Spec v1 EAGLE now follows the same model-config-gated MTP index reuse contract as spec v2. This lets models that declare index_share_for_mtp_iteration reuse the first draft step's NSA/DSA topk indices across internal MTP iterations while keeping the unsafe topk>1 case disabled.
Constraint: select_top_k_tokens can reorder hidden rows when topk > 1, so carried topk indices are only valid under topk == 1.
Rejected: Enable reuse unconditionally | models without the config flag may not have compatible MTP index semantics.
Rejected: Broaden to target-to-draft index reuse | separate semantic change with different correctness risks.
Confidence: high
Scope-risk: narrow
Directive: Keep spec v1 and spec v2 MTP index reuse semantics aligned, including the topk==1 guard and per-draft-forward cleanup.
Tested: python -m pytest test/registered/spec/eagle/test_eagle_v2_draft_extend_contract.py -q
Tested: python -m py_compile python/sglang/srt/speculative/eagle_worker.py test/registered/spec/eagle/test_eagle_v2_draft_extend_contract.py
Not-tested: full spec v1 GLM5 online throughput run
EAGLE V2 draft MTP can avoid recomputing NSA/DSA indexer topk across internal draft iterations when the model declares that those indices are shareable. The port follows the upstream narrow contract: store per-forward topk on ForwardBatch, enable reuse only for topk=1, and clear the transient state after draft_forward.
Constraint: topk > 1 reorders hidden rows in select_top_k_tokens, so carried topk indices would no longer match the hidden states.
Rejected: Reuse target-side topk for draft | broader semantic change not covered by the upstream fix or current tests.
Rejected: Skip loading draft indexer weights | separate memory optimization with correctness risk for models that do not enable MTP index sharing.
Confidence: high
Scope-risk: narrow
Directive: Do not enable index_share_for_mtp_iteration without preserving the topk==1 guard and per-draft-forward cleanup.
Tested: python -m pytest test/registered/spec/eagle/test_eagle_v2_draft_extend_contract.py -q
Tested: python -m py_compile python/sglang/srt/speculative/eagle_worker_v2.py python/sglang/srt/models/deepseek_nextn.py python/sglang/srt/model_executor/forward_batch_info.py test/registered/spec/eagle/test_eagle_v2_draft_extend_contract.py
Not-tested: full GLM5 EAGLE throughput/accuracy run
NSA spec-v2 draft-extend graph replay was still using host-derived sequence lengths and the draft-decode backend allowlist. That kept NSA on eager draft-extend for spec-v2 and left seq_lens_cpu.max()/list-to-GPU tensor construction on the decode critical path.
This ports the small upstream DSA metadata fixes into the local NSA backend: size the captured graph page table to req_to_token width, use the static captured page-table width for graph replay, split v2 draft-extend from variable-length v1 draft-extend, and decide draft-extend graph support from the prefill-style backend.
Constraint: Current branch does not have the full upstream needs_cpu_seq_lens scheduler/FutureMap infra.
Rejected: Cherry-pick the full DSA fused metadata generation series | too broad and overlaps with local NSA fused metadata-copy code.
Confidence: medium
Scope-risk: moderate
Directive: Do not collapse DRAFT_EXTEND and DRAFT_EXTEND_V2 here; v1 keeps variable accept lengths while v2 must stay graph-static.
Tested: local pytest test/registered/spec/eagle/test_eagle_v2_draft_extend_contract.py -q (19 passed)
Tested: local py_compile on nsa_backend.py, nsa_backend_mtp_precompute.py, eagle_worker_v2.py
Tested: remote g0034 cjy-glm5-new pytest test/registered/spec/eagle/test_eagle_v2_draft_extend_contract.py -q (19 passed)
Tested: remote g0034 cjy-glm5-new py_compile on nsa_backend.py, nsa_backend_mtp_precompute.py, eagle_worker_v2.py
Not-tested: full decode E2E with SGLANG_ENABLE_SPEC_V2=1
Spec-v2 draft extend can receive token ids from producers whose dtype is not already int64, while DP collective paths require a stable integer dtype across ranks. EAGLE draft CUDA graph replay also pads raw batches to a captured batch size, so the metadata/replay path must see seq_lens_sum consistent with the padded seq_lens and then restore the caller-visible raw value.
Constraint: Keep this as a narrow correctness port from upstream rather than pulling the larger spec-v2 refactor chain.
Rejected: Cherry-pick broader attention-backend and decode-result refactors | current branch lacks the same upstream forward-context scaffolding and would require a separate port.
Confidence: high
Scope-risk: narrow
Directive: Do not remove the seq_lens_sum restore without rechecking padded EAGLE draft CUDA graph metadata construction.
Tested: python -m pytest test/registered/spec/eagle/test_eagle_v2_draft_extend_contract.py -q
Tested: remote g0034/cjy-glm5-new PYTHONPATH=python python3 -m pytest test/registered/spec/eagle/test_eagle_v2_draft_extend_contract.py -q
Not-tested: full multi-node GLM5 spec-v2 decode startup smoke
Co-authored-by: OmX <omx@oh-my-codex.dev>
Port the fix-decode spec-v2 ownership and plan-stream fixes onto the current branch. Draft extend now keeps the scheduler-owned batch lengths committed until acceptance, binds the draft runner to the draft-extend attention backend, keeps speculative KV allocation monotonic, and lets non-graph target verify initialize metadata after DP padding. The worker also records rebound tensors on the forward stream and orders plan-stream metadata work after current-stream inputs are available.
Constraint: fix-decode commits cd8e47ed9c and 60e3956d9c address CUDA illegal-address failures in spec-v2 decode warmup paths.
Rejected: Cherry-pick the commits blindly | the current branch has intervening decode changes, so a minimal manual port kept the patch surface to the affected files.
Confidence: medium
Scope-risk: moderate
Directive: Do not move target-verify non-graph metadata initialization back into prepare_for_v2_verify without validating DP padding and NSA metadata ordering.
Tested: RED local pytest test/registered/spec/eagle/test_eagle_v2_draft_extend_contract.py -q failed 8/8 before production changes.
Tested: PYTHONPATH=python python3 -m pytest test/registered/spec/eagle/test_eagle_v2_draft_extend_contract.py -q passed 8/8 locally.
Tested: PYTHONPATH=python python3 -m py_compile python/sglang/srt/speculative/eagle_info_v2.py python/sglang/srt/speculative/eagle_worker_v2.py python/sglang/srt/speculative/spec_utils.py passed locally.
Tested: Remote g0034:cjy-glm5-new pytest for test/registered/spec/eagle/test_eagle_v2_draft_extend_contract.py passed 8/8, plus remote py_compile for the three speculative modules.
Tested: Local and remote sha256 sums matched for all four synced files.
Not-tested: Full spec-v2 decode server restart/warmup under production traffic.
