feat(proxy): implement proxy code validation and error handling

tests/api/test_proxy.py

@@ -3,6 +3,7 @@ import importlib
 from core.security import get_auth_context, require_authenticated_user
 from models.proxy import ProxyDocument
 from models.service import ServiceEndpointDocument
+from utils.proxy.validator import ProxyCodeValidationError
 
 proxy_router_module = importlib.import_module("api.proxy.router")
 
@@ -120,11 +121,19 @@ def test_create_proxy_returns_created_document(client, monkeypatch: object):
             port=int(service["port"]),
         )
 
+    async def fake_validate_proxy_code(code: str) -> None:
+        assert code == "def proxy_handler():\n    return 'ok'\n"
+
     monkeypatch.setattr(
         proxy_router_module,
         "get_proxy_by_port",
         fake_get_proxy_by_port,
     )
+    monkeypatch.setattr(
+        proxy_router_module,
+        "validate_proxy_code",
+        fake_validate_proxy_code,
+    )
     monkeypatch.setattr(proxy_router_module, "create_proxy", fake_create_proxy)
 
     response = client.post(
@@ -132,7 +141,7 @@ def test_create_proxy_returns_created_document(client, monkeypatch: object):
         json={
             "proxy_port": 4040,
             "name": "edge",
-            "code": "edge-code",
+            "code": "def proxy_handler():\n    return 'ok'\n",
             "service": {"address": "service.local", "port": 8181},
         },
     )
@@ -143,5 +152,114 @@ def test_create_proxy_returns_created_document(client, monkeypatch: object):
         "proxy_port": 4040,
         "name": "edge",
         "service": {"address": "service.local", "port": 8181},
-        "code": "edge-code",
+        "code": "def proxy_handler():\n    return 'ok'\n",
     }
+
+
+def test_create_proxy_returns_422_when_code_validation_fails(
+    client,
+    monkeypatch: object,
+):
+    create_called = False
+
+    async def fake_get_proxy_by_port(proxy_port: int) -> ProxyDocument | None:
+        assert proxy_port == 4000
+        return None
+
+    async def fake_validate_proxy_code(code: str) -> None:
+        assert code == "invalid-code"
+        raise ProxyCodeValidationError(
+            "Proxy code contains ruff violations",
+            errors=[
+                {
+                    "code": "F821",
+                    "message": "Undefined name `missing_symbol`",
+                    "location": {"row": 1, "column": 1},
+                }
+            ],
+        )
+
+    async def fake_create_proxy(
+        *,
+        proxy_port: int,
+        name: str,
+        service: dict[str, object],
+        code: str,
+    ) -> ProxyDocument:
+        nonlocal create_called
+        create_called = True
+        return make_proxy_document(proxy_port=proxy_port, name=name, code=code)
+
+    monkeypatch.setattr(
+        proxy_router_module,
+        "get_proxy_by_port",
+        fake_get_proxy_by_port,
+    )
+    monkeypatch.setattr(
+        proxy_router_module,
+        "validate_proxy_code",
+        fake_validate_proxy_code,
+    )
+    monkeypatch.setattr(proxy_router_module, "create_proxy", fake_create_proxy)
+
+    response = client.post(
+        "/proxy",
+        json={
+            "proxy_port": 4000,
+            "name": "broken",
+            "code": "invalid-code",
+            "service": {"address": "service.local", "port": 9000},
+        },
+    )
+
+    assert response.status_code == 422
+    body = response.json()["detail"]
+    assert body["message"] == "Proxy code contains ruff violations"
+    assert body["errors"][0]["code"] == "F821"
+    assert create_called is False
+
+
+def test_update_proxy_returns_422_when_code_validation_fails(
+    client,
+    monkeypatch: object,
+):
+    update_called = False
+
+    async def fake_validate_proxy_code(code: str) -> None:
+        assert code == "invalid-code"
+        raise ProxyCodeValidationError(
+            "Proxy code has invalid Python syntax",
+            errors=[
+                {
+                    "code": "COMPILE",
+                    "message": "invalid syntax",
+                    "location": {"row": 1, "column": 1},
+                }
+            ],
+        )
+
+    async def fake_update_proxy(
+        proxy_port: int,
+        payload: object,
+    ) -> ProxyDocument | None:
+        nonlocal update_called
+        update_called = True
+        return make_proxy_document(proxy_port=proxy_port)
+
+    monkeypatch.setattr(
+        proxy_router_module,
+        "validate_proxy_code",
+        fake_validate_proxy_code,
+    )
+    monkeypatch.setattr(proxy_router_module, "update_proxy", fake_update_proxy)
+
+    response = client.put(
+        "/proxy/8123",
+        json={"code": "invalid-code"},
+    )
+
+    assert response.status_code == 422
+    body = response.json()["detail"]
+    assert body["message"] == "Proxy code has invalid Python syntax"
+    assert body["errors"][0]["code"] == "COMPILE"
+    assert update_called is False