fix(map-elites): isolate seeded evolutionary search randomness

evoagentx/optimizers/map_elites_optimizer.py

@@ -48,8 +48,7 @@ def __init__(
         self.exploration_ratio = exploration_ratio
         self.random_seed = random_seed
 
-        if random_seed is not None:
-            random.seed(random_seed)
+        self._rng = random.Random(random_seed)
 
         missing = [d for d in self.feature_dimensions if d not in self.feature_ranges]
         if missing:
@@ -70,8 +69,8 @@ def optimize(self):
         best_entry: Optional[ArchiveEntry] = None
 
         for step in range(self.n_iterations):
-            if archive and random.random() > self.exploration_ratio:
-                parent = random.choice(list(archive.values()))
+            if archive and self._rng.random() > self.exploration_ratio:
+                parent = self._rng.choice(list(archive.values()))
                 cfg = self._mutate_cfg(parent.cfg)
                 source = "mutate"
             else:
@@ -159,17 +158,17 @@ def _bin_index(value: float, lo: float, hi: float, bins: int) -> int:
         return idx
 
     def _random_cfg(self) -> Dict[str, Any]:
-        return {name: copy.deepcopy(random.choice(values)) for name, values in self.search_space.items()}
+        return {name: copy.deepcopy(self._rng.choice(values)) for name, values in self.search_space.items()}
 
     def _mutate_cfg(self, parent_cfg: Dict[str, Any]) -> Dict[str, Any]:
         if not self.search_space:
             return copy.deepcopy(parent_cfg)
         cfg = copy.deepcopy(parent_cfg)
-        key = random.choice(list(self.search_space.keys()))
+        key = self._rng.choice(list(self.search_space.keys()))
         choices = self.search_space[key]
         if len(choices) <= 1:
             return cfg
         current = cfg.get(key)
         alternatives = [v for v in choices if v != current]
-        cfg[key] = copy.deepcopy(random.choice(alternatives)) if alternatives else current
+        cfg[key] = copy.deepcopy(self._rng.choice(alternatives)) if alternatives else current
         return cfg

tests/src/optimizers/test_map_elites_optimizer.py

@@ -54,3 +54,56 @@ def evaluator(output: Dict[str, Any]) -> Dict[str, Any]:
     assert len(archive) >= 5
     assert best.fitness == 8.0
     assert best_cfg["x"] + best_cfg["y"] == 8
+
+
+def make_seeded_optimizer(evaluator):
+    """Build an optimizer with no dependency on the global entry point."""
+    program = DummyProgram()
+    registry = ParamRegistry()
+    registry.track(program, "x", name="x")
+    registry.track(program, "y", name="y")
+    return MapElitesOptimizer(
+        registry=registry,
+        evaluator=evaluator,
+        search_space={"x": list(range(5)), "y": list(range(5))},
+        feature_dimensions=["complexity"],
+        feature_ranges={"complexity": (0.0, 4.0)},
+        n_iterations=20,
+        random_seed=7,
+        program=program.run,
+    )
+
+
+def test_seeded_search_does_not_change_global_random_state():
+    """Seeding and running an optimizer must not reseed unrelated callers."""
+    import random
+
+    before = random.getstate()
+    opt = make_seeded_optimizer(lambda out: {"score": out["x"] + out["y"], "complexity": out["x"]})
+    opt.optimize()
+
+    assert random.getstate() == before
+
+
+def test_seeded_search_is_independent_of_evaluator_random_draws():
+    """Evaluator randomness must not change the sequence of candidate mutations."""
+    import random
+
+    def evaluator(output):
+        """Score a candidate without drawing random numbers."""
+        return {"score": output["x"] + output["y"], "complexity": output["x"]}
+
+    def noisy_evaluator(output):
+        """Return the same score after consuming unrelated randomness."""
+        random.random()
+        return evaluator(output)
+
+    baseline = make_seeded_optimizer(evaluator)
+    noisy = make_seeded_optimizer(noisy_evaluator)
+
+    _, baseline_result = baseline.optimize()
+    _, noisy_result = noisy.optimize()
+
+    assert [step["cfg"] for step in baseline_result["history"]] == [
+        step["cfg"] for step in noisy_result["history"]
+    ]