Use runtime token widths for Triton speculative verification (#39859)

Co-authored-by: raghotham <853234+raghotham@users.noreply.github.com>

test/registered/unit/spec/test_eagle_worker_v2_topk1_fastpath.py

@@ -16,6 +16,7 @@ import torch
 from sglang.srt.model_executor.forward_batch_info import ForwardMode
 from sglang.srt.runtime_context import get_context
 from sglang.srt.speculative.adaptive_runtime_state import SpecRuntimeState
+from sglang.srt.speculative.eagle_info import EagleVerifyInput
 from sglang.srt.speculative.eagle_utils import organize_draft_results
 from sglang.srt.speculative.eagle_worker_v2 import EagleDraftWorker, EAGLEWorkerV2
 from sglang.test.ci.ci_register import register_amd_ci, register_cpu_ci
@@ -135,6 +136,19 @@ class TestEagleWorkerV2Topk1FastPath(CustomTestCase):
         with self.assertRaises(AssertionError):
             worker._rebuild_topk1_chain_buffers()
 
+    def test_idle_verify_input_keeps_required_layout_tensors(self):
+        verify_input = EagleVerifyInput.create_idle_input(
+            topk=1,
+            spec_steps=3,
+            num_verify_tokens=4,
+            device=DEVICE,
+        )
+
+        self.assertEqual(verify_input.custom_mask.dtype, torch.bool)
+        self.assertEqual(verify_input.custom_mask.shape, (0,))
+        self.assertEqual(verify_input.positions.dtype, torch.int64)
+        self.assertEqual(verify_input.positions.shape, (0,))
+
     def test_idle_draft_runs_each_eager_forward_without_tree_layout(self):
         worker = object.__new__(EagleDraftWorker)
         worker.speculative_num_steps = 3