[HotFix][Ling 2.6] Fix HybridLinearAttn dispatcher for Ling-2.6 (#26474)

Co-authored-by: luoyuan.luo <luoyuan.luo@antgroup.com>

test/registered/8-gpu-models/test_ling_2_6_flash.py

@@ -0,0 +1,54 @@
+"""GSM8K accuracy test for Ling-2.6-flash (BailingMoELinearForCausalLM).
+
+Guards the hybrid linear / full attention dispatcher: Ling-2.5/2.6
+has 32 layers with `layer_group_size=8`, so layers {7, 15, 23, 31}
+are full attention (MLA) and the rest are linear (Lightning seg_la).
+Runs on the 8-GPU H200 runner with TP=4.
+"""
+
+import unittest
+
+from sglang.test.ci.ci_register import register_cuda_ci
+from sglang.test.kits.eval_accuracy_kit import GSM8KMixin
+from sglang.test.server_fixtures.default_fixture import DefaultServerBase
+
+register_cuda_ci(est_time=600, stage="base-c", runner_config="8-gpu-h200")
+
+
+class TestLing26Flash(GSM8KMixin, DefaultServerBase):
+    model = "inclusionAI/Ling-2.6-flash"
+
+    # Native 128K context (no YaRN) — avoids the
+    # SGLANG_ALLOW_OVERWRITE_LONGER_CONTEXT_LEN env-var dance and keeps the
+    # smoke test focused on the dispatcher / hybrid-attention path.
+    other_args = [
+        "--tp-size",
+        "4",
+        "--trust-remote-code",
+        "--mamba-scheduler-strategy",
+        "extra_buffer",
+        "--mem-fraction-static",
+        "0.75",
+        "--max-running-requests",
+        "64",
+        "--max-mamba-cache-size",
+        "256",
+        # MTP path also exercises the dispatcher (draft + target verify),
+        # so keep it on to maximize coverage.
+        "--speculative-algorithm",
+        "NEXTN",
+        "--speculative-num-steps",
+        "3",
+        "--speculative-eagle-topk",
+        "1",
+        "--speculative-num-draft-tokens",
+        "4",
+    ]
+
+    # Observed 0.825 on H200 TP=4 + NEXTN MTP with default 200-question GSM8K
+    # (the model card's 0.96 is from full 1319-question runs of the 1T model).
+    gsm8k_accuracy_thres = 0.825
+
+
+if __name__ == "__main__":
+    unittest.main(verbosity=3)