fix: reject unsupported whitespace_pattern in SGLang and TGI adapters

docs/features/core/output_types.md

@@ -178,7 +178,7 @@ output_type = JsonSchema(schema_dict)
 ```
 
 `JsonSchema` accepts two optional parameters:
-- `whitespace_pattern` (defaults to `None`): specifies the pattern to use for JSON syntactic whitespace. If none is provided, the default permissive JSON whitespace rules are used. It is applied by the `outlines_core` backend; the `llguidance` and `xgrammar` backends do not support it and raise an error if one is set.
+- `whitespace_pattern` (defaults to `None`): specifies the pattern to use for JSON syntactic whitespace. If none is provided, the default permissive JSON whitespace rules are used. It is applied by the `outlines_core` backend; the `llguidance` and `xgrammar` backends, and the `SGLang` and `TGI` model integrations, do not support it and raise an error if one is set.
 - `ensure_ascii` (defaults to `True`): defines the value to use for the argument `ensure_ascii` of the `json.dumps` method. If false, non-ASCII characters will be turned into unicodes.
 
 ### Regex Patterns

src/outlines/models/sglang.py

@@ -75,6 +75,13 @@ def format_output_type(self, output_type: Optional[Any] = None) -> dict:
             )
             return {"extra_body": {"ebnf": term.definition}}
         elif isinstance(term, JsonSchema):
+            if term.whitespace_pattern is not None:
+                raise NotImplementedError(
+                    "The SGLang backend does not support the "
+                    "`whitespace_pattern` argument. Set the whitespace "
+                    "pattern on the SGLang server instead, e.g. with "
+                    "`--constrained-json-whitespace-pattern`."
+                )
             return OpenAITypeAdapter().format_json_output_type(
                 json.loads(term.schema)
             )

src/outlines/models/tgi.py

@@ -73,6 +73,11 @@ def format_output_type(self, output_type: Optional[Any] = None) -> dict:
                 "TGI does not support CFG-based structured outputs."
             )
         elif isinstance(term, JsonSchema):
+            if term.whitespace_pattern is not None:
+                raise NotImplementedError(
+                    "The TGI backend does not support the "
+                    "`whitespace_pattern` argument."
+                )
             return {
                 "grammar": {
                     "type": "json",

tests/models/test_sglang_type_adapter.py

@@ -149,20 +149,9 @@ def test_sglang_type_adapter_output_type(
             },
         }
     }
-    # whitespace pattern is ignored
-    assert type_adapter.format_output_type(json_schema_whitespace_instance) == {
-        "response_format": {
-            "type": "json_schema",
-            "json_schema": {
-                "name": "default",
-                "strict": True,
-                "schema": {
-                    **json.loads(JSON_SCHEMA_STRING),
-                    "additionalProperties": False,
-                },
-            },
-        }
-    }
+    # the SGLang server only supports a server-side whitespace pattern
+    with pytest.raises(NotImplementedError, match="whitespace_pattern"):
+        type_adapter.format_output_type(json_schema_whitespace_instance)
     assert type_adapter.format_output_type(int) == {
         "extra_body": {"regex": "([+-]?(0|[1-9][0-9]*))"}
     }

tests/models/test_tgi_model_adapter.py

@@ -62,13 +62,9 @@ def test_tgi_type_adapter_output_type(
             "value": json.loads(JSON_SCHEMA_STRING),
         }
     }
-    # whitespace_pattern is ignored
-    assert type_adapter.format_output_type(json_schema_whitespace_instance) == {
-        "grammar": {
-            "type": "json",
-            "value": json.loads(JSON_SCHEMA_STRING),
-        }
-    }
+    # TGI does not support per-request whitespace patterns
+    with pytest.raises(NotImplementedError, match="whitespace_pattern"):
+        type_adapter.format_output_type(json_schema_whitespace_instance)
     assert type_adapter.format_output_type(int) == {
         "grammar": {
             "type": "regex",