touch=bool(data.get("requires_ranged_touch", False)),
         cast_time=cast_time,
         spell_resistance=bool(data.get("spell_resistance", True)),
+        harmless=bool(data.get("harmless", False)),
         effects=effects,
         description=_as_str(data.get("description", "")),
     )