[Speculative Decoding] Unify Spec and non-spec branch (#6685)

* optimize spec-inference architecture

* delete debug log

* optimize spec_method usage  && fix unit_test

* add claude unit-test skill

* fix some ugly bug

* enhance robustness and bounds check

* unify method & spec_method to method to avoid bug

* activate CI

* fix unit test

* Unify logprobs computation for naive and speculative decoding, fix CUDA kernel

* fix logprob bug && optimize verify kernel

* fix exist_decode() judge

fastdeploy/model_executor/pre_and_post_process.py

@@ -66,14 +66,13 @@ elif current_platform.is_maca():
         speculate_save_output,
         speculate_save_output_topk,
         speculate_set_stop_value_multi_seqs,
-        speculate_set_value_by_flags_and_idx,
         speculate_step_paddle,
         speculate_step_reschedule,
         speculate_step_system_cache,
-        speculate_update,
         step_paddle,
         step_reschedule,
         step_system_cache,
+        unified_update_model_status,
         update_inputs,
         update_inputs_v1,
     )
@@ -88,11 +87,10 @@ else:
         speculate_pre_process,
         speculate_save_output,
         speculate_save_output_topk,
-        speculate_set_value_by_flags_and_idx,
         speculate_step_paddle,
         speculate_step_system_cache,
-        speculate_update,
         speculate_set_stop_value_multi_seqs,
+        unified_update_model_status,
         step_paddle,
         step_system_cache,
         update_inputs,
@@ -425,6 +423,8 @@ def post_process_specualate(
     think_end_id: int = -1,
     splitwise_role_is_decode: bool = False,
     enable_entropy: bool = False,
+    is_naive_mode: bool = False,
+    prefill_one_step_stop: bool = False,
 ):
     if think_end_id > 0:
         speculate_limit_thinking_content_length(
@@ -457,18 +457,30 @@ def post_process_specualate(
     if enable_entropy:
         speculate_calculate_logits_entropy(sampler_output.logits, share_inputs, sampling_metadata.temperature)
 
-    speculate_update(
-        model_output.seq_lens_encoder,
-        model_output.seq_lens_decoder,
-        model_output.not_need_stop,
-        model_output.draft_tokens,
-        model_output.actual_draft_token_num,
-        model_output.accept_tokens,
-        model_output.accept_num,
-        model_output.stop_flags,
-        model_output.seq_lens_this_time,
-        model_output.is_block_step,
-        model_output.mask_rollback,
+    # Unified state update: merges speculate_update + speculate_set_value_by_flags_and_idx
+    # into a single kernel launch. For MTP/ngram paths, verify_draft_tokens has already
+    # handled EOS/max_dec_len detection (replacing tokens + updating step_idx), so
+    # unified_update_model_status acts as a no-op for those checks. For naive mode
+    # (which skips verify), this kernel handles EOS/max_dec_len detection.
+    unified_update_model_status(
+        model_output.seq_lens_encoder,  # seq_lens_encoder
+        model_output.seq_lens_decoder,  # seq_lens_decoder
+        model_output.not_need_stop,  # has_running_seqs
+        model_output.draft_tokens,  # step_input_ids
+        model_output.actual_draft_token_num,  # adaptive_step_input_len
+        model_output.accept_tokens,  # step_output_ids (read-write)
+        model_output.accept_num,  # step_output_len (read-write)
+        model_output.stop_flags,  # stop_flags (read-write)
+        model_output.seq_lens_this_time,  # seq_lens_this_time
+        model_output.is_block_step,  # is_paused
+        model_output.mask_rollback,  # mask_rollback
+        model_output.token_ids_all,  # token_ids_all
+        model_output.prompt_lens,  # prompt_lens
+        model_output.step_idx,  # step_idx (read-write)
+        model_output.eos_token_id,  # end_tokens
+        model_output.max_dec_len,  # max_dec_len
+        is_naive_mode,  # is_naive_mode
+        prefill_one_step_stop,  # prefill_one_step_stop
     )
 
     if not skip_save_output:
@@ -522,20 +534,6 @@ def post_process_specualate(
                 save_each_rank,
             )
 
-    # Update token_ids_all through accept tokens
-
-    speculate_set_value_by_flags_and_idx(
-        model_output.token_ids_all,
-        model_output.prompt_lens,
-        model_output.accept_tokens,
-        model_output.accept_num,
-        model_output.stop_flags,
-        model_output.seq_lens_this_time,
-        model_output.seq_lens_encoder,
-        model_output.seq_lens_decoder,
-        model_output.step_idx,
-    )
-
 
 def post_process(
     sampler_or_pooler_output: Union[SamplerOutput, PoolerOutput],
@@ -550,6 +548,8 @@ def post_process(
     think_end_id: int = -1,
     splitwise_role_is_decode: bool = False,
     enable_entropy: bool = False,
+    is_naive_mode: bool = False,
+    prefill_one_step_stop: bool = False,
 ) -> None:
     """Post-processing steps after completing a single token generation."""
 
@@ -575,6 +575,8 @@ def post_process(
                 think_end_id,
                 splitwise_role_is_decode,
                 enable_entropy,
+                is_naive_mode,
+                prefill_one_step_stop,
             )
         else:
             post_process_normal(