[Spec] Derive NGRAM grammar tree links on the host instead of reading back retrive_next_token (#32380)

test/registered/spec/test_spec_ngram.py

@@ -2,16 +2,26 @@ import unittest
 
 from sglang.test.ci.ci_register import register_cuda_ci
 from sglang.test.kits.eval_accuracy_kit import GSM8KMixin
+from sglang.test.kits.json_constrained_kit import JSONConstrainedMixin
+from sglang.test.kits.regex_constrained_kit import RegexConstrainedMixin
 from sglang.test.kits.spec_server_kits import SpecLogprobKit
 from sglang.test.server_fixtures.ngram_fixture import NgramServerBase
 
 # Per-commit: Paged backend only.
 # - FA3 base test archived to test/manual/spec/test_spec_ngram_fa3.py
 # - Triton + Flashinfer moved to test_spec_ngram_extra.py
-register_cuda_ci(est_time=400, stage="base-b", runner_config="1-gpu-large")
+register_cuda_ci(est_time=460, stage="base-b", runner_config="1-gpu-large")
 
 
-class TestNgramSpeculativeDecodingPaged(NgramServerBase, GSM8KMixin, SpecLogprobKit):
+class TestNgramSpeculativeDecodingPaged(
+    NgramServerBase,
+    GSM8KMixin,
+    SpecLogprobKit,
+    RegexConstrainedMixin,
+    JSONConstrainedMixin,
+):
+    # Constrained mixins reuse this server; they cover the grammar verify path,
+    # where the bitmask is built by walking the host draft tree.
     attention_backend = "flashinfer"
     extra_args = ["--page-size", "64"]