fix: STANDALONE spec-decode hidden-size mismatch crash (#24217)

Co-authored-by: root <root@sharp-heart-runs-fin-03.datacrunch.io>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: kpham-sgl <khoa.pham@radixark.ai>
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Co-authored-by: hnyls2002 <lsyincs@gmail.com>
Co-authored-by: Liangsheng Yin <hnyls2002@gmail.com>

python/sglang/srt/speculative/eagle_draft_extend_cuda_graph_runner.py

@@ -152,12 +152,14 @@ class EAGLEDraftExtendCudaGraphRunner:
                     dtype=self.model_runner.dtype,
                 )
             else:
+                # Use target config: hidden_states carries target output.
+                target_cfg = self.eagle_worker.target_worker.model_runner.model_config
                 hidden_states = torch.zeros(
                     (
                         self.max_num_token,
-                        self.model_runner.model_config.spec_hidden_size,
+                        target_cfg.spec_hidden_size,
                     ),
-                    dtype=self.model_runner.dtype,
+                    dtype=target_cfg.dtype,
                 )
             self.seq_len_fill_value = (
                 self.model_runner.attn_backend.get_cuda_graph_seq_len_fill_value()

python/sglang/srt/speculative/eagle_worker.py

@@ -1130,16 +1130,17 @@ class EAGLEWorker(TpModelWorker):
             # All reqs finished this verify; swap to an idle ExtendInput.
             batch = batch.copy()
             batch.prepare_for_idle()
+            target_cfg = self.target_worker.model_runner.model_config
             hidden_size = (
-                self.model_config.hidden_size * 3
+                target_cfg.hidden_size * 3
                 if self.speculative_algorithm.is_eagle3()
                 and self.eagle_use_aux_hidden_state
-                else self.model_config.spec_hidden_size
+                else target_cfg.spec_hidden_size
             )
             draft_extend_input = EagleDraftExtendInput.create_idle_input(
                 device=self.device,
                 hidden_size=hidden_size,
-                dtype=self.model_config.dtype,
+                dtype=target_cfg.dtype,
                 capture_hidden_mode=CaptureHiddenMode.LAST,
             )
             batch.spec_info = draft_extend_input