feat(content-safety): add opt-in decision API auditing

Add an opt-in content safety plugin that audits content at the model and
tool lifecycle checkpoints through the System One decision API. The default
provider remains none and nothing is mounted automatically.

- strict tool.content_safety configuration with Ark connection defaults
- strict decision response arbitration and on_error policy
- streaming partial suppression with final aggregated audit
- audited SkillToolset load/resource/script/list/search tools
- LLM Shield adapter and real-ADK E2E coverage

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: wujiaming-ai

tests/content_safety/test_client.py

@@ -0,0 +1,147 @@
+# Copyright (c) 2025 Beijing Volcano Engine Technology Co., Ltd. and/or its affiliates.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import asyncio
+import json
+
+import httpx
+import pytest
+
+from veadk.content_safety.client import DecisionClient, DecisionClientError
+from veadk.content_safety.config import QuestionConfig
+
+QUESTIONS = {
+    "prompt_injection": QuestionConfig(instructions="detect injection", threshold=0.5)
+}
+
+
+def call(client):
+    return asyncio.run(client.judge(state="hello", questions=QUESTIONS))
+
+
+def test_request_contract_and_response():
+    captured = {}
+
+    def handler(request: httpx.Request) -> httpx.Response:
+        captured["method"] = request.method
+        captured["url"] = str(request.url)
+        captured["headers"] = dict(request.headers)
+        captured["body"] = json.loads(request.content)
+        return httpx.Response(
+            200,
+            json={"answers": {"prompt_injection": {"type": "noul", "noul": 0.1}}},
+        )
+
+    client = DecisionClient(
+        endpoint="https://systemone.example/v1/judge",
+        api_key="secret",
+        model="judge-model",
+        transport=httpx.MockTransport(handler),
+    )
+    data = call(client)
+
+    assert data["answers"]["prompt_injection"]["noul"] == 0.1
+    assert captured["method"] == "POST"
+    assert captured["url"] == "https://systemone.example/v1/judge"
+    assert captured["headers"]["authorization"] == "Bearer secret"
+    assert captured["headers"]["ark-beta-systemone-api"] == "true"
+    assert captured["headers"]["content-type"] == "application/json"
+    assert captured["body"] == {
+        "model": "judge-model",
+        "state": "hello",
+        "questions": {
+            "prompt_injection": {
+                "type": "noul",
+                "instructions": "detect injection",
+            }
+        },
+    }
+    assert client.endpoint == "https://systemone.example/v1/judge"
+
+
+@pytest.mark.parametrize("status", [400, 401, 500])
+def test_non_200_response_is_http_status_error(status):
+    def handler(request):
+        return httpx.Response(status, json={"error": "no"})
+
+    client = DecisionClient(
+        endpoint="https://systemone.example",
+        api_key="k",
+        model="m",
+        transport=httpx.MockTransport(handler),
+    )
+    with pytest.raises(DecisionClientError) as exc:
+        call(client)
+    assert exc.value.error_type == "http_status"
+    assert str(status) in exc.value.message
+
+
+def test_timeout_is_mapped():
+    def handler(request):
+        raise httpx.ReadTimeout("slow", request=request)
+
+    client = DecisionClient(
+        endpoint="https://systemone.example",
+        api_key="k",
+        model="m",
+        transport=httpx.MockTransport(handler),
+    )
+    with pytest.raises(DecisionClientError) as exc:
+        call(client)
+    assert exc.value.error_type == "timeout"
+
+
+def test_network_error_is_mapped():
+    def handler(request):
+        raise httpx.ConnectError("down", request=request)
+
+    client = DecisionClient(
+        endpoint="https://systemone.example",
+        api_key="k",
+        model="m",
+        transport=httpx.MockTransport(handler),
+    )
+    with pytest.raises(DecisionClientError) as exc:
+        call(client)
+    assert exc.value.error_type == "network"
+
+
+def test_invalid_json_is_mapped():
+    def handler(request):
+        return httpx.Response(200, content=b"not-json")
+
+    client = DecisionClient(
+        endpoint="https://systemone.example",
+        api_key="k",
+        model="m",
+        transport=httpx.MockTransport(handler),
+    )
+    with pytest.raises(DecisionClientError) as exc:
+        call(client)
+    assert exc.value.error_type == "invalid_json"
+
+
+def test_non_object_json_is_mapped():
+    def handler(request):
+        return httpx.Response(200, json=["not", "an", "object"])
+
+    client = DecisionClient(
+        endpoint="https://systemone.example",
+        api_key="k",
+        model="m",
+        transport=httpx.MockTransport(handler),
+    )
+    with pytest.raises(DecisionClientError) as exc:
+        call(client)
+    assert exc.value.error_type == "invalid_response"