---
id: pr-vllm-29624
repo: vllm-project/vllm
pr: 29624
title: '[Attention] Make seq_lens_cpu optional in CommonAttentionMetadata to enable true async spec-decode'
author: LucasWilkinson
date: '2025-12-10'
url: https://github.com/vllm-project/vllm/pull/29624
source_category: upstream-code
architectures:
- sm100
tags: []
techniques: []
hardware_features: []
kernel_types: []
languages: []
captured_at: '2026-05-16'
status: merged
merge_sha: abe93bce5952ed8adf90d4b77af6ed3515958620
inclusion_reason: defer
changed_paths:
- tests/v1/attention/utils.py
- tests/v1/e2e/test_async_spec_decode.py
- tests/v1/spec_decode/test_tree_attention.py
- vllm/attention/layers/cross_attention.py
- vllm/v1/attention/backends/gdn_attn.py
- vllm/v1/attention/backends/utils.py
- vllm/v1/spec_decode/eagle.py
- vllm/v1/worker/gpu/attn_utils.py
- vllm/v1/worker/gpu_model_runner.py
artifact_dir: evidence/pull-bundles/vllm/gh-29624
head_ref_oid: ebff06a13d6d2f284509987d31d83b436664c00b
---
# [Attention] Make seq_lens_cpu optional in CommonAttentionMetadata to enable true async spec-decode

- Repository: `vllm-project/vllm`
- PR: [29624](https://github.com/vllm-project/vllm/pull/29624)
- Decision: `defer`
- Reason: defer

## Changed Paths

- `tests/v1/attention/utils.py`
- `tests/v1/e2e/test_async_spec_decode.py`
- `tests/v1/spec_decode/test_tree_attention.py`
- `vllm/attention/layers/cross_attention.py`
- `vllm/v1/attention/backends/gdn_attn.py`
- `vllm/v1/attention/backends/utils.py`
- `vllm/v1/spec_decode/eagle.py`
- `vllm/v1/worker/gpu/attn_utils.py`
- `vllm/v1/worker/gpu_model_runner.py`

## Evidence Bundle

`evidence/pull-bundles/vllm/gh-29624`
