Merge pull request #4 from codeanker/copilot/merge-llama-cpp-pr-18963

superbarne · web-flow · commit a71a62789f21 · 2026-03-15T21:35:16.000+01:00
server: fix json_schema response_format handling
diff --git a/tools/server/server-common.cpp b/tools/server/server-common.cpp
@@ -927,10 +927,15 @@ json oaicompat_chat_params_parse(
         if (response_type == "json_object") {
             json_schema = json_value(response_format, "schema", json::object());
         } else if (response_type == "json_schema") {
+            // https://platform.openai.com/docs/api-reference/chat/create#chat-create-response_format
+            // OpenAI expects: response_format.json_schema.schema
             auto schema_wrapper = json_value(response_format, "json_schema", json::object());
-            json_schema = json_value(schema_wrapper, "schema", json::object());
+            if (!schema_wrapper.contains("schema")) {
+                throw std::invalid_argument("response_format type \"json_schema\" requires \"json_schema.schema\" to be set");
+            }
+            json_schema = schema_wrapper.at("schema");
         } else if (!response_type.empty() && response_type != "text") {
-            throw std::invalid_argument("response_format type must be one of \"text\" or \"json_object\", but got: " + response_type);
+            throw std::invalid_argument("response_format type must be one of \"text\", \"json_object\", or \"json_schema\", but got: " + response_type);
         }
     }
 
diff --git a/tools/server/tests/unit/test_chat_completion.py b/tools/server/tests/unit/test_chat_completion.py
@@ -176,12 +176,18 @@ def test_apply_chat_template():
     ({"type": "json_object", "schema": {"const": "42"}}, 6, "\"42\""),
     ({"type": "json_object", "schema": {"items": [{"type": "integer"}]}}, 10, "[ -3000 ]"),
     ({"type": "json_schema", "json_schema": {"schema": {"const": "foooooo"}}}, 10, "\"foooooo\""),
+    # json_schema with name field (OpenAI-style)
+    ({"type": "json_schema", "json_schema": {"name": "test", "schema": {"const": "bar"}, "strict": True}}, 6, "\"bar\""),
     ({"type": "json_object"}, 10, "(\\{|John)+"),
     ({"type": "sound"}, 0, None),
     # invalid response format (expected to fail)
     ({"type": "json_object", "schema": 123}, 0, None),
     ({"type": "json_object", "schema": {"type": 123}}, 0, None),
     ({"type": "json_object", "schema": {"type": "hiccup"}}, 0, None),
+    # json_schema missing required json_schema.schema field (should fail)
+    ({"type": "json_schema", "json_schema": {"name": "test"}}, 0, None),
+    ({"type": "json_schema", "json_schema": {}}, 0, None),
+    ({"type": "json_schema"}, 0, None),
 ])
 def test_completion_with_response_format(response_format: dict, n_predicted: int, re_content: str | None):
     global server
@@ -203,6 +209,31 @@ def test_completion_with_response_format(response_format: dict, n_predicted: int
         assert "error" in res.body
 
 
+@pytest.mark.parametrize("response_format,expected_error_message", [
+    # json_schema type requires json_schema.schema to be set
+    ({"type": "json_schema", "json_schema": {"name": "test"}}, "json_schema.schema"),
+    ({"type": "json_schema", "json_schema": {}}, "json_schema.schema"),
+    ({"type": "json_schema"}, "json_schema.schema"),
+    # invalid response_format type should mention valid options
+    ({"type": "invalid_type"}, "json_schema"),
+])
+def test_response_format_error_messages(response_format: dict, expected_error_message: str):
+    """Test that invalid response_format configurations return helpful error messages."""
+    global server
+    server.start()
+    res = server.make_request("POST", "/chat/completions", data={
+        "max_tokens": 10,
+        "messages": [
+            {"role": "user", "content": "test"},
+        ],
+        "response_format": response_format,
+    })
+    assert res.status_code == 400
+    assert "error" in res.body
+    assert expected_error_message in res.body["error"]["message"], \
+        f"Expected '{expected_error_message}' in error message, got: {res.body['error']['message']}"
+
+
 @pytest.mark.parametrize("jinja,json_schema,n_predicted,re_content", [
     (False, {"const": "42"}, 6, "\"42\""),
     (True, {"const": "42"}, 6, "\"42\""),
