CP shared-KV now uses CP-local current rows consistently across MLA/index current reuse, passes fp8 current-index K through the tai-kernel uint8 ABI, and clears the transient EAGLE CP-local hidden marker after draft capture. The disaggregation bootstrap also fingerprints the runtime source contract so prefill/decode mismatches fail fast instead of silently exchanging incompatible KV metadata.
Constraint: CP shared-KV batch paths flatten current K/V rows in CP-rank-local valid order, not global request order.
Constraint: tai-kernel current-index prepare validates current_index_k as uint8 bytes for fp8 payloads.
Rejected: Keep using global extend offsets for bs>1 current-index reuse | corrupts request-local bases once current_index_kv is CP-local.
Rejected: Infer CP-local EAGLE hidden semantics from tensor shape | static padding and bs>1 can make shape-based inference unsafe.
Confidence: medium
Scope-risk: moderate
Directive: Do not reintroduce forward_batch.out_cache_loc slicing in CP shared-KV current reuse without verifying CP-local owner-lane layout.
Tested: Remote container py_compile for touched runtime/test files.
Tested: Remote PYTHONPATH=python pytest -q test/registered/unit/layers/test_nsa_cp_utils.py test/registered/unit/mem_cache/test_cp_shared_kv_runtime.py test/registered/unit/disaggregation/test_common_conn_runtime_fingerprint.py (198 passed, 2 subtests passed).
Not-tested: Full remote ETE traffic after this commit; accept length and garbage-output recovery still require a fresh prefill/decode run.
Co-authored-by: OmX <omx@oh-my-codex.dev>
CP shared-KV bs>1 exposed three distinct padding domains: valid cache rows, CP page-tail compute rows, and MLP-sync flattened static padding. The previous implementation mixed these domains in direct-write and index top-k paths, so real requests failed when q/out_cache_loc lengths matched valid rows while metadata aliases described compute rows.\n\nThis change makes compute split strip only proven flattened static padding, keeps valid cache writes strict except for extend_num_tokens-proven static tails, marks CP-local EAGLE draft hidden state explicitly, and selects NSA index top-k query metadata by the actual q/weight row count.\n\nConstraint: CP shared-KV cache writes must never persist dummy page-tail or MLP static padding rows.\nConstraint: EAGLE draft hidden state can be CP-local before full CP metadata is visible in prepare_mlp_sync_batch.\nRejected: Use compute_padding_enabled as direct-write truncation proof | it silently accepts unknown out_cache_loc tails.\nRejected: Always consume compute q metadata in index top-k | actual q/weights can be valid-only after CP split.\nConfidence: medium\nScope-risk: moderate\nDirective: Do not collapse valid rows, CP compute padding, and MLP static padding into one length condition; use explicit provenance.\nTested: remote py_compile for touched NSA files\nTested: remote targeted CP shared-KV padding/top-k regressions\nTested: remote pytest test_nsa_cp_utils.py test_cp_shared_kv_layout.py test_cp_shared_kv_runtime.py -k 'not test_tai_current_slot_fill_sparse_page_self_test_passes_on_installed_kernel' => 228 passed, 1 deselected, 5 warnings, 2 subtests passed\nNot-tested: full ETE replay after the final index top-k fix\nNot-tested: TAI current-index fast path dtype fallback
Prefill CP only needs the local hidden shard for DeepSeek NextN draft extend. The change adds a draft shared-KV path that captures target hidden locally, feeds only the CP-local slice into the draft model, and keeps draft KV writes/transfers on the same shared logical-to-physical page mapping as target KV.\n\nDebug logs are gated behind SGLANG_CP_DRAFT_SHARED_KV_DEBUG and cover scheduler pool selection, KV manager buffer registration, local physical writes, prefill sender filtering, transfer pages, and decode commit metadata so ETE runs can prove draft KV is sharded rather than full-concatenated on a prefill rank.\n\nConstraint: Prefill runs CP while decode remains DP, so prefill must avoid full hidden/KV materialization but decode still receives full logical KV pages.\nRejected: Keep draft extend on full hidden state | preserves correctness but wastes prefill memory and defeats CP shared-KV intent.\nRejected: Transfer draft KV with a separate mapping | target and draft pools share req_to_token logical indices, so duplicating mapping adds risk without benefit.\nConfidence: medium\nScope-risk: moderate\nDirective: Do not remove the debug logs until ETE evidence confirms draft MLA/index writes and transfer pages are CP-sharded on all ranks.\nTested: Remote compileall for changed CP draft, transfer, scheduler, NSA index, MLA write, and EAGLE files.\nNot-tested: Full GLM-5 EAGLE ETE with SGLANG_CP_DRAFT_SHARED_KV_DEBUG=1 after this logging addition; local pytest intentionally not run.
