fix packer tuple docstring order and add packer="lz4hc"

[com55]

Hi, I noticed two small issues around BundleFile.save(packer=...).

1) Docstring tuple order is wrong

The docstring currently says the custom packer tuple is (block_info_flag, data_flag), but the code does:

elif isinstance(packer, tuple):
    self.save_fs(writer, *packer)

and save_fs is defined as:

def save_fs(self, writer, data_flag: int, block_info_flag: int):

So the actual order is (data_flag, block_info_flag).
Using the documented order raises:

NotImplementedError: UnityPy always writes DirectoryInfo, so data_flag must include 0x40

(because 2 gets passed as data_flag).

2) Add packer="lz4hc"

LZ4HC is already supported through CompressionHelper:

COMPRESSION_MAP = {
    ...
    CompressionFlags.LZ4: compress_lz4,
    CompressionFlags.LZ4HC: compress_lz4,
}

and compress_lz4 already uses mode="high_compression".
packer="original" can also preserve LZ4HC flags from existing bundles.

But there is no string preset for it, and the comment in save_fs still says lz4hc [not implemented], which is outdated.

This PR adds:

elif packer == "lz4hc":
    self.save_fs(writer, data_flag=195, block_info_flag=3)

195 (0xC3) mirrors the existing "lz4" preset (194 / 0xC2):

• 0x80 BlocksInfoAtTheEnd
• 0x40 BlocksAndDirectoryInfoCombined
• low bits = compression type (2 = LZ4, 3 = LZ4HC)

So 0x80 | 0x40 | 3 = 195.

Changes

• Fix docstring: (data_flag, block_info_flag)
• Document lzma / lz4hc in the allowed strings list
• Add packer="lz4hc"
• Update the stale lz4hc [not implemented] comment
• Update Environment.save docstring pack options

Related issues

I searched existing issues first — I didn't find one specifically about the docstring order or a missing lz4hc preset.
Closest nearby issue is #377 (different packer="lz4" save quirk).

Example

import UnityPy

env = UnityPy.load("example.bundle")
data = env.file.save(packer="lz4hc")

# custom flags still work; order is (data_flag, block_info_flag)
data = env.file.save(packer=(0x43, 3))

[Copilot]

Pull request overview

This PR improves the BundleFile.save(packer=...) UX/documentation by correcting the documented tuple argument order and adding an explicit "lz4hc" preset consistent with the existing compression flag handling.

Changes:

• Fix the documented custom packer tuple order to match save_fs(data_flag, block_info_flag).
• Add packer="lz4hc" preset (and update related in-code comments / docstrings).
• Expand documented packer options (including lzma) in relevant docstrings.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
UnityPy/files/BundleFile.py	Corrects packer tuple doc and adds "lz4hc" preset + updates flag comments.
UnityPy/environment.py	Updates Environment.save() docstring to list additional pack options.

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