[DSv4] Loading Time Weight Dequant (#27867)

Co-authored-by: Peng Zhang <aniz1905@gmail.com>

test/registered/models_e2e/test_deepseek_v4_flash_fp4_h200.py

@@ -4,7 +4,10 @@ Launches TP=4 with Marlin FP4 MoE runner + EAGLE speculative decoding.
 Runs 12 ServerSanity probes (correctness, streaming, concurrency, determinism)
 plus a GSM8K accuracy gate.
 
-Registry: base-c-test-deepep-8-gpu-h200 (per-commit, 8x H200 — only 4 used by TP=4)
+Also covers SGLANG_DSV4_FP4_DEQUANT=1 (TP=8): FP4 experts dequantized to FP8
+during loading and served through the plain FP8 MoE path.
+
+Registry: base-c-test-deepep-8-gpu-h200 (per-commit, 8x H200)
 """
 
 import unittest
@@ -21,7 +24,7 @@ from sglang.test.test_utils import (
     try_cached_model,
 )
 
-register_cuda_ci(est_time=370, stage="base-c", runner_config="deepep-8-gpu-h200")
+register_cuda_ci(est_time=600, stage="base-c", runner_config="deepep-8-gpu-h200")
 
 
 def _flashinfer_has_sm90_cutlass_mxfp4() -> bool:
@@ -170,5 +173,45 @@ class TestDSV4FlashFP4NonMTPH200(
             kill_process_tree(cls.process.pid)
 
 
+class TestDSV4FlashFP4DequantTP8H200(
+    BasicDecodeCorrectnessMixin, GSM8KMixin, CustomTestCase
+):
+    """SGLANG_DSV4_FP4_DEQUANT=1: TP=8, FP4 experts dequantized to FP8 during
+    loading, then served through the plain FP8 MoE path (no mxfp4 runner)."""
+
+    gsm8k_accuracy_thres = 0.93
+
+    @classmethod
+    def setUpClass(cls):
+        cls.model = try_cached_model(MODEL)
+        cls.base_url = DEFAULT_URL_FOR_TEST
+        cls.process = popen_launch_server(
+            cls.model,
+            cls.base_url,
+            timeout=SERVER_LAUNCH_TIMEOUT,
+            other_args=[
+                "--trust-remote-code",
+                "--tp",
+                "8",
+                "--speculative-algorithm",
+                "EAGLE",
+                "--speculative-num-steps",
+                "3",
+                "--speculative-eagle-topk",
+                "1",
+                "--speculative-num-draft-tokens",
+                "4",
+                "--watchdog-timeout",
+                "900",
+            ],
+            env={"SGLANG_DSV4_FP4_DEQUANT": "1"},
+        )
+
+    @classmethod
+    def tearDownClass(cls):
+        if hasattr(cls, "process") and cls.process:
+            kill_process_tree(cls.process.pid)
+
+
 if __name__ == "__main__":
     unittest.main()