[Fix] Pass temperature=0.0 to OpenAI/AzureAI instead of dropping it

guidance/models/_openai_base.py

@@ -566,7 +566,7 @@ def rule(self, node: RuleNode, **kwargs) -> Iterator[OutputAttr]:
             raise ValueError("Save stop text not yet supported for OpenAI")
 
         kwargs = kwargs.copy()
-        if node.temperature:
+        if node.temperature is not None:
             kwargs["temperature"] = node.temperature
         if node.max_tokens:
             kwargs["max_completion_tokens"] = node.max_tokens

guidance/models/experimental/_litellm.py

@@ -116,7 +116,7 @@ def rule(self, node: RuleNode, **kwargs) -> Iterator[OutputAttr]:
             raise ValueError(f"stop_capture not yet supported for {self.ep_type} endpoint")
 
         kwargs = kwargs.copy()
-        if node.temperature:
+        if node.temperature is not None:
             kwargs["temperature"] = node.temperature
         if node.max_tokens:
             kwargs["max_tokens"] = node.max_tokens

guidance/models/experimental/_sglang.py

@@ -36,7 +36,7 @@ def rule(self, node: RuleNode, **kwargs) -> Iterator[OutputAttr]:
             raise ValueError("stop_capture not yet supported for sglang endpoint")
 
         kwargs = kwargs.copy()
-        if node.temperature:
+        if node.temperature is not None:
             kwargs["temperature"] = node.temperature
         if node.max_tokens:
             kwargs["max_tokens"] = node.max_tokens

tests/unit/test_openai_base.py

@@ -0,0 +1,33 @@
+from guidance._grammar import gen
+from guidance.models._openai_base import OpenAIRuleMixin
+
+
+def test_temperature_zero_is_passed_through(monkeypatch):
+    """temperature=0.0 is the canonical deterministic/greedy setting and must
+    not be dropped by a truthiness check (it is falsy in Python).
+    """
+    captured: dict = {}
+
+    def fake_run(self, node, **kwargs):
+        captured.update(kwargs)
+        return iter([])
+
+    monkeypatch.setattr(OpenAIRuleMixin, "run", fake_run)
+    interp = OpenAIRuleMixin.__new__(OpenAIRuleMixin)
+    node = gen(temperature=0.0)
+    list(interp.rule(node))
+    assert captured.get("temperature") == 0.0
+
+
+def test_temperature_none_not_passed(monkeypatch):
+    captured: dict = {}
+
+    def fake_run(self, node, **kwargs):
+        captured.update(kwargs)
+        return iter([])
+
+    monkeypatch.setattr(OpenAIRuleMixin, "run", fake_run)
+    interp = OpenAIRuleMixin.__new__(OpenAIRuleMixin)
+    node = gen()
+    list(interp.rule(node))
+    assert "temperature" not in captured