fix: use ConfigRepository.get_param() in _add_router_settings_from_db_config

Router settings stored via /config/update were double-serialized as JSON
strings in the LiteLLM_Config.param_value Json column. On reload,
_add_router_settings_from_db_config used raw table.find_first() which
bypassed ConfigRepository.get_param()'s string-to-dict parsing, causing
isinstance(param_value, dict) to fail and settings like model_group_alias
to be silently dropped.

Fixes #31836

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

litellm/proxy/proxy_server.py

@@ -5282,9 +5282,8 @@ class ProxyConfig:
         4. Update router settings
         """
         if llm_router is not None and prisma_client is not None:
-            db_router_settings = await ConfigRepository(prisma_client).table.find_first(
-                where={"param_name": "router_settings"}
-            )
+            db_router_param = await ConfigRepository(prisma_client).get_param("router_settings")
+            db_param_value = db_router_param.param_value if db_router_param is not None else None
 
             config_router_settings = config_data.get("router_settings", {})
 
@@ -5292,16 +5291,15 @@ class ProxyConfig:
             if (
                 config_router_settings is not None
                 and isinstance(config_router_settings, dict)
-                and db_router_settings is not None
-                and isinstance(db_router_settings.param_value, dict)
+                and isinstance(db_param_value, dict)
             ):
                 from litellm.utils import _update_dictionary
 
-                combined_router_settings = _update_dictionary(config_router_settings, db_router_settings.param_value)
+                combined_router_settings = _update_dictionary(config_router_settings, db_param_value)
             elif config_router_settings is not None and isinstance(config_router_settings, dict):
                 combined_router_settings = config_router_settings
-            elif db_router_settings is not None and isinstance(db_router_settings.param_value, dict):
-                combined_router_settings = db_router_settings.param_value
+            elif isinstance(db_param_value, dict):
+                combined_router_settings = db_param_value
 
             if combined_router_settings:
                 llm_router.update_settings(**combined_router_settings)

tests/test_litellm/proxy/proxy_server/test_proxy_config.py

@@ -1368,7 +1368,7 @@ async def test_ProxyConfig__add_router_settings_from_db_config_updates_router():
     fake_router = MagicMock()
     fake_router.update_settings = MagicMock()
     fake_prisma = MagicMock()
-    fake_prisma.db.litellm_config.find_first = AsyncMock(
+    fake_prisma.db.litellm_config.find_unique = AsyncMock(
         return_value=SimpleNamespace(
             param_value={"timeout": 30, "retries": 2, "fallbacks": []}
         )
@@ -1393,6 +1393,34 @@ async def test_ProxyConfig__add_router_settings_from_db_config_updates_router():
     }
 
 
+@pytest.mark.asyncio
+async def test_ProxyConfig__add_router_settings_from_db_config_handles_json_string():
+    """Regression for #31836: param_value stored as a JSON string must be
+    deserialized before being applied to the router."""
+    import json
+
+    pc = ProxyConfig()
+    fake_router = MagicMock()
+    fake_router.update_settings = MagicMock()
+    fake_prisma = MagicMock()
+    fake_prisma.db.litellm_config.find_unique = AsyncMock(
+        return_value=SimpleNamespace(
+            param_value=json.dumps(
+                {"model_group_alias": {"codex/gpt-5.5:auto": "codex/gpt-5.5"}}
+            )
+        )
+    )
+    await pc._add_router_settings_from_db_config(
+        config_data={},
+        llm_router=fake_router,
+        prisma_client=fake_prisma,
+    )
+    assert fake_router.update_settings.called
+    assert fake_router.update_settings.call_args.kwargs == {
+        "model_group_alias": {"codex/gpt-5.5:auto": "codex/gpt-5.5"},
+    }
+
+
 @pytest.mark.asyncio
 async def test_ProxyConfig__add_router_settings_from_db_config_none_router_noop():
     pc = ProxyConfig()

tests/test_litellm/proxy/test_proxy_server.py

@@ -3776,7 +3776,7 @@ async def test_add_router_settings_from_db_config_merge_logic():
 
     # Mock prisma client
     mock_prisma_client = MagicMock()
-    mock_prisma_client.db.litellm_config.find_first = AsyncMock(
+    mock_prisma_client.db.litellm_config.find_unique = AsyncMock(
         return_value=mock_db_config
     )
 
@@ -3787,8 +3787,8 @@ async def test_add_router_settings_from_db_config_merge_logic():
         prisma_client=mock_prisma_client,
     )
 
-    # Verify find_first was called with correct parameters
-    mock_prisma_client.db.litellm_config.find_first.assert_called_once_with(
+    # Verify find_unique was called with correct parameters
+    mock_prisma_client.db.litellm_config.find_unique.assert_called_once_with(
         where={"param_name": "router_settings"}
     )
 
@@ -3853,7 +3853,7 @@ async def test_add_router_settings_from_db_config_edge_cases():
 
     # Test Case 3: DB returns None (no router_settings in DB)
     mock_prisma_client = MagicMock()
-    mock_prisma_client.db.litellm_config.find_first = AsyncMock(return_value=None)
+    mock_prisma_client.db.litellm_config.find_unique = AsyncMock(return_value=None)
 
     config_data = {"router_settings": {"routing_strategy": "usage-based"}}
 
@@ -3870,7 +3870,7 @@ async def test_add_router_settings_from_db_config_edge_cases():
     # Test Case 4: Config has no router_settings
     mock_db_config = MagicMock()
     mock_db_config.param_value = {"db_setting": "db_value"}
-    mock_prisma_client.db.litellm_config.find_first = AsyncMock(
+    mock_prisma_client.db.litellm_config.find_unique = AsyncMock(
         return_value=mock_db_config
     )
 
@@ -3885,7 +3885,7 @@ async def test_add_router_settings_from_db_config_edge_cases():
     mock_router.reset_mock()
 
     # Test Case 5: Both config and DB router_settings are None/empty
-    mock_prisma_client.db.litellm_config.find_first = AsyncMock(return_value=None)
+    mock_prisma_client.db.litellm_config.find_unique = AsyncMock(return_value=None)
 
     await proxy_config._add_router_settings_from_db_config(
         config_data={}, llm_router=mock_router, prisma_client=mock_prisma_client
@@ -3896,8 +3896,8 @@ async def test_add_router_settings_from_db_config_edge_cases():
 
     # Test Case 6: DB config exists but param_value is not a dict
     mock_db_config_invalid = MagicMock()
-    mock_db_config_invalid.param_value = "not_a_dict"
-    mock_prisma_client.db.litellm_config.find_first = AsyncMock(
+    mock_db_config_invalid.param_value = 42
+    mock_prisma_client.db.litellm_config.find_unique = AsyncMock(
         return_value=mock_db_config_invalid
     )
 
@@ -3951,7 +3951,7 @@ async def test_add_router_settings_shallow_merge_behavior():
     }
 
     mock_prisma_client = MagicMock()
-    mock_prisma_client.db.litellm_config.find_first = AsyncMock(
+    mock_prisma_client.db.litellm_config.find_unique = AsyncMock(
         return_value=mock_db_config
     )
 

tests/test_litellm/test_router_retry_policy_update.py

@@ -220,6 +220,9 @@ class _FakeConfigTable:
     async def find_first(self, where):
         return self.rows.get(where["param_name"])
 
+    async def find_unique(self, where):
+        return self.rows.get(where["param_name"])
+
     async def upsert(self, where, data):
         name = where["param_name"]
         raw = (data["update"] if name in self.rows else data["create"])["param_value"]