fix: add claude-haiku-4-5 to native structured output allowlist

claude-haiku-4-5-20251001 supports native structured output via the
output_format parameter but was missing from the model substring allowlist
in map_openai_params, causing it to fall back to the json_tool_call
synthesis workaround. This broke downstream tool dispatch when the model
also returned legitimate tool calls.

Fixes https://github.com/BerriAI/litellm/issues/25308

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

litellm/llms/anthropic/chat/transformation.py

@@ -989,6 +989,9 @@ class AnthropicConfig(AnthropicModelInfo, BaseConfig):
                 if any(
                     substring in model
                     for substring in {
+                        "haiku-4-5",
+                        "haiku-4.5",
+                        "haiku_4_5",
                         "sonnet-4.5",
                         "sonnet-4-5",
                         "opus-4.1",

tests/llm_translation/test_anthropic_completion.py

@@ -447,6 +447,44 @@ def test_anthropic_tool_helper(cache_control_location):
     assert tool["cache_control"] == {"type": "ephemeral"}
 
 
+def test_haiku_4_5_uses_native_structured_output():
+    """
+    Haiku 4.5 supports native structured output via output_format.
+    It should NOT fall back to json_tool_call synthesis.
+    Regression test for https://github.com/BerriAI/litellm/issues/25308
+    """
+    from litellm.llms.anthropic.chat.transformation import AnthropicConfig
+
+    config = AnthropicConfig()
+    response_format = {
+        "type": "json_schema",
+        "json_schema": {
+            "name": "MovieReview",
+            "schema": {
+                "type": "object",
+                "properties": {
+                    "title": {"type": "string"},
+                    "rating": {"type": "number"},
+                },
+                "required": ["title", "rating"],
+            },
+        },
+    }
+    optional_params = config.map_openai_params(
+        non_default_params={"response_format": response_format},
+        optional_params={},
+        model="claude-haiku-4-5-20251001",
+        drop_params=False,
+    )
+    # Should use native output_format, not json_tool_call
+    assert "output_format" in optional_params, (
+        "haiku-4-5 should use native output_format, not json_tool_call"
+    )
+    assert "tools" not in optional_params or not any(
+        t.get("name") == "json_tool_call" for t in optional_params.get("tools", [])
+    ), "haiku-4-5 should not synthesize a json_tool_call"
+
+
 def test_create_json_tool_call_for_response_format():
     """
     tests using response_format=json with anthropic