config: the record is not an object that gets passed around (#36622)

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

test/registered/spec/dspark/test_dspark_draft_path_default.py

@@ -40,7 +40,7 @@ def _make_dspark_server_args(
     server_args.speculative_algorithm = "DSPARK"
     server_args.speculative_draft_model_path = None
     server_args.speculative_dspark_block_size = 5
-    server_args.model_config = SimpleNamespace(hf_config=hf_config)
+    server_args._model_config = SimpleNamespace(hf_config=hf_config)
     return server_args
 
 

test/registered/unit/configs/test_multimodal_piecewise_cuda_graph.py

@@ -72,7 +72,7 @@ class TestMultimodalPiecewiseCudaGraph(CustomTestCase):
 
     def test_supported_multimodal_model_upgrades_default_to_tc_piecewise(self):
         args = ServerArgs(model_path="dummy")
-        args.model_config = SimpleNamespace(
+        args._model_config = SimpleNamespace(
             is_multimodal_piecewise_cuda_graph_supported=True,
             is_multimodal_breakable_cuda_graph_supported=False,
         )
@@ -101,7 +101,7 @@ class TestMultimodalPiecewiseCudaGraph(CustomTestCase):
         args = ServerArgs(model_path="dummy")
         # trtllm_mla skips the tc_piecewise upgrade and keeps breakable, which
         # now serves MLA by falling back to the flashinfer MLA impl for extend.
-        args.model_config = SimpleNamespace(
+        args._model_config = SimpleNamespace(
             is_multimodal_piecewise_cuda_graph_supported=True,
             is_multimodal=False,
             is_multimodal_breakable_cuda_graph_supported=False,
@@ -169,7 +169,7 @@ class TestMultimodalPiecewiseCudaGraph(CustomTestCase):
 
     def test_embedding_gemma_forces_breakable_prefill(self):
         args = ServerArgs(model_path="dummy")
-        args.model_config = SimpleNamespace(
+        args._model_config = SimpleNamespace(
             is_embedding_gemma=True,
             is_multimodal=False,
             context_len=2048,
@@ -183,7 +183,7 @@ class TestMultimodalPiecewiseCudaGraph(CustomTestCase):
         args.chunked_prefill_size = 2048
 
         with (
-            patch.object(args, "get_model_config", return_value=args.model_config),
+            patch.object(args, "get_model_config", return_value=args._model_config),
             patch("sglang.srt.server_args.is_cuda", return_value=True),
         ):
             args._handle_model_capability_adjustments()
@@ -202,7 +202,7 @@ class TestMultimodalPiecewiseCudaGraph(CustomTestCase):
     def test_encoder_embedding_model_enables_embedding_mode_without_flag(self):
         args = ServerArgs(model_path="dummy")
         args.is_embedding = False
-        args.model_config = SimpleNamespace(
+        args._model_config = SimpleNamespace(
             embedding_model_spec=resolve_embedding_model_spec(
                 ["BertModel"],
                 is_embedding_requested=False,
@@ -212,7 +212,7 @@ class TestMultimodalPiecewiseCudaGraph(CustomTestCase):
             hf_config=SimpleNamespace(architectures=["BertModel"]),
         )
 
-        with patch.object(args, "get_model_config", return_value=args.model_config):
+        with patch.object(args, "get_model_config", return_value=args._model_config):
             args._handle_model_capability_adjustments()
 
         self.assertTrue(resolution_result(args, "is_embedding"))

test/registered/unit/mem_cache/test_decode_retraction_backup.py

@@ -116,7 +116,6 @@ class TestDecodeRetractionBackup(unittest.TestCase):
                 mode=HiCacheDraftMode.SIDECAR,
                 device_pools=(draft_pool,),
             ),
-            server_args=server_args,
         )
         self.assertIn(PoolName.DRAFT, cache.host_pool_group.entry_map)
         cache.validate_retraction_host_capacity()

test/registered/unit/mem_cache/test_hybrid_pool_assembler.py

@@ -86,7 +86,6 @@ class TestDraftSidecarPoolDispatch(CustomTestCase):
         specs, entries = build_full_draft_pools(
             draft_kv_pool=draft_kv_pool,
             tree_cache=None,
-            server_args=None,
         )
 
         self.assertEqual(specs, [])
@@ -124,7 +123,6 @@ class TestDraftSidecarPoolDispatch(CustomTestCase):
             specs, entries = build_full_draft_pools(
                 draft_kv_pool=draft_kv_pool,
                 tree_cache=tree_cache,
-                server_args=server_args,
             )
 
         self.assertEqual(build_host_pool.call_args.kwargs["host_to_device_ratio"], 1.0)

test/registered/unit/server_args/test_model_config_cache.py

@@ -110,7 +110,7 @@ class TestTheModelConfigCache(CustomTestCase):
         server_args = self._resolved(
             model_path=_OBJECT_STORE_URI, load_format="runai_streamer"
         )
-        cached = server_args.__dict__["model_config"]
+        cached = server_args.__dict__["_model_config"]
         self.assertIsInstance(cached, ModelConfig)
         # The record still carries the URI the operator typed, and the
         # configuration carries the directory it read the metadata from.
@@ -162,7 +162,7 @@ class TestTheModelConfigCache(CustomTestCase):
         invalidates it."""
         server_args = ServerArgs(model_path=self._checkpoint(), device="cuda")
         stand_in = SimpleNamespace(model_path="somewhere/else")
-        server_args.model_config = stand_in
+        server_args._model_config = stand_in
 
         self.assertIs(server_args.get_model_config(), stand_in)
 

test/registered/unit/server_args/test_no_public_non_field_slot.py

@@ -0,0 +1,83 @@
+"""The record grows no attribute the projection cannot see.
+
+A publicly-named attribute that is not a dataclass field is invisible to every
+other guard here: the namespace coverage walks fields, the projection walks
+fields, and the read ratchets watch field reads. Three of them accumulated that
+way -- a `ModelConfig` cache, an `moe_ep_size` that only a log line read, and an
+env-derived `grpc_worker_threads` that one entry point read across the boundary.
+
+Leading-underscore names are the record's own bookkeeping and stay: the
+read-only guard classifies writability by that spelling, so a private name is
+already outside the config tier by construction.
+"""
+
+import ast
+import dataclasses
+import pathlib
+import unittest
+
+import sglang
+from sglang.srt.server_args import ServerArgs
+from sglang.test.ci.ci_register import register_cpu_ci
+from sglang.test.test_utils import CustomTestCase
+
+register_cpu_ci(est_time=4, suite="base-a-test-cpu")
+
+
+def _self_written_attributes() -> set:
+    """Names `ServerArgs` writes on itself, by either spelling."""
+    source = (
+        pathlib.Path(next(iter(sglang.__path__))) / "srt" / "server_args.py"
+    ).read_text(encoding="utf-8-sig")
+    tree = ast.parse(source)
+    cls = next(
+        node
+        for node in tree.body
+        if isinstance(node, ast.ClassDef) and node.name == "ServerArgs"
+    )
+    written = set()
+    for node in ast.walk(cls):
+        if isinstance(node, ast.Assign):
+            for target in node.targets:
+                if (
+                    isinstance(target, ast.Attribute)
+                    and isinstance(target.value, ast.Name)
+                    and target.value.id == "self"
+                ):
+                    written.add(target.attr)
+        if (
+            isinstance(node, ast.Call)
+            and getattr(node.func, "attr", None) == "__setattr__"
+            and getattr(getattr(node.func, "value", None), "id", None) == "object"
+            and len(node.args) >= 2
+            and isinstance(node.args[1], ast.Constant)
+        ):
+            written.add(node.args[1].value)
+    return written
+
+
+class TestNoPublicNonFieldSlot(CustomTestCase):
+    def test_every_public_attribute_is_a_field(self):
+        written = _self_written_attributes()
+        self.assertGreater(
+            len(written),
+            5,
+            f"only {len(written)} self-writes found; the scan is broken, not the "
+            "record",
+        )
+        fields = {field.name for field in dataclasses.fields(ServerArgs)}
+        stray = sorted(
+            name for name in written if not name.startswith("_") and name not in fields
+        )
+        self.assertEqual(
+            [],
+            stray,
+            "these are written on the record under a public name but are not "
+            "fields, so the projection cannot see them and no other guard "
+            "watches them: make each a field, or give it the leading underscore "
+            f"that says it is the record's own bookkeeping: {stray}",
+        )
+
+
+if __name__ == "__main__":
+    unittest.main()

test/registered/unit/server_args/test_server_args.py

@@ -283,7 +283,7 @@ class TestImageProcessorBackend(CustomTestCase):
 class TestMultimodalFeatureTransport(CustomTestCase):
     @staticmethod
     def _set_model_type(server_args, *, is_multimodal):
-        server_args.model_config = SimpleNamespace(is_multimodal=is_multimodal)
+        server_args._model_config = SimpleNamespace(is_multimodal=is_multimodal)
 
     @patch("sglang.srt.server_args.is_cuda", return_value=True)
     def test_cuda_ipc_is_explicit_and_bounded(self, _mock_is_cuda):
@@ -920,8 +920,8 @@ class TestFa4PageSizeAutoForce(CustomTestCase):
         # use_mla_backend() (mocked) and is_sm100_supported() (mocked), not a
         # real model_config. Pre-set the attribute so get_model_config returns
         # early without touching ModelConfig.from_server_args.
-        args.model_config = MagicMock()
-        args.model_config.hf_config.dual_chunk_attention_config = None
+        args._model_config = MagicMock()
+        args._model_config.hf_config.dual_chunk_attention_config = None
         return args
 
     @patch("sglang.srt.arg_groups.overrides.is_sm100_supported", return_value=True)
@@ -1809,7 +1809,7 @@ class TestCudaGraphConfigDataclassAccess(CustomTestCase):
 class TestCudaGraphDisaggregationRoles(CustomTestCase):
     def _handled_args(self, **overrides):
         args = ServerArgs(model_path="dummy", **overrides)
-        args.model_config = SimpleNamespace(
+        args._model_config = SimpleNamespace(
             hf_config=SimpleNamespace(architectures=["LlamaForCausalLM"]),
             is_piecewise_cuda_graph_disabled_model=False,
             is_multimodal=False,
@@ -1882,7 +1882,7 @@ class TestPrefillCudaGraphLoRACompatibility(CustomTestCase):
 
     def _handled_args(self, **overrides):
         args = ServerArgs(model_path="dummy", **overrides)
-        args.model_config = SimpleNamespace(
+        args._model_config = SimpleNamespace(
             hf_config=SimpleNamespace(architectures=["LlamaForCausalLM"]),
             is_piecewise_cuda_graph_disabled_model=False,
             is_multimodal=False,
@@ -1915,7 +1915,7 @@ class TestPrefillCudaGraphLoRACompatibility(CustomTestCase):
         # Pin the tc_piecewise LoRA rule itself, with the hardware rule
         # neutralized so this runs on CPU-only CI.
         args = ServerArgs(model_path="dummy", enable_lora=True)
-        args.model_config = SimpleNamespace(
+        args._model_config = SimpleNamespace(
             hf_config=SimpleNamespace(architectures=["LlamaForCausalLM"]),
             is_piecewise_cuda_graph_disabled_model=False,
             is_multimodal=False,
@@ -1945,7 +1945,7 @@ class TestBreakableCudaGraphMultimodalAllowlist(CustomTestCase):
 
     def _handled_args(self, *, architectures, is_multimodal, allowlisted):
         args = ServerArgs(model_path="dummy")
-        args.model_config = SimpleNamespace(
+        args._model_config = SimpleNamespace(
             hf_config=SimpleNamespace(architectures=architectures),
             is_piecewise_cuda_graph_disabled_model=False,
             is_multimodal=is_multimodal,
@@ -2129,7 +2129,7 @@ class TestDeepEPv2Args(CustomTestCase):
 
     def _args(self, **overrides):
         server_args = ServerArgs(model_path="dummy", moe_a2a_backend="deepep_v2")
-        server_args.model_config = SimpleNamespace(
+        server_args._model_config = SimpleNamespace(
             hf_config=SimpleNamespace(architectures=["DeepseekV4ForCausalLM"])
         )
         # The dummy path does not initialize phase configs.
@@ -2152,7 +2152,7 @@ class TestDeepEPv2Args(CustomTestCase):
             "Qwen3MoeForCausalLM",
         ):
             args = self._args(moe_runner_backend="deep_gemm")
-            args.model_config.hf_config.architectures = [architecture]
+            args._model_config.hf_config.architectures = [architecture]
             args._handle_a2a_moe()
 
     def test_unvalidated_and_missing_architectures_rejected(self):
@@ -2163,7 +2163,7 @@ class TestDeepEPv2Args(CustomTestCase):
             None,
         ):
             args = self._args(moe_runner_backend="deep_gemm")
-            args.model_config.hf_config.architectures = architectures
+            args._model_config.hf_config.architectures = architectures
             with self.assertRaisesRegex(ValueError, "not validated"):
                 args._handle_a2a_moe()
 
@@ -2188,7 +2188,7 @@ class TestDeepEPv2Args(CustomTestCase):
             moe_runner_backend="deep_gemm",
             rl_on_policy_target="fsdp",
         )
-        args.model_config.hf_config.architectures = ["Qwen3MoeForCausalLM"]
+        args._model_config.hf_config.architectures = ["Qwen3MoeForCausalLM"]
         with (
             envs.SGLANG_VLM_CACHE_SIZE_MB.override(envs.SGLANG_VLM_CACHE_SIZE_MB.get()),
             envs.SGLANG_ENABLE_DETERMINISTIC_INFERENCE.override(
@@ -2514,7 +2514,7 @@ class TestGrpcServerArgs(CustomTestCase):
         with envs.SGLANG_GRPC_WORKER_THREADS.override(8):
             sa._handle_deprecated_args()
         self.assertEqual(resolution_result(sa, "grpc_port"), 50051)
-        self.assertEqual(sa.grpc_worker_threads, 8)
+        self.assertEqual(resolution_result(sa, "grpc_worker_threads"), 8)
 
     def test_env_grpc_port_enables_native(self):
         sa = self._args(port=30000)
@@ -2698,13 +2698,11 @@ class TestGrpcServerArgs(CustomTestCase):
 
         fake_core = SimpleNamespace(start_server=MagicMock(return_value="handle"))
         fake_bridge = SimpleNamespace(RuntimeHandle=MagicMock(return_value="rt"))
-        # The host comes from the `serving` bag; `grpc_worker_threads` is not a
-        # field (resolution sets it from the environment), so it stays on the
-        # stand-in the call site is handed.
-        override = get_context().override_server_args(host="127.0.0.1", grpc_port=50051)
-        override.install()
+        override = get_context().override_server_args(
+            host="127.0.0.1", grpc_port=50051, grpc_worker_threads=4
+        )
+        server_args = override.install()
         self.addCleanup(override.restore)
-        server_args = SimpleNamespace(grpc_worker_threads=4)
         with (
             patch(
                 "sglang.srt.rust_extensions.load_rust_extension",
@@ -2728,6 +2726,7 @@ class TestGrpcServerArgs(CustomTestCase):
         self.assertEqual(
             set(kwargs), {"host", "port", "runtime_handle", "worker_threads"}
         )
+        self.assertEqual(kwargs["worker_threads"], 4)
         self.assertNotIn("max_prefill_tokens", kwargs)
 
 

test/registered/unit/test_dead_server_args_parameter_ratchet.py

@@ -0,0 +1,86 @@
+"""A function does not take the record it never reads.
+
+A `server_args` parameter that the body never names keeps a reference to the
+whole record alive across a call boundary, and it reads as an invitation: the
+next person to need one value takes it off the parameter that is already there,
+instead of deciding where that value should come from. Removing one usually
+uncovers the next -- the caller that only had a record to pass it along.
+
+Class methods are exempt: a base class, an override, or one implementation of a
+strategy carries the parameter for its contract, and the body of any single one
+of them is not evidence. This walks module-level functions only.
+"""
+
+import ast
+import pathlib
+import unittest
+
+import sglang
+from sglang.test.ci.ci_register import register_cpu_ci
+from sglang.test.test_utils import CustomTestCase
+
+register_cpu_ci(est_time=6, suite="base-a-test-cpu")
+
+_PACKAGE_ROOT = pathlib.Path(next(iter(sglang.__path__)))
+
+# The resolution pipeline builds the record, so a parameter there is the subject
+# rather than a passenger. `multimodal_gen` has a different, same-named class
+# outside this contract, as the mutation ratchet also records.
+_EXCLUDED = ("srt/arg_groups", "srt/server_args.py", "multimodal_gen")
+
+_BASELINE = 0
+
+
+def _dead_parameters():
+    found = []
+    scanned = 0
+    for path in sorted(_PACKAGE_ROOT.rglob("*.py")):
+        rel = path.relative_to(_PACKAGE_ROOT).as_posix()
+        if rel.startswith(_EXCLUDED):
+            continue
+        source = path.read_text(encoding="utf-8-sig")
+        if "server_args" not in source:
+            continue
+        scanned += 1
+        try:
+            tree = ast.parse(source)
+        except SyntaxError:
+            continue
+        for node in tree.body:
+            if not isinstance(node, (ast.FunctionDef, ast.AsyncFunctionDef)):
+                continue
+            taken = [a.arg for a in node.args.args] + [
+                a.arg for a in node.args.kwonlyargs
+            ]
+            if "server_args" not in taken:
+                continue
+            named = any(
+                isinstance(inner, ast.Name) and inner.id == "server_args"
+                for inner in ast.walk(node)
+                if inner is not node
+            )
+            if not named:
+                found.append(f"{rel}:{node.lineno} {node.name}")
+    return found, scanned
+
+
+class TestNoDeadServerArgsParameter(CustomTestCase):
+    def test_no_module_level_function_takes_a_record_it_ignores(self):
+        found, scanned = _dead_parameters()
+        self.assertGreater(
+            scanned,
+            50,
+            f"only {scanned} files mention server_args; the scan is broken, not "
+            "the tree",
+        )
+        self.assertEqual(
+            _BASELINE,
+            len(found),
+            "these functions take `server_args` and never name it; drop the "
+            "parameter and the argument at every call site, then check whether "
+            f"the caller still needs its own: {found}",
+        )
+
+
+if __name__ == "__main__":
+    unittest.main()