The first KV-value pass couldn't compare (reload hashes keyed by the merged
load op's node id, backup hashes per node -> no join). Fix: emit the host-slot
range fingerprint at both backup and reload (host slots are the stable identity
across node id / splits / merge), and the analyzer matches on
(rank, layer, host_fp). Also add a nonzero-byte count (nz): real KV is never
all-zero, so an nz==0 slice is uninitialized/zero KV -- a direct, self-contained
corruption flag that needs no cross-stage matching. This targets the observed
'0|0|0...' garbage on large-cached reloads (store never filled the backed-up
pages, or the round-trip lost them). Gated at SGLANG_CP_HICACHE_KV_TRACE=2.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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