test(proxy): regression test that load_config forwards callback_specific_params

tests/test_litellm/proxy/proxy_server/test_proxy_config.py

@@ -601,6 +601,56 @@ async def test_ProxyConfig_load_config_missing_file_raises(monkeypatch):
         await pc.load_config(router=None, config_file_path="/no/file.yaml")
 
 
+@pytest.mark.asyncio
+async def test_ProxyConfig_load_config_forwards_callback_specific_params(
+    tmp_path, monkeypatch
+):
+    """Regression: callback_settings from config must be forwarded to
+    initialize_callbacks_on_proxy as callback_specific_params.
+
+    Callbacks like DatadogCostManagementLogger read their init params (e.g.
+    cost_tag_keys) from callback_specific_params[<callback_name>]. If the
+    argument is dropped at the call site, they silently initialize with empty
+    params and the configured allowlist never takes effect.
+    """
+    f = tmp_path / "c.yaml"
+    f.write_text(
+        "model_list: []\n"
+        "general_settings: {}\n"
+        "callback_settings:\n"
+        "  datadog_cost_management:\n"
+        "    cost_tag_keys:\n"
+        "      - capability\n"
+        "      - platform\n"
+        "      - ai_product\n"
+        'litellm_settings:\n'
+        '  callbacks: ["datadog_cost_management"]\n'
+    )
+    monkeypatch.setattr("litellm.proxy.proxy_server.prisma_client", None)
+    monkeypatch.setattr("litellm.proxy.proxy_server.store_model_in_db", False)
+    monkeypatch.delenv("LITELLM_CONFIG_BUCKET_NAME", raising=False)
+
+    captured = {}
+
+    def _fake_initialize_callbacks_on_proxy(**kwargs):
+        captured.update(kwargs)
+
+    monkeypatch.setattr(
+        "litellm.proxy.proxy_server.initialize_callbacks_on_proxy",
+        _fake_initialize_callbacks_on_proxy,
+    )
+
+    pc = ProxyConfig()
+    await pc.load_config(router=None, config_file_path=str(f))
+
+    # The callbacks branch must forward the loaded callback_settings.
+    assert captured.get("callback_specific_params") == {
+        "datadog_cost_management": {
+            "cost_tag_keys": ["capability", "platform", "ai_product"]
+        }
+    }
+
+
 # ---------------------------------------------------------------------------
 # ProxyConfig._init_non_llm_configs
 # ---------------------------------------------------------------------------