fix(rules): duplicate summons get disambiguated ids - the engine now counts id occurrences (seeded from the deployed roster) and gives each new summon of the same creature a build_states-style suffix (celestial_wolf, celestial_wolf-2, ...), so two summons no longer share one _LiveStats slot (the second summon used to reset the first one's counters and their attrition merged); run_encounter aggregation verified to report each slot separately; runner 'known limitation' comment updated; +4 tests (id split, distinct slots, per-slot attrition, run_encounter aggregate)

src/pf1e_simulator/combat.py

@@ -1316,6 +1316,14 @@ class CombatEngine:
         self._move_aoo_provoked: dict[str, set[str]] = {}
         self._initiative_keys: dict[str, tuple[float, int, int]] = {}
         self._pending_summons: list[CombatantState] = []
+        # Occurrence counts per combatant id, seeded from the deployed roster:
+        # summons disambiguate duplicate creature ids exactly the way
+        # build_states does (first keeps the bare id, later ones get -2, -3...),
+        # so each summoned creature owns a distinct stats slot.
+        self._id_counts: dict[str, int] = {}
+        for st in states:
+            base = st.combatant.id
+            self._id_counts[base] = self._id_counts.get(base, 0) + 1
         # True while the surprise round runs (SRD "Surprise"): the turn filter
         # then degrades every aware combatant's sequence to a single standard
         # OR move action plus free actions.
@@ -7733,6 +7741,21 @@ class CombatEngine:
         return effect
 
 
+    def _disambiguated_summon_id(self, combatant: Combatant) -> Combatant:
+        """Give a summoned creature a unique id, mirroring build_states.
+
+        The first occurrence of a creature id keeps the bare name; later ones
+        get -2, -3... suffixes. Without this, two summons of the same creature
+        share one _stats slot and their attrition merges (and the second
+        summon resets the first one's counters).
+        """
+        base = combatant.id
+        count = self._id_counts.get(base, 0) + 1
+        self._id_counts[base] = count
+        if count == 1:
+            return combatant
+        return combatant.model_copy(update={"id": f"{base}-{count}"})
+
     def _apply_summon_effect(
         self,
         effect: SummonEffect,
@@ -7755,6 +7778,7 @@ class CombatEngine:
             summoned_combatant = load_combatant(Path(effect.creature))
         except CombatantLoadError:
             return f"summon failed: could not load {effect.creature}"
+        summoned_combatant = self._disambiguated_summon_id(summoned_combatant)
 
         # Find a valid adjacent position for the summoned creature
         center = state.pos

src/pf1e_simulator/runner.py

@@ -196,9 +196,10 @@ def run_encounter(
     # Accumulate whatever ids the engine reports: summoned creatures act in the
     # battle and appear in result.stats, so seeding from the initial states
     # only would KeyError on them. Ids seen for the first time get a fresh
-    # accumulator. Known limitation: two summons of the same creature id share
-    # one engine stats slot (the engine keys _LiveStats by id), so their
-    # attrition is merged, not split.
+    # accumulator. Duplicate summons of the same creature are disambiguated by
+    # the engine the same way build_states does (celestial_wolf,
+    # celestial_wolf-2, ...), so each summoned creature owns its own slot and
+    # their attrition is split, not merged.
     totals: dict[str, CombatantStats] = {}
     transcript: tuple[str, ...] | None = None
     for index in range(runs):