fix(spells): make the bleed spell bleed

PF1e (SRD spells/bleed.md): "Saving Throw Will negates" and the target takes 1 point of damage per round. Two divergences: the JSON declared a Fortitude save, and the bleeding condition never set the engine's bleed_damage field, so the spell was a no-op. Bleed now saves Will; _apply_condition_effect sets bleed_damage = 1 when a spell applies bleeding, and _decrement_durations lands the final tick as the last bleeding condition expires before clearing the field (heal-path clearing already existed in _stop_bleeding). README updated.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

README.md

@@ -987,7 +987,11 @@ Règles modélisées :
   Saignement (`bleeding`, V5b) : une créature qui saigne subit `bleed_damage`
   points de dégâts au **début de son tour** (avant politique et flags) ; tout
   effet restaurant des points de vie (sort de soin, channel energy) stoppe le
-  saignement (`bleed_damage = 0`) et retire la condition. Simplification
+  saignement (`bleed_damage = 0`) et retire la condition ; l'expiration de la
+  dernière condition `bleeding` inflige son **dernier tick** puis remet
+  `bleed_damage = 0` (conformance D2 — SRD « Bleed » : le cantrip, sauvegarde
+  de **Volonté** annule, pose la condition `bleeding` avec `bleed_damage = 1`,
+  donc 1 point de dégâts par round). Simplification
   documentée : le jet de compétence Soin DD 15 n'est pas modélisé (le moteur
   n'a pas d'action Soin).
   Confus (`confused`, V5b) : au début de chaque tour, jet d% — 01-25 agit

data/spells/bleed.json

@@ -3,7 +3,7 @@
   "level": 0,
   "school": "necromancy",
   "range": "close",
-  "save": "fort",
+  "save": "will",
   "base_dc": 10,
   "cast_time": "standard",
   "effects": [
@@ -14,5 +14,5 @@
       "save_negates": true
     }
   ],
-  "description": "A cantrip that causes a wound to bleed: the target takes 1 point of damage per round until healed. Fortitude negates. Modeled as the bleeding condition for 1 round."
+  "description": "SRD spells/bleed.md: a living creature at -1 or fewer hit points begins dying, taking 1 point of damage per round; Will negates. Modeled as the bleeding condition for 1 round with bleed_damage = 1 (the engine's bleed tick deals it at the start of the target's turn)."
 }

src/pf1e_simulator/combat.py

@@ -1732,17 +1732,31 @@ class CombatEngine:
         return speed_mult
 
     def _decrement_durations(self, state: CombatantState) -> None:
-        """Decrement duration rounds for buffs and conditions; remove expired ones."""
+        """Decrement duration rounds for buffs and conditions; remove expired ones.
+
+        A bleeding condition's last round ends with its bleed tick: the DoT
+        lives on ``bleed_damage`` (CRB Conditions — bleeding), so the final
+        damage is applied as the last condition instance expires and the
+        field is cleared (mirrors ``_stop_bleeding`` on healing).
+        """
         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[:] = [
+        kept_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
         ]
+        bleeding_expired = (
+            any(ac.condition.name == "bleeding" for ac in state.active_conditions)
+            and not any(ac.condition.name == "bleeding" for ac in kept_conditions)
+        )
+        state.active_conditions[:] = kept_conditions
+        if bleeding_expired and state.bleed_damage > 0:
+            self._apply_bleed_damage(state)
+            state.bleed_damage = 0
 
     def _turn_gate(self, state: CombatantState) -> bool | None:
         """Start-of-turn effects: bleed tick, confused d% roll, cant_act flag.
@@ -5571,6 +5585,11 @@ class CombatEngine:
                 source=f"spell: {spell_name}",
             )
         )
+        if effect.condition_name == "bleeding":
+            # The bleeding condition's damage-over-time is engine-driven
+            # (CombatantState.bleed_damage, CRB Conditions — bleeding); the
+            # SRD Bleed cantrip (spells/bleed.md) deals 1 bleed damage/round.
+            target.bleed_damage = max(target.bleed_damage, 1)
         return f"{effect.condition_name} ({effect.duration_rounds}r)"
 
     def _apply_heal_effect(

tests/test_spell_registry_batch1.py

@@ -42,7 +42,7 @@ _BATCH1: dict[str, tuple[str, int, str, str, str]] = {
     "Bane": ("bane", 1, "enchantment", "medium", "will"),
     "Bear's Endurance": ("bears_endurance", 2, "transmutation", "touch", "fort"),
     "Bladed Dash": ("bladed_dash", 1, "transmutation", "close", "none"),
-    "Bleed": ("bleed", 0, "necromancy", "close", "fort"),
+    "Bleed": ("bleed", 0, "necromancy", "close", "will"),
     "Bless": ("bless", 1, "enchantment", "medium", "none"),
     "Blindness/Deafness": ("blindness_deafness", 2, "necromancy", "medium", "will"),
     "Charm Person": ("charm_person", 1, "enchantment", "medium", "will"),

tests/test_spells.py

@@ -396,6 +396,38 @@ class TestAreaSavesPerSpellSaveType:
         assert not any(ac.condition.name == "stunned" for ac in t.active_conditions)
 
 
+class TestBleedCantrip:
+    """Given: the Bleed cantrip (SRD spells/bleed.md: Will negates; the target
+    takes 1 point of bleed damage per round)
+    When: the target fails / succeeds its Will save
+    Then: failed — bleeding condition, 1 hp lost at the start of its turn;
+    saved — no condition, no bleed damage."""
+
+    def test_failed_save_deals_one_bleed_damage_per_round(self) -> None:
+        caster = _make_caster()
+        target = _make_target(hp_max=30)
+        # Will save d20=2 (+2) vs DC 14 -> fail.
+        engine, c, t = _make_engine(caster, target, [2])
+        engine._cast_spell(c, t, "Bleed")
+        assert any(ac.condition.name == "bleeding" for ac in t.active_conditions)
+        assert t.bleed_damage == 1
+        # The target's next turn start: the 1-round condition expires and its
+        # final bleed tick lands (1 hp).
+        engine._decrement_durations(t)
+        assert t.hp == 30 - 1
+        assert t.bleed_damage == 0
+
+    def test_successful_save_does_not_bleed(self) -> None:
+        caster = _make_caster()
+        target = _make_target(hp_max=30)
+        # Will save natural 20 -> auto-success (SRD: Will negates).
+        engine, c, t = _make_engine(caster, target, [20])
+        engine._cast_spell(c, t, "Bleed")
+        assert not any(ac.condition.name == "bleeding" for ac in t.active_conditions)
+        assert t.bleed_damage == 0
+        assert t.hp == 30
+
+
 class TestTargetedSpellSaveNegates:
     """Given: a targeted spell with a save (half_on_save=False)
     When: the target succeeds / fails its save