fix(gepa): allow an unset reflection cost budget

Amp-Thread-ID: https://ampcode.com/threads/T-019ffe40-c240-70bb-8cb2-db33146ed8e6
Co-authored-by: Isaac Miller <isaac@cmpnd.ai>

Author: ampagent

dspy/teleprompt/gepa/gepa.py

@@ -457,7 +457,7 @@ def __init__(
         self.component_selector = component_selector
         self.gepa_kwargs = gepa_kwargs or {}
 
-        if "max_reflection_cost" in self.gepa_kwargs:
+        if self.gepa_kwargs.get("max_reflection_cost") is not None:
             raise ValueError("max_reflection_cost is not supported by dspy.GEPA yet.")
 
         if "reflection_prompt_template" in self.gepa_kwargs:

tests/teleprompt/test_gepa.py

@@ -636,6 +636,13 @@ def test_track_best_outputs_result_structure():
 
 
 def test_gepa_rejects_unsupported_reflection_cost_budget():
+    dspy.GEPA(
+        metric=simple_metric,
+        max_metric_calls=1,
+        reflection_lm=DummyLM([]),
+        gepa_kwargs={"max_reflection_cost": None},
+    )
+
     with pytest.raises(ValueError, match="max_reflection_cost"):
         dspy.GEPA(
             metric=simple_metric,