The existing CP MQA prepare integration only used the TAI GetK/GetS+range kernel when current_index_kv was absent. Current-index reuse and full-kernel fallback still launched torch arange and zeros_like before fp8_mqa_logits. Route both cases through the new tai-kernel range-only API while preserving the torch fallback when the kernel is disabled or unavailable.
Constraint: SGLANG_CP_SHARED_KV_FUSED_INDEX_MQA_PREPARE remains the gate for this optimization.
Rejected: Force the full prepare kernel in current_index_kv path | it would redo index KV gathering that current reuse intentionally avoids.
Confidence: high
Scope-risk: narrow
Directive: Do not remove the torch fallback; mixed deployments may run without the updated tai-kernel package.
Related: tai-kernel 34cb7a8
Tested: Remote container g0034 docker py_compile for cp_shared_kv_runtime.py and nsa_indexer.py; tai-kernel range unit tests passed remotely (4 passed).
Not-tested: Full GLM5 prefill/decode server profile after this exact commit.
aa27a444f6