In disaggregated prefill with --enable-single-batch-overlap,
batch.copy() was used to defer process_batch_result, but the copy
omitted spec_info. This caused req.hidden_states_tensor to be None
when using Eagle/spec-v2 speculative decoding on the decode server,
silently degrading draft quality for the first decode round.
The CpSharedKVLayout initialization was gated behind
`if not self.is_draft_worker`, leaving the draft model runner
with `uses_cp_shared_kv=True` but `cp_shared_kv_layout=None`.
This caused an AssertionError in NSAIndexer._filter_shared_index_write
during DRAFT_EXTEND under CP shared KV + MTP.
Move the layout init after the `is_draft_worker` guard so both
target and draft model runners have it available.
Add logger.info statements with [CacheCtrl-write], [MemCache-evict], [MemCache-alloc], [HiCache-write], [HiCache-evict], [HiCache-load] tags across cache_controller.py, common.py, and hiradix_cache.py to improve observability of cache operations.
Add validate_page_aligned_token_indices utility and apply it across
HiCache write/load paths, NSA indexer transfers, and CUDA direct copy
kernels to reject malformed (partial, misaligned, non-contiguous) page
groups before they reach native transfer code. Also validate supported
CP HiCache backend/layout combinations at server startup.
ThomasX