L3 3.0: shared per-node LMDB metadata index (CpL3MetaStore)
content_hash(32B)+payload_kind -> (disk,file,slot,page_bytes,crc,last_access,hit_count,flags).
Validated topology (research C + multi-proc re-bench): owner ranks write durably (serialized on
LMDB's write mutex, ~11x headroom over spill demand), all ranks read exists_prefix lockless
(~1-3us, coherent). writemap=False (multi-process-safe). last_access/hit_count carry the
replicated logical clock so L3 eviction selection is rank-uniform (3.3 consumes it). write_batch
commits an object's entries atomically + durably (data->fsync->index->fsync ordering); iter_entries
+ reopen drive cold-rebuild; clear() is the flush_cache hook. 7/7 unit tests (venv lmdb 2.2.1).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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