Validation

lzvn is a decode-only codec for Apple LZVN. Correctness is established two ways.

1. Apple's encoder as oracle (committed fixtures)

Each tests/data/<name>.lzvn is a real LZVN stream produced by Apple's own COMPRESSION_LZVN encoder (libcompression, constant 0x900) from the bytes in <name>.expected, then padded with trailing bytes after the end-of-stream opcode to mirror a decmpfs resource-fork block. The inputs are synthetic so the fixtures are freely redistributable. Cases span heavy-overlap matches (text_repeats), mixed literals/matches (mixed), and low-compressibility input (near_random). See tests/decode.rs.

2. Real macOS 26.5 (Tahoe) system files

The decoder was validated against 25 genuine type-8 (LZVN resource-fork) blocks read from a read-only-mounted macOS 26.5 (build 25F71) system volume, each decoded and compared byte-for-byte to the kernel's transparent read (and to COMPRESSION_LZVN). Result: 25/25 here vs 0/25 for strict whole-stream decoders (lzfse_rust, the lzvn crate), which reject the 80–300 trailing bytes real blocks carry after end-of-stream. That real-artifact regression corpus lives with the filesystem reader (hfsplus-forensic, tests/data/decmpfs/tahoe_type8.*).

Robustness

#![forbid(unsafe_code)], bounds-checked, typed Error on malformed input. The decode fuzz target ran clean over 1.37M executions (invariant: never panic).