[Spec][LoRA] Support multi-adapter LoRA with EAGLE/NEXTN/DFLASH/DSPARK speculative decoding (#34337)

test/registered/unit/model_executor/test_draft_runner_skips_lora.py

@@ -0,0 +1,51 @@
+"""The draft runner must not build a LoRA manager.
+
+Adapters apply to the target model only. Every worker is handed the same
+published ServerArgs, so `enable_lora` is True for the draft too -- the
+decision is the runner's own, keyed on is_draft_worker. Without it the draft
+tries to load the target's adapters into the draft model, whose layer count
+differs, and startup fails inside LoRAAdapter weight loading.
+
+The LoRA paths downstream then key on `lora_manager is not None` rather than
+the config, so a draft runner skips them by construction.
+"""
+
+import unittest
+from unittest.mock import patch
+
+from sglang.srt.model_executor.model_runner import ModelRunner
+from sglang.test.ci.ci_register import register_cpu_ci
+from sglang.test.test_utils import CustomTestCase
+
+register_cpu_ci(est_time=5, suite="base-a-test-cpu")
+
+
+class TestDraftRunnerSkipsLoRA(CustomTestCase):
+    def _init_lora_called(self, *, is_draft_worker: bool, enable_lora: bool) -> bool:
+        runner = ModelRunner.__new__(ModelRunner)
+        runner.is_draft_worker = is_draft_worker
+        runner.lora_manager = None
+        with patch.object(ModelRunner, "init_lora_manager") as init_lora:
+            with patch("sglang.srt.model_executor.model_runner.get_lora") as get_lora:
+                get_lora.return_value.enable_lora = enable_lora
+                runner.maybe_init_lora_manager()
+        return init_lora.called
+
+    def test_only_the_target_runner_builds_a_lora_manager(self):
+        cases = [
+            (False, True, True),  # target + LoRA -> builds one
+            (True, True, False),  # draft + LoRA -> must not
+            (False, False, False),  # LoRA off -> nobody builds one
+        ]
+        for is_draft_worker, enable_lora, expected in cases:
+            with self.subTest(draft=is_draft_worker, enable_lora=enable_lora):
+                self.assertEqual(
+                    self._init_lora_called(
+                        is_draft_worker=is_draft_worker, enable_lora=enable_lora
+                    ),
+                    expected,
+                )
+
+
+if __name__ == "__main__":
+    unittest.main()

test/registered/unit/model_executor/test_prefill_cuda_graph_runner.py

@@ -69,9 +69,11 @@ class TestPrefillCudaGraphRunnerChunkedPrefix(CustomTestCase):
             device="cuda",
             gpu_id=0,
             is_draft_worker=False,
+            # A real ModelRunner always has this attribute; the prefill gate
+            # reads it rather than the process-wide LoRA config.
+            lora_manager=None,
             spec_algorithm=SimpleNamespace(is_eagle=lambda: False),
             server_args=SimpleNamespace(
-                enable_lora=False,
                 cuda_graph_config=SimpleNamespace(
                     prefill=SimpleNamespace(bs=[1], backend=Backend.BREAKABLE)
                 ),