v0.1.0

First crates.io release. The v0.1 cycle built the engine end-to-
end on a single Unix-only stack: ART core, multi-blob splitBlob
/ mergeBlob / compactBlob, PersistentBackend (O_DIRECT
Linux + F_NOCACHE macOS), physiological WAL with replay,
S3-style range iteration with delimiter rollup. 203 tests on
ubuntu + macOS CI.

Algorithm core

• 9-NodeType ART layout (Leaf 16 B, Prefix 128 B, Blob
  128 B, Node{4,16,48,256}, EmptyRoot 8 B). Every field
  offset pinned at compile time via offset_of! asserts.
• 4 KB BlobHeader + bit-packed SlotEntry
  (ntype << 17 | offset / 8); 10 240-slot table per 512 KB
  blob.
• Recursive walker (insert / lookup / erase / rename) crossing
  blobs transparently via BlobNode.
• splitBlob in-band spillover, compactBlob in-place repack,
  mergeBlob inverse fold (with is_mergeable guard +
  refresh_blob_node_pointers post-compact invariant repair).
• 128 B SPILLOVER_RESERVATION + Prefix ↔ Blob cross-type
  free-list fallback — spillover can always install its
  emergency BlobNode.
• Erase-time node shrink (Node256 → 48 → 16 → 4 at hysteresis
  thresholds 37 / 12 / 3) + terminal lone-child
  Node4 → Prefix([byte]) collapse.
• In-place leaf-value update on same-size writes — zero allocator
  activity.
• SIMD node16_find_byte (SSE2 + NEON + scalar) and SIMD
  longest_common_prefix for leaf-split / prefix-split hot
  paths.

Concurrency

• 3-mode HybridLatch (LeanStore: optimistic / shared /
  exclusive) wired into CachedBlob over
  UnsafeCell<AlignedBlobBuf>.
• Wait-free Tree::get walker — optimistic snapshots with
  validate-after, restart from root on torn read. No Tree-wide
  reader lock.
• put / delete serialise on wal.lock (not a global writer
  mutex); rename keeps a separate rename_lock for its
  multi-step atomicity.

Persistence

• MemoryBackend and PersistentBackend (single packed
  blobs.dat + atomic-rename manifest.bin, O_DIRECT Linux,
  F_NOCACHE macOS).
• Backend trait + AlignedBlobBuf 4 KB-aligned zero-copy
  buffer.
• 10-variant TxnOp codec (MAGIC | LEN | SEQ | TY | BODY | CRC32); torn-tail-tolerant forward replay scanner.
• WalWriter with sync_data-on-flush durability + 64 KB
  group-commit auto-flush.
• Tree::checkpoint flushes WAL + commits BM + truncates WAL
  conditionally; replay reapplies records onto the BM-cached
  blob and resumes next_seq past every replayed record.
• TxnOp::Batch (TY_BATCH = 10) carries N primitive ops under
  one record with shared CRC and derived seqs; replay
  transparently flattens to per-inner callbacks.

Public API

• Tree::open(TreeConfig) single entry, TreeBuilder chainable
  config.
• Tree::put / get / delete / rename (cross-blob via
  lookup_multi / insert_multi / erase_multi).
• Tree::range() stateful iterator — .prefix(p),
  .start_after(k), .delimiter(b) (S3-style rollup with
  CommonPrefix dedup). Forward-only, best-effort snapshot.
• Tree::txn(|batch| { ... }) — batched mutations under one
  TxnOp::Batch WAL record. Crash-atomic, runtime isolation is
  best-effort.
• Tree::checkpoint(), Tree::stats().
• Typed Error (BackendIo / Alloc / Free / KeyTooLong
  / ValueTooLong / NotYetImplemented / NodeCorrupt /
  ReplaySanityFailed / NotFound / DstExists).
  #[non_exhaustive] so new variants are non-breaking in minor
  releases.

Tests + benches + tooling

• 202 tests: unit + property (proptest vs HashMap oracle, in
  memory and crash-and-replay persistent modes) + multi-reader
  stress + multi-blob auto-spillover end-to-end.
• Criterion benches vs RocksDB across three workload shapes
  (kv / objstore / fs) × get / put / mixed × memory /
  persistent.
• Four examples: basic_kv, filesystem_meta, session_store,
  s3_metadata.
• GitHub Actions CI matrix (ubuntu + macOS) × build / test /
  doctest + lint (cargo fmt, cargo clippy -D warnings) +
  docs (cargo doc -D warnings) + MSRV (1.82).
• Windows targets fire a top-of-crate compile_error! — the
  O_DIRECT / F_NOCACHE fast paths have no Windows analog
  worth maintaining.
• MIT license, MSRV pinned to Rust 1.82.