This file records which wire paths are implemented directly and which use pinned in-tree source, so passing round trips cannot disguise a runtime link dependency.

Format or primitive	Encoder	Decoder	External library
Raw DEFLATE	Native fixed-Huffman LZ77 and stored blocks	Native stored, fixed, and dynamic Huffman	None
zlib	Native	Native	None
gzip	Native	Native, including optional header fields	None
CRC-32 / Adler-32	Native	Native validation	None
ZIP32 stored/DEFLATE	Native	Native	None
LZ4 frame / XXH32	Native independent blocks	Native independent and linked blocks	None
Zstandard	Native raw, RLE, and periodic sequence blocks	Native raw, RLE, Huffman/FSE compressed blocks, repeat tables, and skippable frames	None
bzip2	Native RLE, BWT, MTF, RUNA/RUNB, and canonical Huffman blocks	Native multi-table Huffman, inverse BWT, RLE, and concatenated streams	None
xz/LZMA2	Native deterministic uncompressed and literal range-coded chunks	Native LZMA range decoder, LZMA2 chunks, xz metadata, indexes, CRC-32, and CRC-64	None

All advertised wire formats are self-contained and require no external compression library at build or runtime.

Every full-stream codec path is iterator-driven. The compiled span overloads only adapt spans to those templates. Internal spans and vectors are limited to wire blocks, entropy tables, transform workspaces, history dictionaries, ZIP central-directory metadata, and the random-access archive image required by single-pass ZIP extraction.

Current verification

Native DEFLATE decodes an independently produced dynamic-Huffman fixture.
Native LZ4 decodes an independently produced frame with compressed content.
Native Zstandard decodes independently produced Huffman/FSE and multi-block repeat-table fixtures across reference encoder levels 1 through 22.
Native bzip2 decodes independently produced multi-table Huffman streams and emits streams accepted by the reference bzip2 decoder at levels 1 through 9.
Native xz decodes independently produced LZMA2 streams across presets 0 through 9, CRC-32/CRC-64/unchecked streams, and multi-block containers; the reference xz decoder accepts its level-0 and range-coded output.
System gzip -t accepts native gzip output.
System lz4 -t accepts native multi-block LZ4 output and reproduces the exact 256 KiB source payload.
System zstd -t accepts native raw and sequence-compressed Zstandard output; its decoder reproduces the exact 220 KiB periodic source payload.
System bzip2 and xz tools accept output produced through the installed package and reproduce the exact source payload.
Debug, Release, and DebugASAN tests exercise single-pass stream iterators, template dispatch, allocating spans, caller-owned spans, insufficient-capacity errors, corruption, limits, concatenated members, deterministic output, and ZIP validation.