fix(lib): support JSON Schema type arrays in transform_schema (Closes #1876)

src/anthropic/lib/_parse/_transform.py

@@ -32,6 +32,17 @@
 }
 
 
+TYPE_SPECIFIC_KEYWORDS: dict[str, set[str]] = {
+    "object": {"properties", "additionalProperties", "required", "patternProperties", "minProperties", "maxProperties"},
+    "array": {"items", "minItems", "maxItems", "uniqueItems", "contains"},
+    "string": {"format", "pattern", "minLength", "maxLength"},
+    "integer": {"minimum", "maximum", "exclusiveMinimum", "exclusiveMaximum", "multipleOf"},
+    "number": {"minimum", "maximum", "exclusiveMinimum", "exclusiveMaximum", "multipleOf"},
+    "boolean": set(),
+    "null": set(),
+}
+
+
 def get_transformed_string(
     schema: dict[str, Any],
 ) -> dict[str, Any]:
@@ -96,7 +107,7 @@ def transform_schema(
         strict_schema["$ref"] = ref
         return strict_schema
 
-    type_: Optional[SupportedTypes] = json_schema.pop("type", None)
+    type_: Optional[SupportedTypes | list[SupportedTypes]] = json_schema.pop("type", None)
     any_of = json_schema.pop("anyOf", None)
     one_of = json_schema.pop("oneOf", None)
     all_of = json_schema.pop("allOf", None)
@@ -107,6 +118,22 @@ def transform_schema(
         strict_schema["anyOf"] = [transform_schema(cast("dict[str, Any]", variant)) for variant in one_of]
     elif is_list(all_of):
         strict_schema["allOf"] = [transform_schema(cast("dict[str, Any]", variant)) for variant in all_of]
+    elif is_list(type_):
+        variants: list[dict[str, Any]] = []
+        extracted_keywords: dict[str, Any] = {}
+        for t in type_:
+            for kw in TYPE_SPECIFIC_KEYWORDS.get(t, set()):
+                if kw in json_schema:
+                    extracted_keywords[kw] = json_schema.pop(kw)
+
+        for t in type_:
+            branch: dict[str, Any] = {"type": t}
+            for kw in TYPE_SPECIFIC_KEYWORDS.get(t, set()):
+                if kw in extracted_keywords:
+                    branch[kw] = extracted_keywords[kw]
+            variants.append(transform_schema(branch))
+
+        strict_schema["anyOf"] = variants
     else:
         if type_ is None:
             raise ValueError("Schema must have a 'type', 'anyOf', 'oneOf', or 'allOf' field.")
@@ -155,7 +182,7 @@ def transform_schema(
             # add it back so its treated as an extra property and appended to the description
             json_schema["minItems"] = min_items
 
-    elif type_ == "boolean" or type_ == "integer" or type_ == "number" or type_ == "null" or type_ is None:
+    elif type_ == "boolean" or type_ == "integer" or type_ == "number" or type_ == "null" or type_ is None or is_list(type_):
         pass
     else:
         assert_never(type_)

tests/lib/_parse/test_transform.py

@@ -229,3 +229,107 @@ def test_original_schema_not_mutated():
     transform_schema(original_schema)
 
     assert original_schema == original_schema_backup
+
+
+def test_type_array():
+    schema = {
+        "type": ["string", "null"],
+        "description": "Optional text",
+    }
+    result = transform_schema(schema)
+    assert result == {
+        "anyOf": [{"type": "string"}, {"type": "null"}],
+        "description": "Optional text",
+    }
+
+
+def test_type_array_in_object():
+    schema = {
+        "type": "object",
+        "properties": {
+            "name": {
+                "type": ["string", "null"],
+                "description": "Optional name",
+            }
+        },
+        "required": ["name"],
+    }
+    result = transform_schema(schema)
+    assert result == {
+        "type": "object",
+        "properties": {
+            "name": {
+                "anyOf": [{"type": "string"}, {"type": "null"}],
+                "description": "Optional name",
+            }
+        },
+        "required": ["name"],
+        "additionalProperties": False,
+    }
+
+
+def test_type_array_with_items():
+    schema = {
+        "type": ["array", "null"],
+        "items": {"type": "string"},
+        "description": "Optional list of strings",
+    }
+    result = transform_schema(schema)
+    assert result == {
+        "anyOf": [
+            {"type": "array", "items": {"type": "string"}},
+            {"type": "null"},
+        ],
+        "description": "Optional list of strings",
+    }
+
+
+def test_type_array_with_object_properties():
+    schema = {
+        "type": ["object", "null"],
+        "properties": {
+            "title": {"type": "string"},
+        },
+        "required": ["title"],
+    }
+    result = transform_schema(schema)
+    assert result == {
+        "anyOf": [
+            {
+                "type": "object",
+                "properties": {"title": {"type": "string"}},
+                "required": ["title"],
+                "additionalProperties": False,
+            },
+            {"type": "null"},
+        ],
+    }
+
+
+def test_type_array_nested_in_object_with_items():
+    schema = {
+        "type": "object",
+        "properties": {
+            "tags": {
+                "type": ["array", "null"],
+                "items": {"type": "string"},
+            }
+        },
+        "required": ["tags"],
+    }
+    result = transform_schema(schema)
+    assert result == {
+        "type": "object",
+        "properties": {
+            "tags": {
+                "anyOf": [
+                    {"type": "array", "items": {"type": "string"}},
+                    {"type": "null"},
+                ],
+            }
+        },
+        "required": ["tags"],
+        "additionalProperties": False,
+    }
+
+